[LoopUnroll] Unroll and Jam

[dmgreen]

Summary

This is a implementation of unroll and jam, which is something that comes up as useful for our smaller embedded processors (and hopefully for other systems in general)

The basic idea is that we take an outer loop of the for:

for i..
  ForeBlocks(i)
  for j..
    SubLoopBlocks(i, j)
  AftBlocks(i)

Instead of doing normal inner or outer unrolling, we unroll as follows:

for i... i+=2
  ForeBlocks(i)
  ForeBlocks(i+1)
  for j..
    SubLoopBlocks(i, j)
    SubLoopBlocks(i+1, j)
  AftBlocks(i)
  AftBlocks(i+1)
Remainder

To do this we need to ensure that the ForeBlocks(i+1) can be moved before the SubLoopBlocks(i) and AftBlocks(i), which means potentially moving the phi node operands from AftBlocks into Fore. There are also memory dependency checks and other safety checks that are needed. The transform is then a fairly simple job of using the excellent existing unroll code for cloning blocks and gluing them all back together correctly.

• The dependency analysis is built upon DependencyAnalysis that loop interchange uses. This might have been a mistake. I have made some changes to DA to ensure that the AA gave correct results (and enable TBAA). I have split these changes out into D42381. There may be more to do here to get values outside the loop to be ignored.

• I have made this into a separate pass that runs just before the existing loop unroll.

• The performance heuristics might not be sorted correctly yet. Several parts might be over-conservative when disabling for safety. The remainder loop may not be the best, I'm not sure how it will play with vectorisers, etc. It is hopefully a good enough start.

• I have tested this from the C level (i.e. csmith) but not a lot from the IR level with some form of fuzzer.

• Pragmas are mostly copied from unroll.

[dmgreen]

I have split (most of) the Dependency Analysis parts into https://reviews.llvm.org/D42381 and https://reviews.llvm.org/D42382.

[dmgreen]

Ping. Anyone interested in unroll and jam? (I wasn't sure who, if anyone, to add as reviewers)

[hfinkel]

In D41953#998082, @dmgreen wrote:

Ping. Anyone interested in unroll and jam? (I wasn't sure who, if anyone, to add as reviewers)

I'm interested in this, but I might not get to it for a couple of weeks.

[dmgreen]

Thanks Hal. No rush.

lib/Transforms/Scalar/LICM.cpp

506 ↗

(On Diff #131015)

I'm moving the move of this code into a separate commit.

[SjoerdMeijer]

Hi Dave,

I haven't looked at all the nitty gritty details yet, but had some general questions after a first glance:

• this looks like a rather complete implementation (as opposed to some WIP prototype). In your description you mentioned something about testing. I was wondering if you can elaborate a little bit on this, if you had some more experiences with this pass since posting it. E.g., you've obviously added regression tests, but does it trigger also on the test-suite, etc.?
• probably the other thing people first want to know if this is (always) beneficial for their back-end. Do you have some data/experience with this?

[SjoerdMeijer]

lib/Transforms/Utils/LoopUnroll.cpp

255

Looks like this is used by both LoopUnroll and UnrollAndJam. To simplify things, is it worth to separate this out in a different patch if this already used/beneficial by/for LoopUnroll?

[dmgreen]

this looks like a rather complete implementation (as opposed to some WIP prototype)

Hopefully. The things I'm not super happy with are where this fits into the unroll pass, and the tests in test/Other. Whether this is a new pass or a part of unroll is a little awkward because of the way we need to do the outer unroll-and-jam before we do the inner unroll.

The DA Analysis pass either needs to be added to the set of preserved loop passes, or (because it's trivial to create and holds no state) we could just create the DependenceInfo as needed. This would just need an AA in loop unroll.

In your description you mentioned something about testing. I was wondering if you can elaborate a little bit on this, if you had some more experiences with this pass since posting it.

So I've ran the normal set of regression tests / supertest / perennial / test-suite / eembc / geekbench / spec's / etc. All without issue. It has also run probably a few hundred thousand csmith seeds (which is pretty good at creating the kind of nested loops with odd memory accesses that unroll and jam looks for). Those are all with -always-unroll-and-jam to bypass the profitability check. (There can, of course, always be bugs)

probably the other thing people first want to know if this is (always) beneficial for their back-end. Do you have some data/experience with this?

With the way DA and the profitability checks are right now, it may be a little conservative in when it is enabled. I have to look into this with the latest DA changes. I would expect it to be a win in most cases though. The performance is something I hope to work on more, so long as the basics are OK here. When it does fire, in the ideal case, it can help quite a bit with removing extra loads.

lib/Transforms/Utils/LoopUnroll.cpp

255

Sure, sounds good. I have split out the DA and other unrelated parts. This one is less useful on it's own, if it's only used in one place, but I can split it out as a cleanup.

[samparker]

Hi Dave,

With respect to the awkward ordering, I don't understand why this transformation (as a standalone pass) couldn't perform the inner unrolling itself? I don't see why there needs to be a dependency. Also, will have loop rotate as a utility (https://reviews.llvm.org/D44595) help simplify this transform?

cheers,
sam

[SjoerdMeijer]

I think I agree with Sam's reply, also because I think that would avoid a regression that would be possible with this patch: neither loopunroll, nor loopunroll and jam runs. Because when it is determined that loopunroll is profitable, it will never run loopunroll, but loopunroll and jam may actually not happen; it is returning "LoopUnrollResult::Unmodified" in a few (exceptional) cases.

[dmgreen]

Sorry Sam, I missed your comment somehow in a number of other emails. Sorry about that.

By a bit awkward - I wasn't referring to unroll and jam doing the inner unroll. That sounds like a fine idea, like we have here it just tries to call tryToUnrollLoop again.

I just meant that two passes in the same LoopPassManager will process inner loops first for all passes, then move on to the outer loops. So we would either need get the inner loop unroll to not unroll (preventing the outer unroll and jam) or we'd need to ensure the lpm is split in two (which may be fine, and may help with the other issues around analysis dependencies and not needing the explicit inner unroll). Providing this wont change the pass ordering for other code, which I don't think it will if I'm reading this pass pipeline correctly, this sounds like the best way to go to me.

I'll give it a try like that and see how it looks.

[samparker]

Hi Dave,

Sorry, I don't follow you mean by splitting the pass manager. My idea of the problem and phase ordering would be: unroll and jam, as a standalone pass, runs before normal unrolling and, if successful, uses the metadata to prevent further unrolling later on. Can this not be the case? What am I missing here?

cheers,
sam

[dmgreen]

I was being a bit vague, what I meant was that if we have a pass structure like this, as we have now but with added unroll and jam:

Loop Pass Manager
  Induction Variable Simplification
  Recognize loop idioms
  Delete dead loops
  Unroll and Jam
  Unroll loops

With a nest with inner and outer loops, the passes will be done in this order:

IndVar simplify inner loop
Recognise inner loop
Delete Dead inner loop
UnJ inner loop
Unroll inner loop
IndVar simplify outer loop
Recognise outer loop
Delete Dead outer loop
UnJ outer loop
Unroll outer loop

So when Unj gets to the outer loop, the inner loop may have been unrolled. So the unroll for the inner loop would have to know whether the loop nest was profitable to unroll and jam and -not- unroll in that case. To get the UnJ of the outer loop to happen before the unroll of the inner loop, two loop pass managers are needed (in this case one just for the Unroll Loops). This can affect code generation for existing cases, which was something I was hoping to avoid. I saw some cases of infinite loops being generated differently when I had it like that for testing.

What I am hoping is that we won't have to add UnJ here in the pass pipeline, we can add it later at the other place that we do unrolling. This should allow us to more easily have two loop pass managers, simplifying things a lot :)

[dmgreen]

This makes things into a new pass, currently disabled by default. I have attempted to copy what the unrolled does, without duplicating too much code. Pragmas and options should work, although I will need to add a few more tests for the different behaviours. I have tried to make it so that any unroll pragma will prevent unroll-and-jam, and added equivalent options/pragmas for unroll and jam. It still uses the unroll code as much as possible.

I have the clang side of the pragmas too, which I'll put up (although they may only even be useful for testing).

[SjoerdMeijer]

Hi Dave, thanks for making this into a pass, I think this looks a lot better now. I skimmed through the whole diff for first time, and just wrote down some things I noticed, mostly nitpicks, see the comments inlined. I will now study the different bits and pieces in more detail.

include/llvm/Analysis/TargetTransformInfo.h

427

Can you be a bit more explicit here what the threshold exactly is?

427

typo: trashold :)

lib/Analysis/DependenceAnalysis.cpp

110 ↗

(On Diff #142645)

Will other people get unhappy when we flip this switch?

lib/Target/ARM/ARMTargetTransformInfo.cpp

626

Some comments perhaps why it is set to 60?

lib/Transforms/IPO/PassManagerBuilder.cpp

659

Elaborate a bit what you mean here (the 2nd sentence)?

lib/Transforms/Scalar/LoopUnrollAndJamPass.cpp

149

nit: extra space

204

nit: know -> known

306

nit: don't need the "!= 0"

lib/Transforms/Utils/LoopUnrollAndJam.cpp

122

Some more nitpicking here, about names.

Perhaps "Fore" can be confusing: is it another loop, a block? So something like this:

for (i)
  block[i, 0]
  for (j)
    block[j, 0]
  end
  block[i, 1]
end

becomes:

for (i, i+=2)
  block[i, 0]
  block[i+1, 0]
  for (j, j+=4)
    block[j+0, 0]
    block[j+1, 0]
    block[j+2, 0]
    block[j+3, 0]
  end
  block[i, 1]
  block[i+1, 1]
end

Mentioning that the outer loop has been unrolled with a factor of 2, and the inner loop with an unroll factor of 4.

Not sure if the classic loopunroll and jam literature uses standard terminology here, but perhaps inner/outer loop rather than "Fore, Subloop and Aft".

Also, perhaps you want to mention some restrictions somewhere, if there are any. E.g., can this doubly nested loop occur in more deeply nested loop structure (and loopunroll and jam still trigger)?

140

Blocks = outer loops?

So perhaps something along the lines of:

"So the outer loops are unrolled and the inner loops fused ("jammed")."

181

Nit: wont

197

nit: don't need to capitalize this message?

211

same here?

543

typo: shouldnt

[dmgreen]

Thanks for the comments! I'll try to split a few things out and update this accordingly

include/llvm/Analysis/TargetTransformInfo.h

427

trashold?

lib/Analysis/DependenceAnalysis.cpp

110 ↗

(On Diff #142645)

Oh yep, this should probably be a separate change.

I don't think people will be unhappy, but it shouldn't be lumped in here.

lib/Target/ARM/ARMTargetTransformInfo.cpp

626

The limit here is set because the inner loop requires a smaller threshold than the outer, as unroll and jam can increase register pressure in the inner loop significantly. This was chosen semi-randomly to be a something around 20% of the normal threshold, to something that seemed to work in a few cases I tried. More performance testing may be needed to get something better.

lib/Transforms/Scalar/LoopUnrollAndJamPass.cpp

306

This is copied from loop unroll. I think it's clearer this way what it's testing. But I can change it if you are highly opinionated :)

lib/Transforms/Utils/LoopUnrollAndJam.cpp

122

I'm not sure about your loop here. It looks like it has inner loop unrolling, which UnJ doesn't do (that is left to the unroller after the outer loop has been unroll and jammed.

By "Fore" I was referring to blocks in the outer loop, but before the inner loop. "Aft" means blocks in the outer loop but after the inner loop. I made up the names, so am open to suggestions on better ones ;)

Also, perhaps you want to mention some restrictions somewhere, if there are any. E.g., can this doubly nested loop occur in more deeply nested loop structure (and loopunroll and jam still trigger)?

That should work I believe. If it doesn't it's a bug :) But I doubt it will ever be a profitable thing to do. It used to be disabled in the profitability check, but we may have lost that when I was moving things over the the new pass. I'll have a look.

There are restrictions mentioned in the safety checks, in isSafeToUnrollAndJam.

140

I have tried to rewrite this a little.

197

This is copied from loop unroll

211

Same

[dmgreen]

Address feedback and added some pragma tests, with some related fixes. Split out some parts into other commits.

I'm still trying to work on making the analysis more accurate so this works on more loops. It would be good if LAA could be made to work here (to get versioning too) but it looks very vectoriser shaped and doesn't handle outer loop quite yet. DA as used here might be the only way, but may need to learn a few more tricks (or may need some fixes).

[rja]

In D41953#1073753, @dmgreen wrote:

Address feedback and added some pragma tests, with some related fixes. Split out some parts into other commits.

I'm still trying to work on making the analysis more accurate so this works on more loops. It would be good if LAA could be made to work here (to get versioning too) but it looks very vectoriser shaped and doesn't handle outer loop quite yet. DA as used here might be the only way, but may need to learn a few more tricks (or may need some fixes).

Ping, how work is going on?

[SjoerdMeijer]

test/Transforms/LoopUnrollAndJam/unprofitable.ll

226

Nit: do you need all this?

test/Transforms/LoopUnrollAndJam/unroll-and-jam.ll

9

Do we need all these checks? And with all the variable names still there, it looks like a fragile test to me. Same for the other functions below.

[dmgreen]

Ping, how work is going on?

Hello. I've been away for a few days. Is this something you are interested in?

I'm still wading through improvements / bugs in dependency analysis, in an attempt to make the dependency checking here more precise.

[dmgreen]

I've updated the dependency checks to be a bit better. This has shown up some bugs/inaccuracies in DA, which will be needed to make this correct.

I'm also adding some people here who may have opinions about any of this.

[dmgreen]

test/Transforms/LoopUnrollAndJam/unroll-and-jam.ll

9

I think as we are only running a single pass (not -O3 or an entire backend), it should be relatively stable.

I've updated this one to be auto generated and show the entire code output. The others are usually testing some small portion of the resulting function.

[SjoerdMeijer]

Hi Dave,

I think we have looked long enough at it now, and it's time to get some experience with it. :)
It's off by default, so I don't think there's any harm done here. Once it is in, it's easier to throw
more code at it, get more experience, and see if we further need to tweak or tune it; perhaps
we get feedback from others as well who are interested in using it.

Let's wait a few more days with committing to give people one more chance to object :-)

Inlined just a few more comments, mainly nits.

Cheers.

lib/Transforms/Scalar/LoopUnrollAndJamPass.cpp

85

This is *almost* identical to GetUnrollMetadata() in LoopUnroll.cpp. Is this something that could be shared somehow? Or would that be too inconvenient?

230

nit: numInvariant -> NumInvariant

lib/Transforms/Utils/LoopUnrollAndJam.cpp

73

nit: TODOD

399

nit: don't need the brackets here

623

Nit: TODOD

test/Transforms/LoopUnrollAndJam/unroll-and-jam.ll

9

Ok, fair enough, agreed.

[dmgreen]

lib/Transforms/Scalar/LoopUnrollAndJamPass.cpp

85

It's similar, but this version is only testing prefixes, not the whole string.

[dmgreen]

OK thanks. I will leave this for at least a couple more days whilst I run extra tests. Any other comments from anyone are welcome/appreciated.

[xbolva00]

lib/Transforms/Scalar/LoopUnrollAndJamPass.cpp

137

static_cast?

lib/Transforms/Utils/LoopUnrollAndJam.cpp

175

bool CompletelyUnroll = (Count == TripCount);
maybe better?

436

Above you use a different style:
for (unsigned It = 1; It != Count; ++It) {

Can you make it same for all occurrences?

475

This line could be placed above the condition.

[dmgreen]

Review Updates.

[echristo]

It sounded like Hal wanted to review this and I don't know that any of the other people on the review line have any experience with loop passes and so probably shouldn't have been approving this. I might be wrong here, and if so I apologize, but it seems like this went in a bit early.

From a quick glance it also looks like the testcases could be cleaned up a bit. In particular the naming if nothing else.

Thanks.

[dmgreen]

Reverted in 333359 as it's failing on some of the builders. I believe the tests are dependant on the arm backend being built.

I'll fix that and try to clean up the tests as you suggest at the same time. Some of them are longer than I'd like because we are dealing with nested loops.

I was taking Sjoerd review as OK to move things forward and improve things over time once it is in-tree. And I had attempted to leave this open for a while with plenty of people as subscribers, so that anyone could object. I had not added them as reviewers though, sorry if I misstepped.

[hfinkel]

In D41953#1113514, @echristo wrote:

It sounded like Hal wanted to review this

Thanks Eric. I don't need to review this if others who are qualified look at it. I've skimmed the code and it seems reasonable. There are a number of obvious enhancements that might be worthwhile, but I think it's best to work on those after this lands.

and I don't know that any of the other people on the review line have any experience with loop passes and so probably shouldn't have been approving this. I might be wrong here, and if so I apologize, but it seems like this went in a bit early.

From a quick glance it also looks like the testcases could be cleaned up a bit. In particular the naming if nothing else.

Thanks.

llvm/trunk/lib/Transforms/Utils/LoopUnrollAndJam.cpp

726 ↗

(On Diff #148747)

Can this overflow if the exit count is INT_MAX (or similar)? It's generally a good idea to comment on how that's handled.

[SjoerdMeijer]

This looked very reasonable to me as an initial commit. And I thought so too, like Hal and Eric, that different enhancements can still be made. But as I wrote, we can iterate further on this once we've got something in. So I don't think this was a misstep, and once the buildbot failures are resolved, it looks like this can be recommitted. However, as I also mentioned, another reason for an initial commit is more exposure, potentially more people looking at it. So this discussion is great, the more feedback, the better; especially if there's something that needs to be addressed before a recommit.

[hsaito]

David, outer loop vectorization we've been working on and unroll and jam have a lot of similarities and thus there should be code sharing opportunities around legality and cost modeling. Let's collaborate to improve both.

[dmgreen]

In D41953#1113730, @hfinkel wrote:

There are a number of obvious enhancements that might be worthwhile, but I think it's best to work on those after this lands.

Any suggestions on what would be at the top of the list? :)

In D41953#1114289, @hsaito wrote:

David, outer loop vectorization we've been working on and unroll and jam have a lot of similarities and thus there should be code sharing opportunities around legality and cost modeling. Let's collaborate to improve both.

Yeah, sounds like a good idea. Vectorisation is not something I know a huge amount about, it not being useful for the particular cores I'm looking at at the moment. But the work on VPlan sounds interesting and I do wish we had something similar for loop transforms in llvm. I was hoping to get loop versioning working, maybe through LoopAccessAnalysis, but as far as I understand it doesn't handle outer loops yet (and seemed very vectoriser shaped when I looked). From what I remember hearing, this isn't part of the outer loop vectorisation work (instead relying on user directives?). I imagine it's not an easy task to extend this out.

The current legality checks here are based on dependence analysis, and there are a couple of patches needed to make it work correctly. The cost modelling is very adhoc. :) All these things I hope we can improve as we go along.

In D41953#1113514, @echristo wrote:

From a quick glance it also looks like the testcases could be cleaned up a bit. In particular the naming if nothing else.

Do you mean names of the test files, or names of variables in the tests? I had look but didn't feel I was making things much better (apart from the names of some lcssa nodes). Any other suggestions?

llvm/trunk/lib/Transforms/Utils/LoopUnrollAndJam.cpp

726 ↗

(On Diff #148747)

Yep, you are correct. This code comes from unroll-runtime (minus the missing overflow check), and dates back to before unroll-and-jam was a separate pass. I was trying to prevent this function from returning true if the runtime unrolling was going to fail. It can now be safely removed and leave that check to the call to UnrollRuntimeLoopRemainder.

[hsaito]

In D41953#1115101, @dmgreen wrote:

In D41953#1114289, @hsaito wrote:

David, outer loop vectorization we've been working on and unroll and jam have a lot of similarities and thus there should be code sharing opportunities around legality and cost modeling. Let's collaborate to improve both.

Yeah, sounds like a good idea. Vectorisation is not something I know a huge amount about, it not being useful for the particular cores I'm looking at at the moment. But the work on VPlan sounds interesting and I do wish we had something similar for loop transforms in llvm. I was hoping to get loop versioning working, maybe through LoopAccessAnalysis, but as far as I understand it doesn't handle outer loops yet (and seemed very vectoriser shaped when I looked). From what I remember hearing, this isn't part of the outer loop vectorisation work (instead relying on user directives?). I imagine it's not an easy task to extend this out.

The current legality checks here are based on dependence analysis, and there are a couple of patches needed to make it work correctly. The cost modelling is very adhoc. :) All these things I hope we can improve as we go along.

We are currently focusing on directive based implementation, but the same framework can be used for automatic vectorization at the outer loop level. It's not like vectorizer side has a lot of immediately reusable code in place, but I think co-designing the solution makes a lot of sense, to avoid duplicate work (or to consolidate into shared reusable code). For example, uniform control flow check @dcaballe has written is probably shareable. Ditto for Divergence Analysis RFC by Simon Moll. Dependence Analysis for outer loop vectorization isn't something we are currently working on, and thus being able to reuse is a very nice thing.

[dcaballe]

For example, uniform control flow check @dcaballe has written is probably shareable. Ditto for Divergence Analysis RFC by Simon Moll.

You could have a look at isExplicitVecOuterLoop and isUniformLoop in D42447. Currently, they are implementing specific checks for supported outer loops in VPlan but some of this code could be generalized and refactored.
Simon's RFC is here, in case you missed it: http://lists.llvm.org/pipermail/llvm-dev/2018-May/123606.html

Dependence Analysis for outer loop vectorization isn't something we are currently working on, and thus being able to reuse is a very nice thing.

Agreed. Outer loop auto-vectorization and, in particular, extensions in legality analysis to support outer loops, including LoopAccessAnalysis, is something that we are not currently working on. I briefly mentioned that and other open TODOs in my EuroLLVM talk, in case there is any other overlap/reusability opportunity with unroll-and-jam: https://www.youtube.com/watch?v=z6NeHLRNVok&t=27m50s

Thanks,
Diego

[SjoerdMeijer]

Any suggestions on what would be at the top of the list? :)

For me the first thing would probably be a rather straightforward thing: more OptimizationRemarks. I think it currently reports only something after a successful transformation. But perhaps more interesting to know is why it isn't triggering (if that's what you expect): so optimisation remarks about the legality, profitability, or any other reason, would be crucial to understand what's going on. Then, based on this optimisation report, and if the transformation really needs to be triggered, the user can resort to pragmas (for which you have another patch) and/or tweaking options for treshhold values.

This is an implementation detail, but I am still not sure about some of the terminology that is used, e.g. "Fore", "Subloops", etc., but I've not come up yet with convincing alternatives...

Also, we probably want to revise some of the threshold values, and see if we need to tweak them further.

But assuming that the dependence analysis is now conservative/correct, these are the sort of things I was thinking of that we can improve after this lands and we get some more experience with the pass.

[dmgreen]

Attempted to clean up tests and make them not rely on arm. Removed the outer loop IV check, some other small code edits and some comment improvements/formatting.

[SjoerdMeijer]

Cleanup/simplification of the tests looks good to me. Just a nit inlined.

lib/Transforms/Utils/LoopUnrollAndJam.cpp

544

If you move this to after the asserts, the other NDEBUG block , can you then move this statement:

Loop *OuterL = L->getParentLoop();

to inside the other #ifndef NDEBUG block? Thus we avoid having just one statement hash defined here.

[dmgreen]

OK. One DA patch is in, the other is still waiting for review.

Everyone happy with this to go into tree (its off by default)? Hal are you happy enough for us to continue work in tree? Eric you happy enough with the tests? No-one else have any objections?

[SjoerdMeijer]

I think you can commit this. And should there be more comments, then they can be addressed post commit.

[dmgreen]

OK. The important DA patches are in. Unless anyone objects, I will commit this soon (hopefully over the weekend).

include/llvm-c/Transforms/Scalar.h

 void LLVMAddLoopRotatePass(LLVMPassManagerRef PM);
 
 /** See llvm::createLoopRerollPass function. */
 void LLVMAddLoopRerollPass(LLVMPassManagerRef PM);
 
 /** See llvm::createLoopUnrollPass function. */
 void LLVMAddLoopUnrollPass(LLVMPassManagerRef PM);
 
+/** See llvm::createLoopUnrollAndJamPass function. */
+void LLVMAddLoopUnrollAndJamPass(LLVMPassManagerRef PM);
+
 /** See llvm::createLoopUnswitchPass function. */
 void LLVMAddLoopUnswitchPass(LLVMPassManagerRef PM);
 
 /** See llvm::createMemCpyOptPass function. */
 void LLVMAddMemCpyOptPass(LLVMPassManagerRef PM);
 
 /** See llvm::createPartiallyInlineLibCallsPass function. */
 void LLVMAddPartiallyInlineLibCallsPass(LLVMPassManagerRef PM);

include/llvm/Analysis/TargetTransformInfo.h

struct UnrollingPreferences {
     /// (mainly to loops that fail runtime unrolling).
     bool Force;
     /// Allow using trip count upper bound to unroll loops.
     bool UpperBound;
     /// Allow peeling off loop iterations for loops with low dynamic tripcount.
     bool AllowPeeling;
     /// Allow unrolling of all the iterations of the runtime loop remainder.
     bool UnrollRemainder;
+    /// Allow unroll and jam. Used to enable unroll and jam for the target.
+    bool UnrollAndJam;
+    /// Threshold for unroll and jam, for inner loop size. The 'Threshold'
+    /// value above is used during unroll and jam for the outer loop size.
+    /// This value is used in the same manner to limit the size of the inner
+    /// loop.
+    unsigned UnrollAndJamInnerLoopThreshold;
   };
 
   /// \brief Get target-customized preferences for the generic loop unrolling
   /// transformation. The caller will initialize UP with the current
   /// target-independent defaults.
   void getUnrollingPreferences(Loop *L, ScalarEvolution &,
                                UnrollingPreferences &UP) const;
 

include/llvm/InitializePasses.h

 void initializeLoopPassPass(PassRegistry&);
 void initializeLoopPredicationLegacyPassPass(PassRegistry&);
 void initializeLoopRerollPass(PassRegistry&);
 void initializeLoopRotateLegacyPassPass(PassRegistry&);
 void initializeLoopSimplifyCFGLegacyPassPass(PassRegistry&);
 void initializeLoopSimplifyPass(PassRegistry&);
 void initializeLoopStrengthReducePass(PassRegistry&);
 void initializeLoopUnrollPass(PassRegistry&);
+void initializeLoopUnrollAndJamPass(PassRegistry&);
 void initializeLoopUnswitchPass(PassRegistry&);
 void initializeLoopVectorizePass(PassRegistry&);
 void initializeLoopVersioningLICMPass(PassRegistry&);
 void initializeLoopVersioningPassPass(PassRegistry&);
 void initializeLowerAtomicLegacyPassPass(PassRegistry&);
 void initializeLowerEmuTLSPass(PassRegistry&);
 void initializeLowerExpectIntrinsicPass(PassRegistry&);
 void initializeLowerGuardIntrinsicLegacyPassPass(PassRegistry&);

include/llvm/LinkAllPasses.h

ForcePassLinking() {
       (void) llvm::createLoopExtractorPass();
       (void) llvm::createLoopInterchangePass();
       (void) llvm::createLoopPredicationPass();
       (void) llvm::createLoopSimplifyPass();
       (void) llvm::createLoopSimplifyCFGPass();
       (void) llvm::createLoopStrengthReducePass();
       (void) llvm::createLoopRerollPass();
       (void) llvm::createLoopUnrollPass();
+      (void) llvm::createLoopUnrollAndJamPass();
       (void) llvm::createLoopUnswitchPass();
       (void) llvm::createLoopVersioningLICMPass();
       (void) llvm::createLoopIdiomPass();
       (void) llvm::createLoopRotatePass();
       (void) llvm::createLowerExpectIntrinsicPass();
       (void) llvm::createLowerInvokePass();
       (void) llvm::createLowerSwitchPass();
       (void) llvm::createNaryReassociatePass();

include/llvm/Transforms/Scalar.h

 Pass *createLoopUnrollPass(int OptLevel = 2, int Threshold = -1, int Count = -1,
                            int AllowPartial = -1, int Runtime = -1,
                            int UpperBound = -1, int AllowPeeling = -1);
 // Create an unrolling pass for full unrolling that uses exact trip count only.
 Pass *createSimpleLoopUnrollPass(int OptLevel = 2);
 
 //===----------------------------------------------------------------------===//
 //
+// LoopUnrollAndJam - This pass is a simple loop unroll and jam pass.
+//
+Pass *createLoopUnrollAndJamPass(int OptLevel = 2);
+
+//===----------------------------------------------------------------------===//
+//
 // LoopReroll - This pass is a simple loop rerolling pass.
 //
 Pass *createLoopRerollPass();
 
 //===----------------------------------------------------------------------===//
 //
 // LoopRotate - This pass is a simple loop rotating pass.
 //

include/llvm/Transforms/Scalar/LoopUnrollAndJamPass.h

+//===- LoopUnrollAndJamPass.h -----------------------------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_TRANSFORMS_SCALAR_LOOPUNROLLANDJAMPASS_H
+#define LLVM_TRANSFORMS_SCALAR_LOOPUNROLLANDJAMPASS_H
+
+#include "llvm/Analysis/LoopAnalysisManager.h"
+#include "llvm/Analysis/LoopInfo.h"
+#include "llvm/IR/PassManager.h"
+
+namespace llvm {
+
+class Loop;
+class LoopStandardAnalysisResults;
+class LPMUpdater;
+
+/// A simple loop rotation transformation.
+class LoopUnrollAndJamPass : public PassInfoMixin<LoopUnrollAndJamPass> {
+  const int OptLevel;
+
+public:
+  explicit LoopUnrollAndJamPass(int OptLevel = 2) : OptLevel(OptLevel) {}
+  PreservedAnalyses run(Loop &L, LoopAnalysisManager &AM,
+                        LoopStandardAnalysisResults &AR, LPMUpdater &U);
+};
+
+} // end namespace llvm
+
+#endif // LLVM_TRANSFORMS_SCALAR_LOOPUNROLLANDJAMPASS_H

include/llvm/Transforms/Utils/UnrollLoop.h

 //===----------------------------------------------------------------------===//
 
 #ifndef LLVM_TRANSFORMS_UTILS_UNROLLLOOP_H
 #define LLVM_TRANSFORMS_UTILS_UNROLLLOOP_H
 
 #include "llvm/ADT/DenseMap.h"
 #include "llvm/ADT/StringRef.h"
 #include "llvm/Analysis/TargetTransformInfo.h"
+#include "llvm/Transforms/Utils/ValueMapper.h"
 
 namespace llvm {
 
 class AssumptionCache;
 class BasicBlock;
+class DependenceInfo;
 class DominatorTree;
 class Loop;
 class LoopInfo;
 class MDNode;
 class OptimizationRemarkEmitter;
 class ScalarEvolution;
 
 using NewLoopsMap = SmallDenseMap<const Loop *, Loop *, 4>;
void computePeelCount(Loop *L, unsigned LoopSize,
                       TargetTransformInfo::UnrollingPreferences &UP,
                       unsigned &TripCount, ScalarEvolution &SE);
 
 bool canPeel(Loop *L);
 
 bool peelLoop(Loop *L, unsigned PeelCount, LoopInfo *LI, ScalarEvolution *SE,
               DominatorTree *DT, AssumptionCache *AC, bool PreserveLCSSA);
 
+LoopUnrollResult UnrollAndJamLoop(Loop *L, unsigned Count, unsigned TripCount,
+                                  unsigned TripMultiple, bool UnrollRemainder,
+                                  LoopInfo *LI, ScalarEvolution *SE,
+                                  DominatorTree *DT, AssumptionCache *AC,
+                                  OptimizationRemarkEmitter *ORE);
+
+bool isSafeToUnrollAndJam(Loop *L, ScalarEvolution &SE, DominatorTree &DT,
+                          DependenceInfo &DI);
+
+bool computeUnrollCount(Loop *L, const TargetTransformInfo &TTI,
+                        DominatorTree &DT, LoopInfo *LI, ScalarEvolution &SE,
+                        const SmallPtrSetImpl<const Value *> &EphValues,
+                        OptimizationRemarkEmitter *ORE, unsigned &TripCount,
+                        unsigned MaxTripCount, unsigned &TripMultiple,
+                        unsigned LoopSize,
+                        TargetTransformInfo::UnrollingPreferences &UP,
+                        bool &UseUpperBound);
+
+BasicBlock *foldBlockIntoPredecessor(BasicBlock *BB, LoopInfo *LI,
+                                     ScalarEvolution *SE, DominatorTree *DT);
+
+void remapInstruction(Instruction *I, ValueToValueMapTy &VMap);
+
+void simplifyLoopAfterUnroll(Loop *L, bool SimplifyIVs, LoopInfo *LI,
+                             ScalarEvolution *SE, DominatorTree *DT,
+                             AssumptionCache *AC);
+
 MDNode *GetUnrollMetadata(MDNode *LoopID, StringRef Name);
 
+TargetTransformInfo::UnrollingPreferences gatherUnrollingPreferences(
+    Loop *L, ScalarEvolution &SE, const TargetTransformInfo &TTI, int OptLevel,
+    Optional<unsigned> UserThreshold, Optional<unsigned> UserCount,
+    Optional<bool> UserAllowPartial, Optional<bool> UserRuntime,
+    Optional<bool> UserUpperBound, Optional<bool> UserAllowPeeling);
+
+unsigned ApproximateLoopSize(const Loop *L, unsigned &NumCalls,
+                             bool &NotDuplicatable, bool &Convergent,
+                             const TargetTransformInfo &TTI,
+                             const SmallPtrSetImpl<const Value *> &EphValues,
+                             unsigned BEInsns);
+
 } // end namespace llvm
 
 #endif // LLVM_TRANSFORMS_UTILS_UNROLLLOOP_H

lib/Passes/PassBuilder.cpp

 #include "llvm/Transforms/Scalar/LoopIdiomRecognize.h"
 #include "llvm/Transforms/Scalar/LoopLoadElimination.h"
 #include "llvm/Transforms/Scalar/LoopPassManager.h"
 #include "llvm/Transforms/Scalar/LoopPredication.h"
 #include "llvm/Transforms/Scalar/LoopRotation.h"
 #include "llvm/Transforms/Scalar/LoopSimplifyCFG.h"
 #include "llvm/Transforms/Scalar/LoopSink.h"
 #include "llvm/Transforms/Scalar/LoopStrengthReduce.h"
+#include "llvm/Transforms/Scalar/LoopUnrollAndJamPass.h"
 #include "llvm/Transforms/Scalar/LoopUnrollPass.h"
 #include "llvm/Transforms/Scalar/LowerAtomic.h"
 #include "llvm/Transforms/Scalar/LowerExpectIntrinsic.h"
 #include "llvm/Transforms/Scalar/LowerGuardIntrinsic.h"
 #include "llvm/Transforms/Scalar/MemCpyOptimizer.h"
 #include "llvm/Transforms/Scalar/MergedLoadStoreMotion.h"
 #include "llvm/Transforms/Scalar/NaryReassociate.h"
 #include "llvm/Transforms/Scalar/NewGVN.h"

 static cl::opt<bool> EnableGVNHoist(
     "enable-npm-gvn-hoist", cl::init(false), cl::Hidden,
     cl::desc("Enable the GVN hoisting pass for the new PM (default = off)"));
 
 static cl::opt<bool> EnableGVNSink(
     "enable-npm-gvn-sink", cl::init(false), cl::Hidden,
     cl::desc("Enable the GVN hoisting pass for the new PM (default = off)"));
 
+static cl::opt<bool> EnableUnrollAndJam(
+    "enable-npm-unroll-and-jam", cl::init(false), cl::Hidden,
+    cl::desc("Enable the Unroll and Jam pass for the new PM (default = off)"));
+
 static cl::opt<bool> EnableSyntheticCounts(
     "enable-npm-synthetic-counts", cl::init(false), cl::Hidden, cl::ZeroOrMore,
     cl::desc("Run synthetic function entry count generation "
              "pass"));
 
 static Regex DefaultAliasRegex(
     "^(default|thinlto-pre-link|thinlto|lto-pre-link|lto)<(O[0123sz])>$");
 
PassBuilder::buildModuleOptimizationPipeline(OptimizationLevel Level,
   OptimizePM.addPass(InstCombinePass());
 
   // Unroll small loops to hide loop backedge latency and saturate any parallel
   // execution resources of an out-of-order processor. We also then need to
   // clean up redundancies and loop invariant code.
   // FIXME: It would be really good to use a loop-integrated instruction
   // combiner for cleanup here so that the unrolling and LICM can be pipelined
   // across the loop nests.
+  // We do UnrollAndJam in a separate LPM to ensure it happens before unroll
+  if (EnableUnrollAndJam) {
+    OptimizePM.addPass(
+        createFunctionToLoopPassAdaptor(LoopUnrollAndJamPass(Level)));
+    OptimizePM.addPass(InstCombinePass());
+  }
   OptimizePM.addPass(LoopUnrollPass(Level));
   OptimizePM.addPass(InstCombinePass());
   OptimizePM.addPass(RequireAnalysisPass<OptimizationRemarkEmitterAnalysis, Function>());
   OptimizePM.addPass(createFunctionToLoopPassAdaptor(LICMPass(), DebugLogging));
 
   // Now that we've vectorized and unrolled loops, we may have more refined
   // alignment information, try to re-derive it here.
   OptimizePM.addPass(AlignmentFromAssumptionsPass());

lib/Passes/PassRegistry.def

 LOOP_PASS("rotate", LoopRotatePass())
 LOOP_PASS("no-op-loop", NoOpLoopPass())
 LOOP_PASS("print", PrintLoopPass(dbgs()))
 LOOP_PASS("loop-deletion", LoopDeletionPass())
 LOOP_PASS("simplify-cfg", LoopSimplifyCFGPass())
 LOOP_PASS("strength-reduce", LoopStrengthReducePass())
 LOOP_PASS("indvars", IndVarSimplifyPass())
 LOOP_PASS("irce", IRCEPass())
+LOOP_PASS("unroll-and-jam", LoopUnrollAndJamPass())
 LOOP_PASS("unroll-full", LoopFullUnrollPass())
 LOOP_PASS("unswitch", SimpleLoopUnswitchPass())
 LOOP_PASS("print-access-info", LoopAccessInfoPrinterPass(dbgs()))
 LOOP_PASS("print<ivusers>", IVUsersPrinterPass(dbgs()))
 LOOP_PASS("loop-predication", LoopPredicationPass())
 #undef LOOP_PASS

lib/Target/ARM/ARMTargetTransformInfo.cpp

void ARMTTIImpl::getUnrollingPreferences(Loop *L, ScalarEvolution &SE,
   }
 
   DEBUG(dbgs() << "Cost of loop: " << Cost << "\n");
 
   UP.Partial = true;
   UP.Runtime = true;
   UP.UnrollRemainder = true;
   UP.DefaultUnrollRuntimeCount = 4;
+  UP.UnrollAndJam = true;
+  UP.UnrollAndJamInnerLoopThreshold = 60;
 
   // Force unrolling small loops can be very useful because of the branch
   // taken cost of the backedge.
   if (Cost < 12)
     UP.Force = true;
 }

lib/Transforms/IPO/PassManagerBuilder.cpp

UseCFLAA("use-cfl-aa", cl::init(CFLAAType::None), cl::Hidden,
                                    "Enable inclusion-based CFL-AA"),
                         clEnumValN(CFLAAType::Both, "both",
                                    "Enable both variants of CFL-AA")));
 
 static cl::opt<bool> EnableLoopInterchange(
     "enable-loopinterchange", cl::init(false), cl::Hidden,
     cl::desc("Enable the new, experimental LoopInterchange Pass"));
 
+static cl::opt<bool> EnableUnrollAndJam("enable-unroll-and-jam",
+                                        cl::init(false), cl::Hidden,
+                                        cl::desc("Enable Unroll And Jam Pass"));
+
 static cl::opt<bool>
     EnablePrepareForThinLTO("prepare-for-thinlto", cl::init(false), cl::Hidden,
                             cl::desc("Enable preparation for ThinLTO."));
 
 static cl::opt<bool> RunPGOInstrGen(
     "profile-generate", cl::init(false), cl::Hidden,
     cl::desc("Enable PGO instrumentation."));
 
if (OptLevel > 1 && ExtraVectorizerPasses) {
       MPM.add(createEarlyCSEPass());
     }
   }
 
   addExtensionsToPM(EP_Peephole, MPM);
   addInstructionCombiningPass(MPM);
 
   if (!DisableUnrollLoops) {
+    if (EnableUnrollAndJam) {
+      // Unroll and Jam. We do this before unroll but need to be in a separate
+      // loop pass manager in order for the outer loop to be processed by
+      // unroll and jam before the inner loop is unrolled.
+      MPM.add(createLoopUnrollAndJamPass(OptLevel));
+      addInstructionCombiningPass(MPM);
+    }
+
     MPM.add(createLoopUnrollPass(OptLevel));    // Unroll small loops
 
     // LoopUnroll may generate some redundency to cleanup.
     addInstructionCombiningPass(MPM);
 
     // Runtime unrolling will introduce runtime check in loop prologue. If the
     // unrolled loop is a inner loop, then the prologue will be inside the
     // outer loop. LICM pass can help to promote the runtime check out if the

lib/Transforms/Scalar/CMakeLists.txt

add_llvm_library(LLVMScalarOpts
   LoopLoadElimination.cpp
   LoopPassManager.cpp
   LoopPredication.cpp
   LoopRerollPass.cpp
   LoopRotation.cpp
   LoopSimplifyCFG.cpp
   LoopStrengthReduce.cpp
   LoopUnrollPass.cpp
+  LoopUnrollAndJamPass.cpp
   LoopUnswitch.cpp
   LoopVersioningLICM.cpp
   LowerAtomic.cpp
   LowerExpectIntrinsic.cpp
   LowerGuardIntrinsic.cpp
   MemCpyOptimizer.cpp
   MergeICmps.cpp
   MergedLoadStoreMotion.cpp

lib/Transforms/Scalar/LoopUnrollAndJamPass.cpp

+//===- LoopUnrollAndJam.cpp - Loop unroll and jam pass --------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This pass implements an unroll and jam pass. Most of the work is done by
+// Utils/UnrollLoopAndJam.cpp.
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Transforms/Scalar/LoopUnrollAndJamPass.h"
+#include "llvm/ADT/None.h"
+#include "llvm/ADT/STLExtras.h"
+#include "llvm/ADT/SmallPtrSet.h"
+#include "llvm/ADT/StringRef.h"
+#include "llvm/Analysis/AssumptionCache.h"
+#include "llvm/Analysis/CodeMetrics.h"
+#include "llvm/Analysis/DependenceAnalysis.h"
+#include "llvm/Analysis/LoopAnalysisManager.h"
+#include "llvm/Analysis/LoopInfo.h"
+#include "llvm/Analysis/LoopPass.h"
+#include "llvm/Analysis/OptimizationRemarkEmitter.h"
+#include "llvm/Analysis/ScalarEvolution.h"
+#include "llvm/Analysis/TargetTransformInfo.h"
+#include "llvm/IR/BasicBlock.h"
+#include "llvm/IR/CFG.h"
+#include "llvm/IR/Constant.h"
+#include "llvm/IR/Constants.h"
+#include "llvm/IR/Dominators.h"
+#include "llvm/IR/Function.h"
+#include "llvm/IR/Instruction.h"
+#include "llvm/IR/Instructions.h"
+#include "llvm/IR/IntrinsicInst.h"
+#include "llvm/IR/Metadata.h"
+#include "llvm/IR/PassManager.h"
+#include "llvm/Pass.h"
+#include "llvm/Support/Casting.h"
+#include "llvm/Support/CommandLine.h"
+#include "llvm/Support/Debug.h"
+#include "llvm/Support/ErrorHandling.h"
+#include "llvm/Support/raw_ostream.h"
+#include "llvm/Transforms/Scalar.h"
+#include "llvm/Transforms/Scalar/LoopPassManager.h"
+#include "llvm/Transforms/Utils.h"
+#include "llvm/Transforms/Utils/LoopUtils.h"
+#include "llvm/Transforms/Utils/UnrollLoop.h"
+#include <algorithm>
+#include <cassert>
+#include <cstdint>
+#include <string>
+
+using namespace llvm;
+
+#define DEBUG_TYPE "loop-unroll-and-jam"
+
+static cl::opt<unsigned> UnrollAndJamCount(
+    "unroll-and-jam-count", cl::Hidden,
+    cl::desc("Use this unroll count for all loops including those with "
+             "unroll_and_jam_count pragma values, for testing purposes"));
+
+static cl::opt<unsigned> UnrollAndJamThreshold(
+    "unroll-and-jam-threshold", cl::init(60), cl::Hidden,
+    cl::desc("Threshold to use for inner loop when doing unroll and jam."));
+
+static cl::opt<unsigned> PragmaUnrollAndJamThreshold(
+    "pragma-unroll-and-jam-threshold", cl::init(1024), cl::Hidden,
+    cl::desc("Unrolled size limit for loops with an unroll_and_jam(full) or "
+             "unroll_count pragma."));
+
+// Returns the loop hint metadata node with the given name (for example,
+// "llvm.loop.unroll.count").  If no such metadata node exists, then nullptr is
+// returned.
+static MDNode *GetUnrollMetadataForLoop(const Loop *L, StringRef Name) {
+  if (MDNode *LoopID = L->getLoopID())
+    return GetUnrollMetadata(LoopID, Name);
+  return nullptr;
+}
+
+// Returns true if the loop has any metadata starting with Prefix. For example a
+// Prefix of "llvm.loop.unroll." returns true if we have any unroll metadata.
+static bool HasAnyUnrollPragma(const Loop *L, StringRef Prefix) {
+  if (MDNode *LoopID = L->getLoopID()) {
+    // First operand should refer to the loop id itself.
+    assert(LoopID->getNumOperands() > 0 && "requires at least one operand");
+    assert(LoopID->getOperand(0) == LoopID && "invalid loop id");
+
+    for (unsigned i = 1, e = LoopID->getNumOperands(); i < e; ++i) {
+      MDNode *MD = dyn_cast<MDNode>(LoopID->getOperand(i));
+      if (!MD)
+        continue;
+
+      MDString *S = dyn_cast<MDString>(MD->getOperand(0));
+      if (!S)
+        continue;
+
+      if (S->getString().startswith(Prefix))
+        return true;
+    }
+  }
+  return false;
+}
+
+// Returns true if the loop has an unroll_and_jam(enable) pragma.
+static bool HasUnrollAndJamEnablePragma(const Loop *L) {
+  return GetUnrollMetadataForLoop(L, "llvm.loop.unroll_and_jam.enable");
+}
+
+// Returns true if the loop has an unroll_and_jam(disable) pragma.
+static bool HasUnrollAndJamDisablePragma(const Loop *L) {
+  return GetUnrollMetadataForLoop(L, "llvm.loop.unroll_and_jam.disable");
+}
+
+// If loop has an unroll_and_jam_count pragma return the (necessarily
+// positive) value from the pragma.  Otherwise return 0.
+static unsigned UnrollAndJamCountPragmaValue(const Loop *L) {
+  MDNode *MD = GetUnrollMetadataForLoop(L, "llvm.loop.unroll_and_jam.count");
+  if (MD) {
+    assert(MD->getNumOperands() == 2 &&
+           "Unroll count hint metadata should have two operands.");
+    unsigned Count =
+        mdconst::extract<ConstantInt>(MD->getOperand(1))->getZExtValue();
+    assert(Count >= 1 && "Unroll count must be positive.");
+    return Count;
+  }
+  return 0;
+}
+
+// Returns loop size estimation for unrolled loop.
+static uint64_t
+getUnrollAndJammedLoopSize(unsigned LoopSize,
+                           TargetTransformInfo::UnrollingPreferences &UP) {
+  assert(LoopSize >= UP.BEInsns && "LoopSize should not be less than BEInsns!");
+  return (uint64_t)(LoopSize - UP.BEInsns) * UP.Count + UP.BEInsns;
+}
+
+// Calculates unroll and jam count and writes it to UP.Count. Returns true if
+// unroll count was set explicitly.
+static bool computeUnrollAndJamCount(
+    Loop *L, Loop *SubLoop, const TargetTransformInfo &TTI, DominatorTree &DT,
+    LoopInfo *LI, ScalarEvolution &SE,
+    const SmallPtrSetImpl<const Value *> &EphValues,
+    OptimizationRemarkEmitter *ORE, unsigned OuterTripCount,
+    unsigned OuterTripMultiple, unsigned OuterLoopSize, unsigned InnerTripCount,
+    unsigned InnerLoopSize, TargetTransformInfo::UnrollingPreferences &UP) {
+  // Check for explicit Count from the "unroll-and-jam-count" option.
+  bool UserUnrollCount = UnrollAndJamCount.getNumOccurrences() > 0;
+  if (UserUnrollCount) {
+    UP.Count = UnrollAndJamCount;
+    UP.Force = true;
+    if (UP.AllowRemainder &&
+        getUnrollAndJammedLoopSize(OuterLoopSize, UP) < UP.Threshold &&
+        getUnrollAndJammedLoopSize(InnerLoopSize, UP) <
+            UP.UnrollAndJamInnerLoopThreshold)
+      return true;
+  }
+
+  // Check for unroll_and_jam pragmas
+  unsigned PragmaCount = UnrollAndJamCountPragmaValue(L);
+  if (PragmaCount > 0) {
+    UP.Count = PragmaCount;
+    UP.Runtime = true;
+    UP.Force = true;
+    if ((UP.AllowRemainder || (OuterTripMultiple % PragmaCount == 0)) &&
+        getUnrollAndJammedLoopSize(OuterLoopSize, UP) < UP.Threshold &&
+        getUnrollAndJammedLoopSize(InnerLoopSize, UP) <
+            UP.UnrollAndJamInnerLoopThreshold)
+      return true;
+  }
+
+  // Use computeUnrollCount from the loop unroller to get a sensible count
+  // for the unrolling the outer loop. This uses UP.Threshold /
+  // UP.PartialThreshold / UP.MaxCount to come up with sensible loop values.
+  // We have already checked that the loop has no unroll.* pragmas.
+  unsigned MaxTripCount = 0;
+  bool UseUpperBound = false;
+  bool ExplicitUnroll = computeUnrollCount(
+      L, TTI, DT, LI, SE, EphValues, ORE, OuterTripCount, MaxTripCount,
+      OuterTripMultiple, OuterLoopSize, UP, UseUpperBound);
+  if (ExplicitUnroll || UseUpperBound) {
+    // If the user explicitly set the loop as unrolled, dont UnJ it. Leave it
+    // for the unroller instead.
+    UP.Count = 0;
+    return false;
+  }
+
+  bool PragmaEnableUnroll = HasUnrollAndJamEnablePragma(L);
+  ExplicitUnroll = PragmaCount > 0 || PragmaEnableUnroll || UserUnrollCount;
+
+  // If the loop has an unrolling pragma, we want to be more aggressive with
+  // unrolling limits.
+  if (ExplicitUnroll && OuterTripCount != 0)
+    UP.UnrollAndJamInnerLoopThreshold = PragmaUnrollAndJamThreshold;
+
+  if (!UP.AllowRemainder && getUnrollAndJammedLoopSize(InnerLoopSize, UP) >=
+                                UP.UnrollAndJamInnerLoopThreshold) {
+    UP.Count = 0;
+    return false;
+  }
+
+  // If the inner loop count is known and small, leave the entire loop nest to
+  // be the unroller
+  if (!ExplicitUnroll && InnerTripCount &&
+      InnerLoopSize * InnerTripCount < UP.Threshold) {
+    UP.Count = 0;
+    return false;
+  }
+
+  // We have a sensible limit for the outer loop, now adjust it for the inner
+  // loop and UP.UnrollAndJamInnerLoopThreshold.
+  while (UP.Count != 0 && UP.AllowRemainder &&
+         getUnrollAndJammedLoopSize(InnerLoopSize, UP) >=
+             UP.UnrollAndJamInnerLoopThreshold)
+    UP.Count--;
+
+  if (!ExplicitUnroll) {
+    // Check for situations where UnJ is likely to be unprofitable. Including
+    // subloops with more than 1 block.
+    if (SubLoop->getBlocks().size() != 1) {
+      UP.Count = 0;
+      return false;
+    }
+
+    // Limit to loops where there is something to gain from unrolling and
+    // jamming the loop. In this case, look for loads that are invariant in the
+    // outer loop and can become shared.
+    unsigned numInvariant = 0;
+    for (BasicBlock *BB : SubLoop->getBlocks()) {
+      for (Instruction &I : *BB) {
+        if (auto *Ld = dyn_cast<LoadInst>(&I)) {
+          Value *V = Ld->getPointerOperand();
+          const SCEV *LSCEV = SE.getSCEVAtScope(V, L);
+          if (SE.isLoopInvariant(LSCEV, L))
+            numInvariant++;
+        }
+      }
+    }
+    if (numInvariant == 0) {
+      UP.Count = 0;
+      return false;
+    }
+  }
+
+  return ExplicitUnroll;
+}
+
+static LoopUnrollResult
+tryToUnrollAndJamLoop(Loop *L, DominatorTree &DT, LoopInfo *LI,
+                      ScalarEvolution &SE, const TargetTransformInfo &TTI,
+                      AssumptionCache &AC, DependenceInfo &DI,
+                      OptimizationRemarkEmitter &ORE, int OptLevel) {
+  // Quick checks of the correct loop form
+  if (!L->isLoopSimplifyForm() || L->getSubLoops().size() != 1)
+    return LoopUnrollResult::Unmodified;
+  Loop *SubLoop = L->getSubLoops()[0];
+  if (!SubLoop->isLoopSimplifyForm())
+    return LoopUnrollResult::Unmodified;
+
+  BasicBlock *Latch = L->getLoopLatch();
+  BasicBlock *Exit = L->getExitingBlock();
+  BasicBlock *SubLoopLatch = SubLoop->getLoopLatch();
+  BasicBlock *SubLoopExit = SubLoop->getExitingBlock();
+
+  if (Latch != Exit || SubLoopLatch != SubLoopExit)
+    return LoopUnrollResult::Unmodified;
+
+  TargetTransformInfo::UnrollingPreferences UP = gatherUnrollingPreferences(
+      L, SE, TTI, OptLevel, None, None, None, None, None, None);
+  if (UnrollAndJamThreshold.getNumOccurrences() > 0)
+    UP.UnrollAndJamInnerLoopThreshold = UnrollAndJamThreshold;
+  // Exit early if unrolling is disabled.
+  if (!UP.UnrollAndJam || UP.UnrollAndJamInnerLoopThreshold == 0)
+    return LoopUnrollResult::Unmodified;
+
+  DEBUG(dbgs() << "Loop Unroll and Jam: F["
+               << L->getHeader()->getParent()->getName() << "] Loop %"
+               << L->getHeader()->getName() << "\n");
+
+  // A loop with any unroll pragma (enabling/disabling/count/etc) is left for
+  // the unroller, so long as it does not explicitly have unroll_and_jam
+  // metadata. This means #pragma nounroll will disable unroll and jam as well
+  // as unrolling
+  if (HasUnrollAndJamDisablePragma(L) ||
+      (HasAnyUnrollPragma(L, "llvm.loop.unroll.") &&
+       !HasAnyUnrollPragma(L, "llvm.loop.unroll_and_jam."))) {
+    DEBUG(dbgs() << "  Disabled due to pragma.\n");
+    return LoopUnrollResult::Unmodified;
+  }
+
+  if (!isSafeToUnrollAndJam(L, SE, DT, DI)) {
+    DEBUG(dbgs() << "  Disabled due to not being safe.\n");
+    return LoopUnrollResult::Unmodified;
+  }
+
+  // Approximate the loop size and collect useful info
+  unsigned NumInlineCandidates;
+  bool NotDuplicatable;
+  bool Convergent;
+  SmallPtrSet<const Value *, 32> EphValues;
+  CodeMetrics::collectEphemeralValues(L, &AC, EphValues);
+  unsigned InnerLoopSize =
+      ApproximateLoopSize(SubLoop, NumInlineCandidates, NotDuplicatable,
+                          Convergent, TTI, EphValues, UP.BEInsns);
+  unsigned OuterLoopSize =
+      ApproximateLoopSize(L, NumInlineCandidates, NotDuplicatable, Convergent,
+                          TTI, EphValues, UP.BEInsns);
+  DEBUG(dbgs() << "  Outer Loop Size: " << OuterLoopSize << "\n");
+  DEBUG(dbgs() << "  Inner Loop Size: " << InnerLoopSize << "\n");
+  if (NotDuplicatable) {
+    DEBUG(dbgs() << "  Not unrolling loop which contains non-duplicatable "
+                    "instructions.\n");
+    return LoopUnrollResult::Unmodified;
+  }
+  if (NumInlineCandidates != 0) {
+    DEBUG(dbgs() << "  Not unrolling loop with inlinable calls.\n");
+    return LoopUnrollResult::Unmodified;
+  }
+  if (Convergent) {
+    DEBUG(dbgs() << "  Not unrolling loop with convergent instructions.\n");
+    return LoopUnrollResult::Unmodified;
+  }
+
+  // Find trip count and trip multiple
+  unsigned OuterTripCount = SE.getSmallConstantTripCount(L, Latch);
+  unsigned OuterTripMultiple = SE.getSmallConstantTripMultiple(L, Latch);
+  unsigned InnerTripCount = SE.getSmallConstantTripCount(SubLoop, SubLoopLatch);
+
+  // Decide if, and by how much, to unroll
+  bool IsCountSetExplicitly = computeUnrollAndJamCount(
+      L, SubLoop, TTI, DT, LI, SE, EphValues, &ORE, OuterTripCount,
+      OuterTripMultiple, OuterLoopSize, InnerTripCount, InnerLoopSize, UP);
+  if (UP.Count <= 1)
+    return LoopUnrollResult::Unmodified;
+  // Unroll factor (Count) must be less or equal to TripCount.
+  if (OuterTripCount && UP.Count > OuterTripCount)
+    UP.Count = OuterTripCount;
+
+  LoopUnrollResult UnrollResult =
+      UnrollAndJamLoop(L, UP.Count, OuterTripCount, OuterTripMultiple,
+                       UP.UnrollRemainder, LI, &SE, &DT, &AC, &ORE);
+
+  // If loop has an unroll count pragma or unrolled by explicitly set count
+  // mark loop as unrolled to prevent unrolling beyond that requested.
+  if (UnrollResult != LoopUnrollResult::FullyUnrolled && IsCountSetExplicitly)
+    L->setLoopAlreadyUnrolled();
+
+  return UnrollResult;
+}
+
+namespace {
+
+class LoopUnrollAndJam : public LoopPass {
+public:
+  static char ID; // Pass ID, replacement for typeid
+  unsigned OptLevel;
+
+  LoopUnrollAndJam(int OptLevel = 2) : LoopPass(ID), OptLevel(OptLevel) {
+    initializeLoopUnrollAndJamPass(*PassRegistry::getPassRegistry());
+  }
+
+  bool runOnLoop(Loop *L, LPPassManager &LPM) override {
+    if (skipLoop(L))
+      return false;
+
+    Function &F = *L->getHeader()->getParent();
+
+    auto &DT = getAnalysis<DominatorTreeWrapperPass>().getDomTree();
+    LoopInfo *LI = &getAnalysis<LoopInfoWrapperPass>().getLoopInfo();
+    ScalarEvolution &SE = getAnalysis<ScalarEvolutionWrapperPass>().getSE();
+    const TargetTransformInfo &TTI =
+        getAnalysis<TargetTransformInfoWrapperPass>().getTTI(F);
+    auto &AC = getAnalysis<AssumptionCacheTracker>().getAssumptionCache(F);
+    auto &DI = getAnalysis<DependenceAnalysisWrapperPass>().getDI();
+    // For the old PM, we can't use OptimizationRemarkEmitter as an analysis
+    // pass.  Function analyses need to be preserved across loop transformations
+    // but ORE cannot be preserved (see comment before the pass definition).
+    OptimizationRemarkEmitter ORE(&F);
+
+    LoopUnrollResult Result =
+        tryToUnrollAndJamLoop(L, DT, LI, SE, TTI, AC, DI, ORE, OptLevel);
+
+    if (Result == LoopUnrollResult::FullyUnrolled)
+      LPM.markLoopAsDeleted(*L);
+
+    return Result != LoopUnrollResult::Unmodified;
+  }
+
+  /// This transformation requires natural loop information & requires that
+  /// loop preheaders be inserted into the CFG...
+  void getAnalysisUsage(AnalysisUsage &AU) const override {
+    AU.addRequired<AssumptionCacheTracker>();
+    AU.addRequired<TargetTransformInfoWrapperPass>();
+    AU.addRequired<DependenceAnalysisWrapperPass>();
+    getLoopAnalysisUsage(AU);
+  }
+};
+
+} // end anonymous namespace
+
+char LoopUnrollAndJam::ID = 0;
+
+INITIALIZE_PASS_BEGIN(LoopUnrollAndJam, "loop-unroll-and-jam",
+                      "Unroll and Jam loops", false, false)
+INITIALIZE_PASS_DEPENDENCY(AssumptionCacheTracker)
+INITIALIZE_PASS_DEPENDENCY(LoopPass)
+INITIALIZE_PASS_DEPENDENCY(TargetTransformInfoWrapperPass)
+INITIALIZE_PASS_DEPENDENCY(DependenceAnalysisWrapperPass)
+INITIALIZE_PASS_END(LoopUnrollAndJam, "loop-unroll-and-jam",
+                    "Unroll and Jam loops", false, false)
+
+Pass *llvm::createLoopUnrollAndJamPass(int OptLevel) {
+  return new LoopUnrollAndJam(OptLevel);
+}
+
+PreservedAnalyses LoopUnrollAndJamPass::run(Loop &L, LoopAnalysisManager &AM,
+                                            LoopStandardAnalysisResults &AR,
+                                            LPMUpdater &) {
+  const auto &FAM =
+      AM.getResult<FunctionAnalysisManagerLoopProxy>(L, AR).getManager();
+  Function *F = L.getHeader()->getParent();
+
+  auto *ORE = FAM.getCachedResult<OptimizationRemarkEmitterAnalysis>(*F);
+  // FIXME: This should probably be optional rather than required.
+  if (!ORE)
+    report_fatal_error(
+        "LoopUnrollAndJamPass: OptimizationRemarkEmitterAnalysis not cached at "
+        "a higher level");
+
+  DependenceInfo DI(F, &AR.AA, &AR.SE, &AR.LI);
+
+  LoopUnrollResult Result = tryToUnrollAndJamLoop(
+      &L, AR.DT, &AR.LI, AR.SE, AR.TTI, AR.AC, DI, *ORE, OptLevel);
+
+  if (Result == LoopUnrollResult::Unmodified)
+    return PreservedAnalyses::all();
+
+  return getLoopPassPreservedAnalyses();
+}

lib/Transforms/Scalar/LoopUnrollPass.cpp

 
 /// A magic value for use with the Threshold parameter to indicate
 /// that the loop unroll should be performed regardless of how much
 /// code expansion would result.
 static const unsigned NoThreshold = std::numeric_limits<unsigned>::max();
 
 /// Gather the various unrolling parameters based on the defaults, compiler
 /// flags, TTI overrides and user specified parameters.
-static TargetTransformInfo::UnrollingPreferences gatherUnrollingPreferences(
+TargetTransformInfo::UnrollingPreferences llvm::gatherUnrollingPreferences(
     Loop *L, ScalarEvolution &SE, const TargetTransformInfo &TTI, int OptLevel,
     Optional<unsigned> UserThreshold, Optional<unsigned> UserCount,
     Optional<bool> UserAllowPartial, Optional<bool> UserRuntime,
     Optional<bool> UserUpperBound, Optional<bool> UserAllowPeeling) {
   TargetTransformInfo::UnrollingPreferences UP;
 
   // Set up the defaults
   UP.Threshold = OptLevel > 2 ? 300 : 150;
TargetTransformInfo::UnrollingPreferences llvm::gatherUnrollingPreferences(
   UP.Partial = false;
   UP.Runtime = false;
   UP.AllowRemainder = true;
   UP.UnrollRemainder = false;
   UP.AllowExpensiveTripCount = false;
   UP.Force = false;
   UP.UpperBound = false;
   UP.AllowPeeling = true;
+  UP.UnrollAndJam = false;
+  UP.UnrollAndJamInnerLoopThreshold = 60;
 
   // Override with any target specific settings
   TTI.getUnrollingPreferences(L, SE, UP);
 
   // Apply size attributes
   if (L->getHeader()->getParent()->optForSize()) {
     UP.Threshold = UP.OptSizeThreshold;
     UP.PartialThreshold = UP.PartialOptSizeThreshold;
static Optional<EstimatedUnrollCost> analyzeLoopUnrollCost(
 
   DEBUG(dbgs() << "Analysis finished:\n"
                << "UnrolledCost: " << UnrolledCost << ", "
                << "RolledDynamicCost: " << RolledDynamicCost << "\n");
   return {{UnrolledCost, RolledDynamicCost}};
 }
 
 /// ApproximateLoopSize - Approximate the size of the loop.
-static unsigned
-ApproximateLoopSize(const Loop *L, unsigned &NumCalls, bool &NotDuplicatable,
-                    bool &Convergent, const TargetTransformInfo &TTI,
-                    const SmallPtrSetImpl<const Value *> &EphValues,
-                    unsigned BEInsns) {
+unsigned llvm::ApproximateLoopSize(
+    const Loop *L, unsigned &NumCalls, bool &NotDuplicatable, bool &Convergent,
+    const TargetTransformInfo &TTI,
+    const SmallPtrSetImpl<const Value *> &EphValues, unsigned BEInsns) {
   CodeMetrics Metrics;
   for (BasicBlock *BB : L->blocks())
     Metrics.analyzeBasicBlock(BB, TTI, EphValues);
   NumCalls = Metrics.NumInlineCandidates;
   NotDuplicatable = Metrics.notDuplicatable;
   Convergent = Metrics.convergent;
 
   unsigned LoopSize = Metrics.NumInsts;
static uint64_t getUnrolledLoopSize(
     unsigned LoopSize,
     TargetTransformInfo::UnrollingPreferences &UP) {
   assert(LoopSize >= UP.BEInsns && "LoopSize should not be less than BEInsns!");
   return (uint64_t)(LoopSize - UP.BEInsns) * UP.Count + UP.BEInsns;
 }
 
 // Returns true if unroll count was set explicitly.
 // Calculates unroll count and writes it to UP.Count.
-static bool computeUnrollCount(
+bool llvm::computeUnrollCount(
     Loop *L, const TargetTransformInfo &TTI, DominatorTree &DT, LoopInfo *LI,
     ScalarEvolution &SE, const SmallPtrSetImpl<const Value *> &EphValues,
     OptimizationRemarkEmitter *ORE, unsigned &TripCount, unsigned MaxTripCount,
     unsigned &TripMultiple, unsigned LoopSize,
     TargetTransformInfo::UnrollingPreferences &UP, bool &UseUpperBound) {
   // Check for explicit Count.
   // 1st priority is unroll count set by "unroll-count" option.
   bool UserUnrollCount = UnrollCount.getNumOccurrences() > 0;
bool llvm::computeUnrollCount(
   }
 
   bool PragmaEnableUnroll = HasUnrollEnablePragma(L);
   bool ExplicitUnroll = PragmaCount > 0 || PragmaFullUnroll ||
                         PragmaEnableUnroll || UserUnrollCount;
 
   if (ExplicitUnroll && TripCount != 0) {
     // If the loop has an unrolling pragma, we want to be more aggressive with
-    // unrolling limits. Set thresholds to at least the PragmaThreshold value
-    // which is larger than the default limits.
+    // unrolling limits. Set thresholds to at least the PragmaUnrollThreshold
+    // value which is larger than the default limits.
     UP.Threshold = std::max<unsigned>(UP.Threshold, PragmaUnrollThreshold);
     UP.PartialThreshold =
         std::max<unsigned>(UP.PartialThreshold, PragmaUnrollThreshold);
   }
 
   // 3rd priority is full unroll count.
   // Full unroll makes sense only when TripCount or its upper bound could be
   // statically calculated.

lib/Transforms/Scalar/Scalar.cpp

void llvm::initializeScalarOpts(PassRegistry &Registry) {
   initializeLoopDeletionLegacyPassPass(Registry);
   initializeLoopAccessLegacyAnalysisPass(Registry);
   initializeLoopInterchangePass(Registry);
   initializeLoopPredicationLegacyPassPass(Registry);
   initializeLoopRotateLegacyPassPass(Registry);
   initializeLoopStrengthReducePass(Registry);
   initializeLoopRerollPass(Registry);
   initializeLoopUnrollPass(Registry);
+  initializeLoopUnrollAndJamPass(Registry);
   initializeLoopUnswitchPass(Registry);
   initializeLoopVersioningLICMPass(Registry);
   initializeLoopIdiomRecognizeLegacyPassPass(Registry);
   initializeLowerAtomicLegacyPassPass(Registry);
   initializeLowerExpectIntrinsicPass(Registry);
   initializeLowerGuardIntrinsicLegacyPassPass(Registry);
   initializeMemCpyOptLegacyPassPass(Registry);
   initializeMergeICmpsPass(Registry);

 void LLVMAddLoopRerollPass(LLVMPassManagerRef PM) {
   unwrap(PM)->add(createLoopRerollPass());
 }
 
 void LLVMAddLoopUnrollPass(LLVMPassManagerRef PM) {
   unwrap(PM)->add(createLoopUnrollPass());
 }
 
+void LLVMAddLoopUnrollAndJamPass(LLVMPassManagerRef PM) {
+  unwrap(PM)->add(createLoopUnrollAndJamPass());
+}
+
 void LLVMAddLoopUnswitchPass(LLVMPassManagerRef PM) {
   unwrap(PM)->add(createLoopUnswitchPass());
 }
 
 void LLVMAddMemCpyOptPass(LLVMPassManagerRef PM) {
   unwrap(PM)->add(createMemCpyOptPass());
 }
 

lib/Transforms/Utils/CMakeLists.txt

add_llvm_library(LLVMTransformUtils
   InstructionNamer.cpp
   IntegerDivision.cpp
   LCSSA.cpp
   LibCallsShrinkWrap.cpp
   Local.cpp
   LoopRotationUtils.cpp
   LoopSimplify.cpp
   LoopUnroll.cpp
+  LoopUnrollAndJam.cpp
   LoopUnrollPeel.cpp
   LoopUnrollRuntime.cpp
   LoopUtils.cpp
   LoopVersioning.cpp
   LowerInvoke.cpp
   LowerMemIntrinsics.cpp
   LowerSwitch.cpp
   Mem2Reg.cpp

lib/Transforms/Utils/LoopUnroll.cpp

#ifdef NDEBUG
     cl::init(false)
 #else
     cl::init(true)
 #endif
                     );
 
 /// Convert the instruction operands from referencing the current values into
 /// those specified by VMap.
-static inline void remapInstruction(Instruction *I,
-                                    ValueToValueMapTy &VMap) {
+void llvm::remapInstruction(Instruction *I, ValueToValueMapTy &VMap) {
   for (unsigned op = 0, E = I->getNumOperands(); op != E; ++op) {
     Value *Op = I->getOperand(op);
 
     // Unwrap arguments of dbg.value intrinsics.
     bool Wrapped = false;
     if (auto *V = dyn_cast<MetadataAsValue>(Op))
       if (auto *Unwrapped = dyn_cast<ValueAsMetadata>(V->getMetadata())) {
         Op = Unwrapped->getValue();
for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
         PN->setIncomingBlock(i, cast<BasicBlock>(It->second));
     }
   }
 }
 
 /// Folds a basic block into its predecessor if it only has one predecessor, and
 /// that predecessor only has one successor.
 /// The LoopInfo Analysis that is passed will be kept consistent.
-static BasicBlock *
-foldBlockIntoPredecessor(BasicBlock *BB, LoopInfo *LI, ScalarEvolution *SE,
+BasicBlock *llvm::foldBlockIntoPredecessor(BasicBlock *BB, LoopInfo *LI,
+                                           ScalarEvolution *SE,
                                            DominatorTree *DT) {
   // Merge basic blocks into their predecessor if there is only one distinct
   // pred, and if there is only one distinct successor of the predecessor, and
   // if there are no PHI nodes.
   BasicBlock *OnlyPred = BB->getSinglePredecessor();
   if (!OnlyPred) return nullptr;
 
   if (OnlyPred->getTerminator()->getNumSuccessors() != 1)
     return nullptr;
 
-  DEBUG(dbgs() << "Merging: " << *BB << "into: " << *OnlyPred);
+  DEBUG(dbgs() << "Merging: " << BB->getName() << " into "
+               << OnlyPred->getName() << "\n");
 
   // Resolve any PHI nodes at the start of the block.  They are all
   // guaranteed to have exactly one entry if they exist, unless there are
   // multiple duplicate (but guaranteed to be equal) entries for the
   // incoming edges.  This occurs when there are multiple edges from
   // OnlyPred to OnlySucc.
   FoldSingleEntryPHINodes(BB);
 
static bool isEpilogProfitable(Loop *L) {
   assert(PreHeader && Header);
   for (const PHINode &PN : Header->phis()) {
     if (isa<ConstantInt>(PN.getIncomingValueForBlock(PreHeader)))
       return true;
   }
   return false;
 }
 
-static void simplifyLoopAfterUnroll(Loop *L, bool SimplifyIVs, LoopInfo *LI,
-                                    ScalarEvolution *SE, DominatorTree *DT,
-                                    AssumptionCache *AC) {
+void llvm::simplifyLoopAfterUnroll(Loop *L, bool SimplifyIVs, LoopInfo *LI,
   // Simplify any new induction variables in the partially unrolled loop.
   if (SE && SimplifyIVs) {
     SmallVector<WeakTrackingVH, 16> DeadInsts;
     simplifyLoopIVs(L, SE, DT, LI, DeadInsts);
 
     // Aggressively clean up dead instructions that simplifyLoopIVs already
     // identified. Any remaining should be cleaned up below.
     while (!DeadInsts.empty())
LoopUnrollResult llvm::UnrollLoop(
 
   if (RuntimeTripCount && TripMultiple % Count != 0 &&
       !UnrollRuntimeLoopRemainder(L, Count, AllowExpensiveTripCount,
                                   EpilogProfitability, UnrollRemainder, LI, SE,
                                   DT, AC, PreserveLCSSA)) {
     if (Force)
       RuntimeTripCount = false;
     else {
-      DEBUG(
-          dbgs() << "Wont unroll; remainder loop could not be generated"
+      DEBUG(dbgs() << "Won't unroll; remainder loop could not be generated "
                       "when assuming runtime trip count\n");
       return LoopUnrollResult::Unmodified;
     }
   }
 
   // If we know the trip count, we know the multiple...
   unsigned BreakoutTrip = 0;
   if (TripCount != 0) {
     BreakoutTrip = TripCount % Count;

lib/Transforms/Utils/LoopUnrollAndJam.cpp

+//===-- LoopUnrollAndJam.cpp - Loop unrolling utilities -------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file implements loop unroll and jam as a routine, much like
+// LoopUnroll.cpp implements loop unroll.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/ADT/SmallPtrSet.h"
+#include "llvm/ADT/Statistic.h"
+#include "llvm/Analysis/AssumptionCache.h"
+#include "llvm/Analysis/DependenceAnalysis.h"
+#include "llvm/Analysis/InstructionSimplify.h"
+#include "llvm/Analysis/LoopAnalysisManager.h"
+#include "llvm/Analysis/LoopIterator.h"
+#include "llvm/Analysis/LoopPass.h"
+#include "llvm/Analysis/OptimizationRemarkEmitter.h"
+#include "llvm/Analysis/ScalarEvolution.h"
+#include "llvm/Analysis/ScalarEvolutionExpander.h"
+#include "llvm/Analysis/Utils/Local.h"
+#include "llvm/IR/BasicBlock.h"
+#include "llvm/IR/DataLayout.h"
+#include "llvm/IR/DebugInfoMetadata.h"
+#include "llvm/IR/Dominators.h"
+#include "llvm/IR/IntrinsicInst.h"
+#include "llvm/IR/LLVMContext.h"
+#include "llvm/Support/Debug.h"
+#include "llvm/Support/raw_ostream.h"
+#include "llvm/Transforms/Utils/BasicBlockUtils.h"
+#include "llvm/Transforms/Utils/Cloning.h"
+#include "llvm/Transforms/Utils/LoopSimplify.h"
+#include "llvm/Transforms/Utils/LoopUtils.h"
+#include "llvm/Transforms/Utils/SimplifyIndVar.h"
+#include "llvm/Transforms/Utils/UnrollLoop.h"
+using namespace llvm;
+
+#define DEBUG_TYPE "loop-unroll-and-jam"
+
+STATISTIC(NumUnrolledAndJammed, "Number of loops unroll and jammed");
+STATISTIC(NumCompletelyUnrolledAndJammed, "Number of loops unroll and jammed");
+
+static bool containsBB(std::vector<BasicBlock *> &V, BasicBlock *BB) {
+  return std::find(V.begin(), V.end(), BB) != V.end();
+}
+
+// Partition blocks in an outer/inner loop pair into blocks before and after
+// the loop
+static bool partitionOuterLoopBlocks(Loop *L, Loop *SubLoop,
+                                     std::vector<BasicBlock *> &ForeBlocks,
+                                     std::vector<BasicBlock *> &SubLoopBlocks,
+                                     std::vector<BasicBlock *> &AftBlocks,
+                                     DominatorTree *DT) {
+  BasicBlock *SubLoopLatch = SubLoop->getLoopLatch();
+  SubLoopBlocks = SubLoop->getBlocks();
+
+  for (BasicBlock *BB : L->blocks()) {
+    if (!SubLoop->contains(BB)) {
+      if (DT->dominates(SubLoopLatch, BB))
+        AftBlocks.push_back(BB);
+      else
+        ForeBlocks.push_back(BB);
+    }
+  }
+
+  // Check that all blocks in ForeBlocks together dominate the subloop
+  // TODOD: This might ideally be done better with a dominator/postdominators.
+  BasicBlock *SubLoopPreHeader = SubLoop->getLoopPreheader();
+  for (BasicBlock *BB : ForeBlocks) {
+    if (BB == SubLoopPreHeader)
+      continue;
+    TerminatorInst *TI = BB->getTerminator();
+    for (unsigned i = 0, e = TI->getNumSuccessors(); i != e; ++i)
+      if (!containsBB(ForeBlocks, TI->getSuccessor(i)))
+        return false;
+  }
+
+  return true;
+}
+
+// Move the phi operands of Header from Latch out of AftBlocks to InsertLoc.
+static void
+moveHeaderPhiOperandsToForeBlocks(BasicBlock *Header, BasicBlock *Latch,
+                                  Instruction *InsertLoc,
+                                  std::vector<BasicBlock *> &AftBlocks) {
+  // We need to ensure we move the instructions in the correct order,
+  // starting with the earliest required instruction and moving forward.
+  std::vector<Instruction *> Worklist;
+  std::vector<Instruction *> Visited;
+  for (auto &Phi : Header->phis()) {
+    Value *V = Phi.getIncomingValueForBlock(Latch);
+    if (Instruction *I = dyn_cast<Instruction>(V))
+      Worklist.push_back(I);
+  }
+
+  while (!Worklist.empty()) {
+    Instruction *I = Worklist.back();
+    Worklist.pop_back();
+    if (!containsBB(AftBlocks, I->getParent()))
+      continue;
+
+    Visited.push_back(I);
+    for (auto &U : I->operands())
+      if (Instruction *II = dyn_cast<Instruction>(U))
+        Worklist.push_back(II);
+  }
+
+  // Move all instructions in program order to before the InsertLoc
+  BasicBlock *InsertLocBB = InsertLoc->getParent();
+  for (Instruction *I : reverse(Visited)) {
+    if (I->getParent() != InsertLocBB)
+      I->moveBefore(InsertLoc);
+  }
+}
+
+/*
+  This method performs Unroll and Jam. For a simple loop like:
+  for (i = ..)
+    Fore(i)
+    for (j = ..)
+      SubLoop(i, j)
+    Aft(i)
+
+  Instead of doing normal inner or outer unrolling, we do:
+  for (i = .., i+=2)
+    Fore(i)
+    Fore(i+1)
+    for (j = ..)
+      SubLoop(i, j)
+      SubLoop(i+1, j)
+    Aft(i)
+    Aft(i+1)
+
+  So the outer loop is essetially unrolled and then the inner loops are fused
+  ("jammed") together into a single loop. This can increase speed when there
+  are loads in SubLoop that are invariant to i, as they become shared between
+  the now jammed inner loops.
+
+  We do this by spliting the blocks in the loop into Fore, Subloop and Aft.
+  Fore blocks are those before the inner loop, Aft are those after. Normal
+  Unroll code is used to copy each of these sets of blocks and the results are
+  combined together into the final form above.
+
+  isSafeToUnrollAndJam should be used prior to calling this to make sure the
+  unrolling will be valid. Checking profitablility is also advisable.
+*/
+LoopUnrollResult
+llvm::UnrollAndJamLoop(Loop *L, unsigned Count, unsigned TripCount,
+                       unsigned TripMultiple, bool UnrollRemainder,
+                       LoopInfo *LI, ScalarEvolution *SE, DominatorTree *DT,
+                       AssumptionCache *AC, OptimizationRemarkEmitter *ORE) {
+
+  // When we enter here we should have already checked that it is safe
+  BasicBlock *Header = L->getHeader();
+  assert(L->getSubLoops().size() == 1);
+  Loop *SubLoop = *L->begin();
+
+  // Don't enter the unroll code if there is nothing to do.
+  if (TripCount == 0 && Count < 2) {
+    DEBUG(dbgs() << "Won't unroll; almost nothing to do\n");
+    return LoopUnrollResult::Unmodified;
+  }
+
+  assert(Count > 0);
+  assert(TripMultiple > 0);
+  assert(TripCount == 0 || TripCount % TripMultiple == 0);
+
+  // Are we eliminating the loop control altogether?
+  bool CompletelyUnroll = Count == TripCount;
+
+  // We use the runtime remainder in cases where we don't know trip multiple
+  if (TripMultiple == 1 || TripMultiple % Count != 0) {
+    if (!UnrollRuntimeLoopRemainder(L, Count, false /*AllowExpensiveTripCount*/,
+                                    /*UseEpilogRemainder*/ true,
+                                    UnrollRemainder, LI, SE, DT, AC, true)) {
+      DEBUG(dbgs() << "Won't unroll-and-jam; remainder loop could not be "
+                      "generated when assuming runtime trip count\n");
+      return LoopUnrollResult::Unmodified;
+    }
+  }
+
+  // Notify ScalarEvolution that the loop will be substantially changed,
+  // if not outright eliminated.
+  if (SE) {
+    SE->forgetLoop(L);
+    SE->forgetLoop(SubLoop);
+  }
+
+  using namespace ore;
+  // Report the unrolling decision.
+  if (CompletelyUnroll) {
+    DEBUG(dbgs() << "COMPLETELY UNROLL AND JAMMING loop %" << Header->getName()
+                 << " with trip count " << TripCount << "!\n");
+    ORE->emit(OptimizationRemark(DEBUG_TYPE, "FullyUnrolled", L->getStartLoc(),
+                                 L->getHeader())
+              << "completely unroll and jammed loop with "
+              << NV("UnrollCount", TripCount) << " iterations");
+  } else {
+    auto DiagBuilder = [&]() {
+      OptimizationRemark Diag(DEBUG_TYPE, "PartialUnrolled", L->getStartLoc(),
+                              L->getHeader());
+      return Diag << "unroll and jammed loop by a factor of "
+                  << NV("UnrollCount", Count);
+    };
+
+    DEBUG(dbgs() << "UNROLL AND JAMMING loop %" << Header->getName() << " by "
+                 << Count);
+    if (TripMultiple != 1) {
+      DEBUG(dbgs() << " with " << TripMultiple << " trips per branch");
+      ORE->emit([&]() {
+        return DiagBuilder() << " with " << NV("TripMultiple", TripMultiple)
+                             << " trips per branch";
+      });
+    } else {
+      DEBUG(dbgs() << " with run-time trip count");
+      ORE->emit([&]() { return DiagBuilder() << " with run-time trip count"; });
+    }
+    DEBUG(dbgs() << "!\n");
+  }
+
+  BasicBlock *Preheader = L->getLoopPreheader();
+  BasicBlock *LatchBlock = L->getLoopLatch();
+  BranchInst *BI = dyn_cast<BranchInst>(LatchBlock->getTerminator());
+  assert(Preheader && LatchBlock && Header);
+  assert(BI && !BI->isUnconditional());
+  bool ContinueOnTrue = L->contains(BI->getSuccessor(0));
+  BasicBlock *LoopExit = BI->getSuccessor(ContinueOnTrue);
+  bool SubLoopContinueOnTrue = SubLoop->contains(
+      SubLoop->getLoopLatch()->getTerminator()->getSuccessor(0));
+
+  // Partition blocks in an outer/inner loop pair into blocks before and after
+  // the loop
+  std::vector<BasicBlock *> SubLoopBlocks;
+  std::vector<BasicBlock *> ForeBlocks;
+  std::vector<BasicBlock *> AftBlocks;
+  partitionOuterLoopBlocks(L, SubLoop, ForeBlocks, SubLoopBlocks, AftBlocks,
+                           DT);
+
+  // We keep track of the entering/first and exiting/last block of each
+  // of Fore/SubLoop/Aft in each iteration. This helps make the stapling up of
+  // blocks easier.
+  std::vector<BasicBlock *> ForeBlocksFirst;
+  std::vector<BasicBlock *> ForeBlocksLast;
+  std::vector<BasicBlock *> SubLoopBlocksFirst;
+  std::vector<BasicBlock *> SubLoopBlocksLast;
+  std::vector<BasicBlock *> AftBlocksFirst;
+  std::vector<BasicBlock *> AftBlocksLast;
+  ForeBlocksFirst.push_back(Header);
+  ForeBlocksLast.push_back(SubLoop->getLoopPreheader());
+  SubLoopBlocksFirst.push_back(SubLoop->getHeader());
+  SubLoopBlocksLast.push_back(SubLoop->getExitingBlock());
+  AftBlocksFirst.push_back(SubLoop->getExitBlock());
+  AftBlocksLast.push_back(L->getExitingBlock());
+  // Maps Blocks[0] -> Blocks[It]
+  ValueToValueMapTy LastValueMap;
+
+  // Move any instructions from fore phi operands from AftBlocks into Fore.
+  moveHeaderPhiOperandsToForeBlocks(
+      Header, LatchBlock, SubLoop->getLoopPreheader()->getTerminator(),
+      AftBlocks);
+
+  // The current on-the-fly SSA update requires blocks to be processed in
+  // reverse postorder so that LastValueMap contains the correct value at each
+  // exit.
+  LoopBlocksDFS DFS(L);
+  DFS.perform(LI);
+  // Stash the DFS iterators before adding blocks to the loop.
+  LoopBlocksDFS::RPOIterator BlockBegin = DFS.beginRPO();
+  LoopBlocksDFS::RPOIterator BlockEnd = DFS.endRPO();
+
+  if (Header->getParent()->isDebugInfoForProfiling())
+    for (BasicBlock *BB : L->getBlocks())
+      for (Instruction &I : *BB)
+        if (!isa<DbgInfoIntrinsic>(&I))
+          if (const DILocation *DIL = I.getDebugLoc())
+            I.setDebugLoc(DIL->cloneWithDuplicationFactor(Count));
+
+  // Copy all blocks
+  for (unsigned It = 1; It != Count; ++It) {
+    std::vector<BasicBlock *> NewBlocks;
+    // Maps Blocks[It] -> Blocks[It-1]
+    DenseMap<Value *, Value *> PrevItValueMap;
+
+    for (LoopBlocksDFS::RPOIterator BB = BlockBegin; BB != BlockEnd; ++BB) {
+      ValueToValueMapTy VMap;
+      BasicBlock *New = CloneBasicBlock(*BB, VMap, "." + Twine(It));
+      Header->getParent()->getBasicBlockList().push_back(New);
+
+      if (containsBB(ForeBlocks, *BB)) {
+        L->addBasicBlockToLoop(New, *LI);
+
+        if (*BB == ForeBlocksFirst[0])
+          ForeBlocksFirst.push_back(New);
+        if (*BB == ForeBlocksLast[0])
+          ForeBlocksLast.push_back(New);
+      } else if (containsBB(SubLoopBlocks, *BB)) {
+        SubLoop->addBasicBlockToLoop(New, *LI);
+
+        if (*BB == SubLoopBlocksFirst[0])
+          SubLoopBlocksFirst.push_back(New);
+        if (*BB == SubLoopBlocksLast[0])
+          SubLoopBlocksLast.push_back(New);
+      } else if (containsBB(AftBlocks, *BB)) {
+        L->addBasicBlockToLoop(New, *LI);
+
+        if (*BB == AftBlocksFirst[0])
+          AftBlocksFirst.push_back(New);
+        if (*BB == AftBlocksLast[0])
+          AftBlocksLast.push_back(New);
+      } else {
+        llvm_unreachable("BB being cloned should be in Fore/Sub/Aft");
+      }
+
+      // Update our running maps of newest clones
+      PrevItValueMap[New] = (It == 1 ? *BB : LastValueMap[*BB]);
+      LastValueMap[*BB] = New;
+      for (ValueToValueMapTy::iterator VI = VMap.begin(), VE = VMap.end();
+           VI != VE; ++VI) {
+        PrevItValueMap[VI->second] =
+            const_cast<Value *>(It == 1 ? VI->first : LastValueMap[VI->first]);
+        LastValueMap[VI->first] = VI->second;
+      }
+
+      NewBlocks.push_back(New);
+
+      // Update DomTree:
+      if (*BB == ForeBlocksFirst[0])
+        DT->addNewBlock(New, ForeBlocksLast[It - 1]);
+      else if (*BB == SubLoopBlocksFirst[0])
+        DT->addNewBlock(New, SubLoopBlocksLast[It - 1]);
+      else if (*BB == AftBlocksFirst[0])
+        DT->addNewBlock(New, AftBlocksLast[It - 1]);
+      else {
+        // Each set of blocks (Fore/Sub/Aft) will have the same
+        // internal domtree structure.
+        auto BBDomNode = DT->getNode(*BB);
+        auto BBIDom = BBDomNode->getIDom();
+        BasicBlock *OriginalBBIDom = BBIDom->getBlock();
+        assert(OriginalBBIDom);
+        assert(LastValueMap[cast<Value>(OriginalBBIDom)]);
+        DT->addNewBlock(
+            New, cast<BasicBlock>(LastValueMap[cast<Value>(OriginalBBIDom)]));
+      }
+    }
+
+    // Remap all instructions in the most recent iteration
+    for (BasicBlock *NewBlock : NewBlocks) {
+      for (Instruction &I : *NewBlock) {
+        ::remapInstruction(&I, LastValueMap);
+        if (auto *II = dyn_cast<IntrinsicInst>(&I))
+          if (II->getIntrinsicID() == Intrinsic::assume)
+            AC->registerAssumption(II);
+      }
+    }
+
+    // Alter the ForeBlocks phi's, pointing them at the latest version of the
+    // value from the previous iteration's phis
+    for (PHINode &Phi : ForeBlocksFirst[It]->phis()) {
+      Value *OldValue = Phi.getIncomingValueForBlock(AftBlocksLast[It]);
+      assert(OldValue && "should have incoming edge from Aft[It]");
+      Value *NewValue = OldValue;
+      if (Value *PrevValue = PrevItValueMap[OldValue])
+        NewValue = PrevValue;
+
+      assert(Phi.getNumOperands() == 2);
+      Phi.setIncomingBlock(0, ForeBlocksLast[It - 1]);
+      Phi.setIncomingValue(0, NewValue);
+      Phi.removeIncomingValue(1);
+    }
+  }
+
+  // Now that all the basic blocks for the unrolled iterations are in place,
+  // finish up connecting the blocks and phi nodes. At this point LastValueMap
+  // is the last unrolled iterations values.
+
+  // Update Phis in BB from OldBB to point to NewBB
+  auto updatePHIBlocks = [](BasicBlock *BB, BasicBlock *OldBB,
+                            BasicBlock *NewBB) {
+    for (PHINode &Phi : BB->phis()) {
+      int I = Phi.getBasicBlockIndex(OldBB);
+      Phi.setIncomingBlock(I, NewBB);
+    }
+  };
+  // Update Phis in BB from OldBB to point to NewBB and use the latest value
+  // from LastValueMap
+  auto updatePHIBlocksAndValues = [](BasicBlock *BB, BasicBlock *OldBB,
+                                     BasicBlock *NewBB,
+                                     ValueToValueMapTy &LastValueMap) {
+    for (PHINode &Phi : BB->phis()) {
+      for (unsigned b = 0; b < Phi.getNumIncomingValues(); ++b) {
+        if (Phi.getIncomingBlock(b) == OldBB) {
+          Value *OldValue = Phi.getIncomingValue(b);
+          if (Value *LastValue = LastValueMap[OldValue]) {
+            Phi.setIncomingValue(b, LastValue);
+          }
+          Phi.setIncomingBlock(b, NewBB);
+          break;
+        }
+      }
+    }
+  };
+  // Move all the phis from Src into Dest
+  auto movePHIs = [](BasicBlock *Src, BasicBlock *Dest) {
+    Instruction *insertPoint = Dest->getFirstNonPHI();
+    while (PHINode *Phi = dyn_cast<PHINode>(Src->begin()))
+      Phi->moveBefore(insertPoint);
+  };
+
+  // Update the PHI values outside the loop to point to the last block
+  updatePHIBlocksAndValues(LoopExit, AftBlocksLast[0], AftBlocksLast.back(),
+                           LastValueMap);
+
+  // Update ForeBlocks successors and phi nodes
+  BranchInst *ForeTerm =
+      cast<BranchInst>(ForeBlocksLast.back()->getTerminator());
+  BasicBlock *Dest = SubLoopBlocksFirst[0];
+  ForeTerm->setSuccessor(0, Dest);
+
+  if (CompletelyUnroll) {
+    while (PHINode *Phi = dyn_cast<PHINode>(ForeBlocksFirst[0]->begin())) {
+      Phi->replaceAllUsesWith(Phi->getIncomingValueForBlock(Preheader));
+      Phi->getParent()->getInstList().erase(Phi);
+    }
+  } else {
+    // Update the PHI values to point to the last aft block
+    updatePHIBlocksAndValues(ForeBlocksFirst[0], AftBlocksLast[0],
+                             AftBlocksLast.back(), LastValueMap);
+  }
+
+  for (unsigned It = 1; It < Count; It++) {
+    // Remap ForeBlock successors from previous iteration to this
+    BranchInst *ForeTerm =
+        cast<BranchInst>(ForeBlocksLast[It - 1]->getTerminator());
+    BasicBlock *Dest = ForeBlocksFirst[It];
+    ForeTerm->setSuccessor(0, Dest);
+  }
+
+  // Subloop successors and phis
+  BranchInst *SubTerm =
+      cast<BranchInst>(SubLoopBlocksLast.back()->getTerminator());
+  SubTerm->setSuccessor(!SubLoopContinueOnTrue, SubLoopBlocksFirst[0]);
+  SubTerm->setSuccessor(SubLoopContinueOnTrue, AftBlocksFirst[0]);
+  updatePHIBlocks(SubLoopBlocksFirst[0], ForeBlocksLast[0],
+                  ForeBlocksLast.back());
+  updatePHIBlocks(SubLoopBlocksFirst[0], SubLoopBlocksLast[0],
+                  SubLoopBlocksLast.back());
+
+  for (unsigned It = 1; It < Count; It++) {
+    // Replace the conditional branch of the previous iteration subloop
+    // with an unconditional one to this one
+    BranchInst *SubTerm =
+        cast<BranchInst>(SubLoopBlocksLast[It - 1]->getTerminator());
+    BranchInst::Create(SubLoopBlocksFirst[It], SubTerm);
+    SubTerm->eraseFromParent();
+
+    updatePHIBlocks(SubLoopBlocksFirst[It], ForeBlocksLast[It],
+                    ForeBlocksLast.back());
+    updatePHIBlocks(SubLoopBlocksFirst[It], SubLoopBlocksLast[It],
+                    SubLoopBlocksLast.back());
+    movePHIs(SubLoopBlocksFirst[It], SubLoopBlocksFirst[0]);
+  }
+
+  // Aft blocks successors and phis
+  if (CompletelyUnroll) {
+    BranchInst *Term = cast<BranchInst>(AftBlocksLast.back()->getTerminator());
+    BranchInst::Create(LoopExit, Term);
+    Term->eraseFromParent();
+  } else {
+    BranchInst *Term = cast<BranchInst>(AftBlocksLast.back()->getTerminator());
+    Term->setSuccessor(!ContinueOnTrue, ForeBlocksFirst[0]);
+  }
+  updatePHIBlocks(AftBlocksFirst[0], SubLoopBlocksLast[0],
+                  SubLoopBlocksLast.back());
+
+  for (unsigned It = 1; It < Count; It++) {
+    // Replace the conditional branch of the previous iteration subloop
+    // with an unconditional one to this one
+    BranchInst *AftTerm =
+        cast<BranchInst>(AftBlocksLast[It - 1]->getTerminator());
+    BranchInst::Create(AftBlocksFirst[It], AftTerm);
+    AftTerm->eraseFromParent();
+
+    updatePHIBlocks(AftBlocksFirst[It], SubLoopBlocksLast[It],
+                    SubLoopBlocksLast.back());
+    movePHIs(AftBlocksFirst[It], AftBlocksFirst[0]);
+  }
+
+  // Dominator Tree. Remove the old links between Fore, Sub and Aft, adding the
+  // new ones required.
+  if (Count != 1) {
+    SmallVector<DominatorTree::UpdateType, 4> DTUpdates;
+    DTUpdates.emplace_back(DominatorTree::UpdateKind::Delete, ForeBlocksLast[0],
+                           SubLoopBlocksFirst[0]);
+    DTUpdates.emplace_back(DominatorTree::UpdateKind::Delete,
+                           SubLoopBlocksLast[0], AftBlocksFirst[0]);
+
+    DTUpdates.emplace_back(DominatorTree::UpdateKind::Insert,
+                           ForeBlocksLast.back(), SubLoopBlocksFirst[0]);
+    DTUpdates.emplace_back(DominatorTree::UpdateKind::Insert,
+                           SubLoopBlocksLast.back(), AftBlocksFirst[0]);
+    DT->applyUpdates(DTUpdates);
+  }
+
+  // Merge adjacent basic blocks, if possible.
+  SmallPtrSet<BasicBlock *, 16> MergeBlocks;
+  MergeBlocks.insert(ForeBlocksLast.begin(), ForeBlocksLast.end());
+  MergeBlocks.insert(SubLoopBlocksLast.begin(), SubLoopBlocksLast.end());
+  MergeBlocks.insert(AftBlocksLast.begin(), AftBlocksLast.end());
+  while (!MergeBlocks.empty()) {
+    BasicBlock *BB = *MergeBlocks.begin();
+    BranchInst *Term = dyn_cast<BranchInst>(BB->getTerminator());
+    if (Term && Term->isUnconditional() && L->contains(Term->getSuccessor(0))) {
+      BasicBlock *Dest = Term->getSuccessor(0);
+      if (BasicBlock *Fold = foldBlockIntoPredecessor(Dest, LI, SE, DT)) {
+        // Don't remove BB and add Fold as they are the same BB
+        assert(Fold == BB);
+        MergeBlocks.erase(Dest);
+      } else
+        MergeBlocks.erase(BB);
+    } else
+      MergeBlocks.erase(BB);
+  }
+
+  // At this point, the code is well formed.  We now do a quick sweep over the
+  // inserted code, doing constant propagation and dead code elimination as we
+  // go.
+  simplifyLoopAfterUnroll(SubLoop, true, LI, SE, DT, AC);
+  simplifyLoopAfterUnroll(L, !CompletelyUnroll && Count > 1, LI, SE, DT, AC);
+
+  NumCompletelyUnrolledAndJammed += CompletelyUnroll;
+  ++NumUnrolledAndJammed;
+
+  Loop *OuterL = L->getParentLoop();
+  // Update LoopInfo if the loop is completely removed.
+  if (CompletelyUnroll)
+    LI->erase(L);
+
+  // We shouldn't have done anything to break loop simplify form or LCSSA.
+  Loop *OutestLoop = OuterL ? OuterL : (!CompletelyUnroll ? L : SubLoop);
+  assert(OutestLoop->isRecursivelyLCSSAForm(*DT, *LI));
+  if (!CompletelyUnroll)
+    assert(L->isLoopSimplifyForm());
+  assert(SubLoop->isLoopSimplifyForm());
+  assert(DT->verify());
+
+  return CompletelyUnroll ? LoopUnrollResult::FullyUnrolled
+                          : LoopUnrollResult::PartiallyUnrolled;
+}
+
+static bool getLoadsAndStores(std::vector<BasicBlock *> &Blocks,
+                              SmallVector<Value *, 4> &MemInstr) {
+  // Scan the BBs and collect legal loads and stores.
+  // Returns false if non-simple loads/stores are found.
+  for (BasicBlock *BB : Blocks) {
+    for (Instruction &I : *BB) {
+      if (auto *Ld = dyn_cast<LoadInst>(&I)) {
+        if (!Ld->isSimple())
+          return false;
+        MemInstr.push_back(&I);
+      } else if (auto *St = dyn_cast<StoreInst>(&I)) {
+        if (!St->isSimple())
+          return false;
+        MemInstr.push_back(&I);
+      } else if (I.mayReadOrWriteMemory()) {
+        return false;
+      }
+    }
+  }
+  return true;
+}
+
+static bool checkDependencies(SmallVector<Value *, 4> &Earlier,
+                              SmallVector<Value *, 4> &Later,
+                              unsigned LoopDepth, DependenceInfo &DI) {
+  // Use DA to check for dependencies between loads and
+  // stores that make unroll and jam invalid
+  for (Value *I : Earlier) {
+    for (Value *J : Later) {
+      Instruction *Src = cast<Instruction>(I);
+      Instruction *Dst = cast<Instruction>(J);
+      if (Src == Dst)
+        continue;
+      // Ignore Input dependencies.
+      if (isa<LoadInst>(Src) && isa<LoadInst>(Dst))
+        continue;
+
+      // Track dependencies, and if we find them take a conservative approach
+      // by allowing only = or > (not <), altough some < would be safe
+      // (depending upon unroll width).
+      // FIXME: Allow < so long as distance is less than unroll width
+      if (auto D = DI.depends(Src, Dst, true)) {
+        assert(D->isOrdered() && "Expected an output, flow or anti dep.");
+        unsigned Levels = D->getLevels();
+
+        if (D->isConfused())
+          return false;
+        for (unsigned II = LoopDepth; II <= Levels; ++II) {
+          const SCEV *Distance = D->getDistance(II);
+          const SCEVConstant *SCEVConst =
+              dyn_cast_or_null<SCEVConstant>(Distance);
+          if (SCEVConst) {
+            const ConstantInt *CI = SCEVConst->getValue();
+            if (CI->isNegative())
+              return false;
+          } else
+            return false;
+        }
+      }
+    }
+  }
+  return true;
+}
+
+static bool checkDependencies(Loop *L, std::vector<BasicBlock *> &ForeBlocks,
+                              std::vector<BasicBlock *> &SubLoopBlocks,
+                              std::vector<BasicBlock *> &AftBlocks,
+                              DependenceInfo &DI) {
+  // TODOD This needs to properly treat anything outside the outer loop as
+  //   loop-invariant in the dependency checks.
+  // Get all loads/store pairs for each blocks
+  SmallVector<Value *, 4> ForeMemInstr;
+  SmallVector<Value *, 4> SubLoopMemInstr;
+  SmallVector<Value *, 4> AftMemInstr;
+  if (!getLoadsAndStores(ForeBlocks, ForeMemInstr) ||
+      !getLoadsAndStores(SubLoopBlocks, SubLoopMemInstr) ||
+      !getLoadsAndStores(AftBlocks, AftMemInstr))
+    return false;
+
+  // Check for dependencies between any blocks that may change order
+  unsigned LoopDepth = L->getLoopDepth();
+  return checkDependencies(ForeMemInstr, SubLoopMemInstr, LoopDepth, DI) &&
+         checkDependencies(ForeMemInstr, AftMemInstr, LoopDepth, DI) &&
+         checkDependencies(SubLoopMemInstr, AftMemInstr, LoopDepth, DI) &&
+         checkDependencies(SubLoopMemInstr, SubLoopMemInstr, LoopDepth + 1, DI);
+}
+
+bool llvm::isSafeToUnrollAndJam(Loop *L, ScalarEvolution &SE, DominatorTree &DT,
+                                DependenceInfo &DI) {
+  /* We currently handle outer loops like this:
+        |
+    ForeFirst    <----\    }
+     Blocks           |    } ForeBlocks
+    ForeLast          |    }
+        |             |
+    SubLoopFirst  <\  |    }
+     Blocks        |  |    } SubLoopBlocks
+    SubLoopLast   -/  |    }
+        |             |
+    AftFirst          |    }
+     Blocks           |    } AftBlocks
+    AftLast     ------/    }
+        |
+
+    There are (theoretically) any number of blocks in ForeBlocks, SubLoopBlocks
+    and AftBlocks, providing that there is one edge from Fores to SubLoops,
+    one edge from SubLoops to Afts and a single outer loop exit (from Afts).
+    In practice we currently limit Aft blocks to a single block, and limit
+    things further in the profitablility checks of the unroll and jam pass.
+
+    Because of the way we rearrange basic blocks, we also require that
+    the Fore blocks on all unrolled iterations are safe to move before the
+    SubLoop blocks of all iterations. So we require that the phi node looping
+    operands of ForeHeader can be moved to at least the end of ForeEnd, so that
+    we can arrange cloned Fore Blocks before the subloop and match up Phi's
+    correctly.
+
+    i.e. The old order of blocks used to be F1 S1 S1 S1 A1 F2 S2 S2 S2 A2.
+    It needs to be safe to tranform this to F1 F2 S1 S2 S1 S2 S1 S2 A1 A2.
+
+    There are then a number of checks along the lines of no calls, no
+    exceptions, inner loop IV is consistent, etc.
+  */
+
+  if (!L->isLoopSimplifyForm() || L->getSubLoops().size() != 1)
+    return false;
+  Loop *SubLoop = L->getSubLoops()[0];
+  if (!SubLoop->isLoopSimplifyForm())
+    return false;
+
+  BasicBlock *PreHeader = L->getLoopPreheader();
+  BasicBlock *Header = L->getHeader();
+  BasicBlock *Latch = L->getLoopLatch();
+  BasicBlock *Exit = L->getExitingBlock();
+  BasicBlock *SubLoopHeader = SubLoop->getHeader();
+  BasicBlock *SubLoopLatch = SubLoop->getLoopLatch();
+  BasicBlock *SubLoopExit = SubLoop->getExitingBlock();
+
+  if (Latch != Exit)
+    return false;
+  if (SubLoopLatch != SubLoopExit)
+    return false;
+
+  if (Header->hasAddressTaken() || SubLoopHeader->hasAddressTaken())
+    return false;
+
+  // Split blocks into Fore/SubLoop/Aft based on dominators
+  std::vector<BasicBlock *> SubLoopBlocks;
+  std::vector<BasicBlock *> ForeBlocks;
+  std::vector<BasicBlock *> AftBlocks;
+  if (!partitionOuterLoopBlocks(L, SubLoop, ForeBlocks, SubLoopBlocks,
+                                AftBlocks, &DT))
+    return false;
+
+  // Aft blocks may need to move instructions to fore blocks, which
+  // becomes more difficult if there are multiple (potentially conditionally
+  // executed) blocks. For now we just exclude loops with multiple aft blocks.
+  if (AftBlocks.size() != 1)
+    return false;
+
+  // Check outer loop IV is easily calcable
+  const SCEV *BECountSC = SE.getExitCount(L, Latch);
+  if (isa<SCEVCouldNotCompute>(BECountSC) ||
+      !BECountSC->getType()->isIntegerTy())
+    return false;
+  // Add 1 since the backedge count doesn't include the first loop iteration.
+  const SCEV *TripCountSC =
+      SE.getAddExpr(BECountSC, SE.getConstant(BECountSC->getType(), 1));
+  if (isa<SCEVCouldNotCompute>(TripCountSC))
+    return false;
+  BranchInst *PreHeaderBR = cast<BranchInst>(PreHeader->getTerminator());
+  const DataLayout &DL = Header->getModule()->getDataLayout();
+  SCEVExpander Expander(SE, DL, "loop-unroll");
+  if (Expander.isHighCostExpansion(TripCountSC, L, PreHeaderBR))
+    return false;
+
+  // Check inner loop IV is consistent between all iterations
+  const SCEV *SubLoopBECountSC = SE.getExitCount(SubLoop, SubLoopLatch);
+  if (isa<SCEVCouldNotCompute>(SubLoopBECountSC) ||
+      !SubLoopBECountSC->getType()->isIntegerTy())
+    return false;
+  ScalarEvolution::LoopDisposition LD =
+      SE.getLoopDisposition(SubLoopBECountSC, L);
+  if (LD != ScalarEvolution::LoopInvariant)
+    return false;
+
+  // Check the loop safety info for exceptions.
+  LoopSafetyInfo LSI;
+  computeLoopSafetyInfo(&LSI, L);
+  if (LSI.MayThrow)
+    return false;
+
+  // We've ruled out the easy stuff, and need to check that there
+  // are no interdependencies which may prevent us from moving
+  // the:
+  //  ForeBlocks before Subloop and AftBlocks.
+  //  Subloop before AftBlocks.
+  //  ForeBlock phi operands before the subloop
+
+  // Make sure we can move all instructions we need to before the subloop
+  SmallVector<Instruction *, 8> Worklist;
+  SmallPtrSet<Instruction *, 8> Visited;
+  for (auto &Phi : Header->phis()) {
+    Value *V = Phi.getIncomingValueForBlock(Latch);
+    if (Instruction *I = dyn_cast<Instruction>(V))
+      Worklist.push_back(I);
+  }
+  while (!Worklist.empty()) {
+    Instruction *I = Worklist.back();
+    Worklist.pop_back();
+    if (Visited.insert(I).second) {
+      if (SubLoop->contains(I->getParent()))
+        return false;
+      if (containsBB(AftBlocks, I->getParent())) {
+        // If we hit a phi node in afts we know we are done (probably LCSSA)
+        if (isa<PHINode>(I))
+          return false;
+        if (I->mayHaveSideEffects() || I->mayReadOrWriteMemory())
+          return false;
+        for (auto &U : I->operands())
+          if (Instruction *II = dyn_cast<Instruction>(U))
+            Worklist.push_back(II);
+      }
+    }
+  }
+
+  // Check for memory dependencies which prohibit the unrolling
+  // we are doing. Because of the way we are unrolling Fore/Sub/Aft
+  // blocks, we need to check there are no dependencies between
+  // Fore-Sub, Fore-Aft, Sub-Aft and Sub-Sub.
+  if (!checkDependencies(L, ForeBlocks, SubLoopBlocks, AftBlocks, DI))
+    return false;
+
+  return true;
+}

test/Transforms/LoopUnrollAndJam/disable.ll

+; RUN: opt -loop-unroll-and-jam -unroll-and-jam-count=4 -pass-remarks=loop-unroll-and-jam < %s -S 2>&1 | FileCheck %s
+
+target datalayout = "e-m:e-p:32:32-i64:64-v128:64:128-a:0:32-n32-S64"
+target triple = "thumbv8m.main-arm-none-eabi"
+
+;; Common check for all tests. None should be unroll and jammed
+; CHECK-NOT: remark: {{.*}} unroll and jammed
+
+
+; CHECK-LABEL: disabled1
+; Tests for(i) { sum = A[i]; for(j) sum += B[j]; A[i+1] = sum; }
+; A[i] to A[i+1] dependency should block unrollandjam
+define void @disabled1(i32 %I, i32 %J, i32* noalias nocapture %A, i32* noalias nocapture readonly %B) local_unnamed_addr #0 {
+; CHECK: %i.029 = phi i32 [ %add10, %for.latch ], [ 0, %for.preheader ]
+; CHECK: %j.026 = phi i32 [ 0, %for.outer ], [ %inc, %for.inner ]
+entry:
+  %cmp = icmp ne i32 %J, 0
+  %cmp127 = icmp ne i32 %I, 0
+  %or.cond = and i1 %cmp127, %cmp
+  br i1 %or.cond, label %for.preheader, label %return
+
+for.preheader:
+  br label %for.outer
+
+for.outer:
+  %i.029 = phi i32 [ %add10, %for.latch ], [ 0, %for.preheader ]
+  %b.028 = phi i32 [ %inc8, %for.latch ], [ 1, %for.preheader ]
+  %arrayidx = getelementptr inbounds i32, i32* %A, i32 %i.029
+  %0 = load i32, i32* %arrayidx, align 4, !tbaa !5
+  br label %for.inner
+
+for.inner:
+  %j.026 = phi i32 [ 0, %for.outer ], [ %inc, %for.inner ]
+  %sum1.025 = phi i32 [ %0, %for.outer ], [ %add, %for.inner ]
+  %arrayidx6 = getelementptr inbounds i32, i32* %B, i32 %j.026
+  %1 = load i32, i32* %arrayidx6, align 4, !tbaa !5
+  %add = add i32 %1, %sum1.025
+  %inc = add nuw i32 %j.026, 1
+  %exitcond = icmp eq i32 %inc, %J
+  br i1 %exitcond, label %for.latch, label %for.inner
+
+for.latch:
+  %arrayidx7 = getelementptr inbounds i32, i32* %A, i32 %b.028
+  store i32 %add, i32* %arrayidx7, align 4, !tbaa !5
+  %inc8 = add nuw nsw i32 %b.028, 1
+  %add10 = add nuw nsw i32 %i.029, 1
+  %exitcond30 = icmp eq i32 %add10, %I
+  br i1 %exitcond30, label %return, label %for.outer
+
+return:
+  ret void
+}
+
+
+; CHECK-LABEL: disabled2
+; Tests an incompatible block layout (for.outer jumps past for.inner)
+; FIXME: Make this work
+define void @disabled2(i32 %I, i32 %J, i32* noalias nocapture %A, i32* noalias nocapture readonly %B) local_unnamed_addr #0 {
+; CHECK: %i.032 = phi i32 [ %add13, %for.latch ], [ 0, %for.preheader ]
+; CHECK: %j.030 = phi i32 [ %inc, %for.inner ], [ 0, %for.inner.preheader ]
+entry:
+  %cmp = icmp ne i32 %J, 0
+  %cmp131 = icmp ne i32 %I, 0
+  %or.cond = and i1 %cmp131, %cmp
+  br i1 %or.cond, label %for.preheader, label %for.end14
+
+for.preheader:
+  br label %for.outer
+
+for.outer:
+  %i.032 = phi i32 [ %add13, %for.latch ], [ 0, %for.preheader ]
+  %arrayidx = getelementptr inbounds i32, i32* %B, i32 %i.032
+  %0 = load i32, i32* %arrayidx, align 4, !tbaa !5
+  %tobool = icmp eq i32 %0, 0
+  br i1 %tobool, label %for.latch, label %for.inner
+
+for.inner:
+  %j.030 = phi i32 [ %inc, %for.inner ], [ 0, %for.outer ]
+  %sum1.029 = phi i32 [ %sum1.1, %for.inner ], [ 0, %for.outer ]
+  %arrayidx6 = getelementptr inbounds i32, i32* %B, i32 %j.030
+  %1 = load i32, i32* %arrayidx6, align 4, !tbaa !5
+  %tobool7 = icmp eq i32 %1, 0
+  %sub = add i32 %sum1.029, 10
+  %add = sub i32 %sub, %1
+  %sum1.1 = select i1 %tobool7, i32 %sum1.029, i32 %add
+  %inc = add nuw i32 %j.030, 1
+  %exitcond = icmp eq i32 %inc, %J
+  br i1 %exitcond, label %for.latch, label %for.inner
+
+for.latch:
+  %sum1.1.lcssa = phi i32 [ 0, %for.outer ], [ %sum1.1, %for.inner ]
+  %arrayidx11 = getelementptr inbounds i32, i32* %A, i32 %i.032
+  store i32 %sum1.1.lcssa, i32* %arrayidx11, align 4, !tbaa !5
+  %add13 = add nuw i32 %i.032, 1
+  %exitcond33 = icmp eq i32 %add13, %I
+  br i1 %exitcond33, label %for.end14, label %for.outer
+
+for.end14:
+  ret void
+}
+
+
+
+; CHECK-LABEL: disabled3
+; Tests loop carry dependencies in an array S
+define void @disabled3(i32 %I, i32 %J, i32* noalias nocapture %A, i32* noalias nocapture readonly %B) local_unnamed_addr #0 {
+; CHECK: %i.029 = phi i32 [ 0, %for.preheader ], [ %add12, %for.latch ]
+; CHECK: %j.027 = phi i32 [ 0, %for.outer ], [ %inc, %for.inner ]
+entry:
+  %S = alloca [4 x i32], align 4
+  %cmp = icmp eq i32 %J, 0
+  br i1 %cmp, label %return, label %if.end
+
+if.end:
+  %0 = bitcast [4 x i32]* %S to i8*
+  call void @llvm.lifetime.start.p0i8(i64 16, i8* nonnull %0) #2
+  %cmp128 = icmp eq i32 %I, 0
+  br i1 %cmp128, label %for.cond.cleanup, label %for.preheader
+
+for.preheader:
+  %arrayidx9 = getelementptr inbounds [4 x i32], [4 x i32]* %S, i32 0, i32 0
+  br label %for.outer
+
+for.cond.cleanup:
+  call void @llvm.lifetime.end.p0i8(i64 16, i8* nonnull %0) #2
+  br label %return
+
+for.outer:
+  %i.029 = phi i32 [ 0, %for.preheader ], [ %add12, %for.latch ]
+  br label %for.inner
+
+for.inner:
+  %j.027 = phi i32 [ 0, %for.outer ], [ %inc, %for.inner ]
+  %arrayidx = getelementptr inbounds i32, i32* %B, i32 %j.027
+  %l2 = load i32, i32* %arrayidx, align 4, !tbaa !5
+  %add = add i32 %j.027, %i.029
+  %rem = urem i32 %add, %J
+  %arrayidx6 = getelementptr inbounds i32, i32* %B, i32 %rem
+  %l3 = load i32, i32* %arrayidx6, align 4, !tbaa !5
+  %mul = mul i32 %l3, %l2
+  %rem7 = urem i32 %j.027, 3
+  %arrayidx8 = getelementptr inbounds [4 x i32], [4 x i32]* %S, i32 0, i32 %rem7
+  store i32 %mul, i32* %arrayidx8, align 4, !tbaa !5
+  %inc = add nuw i32 %j.027, 1
+  %exitcond = icmp eq i32 %inc, %J
+  br i1 %exitcond, label %for.latch, label %for.inner
+
+for.latch:
+  %l1 = load i32, i32* %arrayidx9, align 4, !tbaa !5
+  %arrayidx10 = getelementptr inbounds i32, i32* %A, i32 %i.029
+  store i32 %l1, i32* %arrayidx10, align 4, !tbaa !5
+  %add12 = add nuw i32 %i.029, 1
+  %exitcond31 = icmp eq i32 %add12, %I
+  br i1 %exitcond31, label %for.cond.cleanup, label %for.outer
+
+return:
+  ret void
+}
+
+
+; CHECK-LABEL: disabled4
+; Inner looop induction variable in not consistent
+; ie for(i = 0..n) for (j = 0..i) sum+=B[j]
+define void @disabled4(i32 %I, i32 %J, i32* noalias nocapture %A, i32* noalias nocapture readonly %B) local_unnamed_addr #0 {
+; CHECK: %indvars.iv = phi i32 [ %indvars.iv.next, %for.latch ], [ 1, %for.preheader ]
+; CHECK: %j.021 = phi i32 [ 0, %for.outer ], [ %inc, %for.inner ]
+entry:
+  %cmp = icmp ne i32 %J, 0
+  %cmp122 = icmp ugt i32 %I, 1
+  %or.cond = and i1 %cmp122, %cmp
+  br i1 %or.cond, label %for.preheader, label %for.end9
+
+for.preheader:
+  br label %for.outer
+
+for.outer:
+  %indvars.iv = phi i32 [ %indvars.iv.next, %for.latch ], [ 1, %for.preheader ]
+  br label %for.inner
+
+for.inner:
+  %j.021 = phi i32 [ 0, %for.outer ], [ %inc, %for.inner ]
+  %sum1.020 = phi i32 [ 0, %for.outer ], [ %add, %for.inner ]
+  %arrayidx = getelementptr inbounds i32, i32* %B, i32 %j.021
+  %0 = load i32, i32* %arrayidx, align 4, !tbaa !5
+  %add = add i32 %0, %sum1.020
+  %inc = add nuw i32 %j.021, 1
+  %exitcond = icmp eq i32 %inc, %indvars.iv
+  br i1 %exitcond, label %for.latch, label %for.inner
+
+for.latch:
+  %arrayidx6 = getelementptr inbounds i32, i32* %A, i32 %indvars.iv
+  store i32 %add, i32* %arrayidx6, align 4, !tbaa !5
+  %indvars.iv.next = add nuw i32 %indvars.iv, 1
+  %exitcond24 = icmp eq i32 %indvars.iv.next, %I
+  br i1 %exitcond24, label %for.end9, label %for.outer
+
+for.end9:
+  ret void
+}
+
+
+; CHECK-LABEL: disabled5
+; Test odd uses of phi nodes where the outer IV cannot be moved into Fore as it hits a PHI
+@f = hidden local_unnamed_addr global i32 0, align 4
+define i32 @disabled5() local_unnamed_addr #0 {
+; CHECK: %0 = phi i32 [ %f.promoted10, %entry ], [ 2, %for.latch ]
+; CHECK: %1 = phi i32 [ %0, %for.outer ], [ 2, %for.inner ]
+entry:
+  %f.promoted10 = load i32, i32* @f, align 4, !tbaa !5
+  br label %for.outer
+
+for.outer:
+  %0 = phi i32 [ %f.promoted10, %entry ], [ 2, %for.latch ]
+  %d.018 = phi i16 [ 0, %entry ], [ %odd.lcssa, %for.latch ]
+  %inc5.sink9 = phi i32 [ 2, %entry ], [ %inc5, %for.latch ]
+  br label %for.inner
+
+for.inner:
+  %1 = phi i32 [ %0, %for.outer ], [ 2, %for.inner ]
+  %inc.sink8 = phi i32 [ 0, %for.outer ], [ %inc, %for.inner ]
+  %inc = add nuw nsw i32 %inc.sink8, 1
+  %exitcond = icmp ne i32 %inc, 7
+  br i1 %exitcond, label %for.inner, label %for.latch
+
+for.latch:
+  %.lcssa = phi i32 [ %1, %for.inner ]
+  %odd.lcssa = phi i16 [ 1, %for.inner ]
+  %inc5 = add nuw nsw i32 %inc5.sink9, 1
+  %exitcond11 = icmp ne i32 %inc5, 7
+  br i1 %exitcond11, label %for.outer, label %for.end
+
+for.end:
+  %.lcssa.lcssa = phi i32 [ %.lcssa, %for.latch ]
+  %inc.lcssa.lcssa = phi i32 [ 7, %for.latch ]
+  ret i32 0
+}
+
+
+; CHECK-LABEL: disabled6
+; There is a dependency in here, between @d and %0 (=@f)
+@d6 = hidden global i16 5, align 2
+@f6 = hidden local_unnamed_addr global i16* @d6, align 4
+define i32 @disabled6() local_unnamed_addr #1 {
+; CHECK: %inc8.sink14.i = phi i16 [ 1, %entry ], [ %inc8.i, %for.cond.cleanup.i ]
+; CHECK: %c.013.i = phi i32 [ 0, %for.body.i ], [ %inc.i, %for.body6.i ]
+entry:
+  store i16 1, i16* @d6, align 2
+  %0 = load i16*, i16** @f6, align 4
+  br label %for.body.i
+
+for.body.i:
+  %inc8.sink14.i = phi i16 [ 1, %entry ], [ %inc8.i, %for.cond.cleanup.i ]
+  %1 = load i16, i16* %0, align 2
+  br label %for.body6.i
+
+for.cond.cleanup.i:
+  %inc8.i = add nuw nsw i16 %inc8.sink14.i, 1
+  store i16 %inc8.i, i16* @d6, align 2
+  %cmp.i = icmp ult i16 %inc8.i, 6
+  br i1 %cmp.i, label %for.body.i, label %test.exit
+
+for.body6.i:
+  %c.013.i = phi i32 [ 0, %for.body.i ], [ %inc.i, %for.body6.i ]
+  %inc.i = add nuw nsw i32 %c.013.i, 1
+  %exitcond.i = icmp eq i32 %inc.i, 7
+  br i1 %exitcond.i, label %for.cond.cleanup.i, label %for.body6.i
+
+test.exit:
+  %conv2.i = sext i16 %1 to i32
+  ret i32 0
+}
+
+
+
+; CHECK-LABEL: disabled7
+; Has negative output dependency
+define void @disabled7(i32 %I, i32 %J, i32* noalias nocapture %A, i32* noalias nocapture readonly %B) local_unnamed_addr #0 {
+; CHECK: %i.028 = phi i32 [ %add11, %for.cond3.for.cond.cleanup5_crit_edge ], [ 0, %for.body.preheader ]
+; CHECK: %j.026 = phi i32 [ 0, %for.body ], [ %add9, %for.body6 ]
+entry:
+  %cmp = icmp ne i32 %J, 0
+  %cmp127 = icmp ne i32 %I, 0
+  %or.cond = and i1 %cmp127, %cmp
+  br i1 %or.cond, label %for.body.preheader, label %for.end12
+
+for.body.preheader:
+  br label %for.body
+
+for.body:
+  %i.028 = phi i32 [ %add11, %for.cond3.for.cond.cleanup5_crit_edge ], [ 0, %for.body.preheader ]
+  %arrayidx = getelementptr inbounds i32, i32* %A, i32 %i.028
+  store i32 0, i32* %arrayidx, align 4, !tbaa !5
+  %sub = add i32 %i.028, -1
+  %arrayidx2 = getelementptr inbounds i32, i32* %A, i32 %sub
+  store i32 2, i32* %arrayidx2, align 4, !tbaa !5
+  br label %for.body6
+
+for.cond3.for.cond.cleanup5_crit_edge:
+  store i32 %add, i32* %arrayidx, align 4, !tbaa !5
+  %add11 = add nuw i32 %i.028, 1
+  %exitcond29 = icmp eq i32 %add11, %I
+  br i1 %exitcond29, label %for.end12, label %for.body
+
+for.body6:
+  %0 = phi i32 [ 0, %for.body ], [ %add, %for.body6 ]
+  %j.026 = phi i32 [ 0, %for.body ], [ %add9, %for.body6 ]
+  %arrayidx7 = getelementptr inbounds i32, i32* %B, i32 %j.026
+  %1 = load i32, i32* %arrayidx7, align 4, !tbaa !5
+  %add = add i32 %1, %0
+  %add9 = add nuw i32 %j.026, 1
+  %exitcond = icmp eq i32 %add9, %J
+  br i1 %exitcond, label %for.cond3.for.cond.cleanup5_crit_edge, label %for.body6
+
+for.end12:
+  ret void
+}
+
+
+; CHECK-LABEL: disabled8
+; Same as above with an extra outer loop nest
+define void @disabled8(i32 %I, i32 %J, i32* noalias nocapture %A, i32* noalias nocapture readonly %B) local_unnamed_addr #0 {
+; CHECK: %i.036 = phi i32 [ %add15, %for.latch ], [ 0, %for.body ]
+; CHECK: %j.034 = phi i32 [ 0, %for.outer ], [ %add13, %for.inner ]
+entry:
+  %cmp = icmp eq i32 %J, 0
+  %cmp335 = icmp eq i32 %I, 0
+  %or.cond = or i1 %cmp, %cmp335
+  br i1 %or.cond, label %for.end18, label %for.body.preheader
+
+for.body.preheader:
+  br label %for.body
+
+for.body:
+  %x.037 = phi i32 [ %inc, %for.cond.cleanup4 ], [ 0, %for.body.preheader ]
+  br label %for.outer
+
+for.cond.cleanup4:
+  %inc = add nuw nsw i32 %x.037, 1
+  %exitcond40 = icmp eq i32 %inc, 5
+  br i1 %exitcond40, label %for.end18, label %for.body
+
+for.outer:
+  %i.036 = phi i32 [ %add15, %for.latch ], [ 0, %for.body ]
+  %arrayidx = getelementptr inbounds i32, i32* %A, i32 %i.036
+  store i32 0, i32* %arrayidx, align 4, !tbaa !5
+  %sub = add i32 %i.036, -1
+  %arrayidx6 = getelementptr inbounds i32, i32* %A, i32 %sub
+  store i32 2, i32* %arrayidx6, align 4, !tbaa !5
+  br label %for.inner
+
+for.latch:
+  store i32 %add, i32* %arrayidx, align 4, !tbaa !5
+  %add15 = add nuw i32 %i.036, 1
+  %exitcond38 = icmp eq i32 %add15, %I
+  br i1 %exitcond38, label %for.cond.cleanup4, label %for.outer
+
+for.inner:
+  %0 = phi i32 [ 0, %for.outer ], [ %add, %for.inner ]
+  %j.034 = phi i32 [ 0, %for.outer ], [ %add13, %for.inner ]
+  %arrayidx11 = getelementptr inbounds i32, i32* %B, i32 %j.034
+  %1 = load i32, i32* %arrayidx11, align 4, !tbaa !5
+  %add = add i32 %1, %0
+  %add13 = add nuw i32 %j.034, 1
+  %exitcond = icmp eq i32 %add13, %J
+  br i1 %exitcond, label %for.latch, label %for.inner
+
+for.end18:
+  ret void
+}
+
+
+; CHECK-LABEL: disabled9
+; Can't prove alias between A and B
+define void @disabled9(i32 %I, i32 %J, i32* nocapture %A, i32* nocapture readonly %B) #0 {
+; CHECK: %i.us = phi i32 [ %add8.us, %for.latch ], [ 0, %for.outer.preheader ]
+; CHECK: %j.us = phi i32 [ 0, %for.outer ], [ %inc.us, %for.inner ]
+entry:
+  %cmp = icmp ne i32 %J, 0
+  %cmp122 = icmp ne i32 %I, 0
+  %or.cond = and i1 %cmp, %cmp122
+  br i1 %or.cond, label %for.outer.preheader, label %for.end
+
+for.outer.preheader:
+  br label %for.outer
+
+for.outer:
+  %i.us = phi i32 [ %add8.us, %for.latch ], [ 0, %for.outer.preheader ]
+  br label %for.inner
+
+for.inner:
+  %j.us = phi i32 [ 0, %for.outer ], [ %inc.us, %for.inner ]
+  %sum1.us = phi i32 [ 0, %for.outer ], [ %add.us, %for.inner ]
+  %arrayidx.us = getelementptr inbounds i32, i32* %B, i32 %j.us
+  %0 = load i32, i32* %arrayidx.us, align 4, !tbaa !5
+  %add.us = add i32 %0, %sum1.us
+  %inc.us = add nuw i32 %j.us, 1
+  %exitcond = icmp eq i32 %inc.us, %J
+  br i1 %exitcond, label %for.latch, label %for.inner
+
+for.latch:
+  %add.us.lcssa = phi i32 [ %add.us, %for.inner ]
+  %arrayidx6.us = getelementptr inbounds i32, i32* %A, i32 %i.us
+  store i32 %add.us.lcssa, i32* %arrayidx6.us, align 4, !tbaa !5
+  %add8.us = add nuw i32 %i.us, 1
+  %exitcond25 = icmp eq i32 %add8.us, %I
+  br i1 %exitcond25, label %for.end.loopexit, label %for.outer
+
+for.end.loopexit:
+  br label %for.end
+
+for.end:
+  ret void
+}
+
+
+; CHECK-LABEL: disable10
+; Simple call
+declare void @f10(i32, i32) local_unnamed_addr #0
+define void @disable10(i32 %I, i32 %J, i32* noalias nocapture %A, i32* noalias nocapture readonly %B) #0 {
+; CHECK: %i.us = phi i32 [ %add8.us, %for.latch ], [ 0, %for.outer.preheader ]
+; CHECK: %j.us = phi i32 [ 0, %for.outer ], [ %inc.us, %for.inner ]
+entry:
+  %cmp = icmp ne i32 %J, 0
+  %cmp122 = icmp ne i32 %I, 0
+  %or.cond = and i1 %cmp, %cmp122
+  br i1 %or.cond, label %for.outer.preheader, label %for.end
+
+for.outer.preheader:
+  br label %for.outer
+
+for.outer:
+  %i.us = phi i32 [ %add8.us, %for.latch ], [ 0, %for.outer.preheader ]
+  br label %for.inner
+
+for.inner:
+  %j.us = phi i32 [ 0, %for.outer ], [ %inc.us, %for.inner ]
+  %sum1.us = phi i32 [ 0, %for.outer ], [ %add.us, %for.inner ]
+  %arrayidx.us = getelementptr inbounds i32, i32* %B, i32 %j.us
+  %0 = load i32, i32* %arrayidx.us, align 4, !tbaa !5
+  %add.us = add i32 %0, %sum1.us
+  %inc.us = add nuw i32 %j.us, 1
+  %exitcond = icmp eq i32 %inc.us, %J
+  tail call void @f10(i32 %i.us, i32 %j.us) nounwind
+  br i1 %exitcond, label %for.latch, label %for.inner
+
+for.latch:
+  %add.us.lcssa = phi i32 [ %add.us, %for.inner ]
+  %arrayidx6.us = getelementptr inbounds i32, i32* %A, i32 %i.us
+  store i32 %add.us.lcssa, i32* %arrayidx6.us, align 4, !tbaa !5
+  %add8.us = add nuw i32 %i.us, 1
+  %exitcond25 = icmp eq i32 %add8.us, %I
+  br i1 %exitcond25, label %for.end.loopexit, label %for.outer
+
+for.end.loopexit:
+  br label %for.end
+
+for.end:
+  ret void
+}
+
+
+; CHECK-LABEL: disable11
+; volatile
+define void @disable11(i32 %I, i32 %J, i32* noalias nocapture %A, i32* noalias nocapture readonly %B) #0 {
+; CHECK: %i.us = phi i32 [ %add8.us, %for.latch ], [ 0, %for.outer.preheader ]
+; CHECK: %j.us = phi i32 [ 0, %for.outer ], [ %inc.us, %for.inner ]
+entry:
+  %cmp = icmp ne i32 %J, 0
+  %cmp122 = icmp ne i32 %I, 0
+  %or.cond = and i1 %cmp, %cmp122
+  br i1 %or.cond, label %for.outer.preheader, label %for.end
+
+for.outer.preheader:
+  br label %for.outer
+
+for.outer:
+  %i.us = phi i32 [ %add8.us, %for.latch ], [ 0, %for.outer.preheader ]
+  br label %for.inner
+
+for.inner:
+  %j.us = phi i32 [ 0, %for.outer ], [ %inc.us, %for.inner ]
+  %sum1.us = phi i32 [ 0, %for.outer ], [ %add.us, %for.inner ]
+  %arrayidx.us = getelementptr inbounds i32, i32* %B, i32 %j.us
+  %0 = load volatile i32, i32* %arrayidx.us, align 4, !tbaa !5
+  %add.us = add i32 %0, %sum1.us
+  %inc.us = add nuw i32 %j.us, 1
+  %exitcond = icmp eq i32 %inc.us, %J
+  br i1 %exitcond, label %for.latch, label %for.inner
+
+for.latch:
+  %add.us.lcssa = phi i32 [ %add.us, %for.inner ]
+  %arrayidx6.us = getelementptr inbounds i32, i32* %A, i32 %i.us
+  store i32 %add.us.lcssa, i32* %arrayidx6.us, align 4, !tbaa !5
+  %add8.us = add nuw i32 %i.us, 1
+  %exitcond25 = icmp eq i32 %add8.us, %I
+  br i1 %exitcond25, label %for.end.loopexit, label %for.outer
+
+for.end.loopexit:
+  br label %for.end
+
+for.end:
+  ret void
+}
+
+
+; CHECK-LABEL: disable12
+; Multiple aft blocks
+define void @disable12(i32 %I, i32 %J, i32* noalias nocapture %A, i32* noalias nocapture readonly %B) #0 {
+; CHECK: %i.us = phi i32 [ %add8.us, %for.latch3 ], [ 0, %for.outer.preheader ]
+; CHECK: %j.us = phi i32 [ 0, %for.outer ], [ %inc.us, %for.inner ]
+entry:
+  %cmp = icmp ne i32 %J, 0
+  %cmp122 = icmp ne i32 %I, 0
+  %or.cond = and i1 %cmp, %cmp122
+  br i1 %or.cond, label %for.outer.preheader, label %for.end
+
+for.outer.preheader:
+  br label %for.outer
+
+for.outer:
+  %i.us = phi i32 [ %add8.us, %for.latch3 ], [ 0, %for.outer.preheader ]
+  br label %for.inner
+
+for.inner:
+  %j.us = phi i32 [ 0, %for.outer ], [ %inc.us, %for.inner ]
+  %sum1.us = phi i32 [ 0, %for.outer ], [ %add.us, %for.inner ]
+  %arrayidx.us = getelementptr inbounds i32, i32* %B, i32 %j.us
+  %0 = load i32, i32* %arrayidx.us, align 4, !tbaa !5
+  %add.us = add i32 %0, %sum1.us
+  %inc.us = add nuw i32 %j.us, 1
+  %exitcond = icmp eq i32 %inc.us, %J
+  br i1 %exitcond, label %for.latch, label %for.inner
+
+for.latch:
+  %add.us.lcssa = phi i32 [ %add.us, %for.inner ]
+  %arrayidx6.us = getelementptr inbounds i32, i32* %A, i32 %i.us
+  store i32 %add.us.lcssa, i32* %arrayidx6.us, align 4, !tbaa !5
+  %cmpl = icmp eq i32 %add.us.lcssa, 10
+  br i1 %cmpl, label %for.latch2, label %for.latch3
+
+for.latch2:
+  br label %for.latch3
+
+for.latch3:
+  %add8.us = add nuw i32 %i.us, 1
+  %exitcond25 = icmp eq i32 %add8.us, %I
+  br i1 %exitcond25, label %for.end.loopexit, label %for.outer
+
+for.end.loopexit:
+  br label %for.end
+
+for.end:
+  ret void
+}
+
+
+; CHECK-LABEL: disable13
+; Two subloops
+define void @disable13(i32 %I, i32 %J, i32* noalias nocapture %A, i32* noalias nocapture readonly %B) #0 {
+; CHECK: %i.us = phi i32 [ %add8.us, %for.latch ], [ 0, %for.outer.preheader ]
+; CHECK: %j.us = phi i32 [ 0, %for.outer ], [ %inc.us, %for.inner ]
+; CHECK: %j.us2 = phi i32 [ %inc.us2, %for.inner2 ], [ 0, %for.inner2.preheader ]
+entry:
+  %cmp = icmp ne i32 %J, 0
+  %cmp122 = icmp ne i32 %I, 0
+  %or.cond = and i1 %cmp, %cmp122
+  br i1 %or.cond, label %for.outer.preheader, label %for.end
+
+for.outer.preheader:
+  br label %for.outer
+
+for.outer:
+  %i.us = phi i32 [ %add8.us, %for.latch ], [ 0, %for.outer.preheader ]
+  br label %for.inner
+
+for.inner:
+  %j.us = phi i32 [ 0, %for.outer ], [ %inc.us, %for.inner ]
+  %sum1.us = phi i32 [ 0, %for.outer ], [ %add.us, %for.inner ]
+  %arrayidx.us = getelementptr inbounds i32, i32* %B, i32 %j.us
+  %0 = load i32, i32* %arrayidx.us, align 4, !tbaa !5
+  %add.us = add i32 %0, %sum1.us
+  %inc.us = add nuw i32 %j.us, 1
+  %exitcond = icmp eq i32 %inc.us, %J
+  br i1 %exitcond, label %for.inner2, label %for.inner
+
+for.inner2:
+  %j.us2 = phi i32 [ 0, %for.inner ], [ %inc.us2, %for.inner2 ]
+  %sum1.us2 = phi i32 [ 0, %for.inner ], [ %add.us2, %for.inner2 ]
+  %arrayidx.us2 = getelementptr inbounds i32, i32* %B, i32 %j.us2
+  %l0 = load i32, i32* %arrayidx.us2, align 4, !tbaa !5
+  %add.us2 = add i32 %l0, %sum1.us2
+  %inc.us2 = add nuw i32 %j.us2, 1
+  %exitcond2 = icmp eq i32 %inc.us2, %J
+  br i1 %exitcond2, label %for.latch, label %for.inner2
+
+for.latch:
+  %add.us.lcssa = phi i32 [ %add.us, %for.inner2 ]
+  %arrayidx6.us = getelementptr inbounds i32, i32* %A, i32 %i.us
+  store i32 %add.us.lcssa, i32* %arrayidx6.us, align 4, !tbaa !5
+  %add8.us = add nuw i32 %i.us, 1
+  %exitcond25 = icmp eq i32 %add8.us, %I
+  br i1 %exitcond25, label %for.end.loopexit, label %for.outer
+
+for.end.loopexit:
+  br label %for.end
+
+for.end:
+  ret void
+}
+
+
+; CHECK-LABEL: disable14
+; Multiple exits blocks
+define void @disable14(i32 %I, i32 %J, i32* noalias nocapture %A, i32* noalias nocapture readonly %B) #0 {
+; CHECK: %i.us = phi i32 [ %add8.us, %for.latch ], [ 0, %for.outer.preheader ]
+; CHECK: %j.us = phi i32 [ %inc.us, %for.inner ], [ 0, %for.inner.preheader ]
+entry:
+  %cmp = icmp ne i32 %J, 0
+  %cmp122 = icmp ne i32 %I, 0
+  %or.cond = and i1 %cmp, %cmp122
+  br i1 %or.cond, label %for.outer.preheader, label %for.end
+
+for.outer.preheader:
+  br label %for.outer
+
+for.outer:
+  %i.us = phi i32 [ %add8.us, %for.latch ], [ 0, %for.outer.preheader ]
+  %add8.us = add nuw i32 %i.us, 1
+  %exitcond23 = icmp eq i32 %add8.us, %I
+  br i1 %exitcond23, label %for.end.loopexit, label %for.inner
+
+for.inner:
+  %j.us = phi i32 [ 0, %for.outer ], [ %inc.us, %for.inner ]
+  %sum1.us = phi i32 [ 0, %for.outer ], [ %add.us, %for.inner ]
+  %arrayidx.us = getelementptr inbounds i32, i32* %B, i32 %j.us
+  %0 = load i32, i32* %arrayidx.us, align 4, !tbaa !5
+  %add.us = add i32 %0, %sum1.us
+  %inc.us = add nuw i32 %j.us, 1
+  %exitcond = icmp eq i32 %inc.us, %J
+  br i1 %exitcond, label %for.latch, label %for.inner
+
+for.latch:
+  %add.us.lcssa = phi i32 [ %add.us, %for.inner ]
+  %arrayidx6.us = getelementptr inbounds i32, i32* %A, i32 %i.us
+  store i32 %add.us.lcssa, i32* %arrayidx6.us, align 4, !tbaa !5
+  %exitcond25 = icmp eq i32 %add8.us, %I
+  br i1 %exitcond25, label %for.end.loopexit, label %for.outer
+
+for.end.loopexit:
+  br label %for.end
+
+for.end:
+  ret void
+}
+
+
+; CHECK-LABEL: disable15
+; Latch != exit
+define void @disable15(i32 %I, i32 %J, i32* noalias nocapture %A, i32* noalias nocapture readonly %B) #0 {
+; CHECK: %i.us = phi i32 [ %add8.us, %for.latch ], [ 0, %for.outer.preheader ]
+; CHECK: %j.us = phi i32 [ %inc.us, %for.inner ], [ 0, %for.inner.preheader ]
+entry:
+  %cmp = icmp ne i32 %J, 0
+  %cmp122 = icmp ne i32 %I, 0
+  %or.cond = and i1 %cmp, %cmp122
+  br i1 %or.cond, label %for.outer.preheader, label %for.end
+
+for.outer.preheader:
+  br label %for.outer
+
+for.outer:
+  %i.us = phi i32 [ %add8.us, %for.latch ], [ 0, %for.outer.preheader ]
+  %add8.us = add nuw i32 %i.us, 1
+  %exitcond25 = icmp eq i32 %add8.us, %I
+  br i1 %exitcond25, label %for.end.loopexit, label %for.inner
+
+for.inner:
+  %j.us = phi i32 [ 0, %for.outer ], [ %inc.us, %for.inner ]
+  %sum1.us = phi i32 [ 0, %for.outer ], [ %add.us, %for.inner ]
+  %arrayidx.us = getelementptr inbounds i32, i32* %B, i32 %j.us
+  %0 = load i32, i32* %arrayidx.us, align 4, !tbaa !5
+  %add.us = add i32 %0, %sum1.us
+  %inc.us = add nuw i32 %j.us, 1
+  %exitcond = icmp eq i32 %inc.us, %J
+  br i1 %exitcond, label %for.latch, label %for.inner
+
+for.latch:
+  %add.us.lcssa = phi i32 [ %add.us, %for.inner ]
+  %arrayidx6.us = getelementptr inbounds i32, i32* %A, i32 %i.us
+  store i32 %add.us.lcssa, i32* %arrayidx6.us, align 4, !tbaa !5
+  br label %for.outer
+
+for.end.loopexit:
+  br label %for.end
+
+for.end:
+  ret void
+}
+
+
+; CHECK-LABEL: disable16
+; Latch != exit
+define void @disable16(i32 %I, i32 %J, i32* noalias nocapture %A, i32* noalias nocapture readonly %B) #0 {
+; CHECK: %i.us = phi i32 [ %add8.us, %for.latch ], [ 0, %for.outer.preheader ]
+; CHECK: %j.us = phi i32 [ 0, %for.outer ], [ %inc.us, %for.inner ]
+entry:
+  %cmp = icmp ne i32 %J, 0
+  %cmp122 = icmp ne i32 %I, 0
+  %or.cond = and i1 %cmp, %cmp122
+  br i1 %or.cond, label %for.outer.preheader, label %for.end
+
+for.outer.preheader:
+  br label %for.outer
+
+for.outer:
+  %i.us = phi i32 [ %add8.us, %for.latch ], [ 0, %for.outer.preheader ]
+  %otherphi = phi i32 [ %other, %for.latch ], [ 0, %for.outer.preheader ]
+  br label %for.inner
+
+for.inner:
+  %j.us = phi i32 [ 0, %for.outer ], [ %inc.us, %for.inner ]
+  %sum1.us = phi i32 [ 0, %for.outer ], [ %add.us, %for.inner ]
+  %arrayidx.us = getelementptr inbounds i32, i32* %B, i32 %j.us
+  %0 = load i32, i32* %arrayidx.us, align 4, !tbaa !5
+  %add.us = add i32 %0, %sum1.us
+  %inc.us = add nuw i32 %j.us, 1
+  %exitcond = icmp eq i32 %inc.us, %J
+  br i1 %exitcond, label %for.latch, label %for.inner
+
+for.latch:
+  %add.us.lcssa = phi i32 [ %add.us, %for.inner ]
+  %arrayidx6.us = getelementptr inbounds i32, i32* %A, i32 %i.us
+  store i32 %add.us.lcssa, i32* %arrayidx6.us, align 4, !tbaa !5
+  %add8.us = add nuw i32 %i.us, 1
+  %exitcond25 = icmp eq i32 %add8.us, %I
+  %loadarr = getelementptr inbounds i32, i32* %A, i32 %i.us
+  %load = load i32, i32* %arrayidx6.us, align 4, !tbaa !5
+  %other = add i32 %otherphi, %load
+  br i1 %exitcond25, label %for.end.loopexit, label %for.outer
+
+for.end.loopexit:
+  br label %for.end
+
+for.end:
+  ret void
+}
+
+
+
+; Function Attrs: argmemonly nounwind
+declare void @llvm.lifetime.start.p0i8(i64, i8* nocapture) #1
+
+; Function Attrs: argmemonly nounwind
+declare void @llvm.lifetime.end.p0i8(i64, i8* nocapture) #1
+
+attributes #0 = { noinline norecurse nounwind "correctly-rounded-divide-sqrt-fp-math"="false" "denormal-fp-math"="preserve-sign" "disable-tail-calls"="false" "less-precise-fpmad"="false" "no-frame-pointer-elim"="false" "no-infs-fp-math"="true" "no-jump-tables"="false" "no-nans-fp-math"="true" "no-signed-zeros-fp-math"="true" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="cortex-m33" "target-features"="+d16,+dsp,+fp-armv8,+fp-only-sp,+hwdiv,+thumb-mode,-crc,-dotprod,-hwdiv-arm,-ras" "unsafe-fp-math"="false" "use-soft-float"="false" }
+attributes #1 = { argmemonly nounwind }
+
+!5 = !{!6, !6, i64 0}
+!6 = !{!"omnipotent char", !7, i64 0}
+!7 = !{!"Simple C/C++ TBAA"}

test/Transforms/LoopUnrollAndJam/pragma.ll

+; RUN: opt -basicaa -tbaa -loop-unroll-and-jam < %s -S | FileCheck %s
+; RUN: opt -basicaa -tbaa -loop-unroll-and-jam -unroll-and-jam-threshold=15 < %s -S | FileCheck %s --check-prefix=CHECK-LOWTHRES
+
+target datalayout = "e-m:e-p:32:32-i64:64-v128:64:128-a:0:32-n32-S64"
+target triple = "thumbv8m.main-arm-none-eabi"
+
+; CHECK-LABEL: test1
+; Basic check that these loops are by default UnJ'd
+define void @test1(i32 %I, i32 %J, i32* noalias nocapture %A, i32* noalias nocapture readonly %B) #0 {
+; CHECK: %i.us = phi i32 [ %add8.us.3, %for.latch ], [ 0, %for.outer.preheader.new ]
+; CHECK-LOWTHRES: %i.us = phi i32 [ %add8.us, %for.latch ], [ 0, %for.outer.preheader ]
+entry:
+  %cmp = icmp ne i32 %J, 0
+  %cmp122 = icmp ne i32 %I, 0
+  %or.cond = and i1 %cmp, %cmp122
+  br i1 %or.cond, label %for.outer.preheader, label %for.end
+
+for.outer.preheader:
+  br label %for.outer
+
+for.outer:
+  %i.us = phi i32 [ %add8.us, %for.latch ], [ 0, %for.outer.preheader ]
+  br label %for.inner
+
+for.inner:
+  %j.us = phi i32 [ 0, %for.outer ], [ %inc.us, %for.inner ]
+  %sum1.us = phi i32 [ 0, %for.outer ], [ %add.us, %for.inner ]
+  %arrayidx.us = getelementptr inbounds i32, i32* %B, i32 %j.us
+  %0 = load i32, i32* %arrayidx.us, align 4
+  %add.us = add i32 %0, %sum1.us
+  %inc.us = add nuw i32 %j.us, 1
+  %exitcond = icmp eq i32 %inc.us, %J
+  br i1 %exitcond, label %for.latch, label %for.inner
+
+for.latch:
+  %add.us.lcssa = phi i32 [ %add.us, %for.inner ]
+  %arrayidx6.us = getelementptr inbounds i32, i32* %A, i32 %i.us
+  store i32 %add.us.lcssa, i32* %arrayidx6.us, align 4
+  %add8.us = add nuw i32 %i.us, 1
+  %exitcond25 = icmp eq i32 %add8.us, %I
+  br i1 %exitcond25, label %for.end.loopexit, label %for.outer
+
+for.end.loopexit:
+  br label %for.end
+
+for.end:
+  ret void
+}
+
+; CHECK-LABEL: nounroll_and_jam
+; #pragma nounroll_and_jam
+define void @nounroll_and_jam(i32 %I, i32 %J, i32* noalias nocapture %A, i32* noalias nocapture readonly %B) #0 {
+; CHECK: %i.us = phi i32 [ %add8.us, %for.latch ], [ 0, %for.outer.preheader ]
+entry:
+  %cmp = icmp ne i32 %J, 0
+  %cmp122 = icmp ne i32 %I, 0
+  %or.cond = and i1 %cmp, %cmp122
+  br i1 %or.cond, label %for.outer.preheader, label %for.end
+
+for.outer.preheader:
+  br label %for.outer
+
+for.outer:
+  %i.us = phi i32 [ %add8.us, %for.latch ], [ 0, %for.outer.preheader ]
+  br label %for.inner
+
+for.inner:
+  %j.us = phi i32 [ 0, %for.outer ], [ %inc.us, %for.inner ]
+  %sum1.us = phi i32 [ 0, %for.outer ], [ %add.us, %for.inner ]
+  %arrayidx.us = getelementptr inbounds i32, i32* %B, i32 %j.us
+  %0 = load i32, i32* %arrayidx.us, align 4
+  %add.us = add i32 %0, %sum1.us
+  %inc.us = add nuw i32 %j.us, 1
+  %exitcond = icmp eq i32 %inc.us, %J
+  br i1 %exitcond, label %for.latch, label %for.inner
+
+for.latch:
+  %add.us.lcssa = phi i32 [ %add.us, %for.inner ]
+  %arrayidx6.us = getelementptr inbounds i32, i32* %A, i32 %i.us
+  store i32 %add.us.lcssa, i32* %arrayidx6.us, align 4
+  %add8.us = add nuw i32 %i.us, 1
+  %exitcond25 = icmp eq i32 %add8.us, %I
+  br i1 %exitcond25, label %for.end.loopexit, label %for.outer, !llvm.loop !1
+
+for.end.loopexit:
+  br label %for.end
+
+for.end:
+  ret void
+}
+
+; CHECK-LABEL: unroll_and_jam_count
+; #pragma unroll_and_jam(8)
+define void @unroll_and_jam_count(i32 %I, i32 %J, i32* noalias nocapture %A, i32* noalias nocapture readonly %B) #0 {
+; CHECK: %i.us = phi i32 [ %add8.us.7, %for.latch ], [ 0, %for.outer.preheader.new ]
+entry:
+  %cmp = icmp ne i32 %J, 0
+  %cmp122 = icmp ne i32 %I, 0
+  %or.cond = and i1 %cmp, %cmp122
+  br i1 %or.cond, label %for.outer.preheader, label %for.end
+
+for.outer.preheader:
+  br label %for.outer
+
+for.outer:
+  %i.us = phi i32 [ %add8.us, %for.latch ], [ 0, %for.outer.preheader ]
+  br label %for.inner
+
+for.inner:
+  %j.us = phi i32 [ 0, %for.outer ], [ %inc.us, %for.inner ]
+  %sum1.us = phi i32 [ 0, %for.outer ], [ %add.us, %for.inner ]
+  %arrayidx.us = getelementptr inbounds i32, i32* %B, i32 %j.us
+  %0 = load i32, i32* %arrayidx.us, align 4
+  %add.us = add i32 %0, %sum1.us
+  %inc.us = add nuw i32 %j.us, 1
+  %exitcond = icmp eq i32 %inc.us, %J
+  br i1 %exitcond, label %for.latch, label %for.inner
+
+for.latch:
+  %add.us.lcssa = phi i32 [ %add.us, %for.inner ]
+  %arrayidx6.us = getelementptr inbounds i32, i32* %A, i32 %i.us
+  store i32 %add.us.lcssa, i32* %arrayidx6.us, align 4
+  %add8.us = add nuw i32 %i.us, 1
+  %exitcond25 = icmp eq i32 %add8.us, %I
+  br i1 %exitcond25, label %for.end.loopexit, label %for.outer, !llvm.loop !3
+
+for.end.loopexit:
+  br label %for.end
+
+for.end:
+  ret void
+}
+
+; CHECK-LABEL: unroll_and_jam
+; #pragma unroll_and_jam
+define void @unroll_and_jam(i32 %I, i32 %J, i32* noalias nocapture %A, i32* noalias nocapture readonly %B) #0 {
+; CHECK: %i.us = phi i32 [ %add8.us.3, %for.latch ], [ 0, %for.outer.preheader.new ]
+; CHECK-LOWTHRES: %i.us = phi i32 [ %add8.us.3, %for.latch ], [ 0, %for.outer.preheader.new ]
+entry:
+  %cmp = icmp ne i32 %J, 0
+  %cmp122 = icmp ne i32 %I, 0
+  %or.cond = and i1 %cmp, %cmp122
+  br i1 %or.cond, label %for.outer.preheader, label %for.end
+
+for.outer.preheader:
+  br label %for.outer
+
+for.outer:
+  %i.us = phi i32 [ %add8.us, %for.latch ], [ 0, %for.outer.preheader ]
+  br label %for.inner
+
+for.inner:
+  %j.us = phi i32 [ 0, %for.outer ], [ %inc.us, %for.inner ]
+  %sum1.us = phi i32 [ 0, %for.outer ], [ %add.us, %for.inner ]
+  %arrayidx.us = getelementptr inbounds i32, i32* %B, i32 %j.us
+  %0 = load i32, i32* %arrayidx.us, align 4
+  %add.us = add i32 %0, %sum1.us
+  %inc.us = add nuw i32 %j.us, 1
+  %exitcond = icmp eq i32 %inc.us, %J
+  br i1 %exitcond, label %for.latch, label %for.inner
+
+for.latch:
+  %add.us.lcssa = phi i32 [ %add.us, %for.inner ]
+  %arrayidx6.us = getelementptr inbounds i32, i32* %A, i32 %i.us
+  store i32 %add.us.lcssa, i32* %arrayidx6.us, align 4
+  %add8.us = add nuw i32 %i.us, 1
+  %exitcond25 = icmp eq i32 %add8.us, %I
+  br i1 %exitcond25, label %for.end.loopexit, label %for.outer, !llvm.loop !5
+
+for.end.loopexit:
+  br label %for.end
+
+for.end:
+  ret void
+}
+
+; CHECK-LABEL: nounroll
+; #pragma nounroll (which we take to mean disable unroll and jam too)
+define void @nounroll(i32 %I, i32 %J, i32* noalias nocapture %A, i32* noalias nocapture readonly %B) #0 {
+; CHECK: %i.us = phi i32 [ %add8.us, %for.latch ], [ 0, %for.outer.preheader ]
+entry:
+  %cmp = icmp ne i32 %J, 0
+  %cmp122 = icmp ne i32 %I, 0
+  %or.cond = and i1 %cmp, %cmp122
+  br i1 %or.cond, label %for.outer.preheader, label %for.end
+
+for.outer.preheader:
+  br label %for.outer
+
+for.outer:
+  %i.us = phi i32 [ %add8.us, %for.latch ], [ 0, %for.outer.preheader ]
+  br label %for.inner
+
+for.inner:
+  %j.us = phi i32 [ 0, %for.outer ], [ %inc.us, %for.inner ]
+  %sum1.us = phi i32 [ 0, %for.outer ], [ %add.us, %for.inner ]
+  %arrayidx.us = getelementptr inbounds i32, i32* %B, i32 %j.us
+  %0 = load i32, i32* %arrayidx.us, align 4
+  %add.us = add i32 %0, %sum1.us
+  %inc.us = add nuw i32 %j.us, 1
+  %exitcond = icmp eq i32 %inc.us, %J
+  br i1 %exitcond, label %for.latch, label %for.inner
+
+for.latch:
+  %add.us.lcssa = phi i32 [ %add.us, %for.inner ]
+  %arrayidx6.us = getelementptr inbounds i32, i32* %A, i32 %i.us
+  store i32 %add.us.lcssa, i32* %arrayidx6.us, align 4
+  %add8.us = add nuw i32 %i.us, 1
+  %exitcond25 = icmp eq i32 %add8.us, %I
+  br i1 %exitcond25, label %for.end.loopexit, label %for.outer, !llvm.loop !7
+
+for.end.loopexit:
+  br label %for.end
+
+for.end:
+  ret void
+}
+
+; CHECK-LABEL: unroll
+; #pragma unroll (which we take to mean disable unroll and jam)
+define void @unroll(i32 %I, i32 %J, i32* noalias nocapture %A, i32* noalias nocapture readonly %B) #0 {
+; CHECK: %i.us = phi i32 [ %add8.us, %for.latch ], [ 0, %for.outer.preheader ]
+entry:
+  %cmp = icmp ne i32 %J, 0
+  %cmp122 = icmp ne i32 %I, 0
+  %or.cond = and i1 %cmp, %cmp122
+  br i1 %or.cond, label %for.outer.preheader, label %for.end
+
+for.outer.preheader:
+  br label %for.outer
+
+for.outer:
+  %i.us = phi i32 [ %add8.us, %for.latch ], [ 0, %for.outer.preheader ]
+  br label %for.inner
+
+for.inner:
+  %j.us = phi i32 [ 0, %for.outer ], [ %inc.us, %for.inner ]
+  %sum1.us = phi i32 [ 0, %for.outer ], [ %add.us, %for.inner ]
+  %arrayidx.us = getelementptr inbounds i32, i32* %B, i32 %j.us
+  %0 = load i32, i32* %arrayidx.us, align 4
+  %add.us = add i32 %0, %sum1.us
+  %inc.us = add nuw i32 %j.us, 1
+  %exitcond = icmp eq i32 %inc.us, %J
+  br i1 %exitcond, label %for.latch, label %for.inner
+
+for.latch:
+  %add.us.lcssa = phi i32 [ %add.us, %for.inner ]
+  %arrayidx6.us = getelementptr inbounds i32, i32* %A, i32 %i.us
+  store i32 %add.us.lcssa, i32* %arrayidx6.us, align 4
+  %add8.us = add nuw i32 %i.us, 1
+  %exitcond25 = icmp eq i32 %add8.us, %I
+  br i1 %exitcond25, label %for.end.loopexit, label %for.outer, !llvm.loop !9
+
+for.end.loopexit:
+  br label %for.end
+
+for.end:
+  ret void
+}
+
+; CHECK-LABEL: nounroll_plus_unroll_and_jam
+; #pragma clang loop nounroll, unroll_and_jam (which we take to mean, do unroll_and_jam)
+define void @nounroll_plus_unroll_and_jam(i32 %I, i32 %J, i32* noalias nocapture %A, i32* noalias nocapture readonly %B) #0 {
+; CHECK: %i.us = phi i32 [ %add8.us.3, %for.latch ], [ 0, %for.outer.preheader.new ]
+entry:
+  %cmp = icmp ne i32 %J, 0
+  %cmp122 = icmp ne i32 %I, 0
+  %or.cond = and i1 %cmp, %cmp122
+  br i1 %or.cond, label %for.outer.preheader, label %for.end
+
+for.outer.preheader:
+  br label %for.outer
+
+for.outer:
+  %i.us = phi i32 [ %add8.us, %for.latch ], [ 0, %for.outer.preheader ]
+  br label %for.inner
+
+for.inner:
+  %j.us = phi i32 [ 0, %for.outer ], [ %inc.us, %for.inner ]
+  %sum1.us = phi i32 [ 0, %for.outer ], [ %add.us, %for.inner ]
+  %arrayidx.us = getelementptr inbounds i32, i32* %B, i32 %j.us
+  %0 = load i32, i32* %arrayidx.us, align 4
+  %add.us = add i32 %0, %sum1.us
+  %inc.us = add nuw i32 %j.us, 1
+  %exitcond = icmp eq i32 %inc.us, %J
+  br i1 %exitcond, label %for.latch, label %for.inner
+
+for.latch:
+  %add.us.lcssa = phi i32 [ %add.us, %for.inner ]
+  %arrayidx6.us = getelementptr inbounds i32, i32* %A, i32 %i.us
+  store i32 %add.us.lcssa, i32* %arrayidx6.us, align 4
+  %add8.us = add nuw i32 %i.us, 1
+  %exitcond25 = icmp eq i32 %add8.us, %I
+  br i1 %exitcond25, label %for.end.loopexit, label %for.outer, !llvm.loop !11
+
+for.end.loopexit:
+  br label %for.end
+
+for.end:
+  ret void
+}
+
+!1 = distinct !{!1, !2}
+!2 = distinct !{!"llvm.loop.unroll_and_jam.disable"}
+!3 = distinct !{!3, !4}
+!4 = distinct !{!"llvm.loop.unroll_and_jam.count", i32 8}
+!5 = distinct !{!5, !6}
+!6 = distinct !{!"llvm.loop.unroll_and_jam.enable"}
+!7 = distinct !{!7, !8}
+!8 = distinct !{!"llvm.loop.unroll.disable"}
+!9 = distinct !{!9, !10}
+!10 = distinct !{!"llvm.loop.unroll.enable"}
+!11 = distinct !{!11, !8, !6}
 No newline at end of file

test/Transforms/LoopUnrollAndJam/unprofitable.ll

+; RUN: opt -loop-unroll-and-jam -pass-remarks=loop-unroll < %s -S 2>&1 | FileCheck %s
+
+target datalayout = "e-m:e-p:32:32-i64:64-v128:64:128-a:0:32-n32-S64"
+target triple = "thumbv8m.main-arm-none-eabi"
+
+;; Common check for all tests. None should be unroll and jammed due to profitability
+; CHECK-NOT: remark: {{.*}} unroll and jammed
+
+
+; CHECK-LABEL: unprof1
+; Multiple inner loop blocks
+define void @unprof1(i32 %I, i32 %J, i32* noalias nocapture %A, i32* noalias nocapture readonly %B) #0 {
+; CHECK: %i.us = phi i32 [ %add8.us, %for.latch ], [ 0, %for.outer.preheader ]
+; CHECK: %j.us = phi i32 [ 0, %for.outer ], [ %inc.us, %for.inner2 ]
+entry:
+  %cmp = icmp ne i32 %J, 0
+  %cmp122 = icmp ne i32 %I, 0
+  %or.cond = and i1 %cmp, %cmp122
+  br i1 %or.cond, label %for.outer.preheader, label %for.end
+
+for.outer.preheader:
+  br label %for.outer
+
+for.outer:
+  %i.us = phi i32 [ %add8.us, %for.latch ], [ 0, %for.outer.preheader ]
+  br label %for.inner
+
+for.inner:
+  %j.us = phi i32 [ 0, %for.outer ], [ %inc.us, %for.inner2 ]
+  %sum1.us = phi i32 [ 0, %for.outer ], [ %add.us, %for.inner2 ]
+  %arrayidx.us = getelementptr inbounds i32, i32* %B, i32 %j.us
+  %0 = load i32, i32* %arrayidx.us, align 4, !tbaa !5
+  %add.us = add i32 %0, %sum1.us
+br label %for.inner2
+
+for.inner2:
+  %inc.us = add nuw i32 %j.us, 1
+  %exitcond = icmp eq i32 %inc.us, %J
+  br i1 %exitcond, label %for.latch, label %for.inner
+
+for.latch:
+  %add.us.lcssa = phi i32 [ %add.us, %for.inner2 ]
+  %arrayidx6.us = getelementptr inbounds i32, i32* %A, i32 %i.us
+  store i32 %add.us.lcssa, i32* %arrayidx6.us, align 4, !tbaa !5
+  %add8.us = add nuw i32 %i.us, 1
+  %exitcond25 = icmp eq i32 %add8.us, %I
+  br i1 %exitcond25, label %for.end.loopexit, label %for.outer
+
+for.end.loopexit:
+  br label %for.end
+
+for.end:
+  ret void
+}
+
+
+; CHECK-LABEL: unprof2
+; Constant inner loop count
+define void @unprof2(i32 %I, i32 %J, i32* noalias nocapture %A, i32* noalias nocapture readonly %B) #0 {
+; CHECK: %i.us = phi i32 [ %add8.us, %for.latch ], [ 0, %for.outer.preheader ]
+; CHECK: %j.us = phi i32 [ 0, %for.outer ], [ %inc.us, %for.inner ]
+entry:
+  %cmp = icmp ne i32 %J, 0
+  %cmp122 = icmp ne i32 %I, 0
+  %or.cond = and i1 %cmp, %cmp122
+  br i1 %or.cond, label %for.outer.preheader, label %for.end
+
+for.outer.preheader:
+  br label %for.outer
+
+for.outer:
+  %i.us = phi i32 [ %add8.us, %for.latch ], [ 0, %for.outer.preheader ]
+  br label %for.inner
+
+for.inner:
+  %j.us = phi i32 [ 0, %for.outer ], [ %inc.us, %for.inner ]
+  %sum1.us = phi i32 [ 0, %for.outer ], [ %add.us, %for.inner ]
+  %arrayidx.us = getelementptr inbounds i32, i32* %B, i32 %j.us
+  %0 = load i32, i32* %arrayidx.us, align 4, !tbaa !5
+  %add.us = add i32 %0, %sum1.us
+  %inc.us = add nuw i32 %j.us, 1
+  %exitcond = icmp eq i32 %inc.us, 10
+  br i1 %exitcond, label %for.latch, label %for.inner
+
+for.latch:
+  %add.us.lcssa = phi i32 [ %add.us, %for.inner ]
+  %arrayidx6.us = getelementptr inbounds i32, i32* %A, i32 %i.us
+  store i32 %add.us.lcssa, i32* %arrayidx6.us, align 4, !tbaa !5
+  %add8.us = add nuw i32 %i.us, 1
+  %exitcond25 = icmp eq i32 %add8.us, %I
+  br i1 %exitcond25, label %for.end.loopexit, label %for.outer
+
+for.end.loopexit:
+  br label %for.end
+
+for.end:
+  ret void
+}
+
+
+; CHECK-LABEL: unprof3
+; Complex inner loop
+define void @unprof3(i32 %I, i32 %J, i32* noalias nocapture %A, i32* noalias nocapture readonly %B) #0 {
+; CHECK: %i.us = phi i32 [ %add8.us, %for.latch ], [ 0, %for.outer.preheader ]
+; CHECK: %j.us = phi i32 [ 0, %for.outer ], [ %inc.us, %for.inner ]
+entry:
+  %cmp = icmp ne i32 %J, 0
+  %cmp122 = icmp ne i32 %I, 0
+  %or.cond = and i1 %cmp, %cmp122
+  br i1 %or.cond, label %for.outer.preheader, label %for.end
+
+for.outer.preheader:
+  br label %for.outer
+
+for.outer:
+  %i.us = phi i32 [ %add8.us, %for.latch ], [ 0, %for.outer.preheader ]
+  br label %for.inner
+
+for.inner:
+  %j.us = phi i32 [ 0, %for.outer ], [ %inc.us, %for.inner ]
+  %sum1.us = phi i32 [ 0, %for.outer ], [ %add.us, %for.inner ]
+  %arrayidx.us = getelementptr inbounds i32, i32* %B, i32 %j.us
+  %0 = load i32, i32* %arrayidx.us, align 4, !tbaa !5
+  %add.us = add i32 %0, %sum1.us
+  %add.us0 = add i32 %0, %sum1.us
+  %add.us1 = add i32 %0, %sum1.us
+  %add.us2 = add i32 %0, %sum1.us
+  %add.us3 = add i32 %0, %sum1.us
+  %add.us4 = add i32 %0, %sum1.us
+  %add.us5 = add i32 %0, %sum1.us
+  %add.us6 = add i32 %0, %sum1.us
+  %add.us7 = add i32 %0, %sum1.us
+  %add.us8 = add i32 %0, %sum1.us
+  %add.us9 = add i32 %0, %sum1.us
+  %add.us10 = add i32 %0, %sum1.us
+  %add.us11 = add i32 %0, %sum1.us
+  %add.us12 = add i32 %0, %sum1.us
+  %add.us13 = add i32 %0, %sum1.us
+  %add.us14 = add i32 %0, %sum1.us
+  %add.us15 = add i32 %0, %sum1.us
+  %add.us16 = add i32 %0, %sum1.us
+  %add.us17 = add i32 %0, %sum1.us
+  %add.us18 = add i32 %0, %sum1.us
+  %add.us19 = add i32 %0, %sum1.us
+  %add.us20 = add i32 %0, %sum1.us
+  %add.us21 = add i32 %0, %sum1.us
+  %add.us22 = add i32 %0, %sum1.us
+  %add.us23 = add i32 %0, %sum1.us
+  %add.us24 = add i32 %0, %sum1.us
+  %add.us25 = add i32 %0, %sum1.us
+  %add.us26 = add i32 %0, %sum1.us
+  %add.us27 = add i32 %0, %sum1.us
+  %add.us28 = add i32 %0, %sum1.us
+  %add.us29 = add i32 %0, %sum1.us
+  %inc.us = add nuw i32 %j.us, 1
+  %exitcond = icmp eq i32 %inc.us, %J
+  br i1 %exitcond, label %for.latch, label %for.inner
+
+for.latch:
+  %add.us.lcssa = phi i32 [ %add.us, %for.inner ]
+  %arrayidx6.us = getelementptr inbounds i32, i32* %A, i32 %i.us
+  store i32 %add.us.lcssa, i32* %arrayidx6.us, align 4, !tbaa !5
+  %add8.us = add nuw i32 %i.us, 1
+  %exitcond25 = icmp eq i32 %add8.us, %I
+  br i1 %exitcond25, label %for.end.loopexit, label %for.outer
+
+for.end.loopexit:
+  br label %for.end
+
+for.end:
+  ret void
+}
+
+
+; CHECK-LABEL: unprof4
+; No loop invariant loads
+define void @unprof4(i32 %I, i32 %J, i32* noalias nocapture %A, i32* noalias nocapture readonly %B) #0 {
+; CHECK: %i.us = phi i32 [ %add8.us, %for.latch ], [ 0, %for.outer.preheader ]
+; CHECK: %j.us = phi i32 [ 0, %for.outer ], [ %inc.us, %for.inner ]
+entry:
+  %cmp = icmp ne i32 %J, 0
+  %cmp122 = icmp ne i32 %I, 0
+  %or.cond = and i1 %cmp, %cmp122
+  br i1 %or.cond, label %for.outer.preheader, label %for.end
+
+for.outer.preheader:
+  br label %for.outer
+
+for.outer:
+  %i.us = phi i32 [ %add8.us, %for.latch ], [ 0, %for.outer.preheader ]
+  br label %for.inner
+
+for.inner:
+  %j.us = phi i32 [ 0, %for.outer ], [ %inc.us, %for.inner ]
+  %sum1.us = phi i32 [ 0, %for.outer ], [ %add.us, %for.inner ]
+  %j2 = add i32 %j.us, %i.us
+  %arrayidx.us = getelementptr inbounds i32, i32* %B, i32 %j2
+  %0 = load i32, i32* %arrayidx.us, align 4, !tbaa !5
+  %add.us = add i32 %0, %sum1.us
+  %inc.us = add nuw i32 %j.us, 1
+  %exitcond = icmp eq i32 %inc.us, %J
+  br i1 %exitcond, label %for.latch, label %for.inner
+
+for.latch:
+  %add.us.lcssa = phi i32 [ %add.us, %for.inner ]
+  %arrayidx6.us = getelementptr inbounds i32, i32* %A, i32 %i.us
+  store i32 %add.us.lcssa, i32* %arrayidx6.us, align 4, !tbaa !5
+  %add8.us = add nuw i32 %i.us, 1
+  %exitcond25 = icmp eq i32 %add8.us, %I
+  br i1 %exitcond25, label %for.end.loopexit, label %for.outer
+
+for.end.loopexit:
+  br label %for.end
+
+for.end:
+  ret void
+}
+
+
+; Function Attrs: argmemonly nounwind
+declare void @llvm.lifetime.start.p0i8(i64, i8* nocapture) #1
+
+; Function Attrs: argmemonly nounwind
+declare void @llvm.lifetime.end.p0i8(i64, i8* nocapture) #1
+
+attributes #0 = { noinline norecurse nounwind "correctly-rounded-divide-sqrt-fp-math"="false" "denormal-fp-math"="preserve-sign" "disable-tail-calls"="false" "less-precise-fpmad"="false" "no-frame-pointer-elim"="false" "no-infs-fp-math"="true" "no-jump-tables"="false" "no-nans-fp-math"="true" "no-signed-zeros-fp-math"="true" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="cortex-m33" "target-features"="+d16,+dsp,+fp-armv8,+fp-only-sp,+hwdiv,+thumb-mode,-crc,-dotprod,-hwdiv-arm,-ras" "unsafe-fp-math"="false" "use-soft-float"="false" }
+attributes #1 = { argmemonly nounwind }
+
+!5 = !{!6, !6, i64 0}
+!6 = !{!"omnipotent char", !7, i64 0}
+!7 = !{!"Simple C/C++ TBAA"}

test/Transforms/LoopUnrollAndJam/unroll-and-jam.ll

+; RUN: opt -basicaa -tbaa -loop-unroll-and-jam -unroll-and-jam-count=4 < %s -S | FileCheck %s
+
+target datalayout = "e-m:e-p:32:32-i64:64-v128:64:128-a:0:32-n32-S64"
+target triple = "thumbv8m.main-arm-none-eabi"
+
+; CHECK-LABEL: test1
+; Tests for(i) { sum = 0; for(j) sum += B[j]; A[i] = sum; }
+; CHECK: entry:
+; CHECK:   br i1 %or.cond, label %for.outer.preheader, label %for.end
+; CHECK: for.outer.preheader:
+; CHECK:   br i1 %1, label %for.end.loopexit.unr-lcssa, label %for.outer.preheader.new
+; CHECK: for.outer.preheader.new:
+; CHECK:   br label %for.outer
+; CHECK: for.outer:
+; CHECK:   %i.us = phi i32 [ %add8.us.3, %for.latch ], [ 0, %for.outer.preheader.new ]
+; CHECK:   %niter = phi i32 [ %unroll_iter, %for.outer.preheader.new ], [ %niter.nsub.3, %for.latch ]
+; CHECK:   %add8.us = add nuw nsw i32 %i.us, 1
+; CHECK:   %niter.nsub = sub i32 %niter, 1
+; CHECK:   %add8.us.1 = add nuw nsw i32 %add8.us, 1
+; CHECK:   %niter.nsub.1 = sub i32 %niter.nsub, 1
+; CHECK:   %add8.us.2 = add nuw nsw i32 %add8.us.1, 1
+; CHECK:   %niter.nsub.2 = sub i32 %niter.nsub.1, 1
+; CHECK:   %add8.us.3 = add nuw i32 %add8.us.2, 1
+; CHECK:   %niter.nsub.3 = sub i32 %niter.nsub.2, 1
+; CHECK:   br label %for.inner
+; CHECK: for.inner:
+; CHECK:   %j.us = phi i32 [ 0, %for.outer ], [ %inc.us, %for.inner ]
+; CHECK:   %sum1.us = phi i32 [ 0, %for.outer ], [ %add.us, %for.inner ]
+; CHECK:   %j.us.1 = phi i32 [ 0, %for.outer ], [ %inc.us.1, %for.inner ]
+; CHECK:   %sum1.us.1 = phi i32 [ 0, %for.outer ], [ %add.us.1, %for.inner ]
+; CHECK:   %j.us.2 = phi i32 [ 0, %for.outer ], [ %inc.us.2, %for.inner ]
+; CHECK:   %sum1.us.2 = phi i32 [ 0, %for.outer ], [ %add.us.2, %for.inner ]
+; CHECK:   %j.us.3 = phi i32 [ 0, %for.outer ], [ %inc.us.3, %for.inner ]
+; CHECK:   %sum1.us.3 = phi i32 [ 0, %for.outer ], [ %add.us.3, %for.inner ]
+; CHECK:   %arrayidx.us = getelementptr inbounds i32, i32* %B, i32 %j.us
+; CHECK:   %2 = load i32, i32* %arrayidx.us, align 4, !tbaa !0
+; CHECK:   %add.us = add i32 %2, %sum1.us
+; CHECK:   %inc.us = add nuw i32 %j.us, 1
+; CHECK:   %arrayidx.us.1 = getelementptr inbounds i32, i32* %B, i32 %j.us.1
+; CHECK:   %3 = load i32, i32* %arrayidx.us.1, align 4, !tbaa !0
+; CHECK:   %add.us.1 = add i32 %3, %sum1.us.1
+; CHECK:   %inc.us.1 = add nuw i32 %j.us.1, 1
+; CHECK:   %arrayidx.us.2 = getelementptr inbounds i32, i32* %B, i32 %j.us.2
+; CHECK:   %4 = load i32, i32* %arrayidx.us.2, align 4, !tbaa !0
+; CHECK:   %add.us.2 = add i32 %4, %sum1.us.2
+; CHECK:   %inc.us.2 = add nuw i32 %j.us.2, 1
+; CHECK:   %arrayidx.us.3 = getelementptr inbounds i32, i32* %B, i32 %j.us.3
+; CHECK:   %5 = load i32, i32* %arrayidx.us.3, align 4, !tbaa !0
+; CHECK:   %add.us.3 = add i32 %5, %sum1.us.3
+; CHECK:   %inc.us.3 = add nuw i32 %j.us.3, 1
+; CHECK:   %exitcond.3 = icmp eq i32 %inc.us.3, %J
+; CHECK:   br i1 %exitcond.3, label %for.latch, label %for.inner
+; CHECK: for.latch:
+; CHECK:   %add.us.lcssa = phi i32 [ %add.us, %for.inner ]
+; CHECK:   %add.us.lcssa.1 = phi i32 [ %add.us.1, %for.inner ]
+; CHECK:   %add.us.lcssa.2 = phi i32 [ %add.us.2, %for.inner ]
+; CHECK:   %add.us.lcssa.3 = phi i32 [ %add.us.3, %for.inner ]
+; CHECK:   %arrayidx6.us = getelementptr inbounds i32, i32* %A, i32 %i.us
+; CHECK:   store i32 %add.us.lcssa, i32* %arrayidx6.us, align 4, !tbaa !0
+; CHECK:   %arrayidx6.us.1 = getelementptr inbounds i32, i32* %A, i32 %add8.us
+; CHECK:   store i32 %add.us.lcssa.1, i32* %arrayidx6.us.1, align 4, !tbaa !0
+; CHECK:   %arrayidx6.us.2 = getelementptr inbounds i32, i32* %A, i32 %add8.us.1
+; CHECK:   store i32 %add.us.lcssa.2, i32* %arrayidx6.us.2, align 4, !tbaa !0
+; CHECK:   %arrayidx6.us.3 = getelementptr inbounds i32, i32* %A, i32 %add8.us.2
+; CHECK:   store i32 %add.us.lcssa.3, i32* %arrayidx6.us.3, align 4, !tbaa !0
+; CHECK:   %niter.ncmp.3 = icmp eq i32 %niter.nsub.3, 0
+; CHECK:   br i1 %niter.ncmp.3, label %for.end.loopexit.unr-lcssa.loopexit, label %for.outer
+; CHECK: for.end.loopexit.unr-lcssa.loopexit:
+; CHECK:   %i.us.unr.ph = phi i32 [ %add8.us.3, %for.latch ]
+; CHECK:   br label %for.end.loopexit.unr-lcssa
+; CHECK: for.end.loopexit.unr-lcssa:
+; CHECK:   br i1 %lcmp.mod, label %for.outer.epil.preheader, label %for.end.loopexit
+; CHECK: for.outer.epil.preheader:
+; CHECK:   br label %for.outer.epil
+; CHECK: for.outer.epil:
+; CHECK:   br label %for.inner.epil
+; CHECK: for.inner.epil:
+; CHECK:   br i1 %exitcond.epil, label %for.latch.epil, label %for.inner.epil
+; CHECK: for.latch.epil:
+; CHECK:   br i1 %epil.iter.cmp, label %for.outer.epil.1, label %for.end.loopexit.epilog-lcssa
+; CHECK: for.end.loopexit.epilog-lcssa:
+; CHECK:   br label %for.end.loopexit
+; CHECK: for.end.loopexit:
+; CHECK:   br label %for.end
+; CHECK: for.end:
+; CHECK:   ret void
+; CHECK: for.outer.epil.1:
+; CHECK:   br label %for.inner.epil.1
+; CHECK: for.inner.epil.1:
+; CHECK:   br i1 %exitcond.epil.1, label %for.latch.epil.1, label %for.inner.epil.1
+; CHECK: for.latch.epil.1:
+; CHECK:   br i1 %epil.iter.cmp.1, label %for.outer.epil.2, label %for.end.loopexit.epilog-lcssa
+; CHECK: for.outer.epil.2:
+; CHECK:   br label %for.inner.epil.2
+; CHECK: for.inner.epil.2:
+; CHECK:   br i1 %exitcond.epil.2, label %for.latch.epil.2, label %for.inner.epil.2
+; CHECK: for.latch.epil.2:
+; CHECK:   br label %for.end.loopexit.epilog-lcssa
+define void @test1(i32 %I, i32 %J, i32* noalias nocapture %A, i32* noalias nocapture readonly %B) #0 {
+entry:
+  %cmp = icmp ne i32 %J, 0
+  %cmp122 = icmp ne i32 %I, 0
+  %or.cond = and i1 %cmp, %cmp122
+  br i1 %or.cond, label %for.outer.preheader, label %for.end
+
+for.outer.preheader:
+  br label %for.outer
+
+for.outer:
+  %i.us = phi i32 [ %add8.us, %for.latch ], [ 0, %for.outer.preheader ]
+  br label %for.inner
+
+for.inner:
+  %j.us = phi i32 [ 0, %for.outer ], [ %inc.us, %for.inner ]
+  %sum1.us = phi i32 [ 0, %for.outer ], [ %add.us, %for.inner ]
+  %arrayidx.us = getelementptr inbounds i32, i32* %B, i32 %j.us
+  %0 = load i32, i32* %arrayidx.us, align 4, !tbaa !5
+  %add.us = add i32 %0, %sum1.us
+  %inc.us = add nuw i32 %j.us, 1
+  %exitcond = icmp eq i32 %inc.us, %J
+  br i1 %exitcond, label %for.latch, label %for.inner
+
+for.latch:
+  %add.us.lcssa = phi i32 [ %add.us, %for.inner ]
+  %arrayidx6.us = getelementptr inbounds i32, i32* %A, i32 %i.us
+  store i32 %add.us.lcssa, i32* %arrayidx6.us, align 4, !tbaa !5
+  %add8.us = add nuw i32 %i.us, 1
+  %exitcond25 = icmp eq i32 %add8.us, %I
+  br i1 %exitcond25, label %for.end.loopexit, label %for.outer
+
+for.end.loopexit:
+  br label %for.end
+
+for.end:
+  ret void
+}
+
+; CHECK-LABEL: test2
+; Tests for(i) { sum = A[i]; for(j) sum += B[j]; A[i] = sum; }
+; A[i] load/store dependency should not block unroll-and-jam
+; CHECK: for.outer:
+; CHECK:   %i.us = phi i32 [ %add9.us.3, %for.latch ], [ 0, %for.outer.preheader.new ]
+; CHECK:   %niter = phi i32 [ %unroll_iter, %for.outer.preheader.new ], [ %niter.nsub.3, %for.latch ]
+; CHECK:   br label %for.inner
+; CHECK: for.inner:
+; CHECK:   %j.us = phi i32 [ 0, %for.outer ], [ %inc.us, %for.inner ]
+; CHECK:   %sum1.us = phi i32 [ %2, %for.outer ], [ %add.us, %for.inner ]
+; CHECK:   %j.us.1 = phi i32 [ 0, %for.outer ], [ %inc.us.1, %for.inner ]
+; CHECK:   %sum1.us.1 = phi i32 [ %3, %for.outer ], [ %add.us.1, %for.inner ]
+; CHECK:   %j.us.2 = phi i32 [ 0, %for.outer ], [ %inc.us.2, %for.inner ]
+; CHECK:   %sum1.us.2 = phi i32 [ %4, %for.outer ], [ %add.us.2, %for.inner ]
+; CHECK:   %j.us.3 = phi i32 [ 0, %for.outer ], [ %inc.us.3, %for.inner ]
+; CHECK:   %sum1.us.3 = phi i32 [ %5, %for.outer ], [ %add.us.3, %for.inner ]
+; CHECK:   br i1 %exitcond.3, label %for.latch, label %for.inner
+; CHECK: for.latch:
+; CHECK:   %add.us.lcssa = phi i32 [ %add.us, %for.inner ]
+; CHECK:   %add.us.lcssa.1 = phi i32 [ %add.us.1, %for.inner ]
+; CHECK:   %add.us.lcssa.2 = phi i32 [ %add.us.2, %for.inner ]
+; CHECK:   %add.us.lcssa.3 = phi i32 [ %add.us.3, %for.inner ]
+; CHECK:   br i1 %niter.ncmp.3, label %for.end10.loopexit.unr-lcssa.loopexit, label %for.outer
+; CHECK: for.end10.loopexit.unr-lcssa.loopexit:
+define void @test2(i32 %I, i32 %J, i32* noalias nocapture %A, i32* noalias nocapture readonly %B) #0 {
+entry:
+  %cmp = icmp ne i32 %J, 0
+  %cmp125 = icmp ne i32 %I, 0
+  %or.cond = and i1 %cmp, %cmp125
+  br i1 %or.cond, label %for.outer.preheader, label %for.end10
+
+for.outer.preheader:
+  br label %for.outer
+
+for.outer:
+  %i.us = phi i32 [ %add9.us, %for.latch ], [ 0, %for.outer.preheader ]
+  %arrayidx.us = getelementptr inbounds i32, i32* %A, i32 %i.us
+  %0 = load i32, i32* %arrayidx.us, align 4, !tbaa !5
+  br label %for.inner
+
+for.inner:
+  %j.us = phi i32 [ 0, %for.outer ], [ %inc.us, %for.inner ]
+  %sum1.us = phi i32 [ %0, %for.outer ], [ %add.us, %for.inner ]
+  %arrayidx6.us = getelementptr inbounds i32, i32* %B, i32 %j.us
+  %1 = load i32, i32* %arrayidx6.us, align 4, !tbaa !5
+  %add.us = add i32 %1, %sum1.us
+  %inc.us = add nuw i32 %j.us, 1
+  %exitcond = icmp eq i32 %inc.us, %J
+  br i1 %exitcond, label %for.latch, label %for.inner
+
+for.latch:
+  %add.us.lcssa = phi i32 [ %add.us, %for.inner ]
+  store i32 %add.us.lcssa, i32* %arrayidx.us, align 4, !tbaa !5
+  %add9.us = add nuw i32 %i.us, 1
+  %exitcond28 = icmp eq i32 %add9.us, %I
+  br i1 %exitcond28, label %for.end10.loopexit, label %for.outer
+
+for.end10.loopexit:
+  br label %for.end10
+
+for.end10:
+  ret void
+}
+
+
+; CHECK-LABEL: test3
+; Tests Complete unroll-and-jam of the outer loop
+; CHECK: for.outer:
+; CHECK:   br label %for.inner
+; CHECK: for.inner:
+; CHECK:   %j.021 = phi i32 [ 0, %for.outer ], [ %inc, %for.inner ]
+; CHECK:   %sum1.020 = phi i32 [ 0, %for.outer ], [ %add, %for.inner ]
+; CHECK:   %j.021.1 = phi i32 [ 0, %for.outer ], [ %inc.1, %for.inner ]
+; CHECK:   %sum1.020.1 = phi i32 [ 0, %for.outer ], [ %add.1, %for.inner ]
+; CHECK:   %j.021.2 = phi i32 [ 0, %for.outer ], [ %inc.2, %for.inner ]
+; CHECK:   %sum1.020.2 = phi i32 [ 0, %for.outer ], [ %add.2, %for.inner ]
+; CHECK:   %j.021.3 = phi i32 [ 0, %for.outer ], [ %inc.3, %for.inner ]
+; CHECK:   %sum1.020.3 = phi i32 [ 0, %for.outer ], [ %add.3, %for.inner ]
+; CHECK:   br i1 %exitcond.3, label %for.latch, label %for.inner
+; CHECK: for.latch:
+; CHECK:   %add.lcssa = phi i32 [ %add, %for.inner ]
+; CHECK:   %add.lcssa.1 = phi i32 [ %add.1, %for.inner ]
+; CHECK:   %add.lcssa.2 = phi i32 [ %add.2, %for.inner ]
+; CHECK:   %add.lcssa.3 = phi i32 [ %add.3, %for.inner ]
+; CHECK:   br label %for.end
+; CHECK: for.end:
+define void @test3(i32 %I, i32 %J, i32* noalias nocapture %A, i32* noalias nocapture readonly %B) local_unnamed_addr #0 {
+entry:
+  %cmp = icmp eq i32 %J, 0
+  br i1 %cmp, label %for.end, label %for.preheader
+
+for.preheader:
+  br label %for.outer
+
+for.outer:
+  %i.022 = phi i32 [ %add8, %for.latch ], [ 0, %for.preheader ]
+  br label %for.inner
+
+for.inner:
+  %j.021 = phi i32 [ 0, %for.outer ], [ %inc, %for.inner ]
+  %sum1.020 = phi i32 [ 0, %for.outer ], [ %add, %for.inner ]
+  %arrayidx = getelementptr inbounds i32, i32* %B, i32 %j.021
+  %0 = load i32, i32* %arrayidx, align 4, !tbaa !5
+  %sub = add i32 %sum1.020, 10
+  %add = sub i32 %sub, %0
+  %inc = add nuw i32 %j.021, 1
+  %exitcond = icmp eq i32 %inc, %J
+  br i1 %exitcond, label %for.latch, label %for.inner
+
+for.latch:
+  %arrayidx6 = getelementptr inbounds i32, i32* %A, i32 %i.022
+  store i32 %add, i32* %arrayidx6, align 4, !tbaa !5
+  %add8 = add nuw nsw i32 %i.022, 1
+  %exitcond23 = icmp eq i32 %add8, 4
+  br i1 %exitcond23, label %for.end, label %for.outer
+
+for.end:
+  ret void
+}
+
+; CHECK-LABEL: test4
+; Tests Complete unroll-and-jam with a trip count of 1
+; CHECK: for.outer:
+; CHECK:   br label %for.inner
+; CHECK: for.inner:
+; CHECK:   %j.021 = phi i32 [ 0, %for.outer ], [ %inc, %for.inner ]
+; CHECK:   %sum1.020 = phi i32 [ 0, %for.outer ], [ %add, %for.inner ]
+; CHECK:   br i1 %exitcond, label %for.latch, label %for.inner
+; CHECK: for.latch:
+; CHECK:   %add.lcssa = phi i32 [ %add, %for.inner ]
+; CHECK:   br label %for.end
+; CHECK: for.end:
+define void @test4(i32 %I, i32 %J, i32* noalias nocapture %A, i32* noalias nocapture readonly %B) local_unnamed_addr #0 {
+entry:
+  %cmp = icmp eq i32 %J, 0
+  br i1 %cmp, label %for.end, label %for.preheader
+
+for.preheader:
+  br label %for.outer
+
+for.outer:
+  %i.022 = phi i32 [ %add8, %for.latch ], [ 0, %for.preheader ]
+  br label %for.inner
+
+for.inner:
+  %j.021 = phi i32 [ 0, %for.outer ], [ %inc, %for.inner ]
+  %sum1.020 = phi i32 [ 0, %for.outer ], [ %add, %for.inner ]
+  %arrayidx = getelementptr inbounds i32, i32* %B, i32 %j.021
+  %0 = load i32, i32* %arrayidx, align 4, !tbaa !5
+  %sub = add i32 %sum1.020, 10
+  %add = sub i32 %sub, %0
+  %inc = add nuw i32 %j.021, 1
+  %exitcond = icmp eq i32 %inc, %J
+  br i1 %exitcond, label %for.latch, label %for.inner
+
+for.latch:
+  %arrayidx6 = getelementptr inbounds i32, i32* %A, i32 %i.022
+  store i32 %add, i32* %arrayidx6, align 4, !tbaa !5
+  %add8 = add nuw nsw i32 %i.022, 1
+  %exitcond23 = icmp eq i32 %add8, 1
+  br i1 %exitcond23, label %for.end, label %for.outer
+
+for.end:
+  ret void
+}
+
+
+
+
+
+; CHECK-LABEL: test5
+; Multiple SubLoopBlocks
+; CHECK: for.outer:
+; CHECK:   br label %for.inner
+; CHECK: for.inner:
+; CHECK:   %inc8.sink15 = phi i32 [ 0, %for.outer ], [ %inc8, %for.inc.1 ]
+; CHECK:   %inc8.sink15.1 = phi i32 [ 0, %for.outer ], [ %inc8.1, %for.inc.1 ]
+; CHECK:   br label %for.inner2
+; CHECK: for.inner2:
+; CHECK:   br i1 %tobool, label %for.cond4, label %for.inc
+; CHECK: for.cond4:
+; CHECK:   br i1 %tobool.1, label %for.cond4a, label %for.inc
+; CHECK: for.cond4a:
+; CHECK:   br label %for.inc
+; CHECK: for.inc:
+; CHECK:   br i1 %tobool.11, label %for.cond4.1, label %for.inc.1
+; CHECK: for.latch:
+; CHECK:   br label %for.end
+; CHECK: for.end:
+; CHECK:   ret i32 0
+; CHECK: for.cond4.1:
+; CHECK:   br i1 %tobool.1.1, label %for.cond4a.1, label %for.inc.1
+; CHECK: for.cond4a.1:
+; CHECK:   br label %for.inc.1
+; CHECK: for.inc.1:
+; CHECK:   br i1 %exitcond.1, label %for.latch, label %for.inner
+@a = hidden local_unnamed_addr global [1 x i32] zeroinitializer, align 4
+define i32 @test5() local_unnamed_addr #0 {
+entry:
+  br label %for.outer
+
+for.outer:
+  %.sink16 = phi i32 [ 0, %entry ], [ %add, %for.latch ]
+  br label %for.inner
+
+for.inner:
+  %inc8.sink15 = phi i32 [ 0, %for.outer ], [ %inc8, %for.inc ]
+  br label %for.inner2
+
+for.inner2:
+  %l1 = load i32, i32* getelementptr inbounds ([1 x i32], [1 x i32]* @a, i32 0, i32 0), align 4
+  %tobool = icmp eq i32 %l1, 0
+  br i1 %tobool, label %for.cond4, label %for.inc
+
+for.cond4:
+  %l0 = load i32, i32* getelementptr inbounds ([1 x i32], [1 x i32]* @a, i32 1, i32 0), align 4
+  %tobool.1 = icmp eq i32 %l0, 0
+  br i1 %tobool.1, label %for.cond4a, label %for.inc
+
+for.cond4a:
+  br label %for.inc
+
+for.inc:
+  %l2 = phi i32 [ 0, %for.inner2 ], [ 1, %for.cond4 ], [ 2, %for.cond4a ]
+  %inc8 = add nuw nsw i32 %inc8.sink15, 1
+  %exitcond = icmp eq i32 %inc8, 3
+  br i1 %exitcond, label %for.latch, label %for.inner
+
+for.latch:
+  %.lcssa = phi i32 [ %l2, %for.inc ]
+  %conv11 = and i32 %.sink16, 255
+  %add = add nuw nsw i32 %conv11, 4
+  %cmp = icmp eq i32 %add, 8
+  br i1 %cmp, label %for.end, label %for.outer
+
+for.end:
+  %.lcssa.lcssa = phi i32 [ %.lcssa, %for.latch ]
+  ret i32 0
+}
+
+
+
+
+; CHECK-LABEL: test6
+; Test odd uses of phi nodes
+; CHECK: for.outer:
+; CHECK:   br label %for.inner
+; CHECK: for.inner:
+; CHECK:   br i1 %exitcond.3, label %for.inner, label %for.latch
+; CHECK: for.latch:
+; CHECK:   br label %for.end
+; CHECK: for.end:
+; CHECK:   ret i32 0
+@f = hidden local_unnamed_addr global i32 0, align 4
+define i32 @test6() local_unnamed_addr #0 {
+entry:
+  %f.promoted10 = load i32, i32* @f, align 4, !tbaa !5
+  br label %for.outer
+
+for.outer:
+  %p0 = phi i32 [ %f.promoted10, %entry ], [ 2, %for.latch ]
+  %inc5.sink9 = phi i32 [ 2, %entry ], [ %inc5, %for.latch ]
+  br label %for.inner
+
+for.inner:
+  %p1 = phi i32 [ %p0, %for.outer ], [ 2, %for.inner ]
+  %inc.sink8 = phi i32 [ 0, %for.outer ], [ %inc, %for.inner ]
+  %inc = add nuw nsw i32 %inc.sink8, 1
+  %exitcond = icmp ne i32 %inc, 7
+  br i1 %exitcond, label %for.inner, label %for.latch
+
+for.latch:
+  %.lcssa = phi i32 [ %p1, %for.inner ]
+  %inc5 = add nuw nsw i32 %inc5.sink9, 1
+  %exitcond11 = icmp ne i32 %inc5, 7
+  br i1 %exitcond11, label %for.outer, label %for.end
+
+for.end:
+  %.lcssa.lcssa = phi i32 [ %.lcssa, %for.latch ]
+  %inc.lcssa.lcssa = phi i32 [ 7, %for.latch ]
+  ret i32 0
+}
+
+
+
+; CHECK-LABEL: test7
+; Has a positive dependency between two stores. Still valid.
+; The negative dependecy is in unroll-and-jam-disabled.ll
+; CHECK: for.outer:
+; CHECK:   %i = phi i32 [ %add.3, %for.latch ], [ 0, %for.preheader.new ]
+; CHECK:   %niter = phi i32 [ %unroll_iter, %for.preheader.new ], [ %niter.nsub.3, %for.latch ]
+; CHECK:   br label %for.inner
+; CHECK: for.latch:
+; CHECK:   %add9.lcssa = phi i32 [ %add9, %for.inner ]
+; CHECK:   %add9.lcssa.1 = phi i32 [ %add9.1, %for.inner ]
+; CHECK:   %add9.lcssa.2 = phi i32 [ %add9.2, %for.inner ]
+; CHECK:   %add9.lcssa.3 = phi i32 [ %add9.3, %for.inner ]
+; CHECK:   br i1 %niter.ncmp.3, label %for.end.loopexit.unr-lcssa.loopexit, label %for.outer
+; CHECK: for.inner:
+; CHECK:   %sum = phi i32 [ 0, %for.outer ], [ %add9, %for.inner ]
+; CHECK:   %j = phi i32 [ 0, %for.outer ], [ %add10, %for.inner ]
+; CHECK:   %sum.1 = phi i32 [ 0, %for.outer ], [ %add9.1, %for.inner ]
+; CHECK:   %j.1 = phi i32 [ 0, %for.outer ], [ %add10.1, %for.inner ]
+; CHECK:   %sum.2 = phi i32 [ 0, %for.outer ], [ %add9.2, %for.inner ]
+; CHECK:   %j.2 = phi i32 [ 0, %for.outer ], [ %add10.2, %for.inner ]
+; CHECK:   %sum.3 = phi i32 [ 0, %for.outer ], [ %add9.3, %for.inner ]
+; CHECK:   %j.3 = phi i32 [ 0, %for.outer ], [ %add10.3, %for.inner ]
+; CHECK:   br i1 %exitcond.3, label %for.latch, label %for.inner
+; CHECK: for.end.loopexit.unr-lcssa.loopexit:
+define void @test7(i32 %I, i32 %J, i32* noalias nocapture %A, i32* noalias nocapture readonly %B) local_unnamed_addr #0 {
+entry:
+  %cmp = icmp ne i32 %J, 0
+  %cmp128 = icmp ne i32 %I, 0
+  %or.cond = and i1 %cmp128, %cmp
+  br i1 %or.cond, label %for.preheader, label %for.end
+
+for.preheader:
+  br label %for.outer
+
+for.outer:
+  %i = phi i32 [ %add, %for.latch ], [ 0, %for.preheader ]
+  %arrayidx = getelementptr inbounds i32, i32* %A, i32 %i
+  store i32 0, i32* %arrayidx, align 4, !tbaa !5
+  %add = add nuw i32 %i, 1
+  %arrayidx2 = getelementptr inbounds i32, i32* %A, i32 %add
+  store i32 2, i32* %arrayidx2, align 4, !tbaa !5
+  br label %for.inner
+
+for.latch:
+  store i32 %add9, i32* %arrayidx, align 4, !tbaa !5
+  %exitcond30 = icmp eq i32 %add, %I
+  br i1 %exitcond30, label %for.end, label %for.outer
+
+for.inner:
+  %sum = phi i32 [ 0, %for.outer ], [ %add9, %for.inner ]
+  %j = phi i32 [ 0, %for.outer ], [ %add10, %for.inner ]
+  %arrayidx7 = getelementptr inbounds i32, i32* %B, i32 %j
+  %l1 = load i32, i32* %arrayidx7, align 4, !tbaa !5
+  %add9 = add i32 %l1, %sum
+  %add10 = add nuw i32 %j, 1
+  %exitcond = icmp eq i32 %add10, %J
+  br i1 %exitcond, label %for.latch, label %for.inner
+
+for.end:
+  ret void
+}
+
+
+
+; CHECK-LABEL: test8
+; Same as test7 with an extra outer loop nest
+; CHECK: for.outest:
+; CHECK:   br label %for.outer
+; CHECK: for.outer:
+; CHECK:   %i = phi i32 [ %add.3, %for.latch ], [ 0, %for.outest.new ]
+; CHECK:   %niter = phi i32 [ %unroll_iter, %for.outest.new ], [ %niter.nsub.3, %for.latch ]
+; CHECK:   br label %for.inner
+; CHECK: for.inner:
+; CHECK:   %sum = phi i32 [ 0, %for.outer ], [ %add9, %for.inner ]
+; CHECK:   %j = phi i32 [ 0, %for.outer ], [ %add10, %for.inner ]
+; CHECK:   %sum.1 = phi i32 [ 0, %for.outer ], [ %add9.1, %for.inner ]
+; CHECK:   %j.1 = phi i32 [ 0, %for.outer ], [ %add10.1, %for.inner ]
+; CHECK:   %sum.2 = phi i32 [ 0, %for.outer ], [ %add9.2, %for.inner ]
+; CHECK:   %j.2 = phi i32 [ 0, %for.outer ], [ %add10.2, %for.inner ]
+; CHECK:   %sum.3 = phi i32 [ 0, %for.outer ], [ %add9.3, %for.inner ]
+; CHECK:   %j.3 = phi i32 [ 0, %for.outer ], [ %add10.3, %for.inner ]
+; CHECK:   br i1 %exitcond.3, label %for.latch, label %for.inner
+; CHECK: for.latch:
+; CHECK:   %add9.lcssa = phi i32 [ %add9, %for.inner ]
+; CHECK:   %add9.lcssa.1 = phi i32 [ %add9.1, %for.inner ]
+; CHECK:   %add9.lcssa.2 = phi i32 [ %add9.2, %for.inner ]
+; CHECK:   %add9.lcssa.3 = phi i32 [ %add9.3, %for.inner ]
+; CHECK:   br i1 %niter.ncmp.3, label %for.cleanup.unr-lcssa.loopexit, label %for.outer
+; CHECK: for.cleanup.epilog-lcssa:
+; CHECK:   br label %for.cleanup
+; CHECK: for.cleanup:
+; CHECK:   br i1 %exitcond41, label %for.end.loopexit, label %for.outest
+; CHECK: for.end.loopexit:
+; CHECK:   br label %for.end
+define void @test8(i32 %I, i32 %J, i32* noalias nocapture %A, i32* noalias nocapture readonly %B) local_unnamed_addr #0 {
+entry:
+  %cmp = icmp eq i32 %J, 0
+  %cmp336 = icmp eq i32 %I, 0
+  %or.cond = or i1 %cmp, %cmp336
+  br i1 %or.cond, label %for.end, label %for.preheader
+
+for.preheader:
+  br label %for.outest
+
+for.outest:
+  %x.038 = phi i32 [ %inc, %for.cleanup ], [ 0, %for.preheader ]
+  br label %for.outer
+
+for.outer:
+  %i = phi i32 [ %add, %for.latch ], [ 0, %for.outest ]
+  %arrayidx = getelementptr inbounds i32, i32* %A, i32 %i
+  store i32 0, i32* %arrayidx, align 4, !tbaa !5
+  %add = add nuw i32 %i, 1
+  %arrayidx6 = getelementptr inbounds i32, i32* %A, i32 %add
+  store i32 2, i32* %arrayidx6, align 4, !tbaa !5
+  br label %for.inner
+
+for.inner:
+  %sum = phi i32 [ 0, %for.outer ], [ %add9, %for.inner ]
+  %j = phi i32 [ 0, %for.outer ], [ %add10, %for.inner ]
+  %arrayidx11 = getelementptr inbounds i32, i32* %B, i32 %j
+  %l1 = load i32, i32* %arrayidx11, align 4, !tbaa !5
+  %add9 = add i32 %l1, %sum
+  %add10 = add nuw i32 %j, 1
+  %exitcond = icmp eq i32 %add10, %J
+  br i1 %exitcond, label %for.latch, label %for.inner
+
+for.latch:
+  store i32 %add9, i32* %arrayidx, align 4, !tbaa !5
+  %exitcond39 = icmp eq i32 %add, %I
+  br i1 %exitcond39, label %for.cleanup, label %for.outer
+
+for.cleanup:
+  %inc = add nuw nsw i32 %x.038, 1
+  %exitcond41 = icmp eq i32 %inc, 5
+  br i1 %exitcond41, label %for.end, label %for.outest
+
+
+for.end:
+  ret void
+}
+
+; CHECK-LABEL: test9
+; Same as test1 with tbaa, not noalias
+; CHECK: for.outer:
+; CHECK:   %i.us = phi i32 [ %add8.us.3, %for.latch ], [ 0, %for.outer.preheader.new ]
+; CHECK:   %niter = phi i32 [ %unroll_iter, %for.outer.preheader.new ], [ %niter.nsub.3, %for.latch ]
+; CHECK:   br label %for.inner
+; CHECK: for.inner:
+; CHECK:   %j.us = phi i32 [ 0, %for.outer ], [ %inc.us, %for.inner ]
+; CHECK:   %sum1.us = phi i32 [ 0, %for.outer ], [ %add.us, %for.inner ]
+; CHECK:   %j.us.1 = phi i32 [ 0, %for.outer ], [ %inc.us.1, %for.inner ]
+; CHECK:   %sum1.us.1 = phi i32 [ 0, %for.outer ], [ %add.us.1, %for.inner ]
+; CHECK:   %j.us.2 = phi i32 [ 0, %for.outer ], [ %inc.us.2, %for.inner ]
+; CHECK:   %sum1.us.2 = phi i32 [ 0, %for.outer ], [ %add.us.2, %for.inner ]
+; CHECK:   %j.us.3 = phi i32 [ 0, %for.outer ], [ %inc.us.3, %for.inner ]
+; CHECK:   %sum1.us.3 = phi i32 [ 0, %for.outer ], [ %add.us.3, %for.inner ]
+; CHECK:   br i1 %exitcond.3, label %for.latch, label %for.inner
+; CHECK: for.latch:
+; CHECK:   %add.us.lcssa = phi i32 [ %add.us, %for.inner ]
+; CHECK:   %add.us.lcssa.1 = phi i32 [ %add.us.1, %for.inner ]
+; CHECK:   %add.us.lcssa.2 = phi i32 [ %add.us.2, %for.inner ]
+; CHECK:   %add.us.lcssa.3 = phi i32 [ %add.us.3, %for.inner ]
+; CHECK:   br i1 %niter.ncmp.3, label %for.end.loopexit.unr-lcssa.loopexit, label %for.outer
+; CHECK: for.end.loopexit.unr-lcssa.loopexit:
+define void @test9(i32 %I, i32 %J, i32* nocapture %A, i16* nocapture readonly %B) #0 {
+entry:
+  %cmp = icmp ne i32 %J, 0
+  %cmp122 = icmp ne i32 %I, 0
+  %or.cond = and i1 %cmp, %cmp122
+  br i1 %or.cond, label %for.outer.preheader, label %for.end
+
+for.outer.preheader:
+  br label %for.outer
+
+for.outer:
+  %i.us = phi i32 [ %add8.us, %for.latch ], [ 0, %for.outer.preheader ]
+  br label %for.inner
+
+for.inner:
+  %j.us = phi i32 [ 0, %for.outer ], [ %inc.us, %for.inner ]
+  %sum1.us = phi i32 [ 0, %for.outer ], [ %add.us, %for.inner ]
+  %arrayidx.us = getelementptr inbounds i16, i16* %B, i32 %j.us
+  %0 = load i16, i16* %arrayidx.us, align 4, !tbaa !9
+  %sext = sext i16 %0 to i32
+  %add.us = add i32 %sext, %sum1.us
+  %inc.us = add nuw i32 %j.us, 1
+  %exitcond = icmp eq i32 %inc.us, %J
+  br i1 %exitcond, label %for.latch, label %for.inner
+
+for.latch:
+  %add.us.lcssa = phi i32 [ %add.us, %for.inner ]
+  %arrayidx6.us = getelementptr inbounds i32, i32* %A, i32 %i.us
+  store i32 %add.us.lcssa, i32* %arrayidx6.us, align 4, !tbaa !5
+  %add8.us = add nuw i32 %i.us, 1
+  %exitcond25 = icmp eq i32 %add8.us, %I
+  br i1 %exitcond25, label %for.end.loopexit, label %for.outer
+
+for.end.loopexit:
+  br label %for.end
+
+for.end:
+  ret void
+}
+
+
+
+; CHECK-LABEL: test10
+; Be careful not to incorrectly update the exit phi nodes
+; CHECK: %dec19.lcssa.lcssa.lcssa.ph.ph = phi i64 [ 0, %for.inc24 ]
+%struct.a = type { i64 }
+@g = common local_unnamed_addr global %struct.a zeroinitializer, align 8
+@c = common local_unnamed_addr global [1 x i8] zeroinitializer, align 1
+; Function Attrs: noinline norecurse nounwind uwtable
+define signext i16 @test10(i32 %k) local_unnamed_addr #0 {
+entry:
+  %0 = load i8, i8* getelementptr inbounds ([1 x i8], [1 x i8]* @c, i64 0, i64 0), align 1
+  %tobool9 = icmp eq i8 %0, 0
+  %tobool13 = icmp ne i32 %k, 0
+  br label %for.body
+
+for.body:                                         ; preds = %entry, %for.inc24
+  %storemerge82 = phi i64 [ 0, %entry ], [ %inc25, %for.inc24 ]
+  br label %for.body2
+
+for.body2:                                        ; preds = %for.body, %for.inc21
+  %storemerge2881 = phi i64 [ 4, %for.body ], [ %dec22, %for.inc21 ]
+  br i1 %tobool9, label %for.body2.split, label %for.body2.split.us
+
+for.body2.split.us:                               ; preds = %for.body2
+  br i1 %tobool13, label %for.inc21, label %for.inc21.loopexit83
+
+for.body2.split:                                  ; preds = %for.body2
+  br i1 %tobool13, label %for.inc21, label %for.inc21.loopexit85
+
+for.inc21.loopexit83:                             ; preds = %for.body2.split.us
+  %storemerge31.us37.lcssa.lcssa = phi i64 [ 0, %for.body2.split.us ]
+  br label %for.inc21
+
+for.inc21.loopexit85:                             ; preds = %for.body2.split
+  %storemerge31.lcssa.lcssa87 = phi i64 [ 0, %for.body2.split ]
+  %storemerge30.lcssa.lcssa86 = phi i32 [ 0, %for.body2.split ]
+  br label %for.inc21
+
+for.inc21:                                        ; preds = %for.body2.split, %for.body2.split.us, %for.inc21.loopexit85, %for.inc21.loopexit83
+  %storemerge31.lcssa.lcssa = phi i64 [ %storemerge31.us37.lcssa.lcssa, %for.inc21.loopexit83 ], [ %storemerge31.lcssa.lcssa87, %for.inc21.loopexit85 ], [ 4, %for.body2.split.us ], [ 4, %for.body2.split ]
+  %storemerge30.lcssa.lcssa = phi i32 [ 0, %for.inc21.loopexit83 ], [ %storemerge30.lcssa.lcssa86, %for.inc21.loopexit85 ], [ 0, %for.body2.split.us ], [ 0, %for.body2.split ]
+  %dec22 = add nsw i64 %storemerge2881, -1
+  %tobool = icmp eq i64 %dec22, 0
+  br i1 %tobool, label %for.inc24, label %for.body2
+
+for.inc24:                                        ; preds = %for.inc21
+  %storemerge31.lcssa.lcssa.lcssa = phi i64 [ %storemerge31.lcssa.lcssa, %for.inc21 ]
+  %storemerge30.lcssa.lcssa.lcssa = phi i32 [ %storemerge30.lcssa.lcssa, %for.inc21 ]
+  %inc25 = add nuw nsw i64 %storemerge82, 1
+  %exitcond = icmp ne i64 %inc25, 5
+  br i1 %exitcond, label %for.body, label %for.end26
+
+for.end26:                                        ; preds = %for.inc24
+  %dec19.lcssa.lcssa.lcssa = phi i64 [ 0, %for.inc24 ]
+  %storemerge31.lcssa.lcssa.lcssa.lcssa = phi i64 [ %storemerge31.lcssa.lcssa.lcssa, %for.inc24 ]
+  %storemerge30.lcssa.lcssa.lcssa.lcssa = phi i32 [ %storemerge30.lcssa.lcssa.lcssa, %for.inc24 ]
+  store i64 %dec19.lcssa.lcssa.lcssa, i64* getelementptr inbounds (%struct.a, %struct.a* @g, i64 0, i32 0), align 8
+  ret i16 0
+}
+
+
+attributes #0 = { noinline norecurse nounwind "correctly-rounded-divide-sqrt-fp-math"="false" "denormal-fp-math"="preserve-sign" "disable-tail-calls"="false" "less-precise-fpmad"="false" "no-frame-pointer-elim"="false" "no-infs-fp-math"="true" "no-jump-tables"="false" "no-nans-fp-math"="true" "no-signed-zeros-fp-math"="true" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="cortex-m33" "target-features"="+d16,+dsp,+fp-armv8,+fp-only-sp,+hwdiv,+thumb-mode,-crc,-dotprod,-hwdiv-arm,-ras" "unsafe-fp-math"="false" "use-soft-float"="false" }
+
+!5 = !{!6, !6, i64 0}
+!6 = !{!"int", !7, i64 0}
+!7 = !{!"omnipotent char", !8, i64 0}
+!8 = !{!"Simple C/C++ TBAA"}
+!9 = !{!10, !10, i64 0}
+!10 = !{!"short", !7, i64 0}