with a funny command line like clang -Oz -flto -o foo a.o b.c, where one (or all) of the input arguments is a source file? Would it invoke the bitcode compile of the source files with the requested -Oz and then invoke the LTO linker plugin with -O2/-O3?

I assume I might be missing something here, though, since someone mentioned this above (I don't understand the response to it though).

In D65774#1616200, @mehdi_amini wrote:

Isn't clang warning in the other direction? (incompatible with GCC)

Isn't clang warning in the other direction? (incompatible with GCC)

• Improve output when asking the user a question
• simplify python 2/3 compatibility

@jyknight : ping?

In D65295#1602763, @beanz wrote:

The CMake build system option PLUGIN_TOOL on add_llvm_loadable_module is for this specific purpose, it instructs the link step for the plugin dylib to resolve symbols against the tool.

Polly likely needs to generate different libraries for being a clang plugin vs being an opt plugin, but that is expected and the correct solution to this problem.

unfortunately does not solve the more general problem that not all symbols are available to plugins in statically linked tools. I am open for better solutions.

default to No

Change abort message to "Aborting"

Fix python 2/3 compatibility

The motivation is unclear to me at the moment? Why is it a good thing?

LGTM (after you remove the typo)

In D63976#1566236, @ruiu wrote:

I agree with Teresa. I don't think automatically setting O3 for Os and Oz is a good idea because these three options are different (that's why we have three different options in the first place). Adding an Os and Oz to lld's LTO option seems like a good idea, but they should be mapped to their corresponding features.

In D60495#1563127, @tejohnson wrote:

In D60495#1563124, @mehdi_amini wrote:

LGTM, but it'd be nice if @tejohnson or @pcc would also approve.

I added a suggestion a couple hours ago, just for commoning the code between the two LTO APIs.

LGTM, but it'd be nice if @tejohnson or @pcc would also approve.

Sorry I missed the previous updates.

LGTM

LGTM, thanks!

(Patch is missing context)

Wow that's much simpler!

LGTM.

It is good idea, thanks for putting this together!

Looks great! Thanks.

Thanks!

In D58391#1408322, @tejohnson wrote:

In D58391#1403188, @efriedma wrote:

What's the general state of the LTO pipeline at this point? PassManagerBuilder::addLTOOptimizationPasses is adding passes in a really weird order (in particular, the placement of the inliner is really strange). Has anyone looked at it recently? Would it be worth killing it off in favor of the ThinLTO pipeline just so we don't have to maintain it?

The reason they don't use the same pipeline is that it would be too expensive for regular LTO mode which is serial. ThinLTO can use a more aggressive post-link pipeline due to the parallelism. Mehdi did some measurements a couple years ago and found that using the ThinLTO pipeline for regular LTO increases the compile time in that mode significantly.

LGTM, but you should probably wait to hear from someone else as well

In D58384#1402418, @evgeny777 wrote:

Summary clusters, nodes and edges are retrieved from DenseMap with arbitrary order, which doesn't make result DOT file invalid.
Reverse iteration just exposes test issues.

Is it expected that the test output is sensitive to reverse iteration?
It sounds to me more like an issue with the code than with how the test is expressed.

In D58157#1397302, @rnk wrote:

In D58157#1397274, @mehdi_amini wrote:

It'd still be nice to identify the end goal with most cfe people (i.e. even if you land this right now, discussing the desired layout in the monorepo)

I sent off http://lists.llvm.org/pipermail/cfe-dev/2019-February/061290.html, so the larger community is aware of this change. I don't have much to add to a larger discussion about possible code reorganizations, but I suppose folks may come forward to express their opinions.

In D58157#1396824, @rnk wrote:

And, this change really just keeps us at parity with what we had with svn. We can always revisit the decision to merge the clang tools into clang. This particular change just gives us more options, today.

In D58157#1396072, @thakis wrote:

In D58157#1395762, @mehdi_amini wrote:

In D58157#1395716, @rnk wrote:

I think we have consensus,

Based on three comments in a revision? Seems strange to me.
I don't really care about this, so do whatever you want, but I would expect that "consensus" means an actual wider discussion (i.e. llvm-dev + cfe-dev).

Please cite said discussion for when you added this, as requested above.

In D58157#1395716, @rnk wrote:

I think we have consensus,

What is the motivation to change this now?

Could we sanitize the list of LLVM_ENABLE_PROJECTS and error for unknown entries?

@dexonsmith: I'm not sure why a new differential should be created? I updated reviewers in this one.

Thanks for fixing this!

In D57422#1376600, @pcc wrote:

In D57422#1376550, @sbc100 wrote:

Can I ask why you don't want --lto-O0 to set CGOptLevel to None?

The brief answer is: --lto-O0 means no cross-module optimizations,

You can avoid the git status pollution by adding the build directory to .git/info/exclude.

In D57330#1375096, @labath wrote:

This is not an full out-of-source build, since the build folder is still a subfolder of the repo root

LGTM, but for one comment that requires a fix I believe (lld on Windows)

In D56485#1363031, @filcab wrote:

@pcc: Since this impacts CFI, can you say if the perf impact is acceptable on your end?
@mehdi_amini: Same Qs, but about macOS

LGTM.

In D47073#1360077, @jfb wrote:

That's incorrect. I don't care what the policy is as long as it's sane. 3 years was proposed on the RFC, we went with it. Then nuance was asked for on this review, we went with it. Then it was asked that time was made a soft constraint, we went with it. Then more bikeshed happened.

I can't add much more than what @jyknight wrote here: https://reviews.llvm.org/D47073#1358937 ; this summarize perfectly my view of the situation.

I don't want to give the impression I'm stalling this just for the sake of being difficult, and since it is easier to talk "with code" I quickly wrote this: https://reviews.llvm.org/D56770 . This *not* a patch intended to be submitted, it is just a stripped-down version of how I'd phrase/structure it intended to support my arguments in this thread. Note that I would intentionally left out any compiler minimum bump out of the policy upgrade change, as these are conceptually separate change anyway.

In D47073#1358663, @jfb wrote:

s/two/one/ : I've talked to Chandler already, and he was leaning on others (in large parts, me) to help Erich with the review

In D47073#1358640, @jfb wrote:

In D47073#1358626, @mehdi_amini wrote:

In D47073#1358593, @jfb wrote:

OK I think we've had more than enough bikeshed, over months, and in-person at the LLVM dev meeting. This is good enough, we want to warn people for the LLVM 8 branch which is tomorrow. Let's get this checked in today. We'll start a discussion on LLVM dev when anything *actually* changes, so nobody needs to panic just yet.

I strongly disagree with this right now: this is *not* OK to rush this as is.

If you need something in the release, then it can be done in a much less controversial way.

What makes you say this is being rushed?

In D47073#1358593, @jfb wrote:

OK I think we've had more than enough bikeshed, over months, and in-person at the LLVM dev meeting. This is good enough, we want to warn people for the LLVM 8 branch which is tomorrow. Let's get this checked in today. We'll start a discussion on LLVM dev when anything *actually* changes, so nobody needs to panic just yet.