[PGO] Control Height Reduction

[hjyamauchi]

Summary

Control height reduction merges conditional blocks of code and reduces the
number of conditional branches in the hot path based on profiles.

if (hot_cond1) { // Likely true.

do_stg_hot1();

}
if (hot_cond2) { // Likely true.

do_stg_hot2();

}

->

if (hot_cond1 && hot_cond2) { // Hot path.

do_stg_hot1();
do_stg_hot2();

} else { // Cold path.

if (hot_cond1) {
  do_stg_hot1();
}
if (hot_cond2) {
  do_stg_hot2();
}

}

This speeds up some internal benchmarks up to ~30%.

[davidxl]

The request for test case description also applies to other new test cases.

test/Transforms/PGOProfile/chr.ll

9

Also add a simple test case to make sure cold functions are skipped.

15

Can you add check of the meta data itself (for testing of profile meta data merging)?

61

Can you add more detailed description of test case using C?

122

Similarly add test case description.

[davidxl]

lib/Passes/PassBuilder.cpp

198

what is npm?

199

Enable CHR --> Enable control height reduction optimization (CHR)

494

How about SamplePGO ?

lib/Transforms/Instrumentation/ControlHeightReduction.cpp

389

CHRModules should be checked before function name demangling and check.

394

For stress testing purpose, perhaps adding a force-chr option so that it is applied on cold functions as well?

441

need documentation comment for the function.

535

Make it an internal option.

538

the comment does not match the implementation: it returns true as long as MD is well formed.

596

Can some refactoriing be done to share some of the implementation with CheckBiasedBranch?

658

This method looks pretty big. Can it be broken up?

[davidxl]

lib/Transforms/Instrumentation/ControlHeightReduction.cpp

1379

this method is also gigantic. Suggest breaking it up (the debug check code can also be put into separate helpers).

[hjyamauchi]

Updated the test file.

[hjyamauchi]

test/Transforms/PGOProfile/chr.ll

15

There's already a check for !15 (at the end of this line). I added a few more.

[davidxl]

test/Transforms/PGOProfile/chr.ll

15

that is not what I meant. I think what is missing is the prof meta data's content. For instance

CHECK-NEXT: br i1 ....... !prof ![[COMBINED_PROF:%.*]]

CHECK:![[COMBINED_PROF] = ...

95

should be == 0

269

If this can be hoisted above, will the optimization combine (t1 & 3) | (t2 &12) ?

533

&& should be bitwise &

635

&& -> &

1085

Not sure if I understand the comments about bad hoisting here. You want to test the bad hoisting does not happen? What does the bad hoisting look like?

1243

likely true?

1244

likely true ?

1255

is z != 1 redundant?

1257

why was it inserted?

1440

should it be:

; t0 = *i
; v40 = t0 + 44
; if ((t0 & 3) == 3) Likely true
; foo()
; v41 = t0 + 99
; foo()
; } else {
; if ((t0 & 1) != 0) Likely true
; foo()
; if ((t0 & 2) != 0) // Likely true
; v41_nc = t0 + 99
; foo()
; }
; }
; v42 = phi (v41, v41_nc, v40)
; return v42 + v40

[hjyamauchi]

Updated the .cpp file.

[hjyamauchi]

lib/Passes/PassBuilder.cpp

198

New pass manager, following the options above.

[hjyamauchi]

Addressed more comments.

[hjyamauchi]

test/Transforms/PGOProfile/chr.ll

15

Had understood that. I should have said "at the end of the *file*". There are checks on the prof metadata content there.

269

Currently no if t1 and t2 are separate loads., and yes if t1/t2 are merged into one load.

1085

This is a regression test against a specific bug that existed regarding moving %conv. I think the bad hoisting looked like:

entry:

...
%div = fdiv double 1.000000e+00, %conv
%conv = sitofp i32 %0 to double
%mul16 = fmul double %div, %conv

It moved %conv to the end of %entry once for %div (from %bb1) and once more for %mul16 (within %entry).

Updated the comment.

1243

This should be false because the branch weight is 0:1.

1244

Same.

1255

yes, I think instcombine doesn't seem to fold due to limited reassociation. This doesn't matter for the point of the test, I think.

1257

As part of the CHR transformation, a trivial phi is inserted at the exit of a region when CHR is applied so that we can easily know what variables/values are live at the exit and need to have the incoming values corresponding to the cloned cold path added to those phis. IOW, when we split/clone a path/region into two, we need a new phi for anything that's alive at the exit. To make this easier, we first insert trivial phis at the exit for anything alive there and later add operands corresponding to the second path to those phis. This is also a regression test for an old bug.

1440

That's valid optimization but, I don't think CHR/instcombine don't specifically try hoisting v40.

[davidxl]

lib/Transforms/Instrumentation/ControlHeightReduction.cpp

740

Add an comment describing the source pattern for this case.

740

perhaps do

if (loopy)

return nullptr;

746

Reads better if it is an early return 'return nullptr'

755

Should it return nullptr if HasBranch == false?

765

describe the source pattern here.

784

The code can be simplified:

auto AddSeelctsRegion = [&](RegionInfo &RegI) {

for (auto *SI : Selects) {
    if (CheckBiasedSelect(SI, R,
                          TrueBiasedSelectsGlobal,
                          FalseBiasedSelectsGlobal,
                          SelectBiasMap))
      RI.Selects.push_back(SI);
  }

};

if (!Result) {

 RegInfo RI(R);
 AddSelectsRegion(&RI);
Result = new CHRScope(RI);
Scopes.insert(Result);

} else {

AddSelectsRegion(Result->RegionInfos[0].R);

}

815

It is unclear from the comments what the method is check. Perhaps using a little C example to show what it checks.

831

can depend on or 'can't' depend on. It is unclear what the comment means. Perhaps explain more?

846

this code is confusing:

if (not hoistable) {

unhoistable.erase(...);

}

853

Line 827 does the same. Should it be moved above line 826?

[hjyamauchi]

Addressed comments.

[hjyamauchi]

lib/Transforms/Instrumentation/ControlHeightReduction.cpp

746

Can't do an early return here because we will fall through to look for selects below.

755

Likewise, we don't want to return yet because we look for selects below and because we try to curb out a larger scope (keep scopes connected) even if the branch is unbiased in the middle to increase the chance/scope of the branch merging (eg. merging three branches h1, u, h2 in a row into one where h1 and h2 are biased and u isn't).

831

It means to say a branch instruction doesn't produce a value (in terms of SSA) so no other instruction can't have a use-def edge (data dependence) to a branch instruction. Updated comment.

846

Since we initialized Unhoistables with the selects above and we are dropping this select, we also remove it from Unhoistables. Added a comment.

853

This is not redundant. Since we may remove a select above, the insert point may change here. Added a comment.

[davidxl]

lib/Transforms/Instrumentation/ControlHeightReduction.cpp

753

is it possible to have S0 == S1?

829

In this example, if the selects are after if (c3) {}, then the insertion point won't be before the first select, or is it handled in other way?

931

Add a description that this methods find all nested scopes and merge them if possible.

934

Why can' this scope be merged with subsequent ones?

936

This early check does not seem necessary -- it does not save much compile time, but makes the code less clean.

[hjyamauchi]

Addressed comments.

[hjyamauchi]

lib/Transforms/Instrumentation/ControlHeightReduction.cpp

753

I think it's unlikely but possible because we could have a branch instruction that has the same label for the true and the false targets.

829

The insert point would be the branch or the first select *in the first block" (if any). This particular sentence is specifically about this example. If the selects are instead after if (c3) {}, there's no select in the first block and the insert point would be right before the branch.

934

This will be merged with subsequent ones, if possible, after it's returned to the recursive call site in line 943. At the top level of the recursion, there's the sentinel top-level region at the root of the region tree, which doesn't have a subsequent region. So no merging opportunities missed.

[davidxl]

lib/Transforms/Instrumentation/ControlHeightReduction.cpp

363

maybe rename it to 'classifyBiasedScopes' -- which means classify them into true or false biased regions?

589

Through out the patch, 'double' is used for branch probability type. Please use existing fixed point representation BranchProbability type in Support/

1728

Is is possible for this be 'folded' into unconditional branch given the true predicate?

1731

Is it better to use IRBuilder interface here?

[hjyamauchi]

Added one more metric to the stats.

[hjyamauchi]

Addressed comments.

[hjyamauchi]

lib/Transforms/Instrumentation/ControlHeightReduction.cpp

1728

The true predicate is a placeholder. It will be replaced later in fixupBranchesAndSelects(). Added a comment.

1731

I'll keep it here as is to be symmetric with the removal of the old branch instruction above. But I'll use IRBuilder in the other places (addToMergedCondition()).

[davidxl]

lib/Transforms/Instrumentation/ControlHeightReduction.cpp

1809

This might be too conservative that the merged branch becomes less biased as it can be. It is very likely that the contributing branches are correlated. How about taking the 'min' BranchProb as the resulting BP?

[hjyamauchi]

Updated.

lib/Transforms/Instrumentation/ControlHeightReduction.cpp

1809

Done.

[davidxl]

lgtm.

lib/Passes/PassBuilder.cpp

494

In thinLTO mode, you may want to only do this in the backend compilation, otherwise, there is a risk that that fallback path gets CHRed again which is not desirable.

[hjyamauchi]

lib/Passes/PassBuilder.cpp

494

Will look into this later.

[hjyamauchi]

Rebased.

[rtrieu]

llvm/trunk/lib/Transforms/Instrumentation/ControlHeightReduction.cpp

610–616 ↗

(On Diff #163860)

This calculation is in danger of overflowing when the weights are large. I made a fix in r341444 to calculate the sum weight in 64 bits to prevent the overflow.

[hjyamauchi]

llvm/trunk/lib/Transforms/Instrumentation/ControlHeightReduction.cpp

610–616 ↗

(On Diff #163860)

Thanks for the fix.

include/llvm/InitializePasses.h

 void initializeCallGraphViewerPass(PassRegistry&);
 void initializeCallGraphWrapperPassPass(PassRegistry&);
 void initializeCallSiteSplittingLegacyPassPass(PassRegistry&);
 void initializeCalledValuePropagationLegacyPassPass(PassRegistry &);
 void initializeCodeGenPreparePass(PassRegistry&);
 void initializeConstantHoistingLegacyPassPass(PassRegistry&);
 void initializeConstantMergeLegacyPassPass(PassRegistry&);
 void initializeConstantPropagationPass(PassRegistry&);
+void initializeControlHeightReductionLegacyPassPass(PassRegistry&);
 void initializeCorrelatedValuePropagationPass(PassRegistry&);
 void initializeCostModelAnalysisPass(PassRegistry&);
 void initializeCrossDSOCFIPass(PassRegistry&);
 void initializeDAEPass(PassRegistry&);
 void initializeDAHPass(PassRegistry&);
 void initializeDCELegacyPassPass(PassRegistry&);
 void initializeDSELegacyPassPass(PassRegistry&);
 void initializeDataFlowSanitizerPass(PassRegistry&);

include/llvm/LinkAllPasses.h

ForcePassLinking() {
       (void) llvm::createCFGSimplificationPass();
       (void) llvm::createCFLAndersAAWrapperPass();
       (void) llvm::createCFLSteensAAWrapperPass();
       (void) llvm::createStructurizeCFGPass();
       (void) llvm::createLibCallsShrinkWrapPass();
       (void) llvm::createCalledValuePropagationPass();
       (void) llvm::createConstantMergePass();
       (void) llvm::createConstantPropagationPass();
+      (void) llvm::createControlHeightReductionLegacyPass();
       (void) llvm::createCostModelAnalysisPass();
       (void) llvm::createDeadArgEliminationPass();
       (void) llvm::createDeadCodeEliminationPass();
       (void) llvm::createDeadInstEliminationPass();
       (void) llvm::createDeadStoreEliminationPass();
       (void) llvm::createDependenceAnalysisWrapperPass();
       (void) llvm::createDivergenceAnalysisPass();
       (void) llvm::createDomOnlyPrinterPass();

include/llvm/Transforms/Instrumentation/ControlHeightReduction.h

+//===- ControlHeightReduction.h - Control Height Reduction ------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This pass merges conditional blocks of code and reduces the number of
+// conditional branches in the hot paths based on profiles.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_TRANSFORMS_INSTRUMENTATION_CONTROLHEIGHTREDUCTION_H
+#define LLVM_TRANSFORMS_INSTRUMENTATION_CONTROLHEIGHTREDUCTION_H
+
+#include "llvm/Analysis/LoopInfo.h"
+#include "llvm/IR/PassManager.h"
+#include "llvm/Transforms/Scalar/LoopPassManager.h"
+
+namespace llvm {
+
+class ControlHeightReductionPass :
+      public PassInfoMixin<ControlHeightReductionPass> {
+public:
+  ControlHeightReductionPass();
+  PreservedAnalyses run(Function &F, FunctionAnalysisManager &FAM);
+};
+} // end namespace llvm
+
+#endif // LLVM_TRANSFORMS_INSTRUMENTATION_CONTROLHEIGHTREDUCTION_H

include/llvm/Transforms/Utils.h

 //   AU.addRequiredID(LoopSimplifyID);
 //
 Pass *createLoopSimplifyPass();
 extern char &LoopSimplifyID;
 
 /// This function returns a new pass that downgrades the debug info in the
 /// module to line tables only.
 ModulePass *createStripNonLineTableDebugInfoPass();
+
+//===----------------------------------------------------------------------===//
+//
+// ControlHeightReudction - Merges conditional blocks of code and reduces the
+// number of conditional branches in the hot paths based on profiles.
+//
+FunctionPass *createControlHeightReductionLegacyPass();
 }
 
 #endif

lib/Passes/PassBuilder.cpp

 #include "llvm/Transforms/IPO/PartialInlining.h"
 #include "llvm/Transforms/IPO/SCCP.h"
 #include "llvm/Transforms/IPO/SampleProfile.h"
 #include "llvm/Transforms/IPO/StripDeadPrototypes.h"
 #include "llvm/Transforms/IPO/SyntheticCountsPropagation.h"
 #include "llvm/Transforms/IPO/WholeProgramDevirt.h"
 #include "llvm/Transforms/InstCombine/InstCombine.h"
 #include "llvm/Transforms/Instrumentation/BoundsChecking.h"
+#include "llvm/Transforms/Instrumentation/ControlHeightReduction.h"
 #include "llvm/Transforms/Instrumentation/GCOVProfiler.h"
 #include "llvm/Transforms/Instrumentation/InstrProfiling.h"
 #include "llvm/Transforms/Instrumentation/PGOInstrumentation.h"
 #include "llvm/Transforms/Scalar/ADCE.h"
 #include "llvm/Transforms/Scalar/AlignmentFromAssumptions.h"
 #include "llvm/Transforms/Scalar/BDCE.h"
 #include "llvm/Transforms/Scalar/CallSiteSplitting.h"
 #include "llvm/Transforms/Scalar/ConstantHoisting.h"

 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])>$");
 
+static cl::opt<bool>
+    EnableCHR("enable-chr-npm", cl::init(true), cl::Hidden,
+              cl::desc("Enable control height reduction optimization (CHR)"));
+
 static bool isOptimizingForSize(PassBuilder::OptimizationLevel Level) {
   switch (Level) {
   case PassBuilder::O0:
   case PassBuilder::O1:
   case PassBuilder::O2:
   case PassBuilder::O3:
     return false;
 
PassBuilder::buildFunctionSimplificationPipeline(OptimizationLevel Level,
 
   // Finally, do an expensive DCE pass to catch all the dead code exposed by
   // the simplifications and basic cleanup after all the simplifications.
   FPM.addPass(ADCEPass());
   FPM.addPass(SimplifyCFGPass());
   FPM.addPass(InstCombinePass());
   invokePeepholeEPCallbacks(FPM, Level);
 
+  if (EnableCHR && Level == O3 && PGOOpt &&
+      (!PGOOpt->ProfileUseFile.empty() || !PGOOpt->SampleProfileFile.empty()))
+    FPM.addPass(ControlHeightReductionPass());
+
   return FPM;
 }
 
 void PassBuilder::addPGOInstrPasses(ModulePassManager &MPM, bool DebugLogging,
                                     PassBuilder::OptimizationLevel Level,
                                     bool RunProfileGen,
                                     std::string ProfileGenFile,
                                     std::string ProfileUseFile) {

lib/Passes/PassRegistry.def

 FUNCTION_PASS("add-discriminators", AddDiscriminatorsPass())
 FUNCTION_PASS("aggressive-instcombine", AggressiveInstCombinePass())
 FUNCTION_PASS("alignment-from-assumptions", AlignmentFromAssumptionsPass())
 FUNCTION_PASS("bdce", BDCEPass())
 FUNCTION_PASS("bounds-checking", BoundsCheckingPass())
 FUNCTION_PASS("break-crit-edges", BreakCriticalEdgesPass())
 FUNCTION_PASS("callsite-splitting", CallSiteSplittingPass())
 FUNCTION_PASS("consthoist", ConstantHoistingPass())
+FUNCTION_PASS("chr", ControlHeightReductionPass())
 FUNCTION_PASS("correlated-propagation", CorrelatedValuePropagationPass())
 FUNCTION_PASS("dce", DCEPass())
 FUNCTION_PASS("div-rem-pairs", DivRemPairsPass())
 FUNCTION_PASS("dse", DSEPass())
 FUNCTION_PASS("dot-cfg", CFGPrinterPass())
 FUNCTION_PASS("dot-cfg-only", CFGOnlyPrinterPass())
 FUNCTION_PASS("early-cse", EarlyCSEPass(/*UseMemorySSA=*/false))
 FUNCTION_PASS("early-cse-memssa", EarlyCSEPass(/*UseMemorySSA=*/true))

lib/Transforms/IPO/PassManagerBuilder.cpp

static cl::opt<bool> EnableSimpleLoopUnswitch(
     "enable-simple-loop-unswitch", cl::init(false), cl::Hidden,
     cl::desc("Enable the simple loop unswitch pass. Also enables independent "
              "cleanup passes integrated into the loop pass manager pipeline."));
 
 static cl::opt<bool> EnableGVNSink(
     "enable-gvn-sink", cl::init(false), cl::Hidden,
     cl::desc("Enable the GVN sinking pass (default = off)"));
 
+static cl::opt<bool>
+    EnableCHR("enable-chr", cl::init(true), cl::Hidden,
+              cl::desc("Enable control height reduction optimization (CHR)"));
+
 PassManagerBuilder::PassManagerBuilder() {
     OptLevel = 2;
     SizeLevel = 0;
     LibraryInfo = nullptr;
     Inliner = nullptr;
     DisableUnrollLoops = false;
     SLPVectorize = RunSLPVectorization;
     LoopVectorize = RunLoopVectorization;
void PassManagerBuilder::addFunctionSimplificationPasses(
   if (!RunSLPAfterLoopVectorization && SLPVectorize)
     MPM.add(createSLPVectorizerPass()); // Vectorize parallel scalar chains.
 
   MPM.add(createAggressiveDCEPass());         // Delete dead instructions
   MPM.add(createCFGSimplificationPass()); // Merge & remove BBs
   // Clean up after everything.
   addInstructionCombiningPass(MPM);
   addExtensionsToPM(EP_Peephole, MPM);
+
+  if (EnableCHR && OptLevel >= 3 &&
+      (!PGOInstrUse.empty() || !PGOSampleUse.empty()))
+    MPM.add(createControlHeightReductionLegacyPass());
 }
 
 void PassManagerBuilder::populateModulePassManager(
     legacy::PassManagerBase &MPM) {
   if (!PGOSampleUse.empty()) {
     MPM.add(createPruneEHPass());
     MPM.add(createSampleProfileLoaderPass(PGOSampleUse));
   }

lib/Transforms/Instrumentation/CMakeLists.txt

 add_llvm_library(LLVMInstrumentation
   AddressSanitizer.cpp
   BoundsChecking.cpp
   CGProfile.cpp
+  ControlHeightReduction.cpp
   DataFlowSanitizer.cpp
   GCOVProfiling.cpp
   MemorySanitizer.cpp
   IndirectCallPromotion.cpp
   Instrumentation.cpp
   InstrProfiling.cpp
   PGOInstrumentation.cpp
   PGOMemOPSizeOpt.cpp

lib/Transforms/Instrumentation/ControlHeightReduction.cpp

+//===-- ControlHeightReduction.cpp - Control Height Reduction -------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This pass merges conditional blocks of code and reduces the number of
+// conditional branches in the hot paths based on profiles.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Transforms/Instrumentation/ControlHeightReduction.h"
+#include "llvm/Transforms/Utils.h"
+#include "llvm/Transforms/Utils/BasicBlockUtils.h"
+#include "llvm/Transforms/Utils/Cloning.h"
+#include "llvm/Transforms/Utils/ValueMapper.h"
+#include "llvm/ADT/DenseMap.h"
+#include "llvm/ADT/DenseSet.h"
+#include "llvm/ADT/SmallVector.h"
+#include "llvm/ADT/StringSet.h"
+#include "llvm/Analysis/ProfileSummaryInfo.h"
+#include "llvm/Analysis/RegionInfo.h"
+#include "llvm/Analysis/RegionIterator.h"
+#include "llvm/Analysis/ValueTracking.h"
+#include "llvm/IR/CFG.h"
+#include "llvm/IR/Dominators.h"
+#include "llvm/IR/IRBuilder.h"
+#include "llvm/IR/MDBuilder.h"
+#include "llvm/Support/MemoryBuffer.h"
+#include "llvm/Transforms/Scalar.h"
+
+#include <cxxabi.h>
+#include <set>
+#include <sstream>
+
+using namespace llvm;
+
+#define DEBUG_TYPE "chr"
+
+#define CHR_DEBUG(X) LLVM_DEBUG(X)
+
+static cl::opt<bool> ForceCHR("force-chr", cl::init(false), cl::Hidden,
+                              cl::desc("Apply CHR for all functions"));
+
+static cl::opt<double> CHRBiasThreshold(
+    "chr-bias-threshold", cl::init(0.99), cl::Hidden,
+    cl::desc("CHR considers a branch bias greater than this ratio as biased"));
+
+static cl::opt<unsigned> CHRMergeThreshold(
+    "chr-merge-threshold", cl::init(2), cl::Hidden,
+    cl::desc("CHR merges a group of N branches/selects where N >= this value"));
+
+static cl::opt<std::string> CHRModuleList(
+    "chr-module-list", cl::init(""), cl::Hidden,
+    cl::desc("Specify file to retrieve the list of modules to apply CHR to"));
+
+static cl::opt<std::string> CHRFunctionList(
+    "chr-function-list", cl::init(""), cl::Hidden,
+    cl::desc("Specify file to retrieve the list of functions to apply CHR to"));
+
+static StringSet<> CHRModules;
+static StringSet<> CHRFunctions;
+
+static void ParseCHRFilterFiles() {
+  if (!CHRModuleList.empty()) {
+    auto FileOrErr = MemoryBuffer::getFile(CHRModuleList);
+    if (!FileOrErr) {
+      errs() << "Error: Couldn't read the chr-module-list file " << CHRModuleList << "\n";
+      std::exit(1);
+    }
+    StringRef Buf = FileOrErr->get()->getBuffer();
+    SmallVector<StringRef, 0> Lines;
+    Buf.split(Lines, '\n');
+    for (StringRef Line : Lines) {
+      Line = Line.trim();
+      if (!Line.empty())
+        CHRModules.insert(Line);
+    }
+  }
+  if (!CHRFunctionList.empty()) {
+    auto FileOrErr = MemoryBuffer::getFile(CHRFunctionList);
+    if (!FileOrErr) {
+      errs() << "Error: Couldn't read the chr-function-list file " << CHRFunctionList << "\n";
+      std::exit(1);
+    }
+    StringRef Buf = FileOrErr->get()->getBuffer();
+    SmallVector<StringRef, 0> Lines;
+    Buf.split(Lines, '\n');
+    for (StringRef Line : Lines) {
+      Line = Line.trim();
+      if (!Line.empty())
+        CHRFunctions.insert(Line);
+    }
+  }
+}
+
+namespace {
+class ControlHeightReductionLegacyPass : public FunctionPass {
+public:
+  static char ID;
+
+  ControlHeightReductionLegacyPass() : FunctionPass(ID) {
+    initializeControlHeightReductionLegacyPassPass(
+        *PassRegistry::getPassRegistry());
+    ParseCHRFilterFiles();
+  }
+
+  bool runOnFunction(Function &F) override;
+  void getAnalysisUsage(AnalysisUsage &AU) const override {
+    AU.addRequired<DominatorTreeWrapperPass>();
+    AU.addRequired<ProfileSummaryInfoWrapperPass>();
+    AU.addRequired<RegionInfoPass>();
+    AU.addPreserved<GlobalsAAWrapperPass>();
+  }
+};
+} // end anonymous namespace
+
+char ControlHeightReductionLegacyPass::ID = 0;
+
+INITIALIZE_PASS_BEGIN(ControlHeightReductionLegacyPass,
+                      "chr",
+                      "Reduce control height in the hot paths",
+                      false, false)
+INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)
+INITIALIZE_PASS_DEPENDENCY(ProfileSummaryInfoWrapperPass)
+INITIALIZE_PASS_DEPENDENCY(RegionInfoPass)
+INITIALIZE_PASS_END(ControlHeightReductionLegacyPass,
+                    "chr",
+                    "Reduce control height in the hot paths",
+                    false, false)
+
+FunctionPass *llvm::createControlHeightReductionLegacyPass() {
+  return new ControlHeightReductionLegacyPass();
+}
+
+namespace {
+
+struct CHRStats {
+  CHRStats() : NumBranches(0), NumBranchesDelta(0) {}
+  void print(raw_ostream &OS) const {
+    OS << "CHRStats: NumBranches=" << NumBranches
+       << ", NumBranchesDelta=" << NumBranchesDelta;
+  }
+  uint64_t NumBranches;       // The original number of conditional branches /
+                              // selects
+  uint64_t NumBranchesDelta;  // The decrease of the number of conditional
+                              // branches / selects in the hot paths due to CHR.
+};
+
+inline raw_ostream &operator<<(raw_ostream &OS, const CHRStats &Stats) {
+  Stats.print(OS);
+  return OS;
+}
+
+// RegInfo - some properties of a Region.
+struct RegInfo {
+  RegInfo() : R(nullptr), HasBranch(false) {}
+  RegInfo(Region *RegionIn) : R(RegionIn), HasBranch(false) {}
+  Region *R;
+  bool HasBranch;
+  SmallVector<SelectInst *, 8> Selects;
+};
+
+typedef DenseMap<Region *, DenseSet<Instruction *>> HoistStopMapTy;
+
+// CHRScope - a sequence of regions to CHR together. It corresponds to a
+// sequence of conditional blocks. It can have subscopes which correspond to
+// nested conditional blocks. Nested CHRScopes form a tree.
+class CHRScope {
+ public:
+  CHRScope(RegInfo RI) : BranchInsertPoint(nullptr) {
+    assert(RI.R && "Null RegionIn");
+    RegInfos.push_back(RI);
+  }
+
+  Region *getParentRegion() {
+    assert(RegInfos.size() > 0 && "Empty CHRScope");
+    Region *Parent = RegInfos[0].R->getParent();
+    assert(Parent && "Unexpected to call this on the top-level region");
+    return Parent;
+  }
+
+  BasicBlock *getEntryBlock() {
+    assert(RegInfos.size() > 0 && "Empty CHRScope");
+    return RegInfos.front().R->getEntry();
+  }
+
+  BasicBlock *getExitBlock() {
+    assert(RegInfos.size() > 0 && "Empty CHRScope");
+    return RegInfos.back().R->getExit();
+  }
+
+  bool appendable(CHRScope *Next) {
+    // The next scope is appendable only if this scope is directly connected to
+    // it (which implies it post-dominates this scope) and this scope dominates
+    // it (no edge to the next scope outside this scope).
+    BasicBlock *NextEntry = Next->getEntryBlock();
+    if (getExitBlock() != NextEntry)
+      // Not directly connected.
+      return false;
+    Region *LastRegion = RegInfos.back().R;
+    for (BasicBlock *Pred : predecessors(NextEntry))
+      if (!LastRegion->contains(Pred))
+        // There's an edge going into the entry of the next scope from outside
+        // of this scope.
+        return false;
+    return true;
+  }
+
+  void append(CHRScope *Next) {
+    assert(RegInfos.size() > 0 && "Empty CHRScope");
+    assert(Next->RegInfos.size() > 0 && "Empty CHRScope");
+    assert(getParentRegion() == Next->getParentRegion() &&
+           "Must be siblings");
+    assert(getExitBlock() == Next->getEntryBlock() &&
+           "Must be adjacent");
+    for (RegInfo &RI : Next->RegInfos)
+      RegInfos.push_back(RI);
+    for (CHRScope *Sub : Next->Subs)
+      Subs.push_back(Sub);
+  }
+
+  void addSub(CHRScope *SubIn) {
+#ifndef NDEBUG
+    bool is_child = false;
+    for (RegInfo &RI : RegInfos)
+      if (RI.R == SubIn->getParentRegion()) {
+        is_child = true;
+        break;
+      }
+    assert(is_child && "Must be a child");
+#endif
+    Subs.push_back(SubIn);
+  }
+
+  // Split this scope at the boundary region into two, which will belong to the
+  // tail and returns the tail.
+  CHRScope *split(Region *Boundary) {
+    assert(Boundary && "Boundary null");
+    assert(RegInfos.begin()->R != Boundary &&
+           "Can't be split at beginning");
+    auto BoundaryIt = std::find_if(RegInfos.begin(), RegInfos.end(),
+                                   [&Boundary](const RegInfo& RI) {
+                                     return Boundary == RI.R;
+                                   });
+    if (BoundaryIt == RegInfos.end())
+      return nullptr;
+    SmallVector<RegInfo, 8> TailRegInfos;
+    SmallVector<CHRScope *, 8> TailSubs;
+    TailRegInfos.insert(TailRegInfos.begin(), BoundaryIt, RegInfos.end());
+    RegInfos.resize(BoundaryIt - RegInfos.begin());
+    DenseSet<Region *> TailRegionSet;
+    for (RegInfo &RI : TailRegInfos)
+      TailRegionSet.insert(RI.R);
+    for (auto It = Subs.begin(); It != Subs.end(); ) {
+      CHRScope *Sub = *It;
+      assert(Sub && "null Sub");
+      Region *Parent = Sub->getParentRegion();
+      if (TailRegionSet.count(Parent)) {
+        TailSubs.push_back(Sub);
+        It = Subs.erase(It);
+      } else {
+        assert(std::find_if(RegInfos.begin(), RegInfos.end(),
+                            [&Parent](const RegInfo& RI) {
+                              return Parent == RI.R;
+                            }) != RegInfos.end() &&
+               "Must be in head");
+        ++It;
+      }
+    }
+    assert(HoistStopMap.empty() && "MapHoistStops must be empty");
+    return new CHRScope(TailRegInfos, TailSubs);
+  }
+
+  bool contains(Instruction *I) const {
+    BasicBlock *Parent = I->getParent();
+    for (const RegInfo &RI : RegInfos)
+      if (RI.R->contains(Parent))
+        return true;
+    return false;
+  }
+
+  void print(raw_ostream &OS) const;
+
+  SmallVector<RegInfo, 8> RegInfos; // Regions that belong to this scope
+  SmallVector<CHRScope *, 8> Subs;  // Subscopes.
+
+  // The instruction at which to insert the CHR conditional branch (and hoist
+  // the dependent condition values).
+  Instruction *BranchInsertPoint;
+
+  // True-biased and false-biased regions (conditional blocks),
+  // respectively. Used only for the outermost scope and includes regions in
+  // subscopes. The rest are unbiased.
+  DenseSet<Region *> TrueBiasedRegions;
+  DenseSet<Region *> FalseBiasedRegions;
+  // Among the biased regions, the regions that get CHRed.
+  SmallVector<RegInfo, 8> CHRRegions;
+
+  // True-biased and false-biased selects, respectively. Used only for the
+  // outermost scope and includes ones in subscopes.
+  DenseSet<SelectInst *> TrueBiasedSelects;
+  DenseSet<SelectInst *> FalseBiasedSelects;
+
+  // Map from one of the above regions to the instructions to stop
+  // hoisting instructions at through use-def chains.
+  HoistStopMapTy HoistStopMap;
+
+ private:
+  CHRScope(SmallVector<RegInfo, 8> &RegInfosIn,
+           SmallVector<CHRScope *, 8> &SubsIn)
+    : RegInfos(RegInfosIn), Subs(SubsIn), BranchInsertPoint(nullptr) {}
+};
+
+inline raw_ostream &operator<<(raw_ostream &OS, const CHRScope &Scope) {
+  Scope.print(OS);
+  return OS;
+}
+
+class CHR {
+ public:
+  CHR(Function &Fin, DominatorTree &DTin, ProfileSummaryInfo &PSIin,
+      RegionInfo &RIin)
+      : F(Fin), DT(DTin), PSI(PSIin), RI(RIin) {}
+
+  ~CHR() {
+    for (CHRScope *Scope : Scopes) {
+      delete Scope;
+    }
+  }
+
+  bool run();
+
+ private:
+  // See the comments in CHR::run() for the high level flow of the algorithm and
+  // what the following functions do.
+
+  void findScopes(SmallVectorImpl<CHRScope *> &Output) {
+    Region *R = RI.getTopLevelRegion();
+    CHRScope *Scope = findScopes(R, nullptr, nullptr, Output);
+    if (Scope) {
+      Output.push_back(Scope);
+    }
+  }
+  CHRScope *findScopes(Region *R, Region *NextRegion, Region *ParentRegion,
+                        SmallVectorImpl<CHRScope *> &Scopes);
+  CHRScope *findScope(Region *R);
+  void checkScopeHoistable(CHRScope *Scope);
+
+  void splitScopes(SmallVectorImpl<CHRScope *> &Input,
+                   SmallVectorImpl<CHRScope *> &Output);
+  SmallVector<CHRScope *, 8> splitScope(CHRScope *Scope,
+                                        CHRScope *Outer,
+                                        DenseSet<Value *> *OuterConditionValues,
+                                        Instruction *OuterInsertPoint,
+                                        SmallVectorImpl<CHRScope *> &Output,
+                                        DenseSet<Instruction *> &Unhoistables);
+
+  void setPerScopeBias(SmallVectorImpl<CHRScope *> &Scopes);
+  void setPerScopeBias(CHRScope *Scope, CHRScope *OutermostScope);
+
+  void filterScopes(SmallVectorImpl<CHRScope *> &Input,
+                    SmallVectorImpl<CHRScope *> &Output);
+
+  void setCHRRegions(SmallVectorImpl<CHRScope *> &Input,
+                     SmallVectorImpl<CHRScope *> &Output);
+  void setCHRRegions(CHRScope *Scope, CHRScope *OutermostScope);
+
+  void sortScopes(SmallVectorImpl<CHRScope *> &Input,
+                  SmallVectorImpl<CHRScope *> &Output);
+
+  void transformScopes(SmallVectorImpl<CHRScope *> &CHRScopes);
+  void transformScopes(CHRScope *Scope, DenseSet<PHINode *> &TrivialPHIs);
+  void cloneScopeBlocks(CHRScope *Scope,
+                        BasicBlock *PreEntryBlock,
+                        BasicBlock *ExitBlock,
+                        Region *LastRegion,
+                        ValueToValueMapTy &VMap);
+  BranchInst *createMergedBranch(BasicBlock *PreEntryBlock,
+                                 BasicBlock *EntryBlock,
+                                 BasicBlock *NewEntryBlock,
+                                 ValueToValueMapTy &VMap);
+  void fixupBranchesAndSelects(CHRScope *Scope,
+                               BasicBlock *PreEntryBlock,
+                               BranchInst *MergedBR);
+  void fixupBranch(Region *R,
+                   CHRScope *Scope,
+                   BasicBlock *PreEntryBlock,
+                   Value *&MergedCondition, double &CHRBranchBias);
+  void fixupSelect(SelectInst* SI,
+                   CHRScope *Scope,
+                   BasicBlock *PreEntryBlock,
+                   Value *&MergedCondition, double &CHRBranchBias);
+  void addToMergedCondition(bool IsTrueBiased, Value *Cond,
+                            Instruction *BranchOrSelect,
+                            CHRScope *Scope,
+                            BasicBlock *PreEntryBlock,
+                            Value *&MergedCondition);
+
+  Function &F;
+  DominatorTree &DT;
+  ProfileSummaryInfo &PSI;
+  RegionInfo &RI;
+  CHRStats Stats;
+
+  // All the true-biased regions in the function
+  DenseSet<Region *> TrueBiasedRegionsGlobal;
+  // All the false-biased regions in the function
+  DenseSet<Region *> FalseBiasedRegionsGlobal;
+  // All the true-biased selects in the function
+  DenseSet<SelectInst *> TrueBiasedSelectsGlobal;
+  // All the false-biased selects in the function
+  DenseSet<SelectInst *> FalseBiasedSelectsGlobal;
+  // A map from biased regions to their branch bias
+  DenseMap<Region *, double> BranchBiasMap;
+  // A map from biased selects to their branch bias
+  DenseMap<SelectInst *, double> SelectBiasMap;
+  // All the scopes.
+  DenseSet<CHRScope *> Scopes;
+};
+
+} // end anonymous namespace
+
+static bool shouldApply(Function &F, ProfileSummaryInfo& PSI) {
+  if (ForceCHR)
+    return true;
+
+  if (!CHRModuleList.empty() || !CHRFunctionList.empty()) {
+    if (CHRModules.count(F.getParent()->getName()))
+      return true;
+    StringRef Name = F.getName();
+    if (CHRFunctions.count(Name))
+      return true;
+    const char* DemangledName = nullptr;
+    int Status = -1;
+    DemangledName = abi::__cxa_demangle(Name.str().c_str(),
+                                        nullptr, nullptr, &Status);
+    return DemangledName && CHRFunctions.count(DemangledName);
+  }
+
+  assert(PSI.hasProfileSummary() && "Empty PSI?");
+  return PSI.isFunctionEntryHot(&F);
+}
+
+static void dumpIR(Function &F, const char *Label, CHRStats *Stats) {
+  std::string Name = F.getName().str();
+  const char *DemangledName = nullptr;
+  int Status = -1;
+  DemangledName = abi::__cxa_demangle(Name.c_str(),
+                                      nullptr, nullptr, &Status);
+  if (DemangledName == nullptr) {
+    DemangledName = "<NOT-MANGLED>";
+  }
+  std::string ModuleName = F.getParent()->getName().str();
+  CHR_DEBUG(dbgs() << "CHR IR dump " << Label << " " << ModuleName << " "
+            << Name << "\n");
+  if (Stats)
+    CHR_DEBUG(dbgs() << "Stats " << *Stats << "\n");
+  CHR_DEBUG(F.dump());
+}
+
+
+void CHRScope::print(raw_ostream &OS) const {
+  assert(RegInfos.size() > 0 && "Empty CHRScope");
+  OS << "CHRScope[";
+  OS << RegInfos.size() << ", Regions[";
+  for (const RegInfo &RI : RegInfos) {
+    OS << RI.R->getNameStr();
+    if (RI.HasBranch)
+      OS << " B";
+    if (RI.Selects.size() > 0)
+      OS << " S" << RI.Selects.size();
+    OS << ", ";
+  }
+  if (RegInfos[0].R->getParent()) {
+    OS << "], Parent " << RegInfos[0].R->getParent()->getNameStr();
+  } else {
+    // top level region
+    OS << "]";
+  }
+  OS << ", Subs[";
+  for (CHRScope *Sub : Subs) {
+    OS << *Sub << ", ";
+  }
+  OS << "]]";
+}
+
+// Return true if the given instruction type can be hoisted by CHR.
+static bool isHoistableInstructionType(Instruction *I) {
+  return isa<BinaryOperator>(I) || isa<CastInst>(I) || isa<SelectInst>(I) ||
+      isa<GetElementPtrInst>(I) || isa<CmpInst>(I) ||
+      isa<InsertElementInst>(I) || isa<ExtractElementInst>(I) ||
+      isa<ShuffleVectorInst>(I) || isa<ExtractValueInst>(I) ||
+      isa<InsertValueInst>(I);
+}
+
+// Return true if the given instruction can be hoisted by CHR.
+static bool isHoistable(Instruction *I, DominatorTree &DT) {
+  if (!isHoistableInstructionType(I))
+    return false;
+  return isSafeToSpeculativelyExecute(I, nullptr, &DT);
+}
+
+// Recursively traverse the use-def chains of the given value and return a set
+// of the unhoistable base values defined within the scope (excluding the
+// first-region entry block) or the (hoistable or unhoistable) base values that
+// are defined outside (including the first-region entry block) of the
+// scope. The returned set doesn't include constants.
+static std::set<Value *> getBaseValues(Value *V,
+                                       DominatorTree &DT) {
+  std::set<Value *> Result;
+  if (auto *I = dyn_cast<Instruction>(V)) {
+    // We don't stop at a block that's not in the Scope because we would miss some
+    // instructions that are based on the same base values if we stop there.
+    if (!isHoistable(I, DT)) {
+      Result.insert(I);
+      return Result;
+    }
+    // I is hoistable above the Scope.
+    for (Value *Op : I->operands()) {
+      std::set<Value *> OpResult = getBaseValues(Op, DT);
+      Result.insert(OpResult.begin(), OpResult.end());
+    }
+    return Result;
+  }
+  if (isa<Argument>(V)) {
+    Result.insert(V);
+    return Result;
+  }
+  // We don't include others like constants because those won't lead to any
+  // chance of folding of conditions (eg two bit checks merged into one check)
+  // after CHR.
+  return Result;  // empty
+}
+
+// Return true if V is already hoisted or can be hoisted (along with its
+// operands) above the insert point. When it returns true and HoistStops is
+// non-null, the instructions to stop hoisting at through the use-def chains are
+// inserted into HoistStops.
+static bool
+checkHoistValue(Value *V, Instruction *InsertPoint, DominatorTree &DT,
+                DenseSet<Instruction *> &Unhoistables,
+                DenseSet<Instruction *> *HoistStops) {
+  assert(InsertPoint && "Null InsertPoint");
+  if (auto *I = dyn_cast<Instruction>(V)) {
+    assert(DT.getNode(I->getParent()) && "DT must contain I's parent block");
+    assert(DT.getNode(InsertPoint->getParent()) && "DT must contain Destination");
+    if (Unhoistables.count(I)) {
+      // Don't hoist if they are not to be hoisted.
+      return false;
+    }
+    if (DT.dominates(I, InsertPoint)) {
+      // We are already above the insert point. Stop here.
+      if (HoistStops)
+        HoistStops->insert(I);
+      return true;
+    }
+    // We aren't not above the insert point, check if we can hoist it above the
+    // insert point.
+    if (isHoistable(I, DT)) {
+      // Check operands first.
+      DenseSet<Instruction *> OpsHoistStops;
+      bool AllOpsHoisted = true;
+      for (Value *Op : I->operands()) {
+        if (!checkHoistValue(Op, InsertPoint, DT, Unhoistables, &OpsHoistStops)) {
+          AllOpsHoisted = false;
+          break;
+        }
+      }
+      if (AllOpsHoisted) {
+        CHR_DEBUG(dbgs() << "checkHoistValue " << *I << "\n");
+        if (HoistStops)
+          HoistStops->insert(OpsHoistStops.begin(), OpsHoistStops.end());
+        return true;
+      }
+    }
+    return false;
+  }
+  // Non-instructions are considered hoistable.
+  return true;
+}
+
+// Returns true and sets the true probability and false probability of an
+// MD_prof metadata if it's well-formed.
+static bool CheckMDProf(MDNode *MD, double &TrueProb, double &FalseProb) {
+  if (!MD) return false;
+  MDString *MDName = cast<MDString>(MD->getOperand(0));
+  if (MDName->getString() != "branch_weights" ||
+      MD->getNumOperands() != 3)
+    return false;
+  ConstantInt *TrueWeight = mdconst::extract<ConstantInt>(MD->getOperand(1));
+  ConstantInt *FalseWeight = mdconst::extract<ConstantInt>(MD->getOperand(2));
+  if (!TrueWeight || !FalseWeight)
+    return false;
+  double TrueWeightD = TrueWeight->getValue().roundToDouble();
+  double FalseWeightD = FalseWeight->getValue().roundToDouble();
+  TrueProb = TrueWeightD / (TrueWeightD + FalseWeightD);
+  FalseProb = FalseWeightD / (TrueWeightD + FalseWeightD);
+  return true;
+}
+
+// A helper for CheckBiasedBranch and CheckBiasedSelect. If TrueProb >=
+// CHRBiasThreshold, put Key into TrueSet and return true. If FalseProb >=
+// CHRBiasThreshold, put Key into FalseSet and return true. Otherwise, return
+// false.
+template<typename K, typename S, typename M>
+bool CheckBias(K *Key, double TrueProb, double FalseProb,
+               S &TrueSet, S &FalseSet, M &BiasMap) {
+  if (TrueProb >= CHRBiasThreshold) {
+    TrueSet.insert(Key);
+    BiasMap[Key] = TrueProb;
+    return true;
+  } else if (FalseProb >= CHRBiasThreshold) {
+    FalseSet.insert(Key);
+    BiasMap[Key] = FalseProb;
+    return true;
+  }
+  return false;
+}
+
+// Returns true and insert a region into the right biased set and the map if the
+// branch of the region is biased.
+static bool CheckBiasedBranch(BranchInst *BI, Region *R,
+                              DenseSet<Region *> &TrueBiasedRegionsGlobal,
+                              DenseSet<Region *> &FalseBiasedRegionsGlobal,
+                              DenseMap<Region *, double> &BranchBiasMap) {
+  if (!BI->isConditional())
+    return false;
+  double ThenProb = 0, ElseProb = 0;
+  if (!CheckMDProf(BI->getMetadata(LLVMContext::MD_prof),
+                   ThenProb, ElseProb))
+    return false;
+  BasicBlock *IfThen = BI->getSuccessor(0);
+  BasicBlock *IfElse = BI->getSuccessor(1);
+  assert((IfThen == R->getExit() || IfElse == R->getExit()) &&
+         IfThen != IfElse &&
+         "Invariant from findScopes");
+  if (IfThen == R->getExit()) {
+    // Swap them so that IfThen/ThenProb means going into the conditional code
+    // and IfElse/ElseProb means skipping it.
+    std::swap(IfThen, IfElse);
+    std::swap(ThenProb, ElseProb);
+  }
+  CHR_DEBUG(dbgs() << "BI " << *BI << " ");
+  CHR_DEBUG(dbgs() << "ThenProb " << ThenProb << " ");
+  CHR_DEBUG(dbgs() << "ElseProb " << ElseProb << "\n");
+  return CheckBias(R, ThenProb, ElseProb,
+                   TrueBiasedRegionsGlobal, FalseBiasedRegionsGlobal,
+                   BranchBiasMap);
+}
+
+// Returns true and insert a select into the right biased set and the map if the
+// select is biased.
+static bool CheckBiasedSelect(
+    SelectInst *SI, Region *R,
+    DenseSet<SelectInst *> &TrueBiasedSelectsGlobal,
+    DenseSet<SelectInst *> &FalseBiasedSelectsGlobal,
+    DenseMap<SelectInst *, double> &SelectBiasMap) {
+  double TrueProb = 0, FalseProb = 0;
+  if (!CheckMDProf(SI->getMetadata(LLVMContext::MD_prof),
+                   TrueProb, FalseProb))
+    return false;
+  CHR_DEBUG(dbgs() << "SI " << *SI << " ");
+  CHR_DEBUG(dbgs() << "TrueProb " << TrueProb << " ");
+  CHR_DEBUG(dbgs() << "FalseProb " << FalseProb << "\n");
+  return CheckBias(SI, TrueProb, FalseProb,
+                   TrueBiasedSelectsGlobal, FalseBiasedSelectsGlobal,
+                   SelectBiasMap);
+}
+
+// Returns the instruction at which to hoist the dependent condition values and
+// insert the CHR branch for a region. This is the terminator branch in the
+// entry block or the first select in the entry block, if any.
+static Instruction* getBranchInsertPoint(RegInfo &RI) {
+  Region *R = RI.R;
+  BasicBlock *EntryBB = R->getEntry();
+  // The hoist point is by default the terminator of the entry block, which is
+  // the same as the branch instruction if RI.HasBranch is true.
+  Instruction *HoistPoint = EntryBB->getTerminator();
+  for (SelectInst *SI : RI.Selects) {
+    if (SI->getParent() == EntryBB) {
+      // Pick the first select in Selects in the entry block.  Note Selects is
+      // sorted in the instruction order within a block (asserted below).
+      HoistPoint = SI;
+      break;
+    }
+  }
+  assert(HoistPoint && "Null HoistPoint");
+#ifndef NDEBUG
+  // Check that HoistPoint is the first one in Selects in the entry block,
+  // if any.
+  DenseSet<Instruction *> EntryBlockSelectSet;
+  for (SelectInst *SI : RI.Selects) {
+    if (SI->getParent() == EntryBB) {
+      EntryBlockSelectSet.insert(SI);
+    }
+  }
+  for (Instruction &I : *EntryBB) {
+    if (EntryBlockSelectSet.count(&I) > 0) {
+      assert(&I == HoistPoint &&
+             "HoistPoint must be the first one in Selects");
+      break;
+    }
+  }
+#endif
+  return HoistPoint;
+}
+
+// Find a CHR scope in the given region.
+CHRScope * CHR::findScope(Region *R) {
+  CHRScope *Result = nullptr;
+  BasicBlock *Entry = R->getEntry();
+  BasicBlock *Exit = R->getExit();  // null if top level.
+  assert(Entry && "Entry must not be null");
+  assert((Exit == nullptr) == (R->isTopLevelRegion()) &&
+         "Only top level region has a null exit");
+  if (Entry)
+    CHR_DEBUG(dbgs() << "Entry " << Entry->getName() << "\n");
+  else
+    CHR_DEBUG(dbgs() << "Entry null\n");
+  if (Exit)
+    CHR_DEBUG(dbgs() << "Exit " << Exit->getName() << "\n");
+  else
+    CHR_DEBUG(dbgs() << "Exit null\n");
+  // Exclude cases where Entry is part of a subregion (hence it doesn't belong
+  // to this region).
+  bool EntryInSubregion = RI.getRegionFor(Entry) != R;
+  // Exclude loops
+  bool loopy = false;
+  for (BasicBlock *Pred : predecessors(Entry)) {
+    if (R->contains(Pred)) {
+      loopy = true;
+      break;
+    }
+  }
+  if (Exit && !loopy) {
+    auto *BI = dyn_cast<BranchInst>(Entry->getTerminator());
+    if (BI)
+      CHR_DEBUG(dbgs() << "BI.isConditional " << BI->isConditional() << "\n");
+    else
+      CHR_DEBUG(dbgs() << "BI null\n");
+    if (BI && BI->isConditional()) {
+      BasicBlock *S0 = BI->getSuccessor(0);
+      BasicBlock *S1 = BI->getSuccessor(1);
+      CHR_DEBUG(dbgs() << "S0 " << S0->getName() << "\n");
+      CHR_DEBUG(dbgs() << "S1 " << S1->getName() << "\n");
+      if (S0 != S1 && (S0 == Exit || S1 == Exit)) {
+        assert(!EntryInSubregion &&
+               "Must not find an if-then when Entry is in a subregion");
+        RegInfo RI(R);
+        RI.HasBranch = CheckBiasedBranch(
+            BI, R, TrueBiasedRegionsGlobal, FalseBiasedRegionsGlobal,
+            BranchBiasMap);
+        Result = new CHRScope(RI);
+        Scopes.insert(Result);
+        CHR_DEBUG(dbgs() << "Found a region with a branch\n");
+        ++Stats.NumBranches;
+      }
+    }
+  }
+  if (!EntryInSubregion && !loopy) {
+    SmallVector<SelectInst *, 8> Selects;
+    // Find Selects in the direct child blocks of R.
+    for (RegionNode *E : R->elements()) {
+      if (E->isSubRegion())
+        continue;
+      // This returns the basic block of E if E is a direct child of R (not a
+      // subregion.)
+      BasicBlock *BB = E->getEntry();
+      // Need to push in the order to make it easier to find the first Select
+      // later.
+      for (Instruction &I : *BB) {
+        if (auto *SI = dyn_cast<SelectInst>(&I)) {
+          Selects.push_back(SI);
+          ++Stats.NumBranches;
+        }
+      }
+    }
+    if (Selects.size() > 0) {
+      if (!Result) {
+        CHR_DEBUG(dbgs() << "Found a select-only region\n");
+        RegInfo RI(R);
+        for (auto *SI : Selects) {
+          if (CheckBiasedSelect(SI, R,
+                                TrueBiasedSelectsGlobal,
+                                FalseBiasedSelectsGlobal,
+                                SelectBiasMap))
+            RI.Selects.push_back(SI);
+        }
+        Result = new CHRScope(RI);
+        Scopes.insert(Result);
+      } else {
+        CHR_DEBUG(dbgs() << "Found select(s) in a region with a branch\n");
+        for (auto *SI : Selects) {
+          if (CheckBiasedSelect(SI, Result->RegInfos[0].R,
+                                TrueBiasedSelectsGlobal,
+                                FalseBiasedSelectsGlobal,
+                                SelectBiasMap))
+            Result->RegInfos[0].Selects.push_back(SI);
+        }
+      }
+    }
+  }
+
+  if (Result) {
+    checkScopeHoistable(Result);
+  }
+  return Result;
+}
+
+// Check that any of the branch and the selects in the region could be
+// hoisted above the the CHR branch insert point (the most dominating of
+// them, either the branch (at the end of the first block) or the first
+// select in the first block). If the branch can't be hoisted, drop the
+// selects in the first blocks.
+void CHR::checkScopeHoistable(CHRScope *Scope) {
+  RegInfo &RI = Scope->RegInfos[0];
+  Region *R = RI.R;
+  BasicBlock *EntryBB = R->getEntry();
+  auto *Branch = RI.HasBranch ?
+                 cast<BranchInst>(EntryBB->getTerminator()) : nullptr;
+  SmallVector<SelectInst *, 8> &Selects = RI.Selects;
+  if (RI.HasBranch || !Selects.empty()) {
+    Instruction *InsertPoint = getBranchInsertPoint(RI);
+    CHR_DEBUG(dbgs() << "InsertPoint " << *InsertPoint << "\n");
+    // Avoid a dependence from a select or a branch to a(nother)
+    // select. Note no instruction can't depend on a branch.
+    DenseSet<Instruction *> Unhoistables;
+    for (SelectInst *SI : Selects) {
+      Unhoistables.insert(SI);
+    }
+    // Remove Selects that can't be hoisted.
+    for (auto it = Selects.begin(); it != Selects.end(); ) {
+      SelectInst *SI = *it;
+      if (SI == InsertPoint) {
+        ++it;
+        continue;
+      }
+      bool IsHoistable = true;
+      IsHoistable = checkHoistValue(SI->getCondition(), InsertPoint,
+                                    DT, Unhoistables, nullptr);
+      if (!IsHoistable) {
+        CHR_DEBUG(dbgs() << "Dropping select " << *SI << "\n");
+        it = Selects.erase(it);
+        Unhoistables.erase(SI);
+      } else
+        ++it;
+    }
+    InsertPoint = getBranchInsertPoint(RI);
+    CHR_DEBUG(dbgs() << "InsertPoint " << *InsertPoint << "\n");
+    if (RI.HasBranch && InsertPoint != Branch) {
+      bool IsHoistable = true;
+      IsHoistable = checkHoistValue(Branch->getCondition(), InsertPoint,
+                                    DT, Unhoistables, nullptr);
+      if (!IsHoistable) {
+        // If the branch isn't hoistable, drop the selects in the entry
+        // block, preferring the branch, which makes the branch the hoist
+        // point.
+        assert(InsertPoint != Branch && "Branch must not be the hoist point");
+        CHR_DEBUG(dbgs() << "Dropping selects in entry block \n");
+        CHR_DEBUG(
+            for (SelectInst *SI : Selects) {
+              dbgs() << "SI " << *SI << "\n";
+            });
+        Selects.erase(std::remove_if(Selects.begin(), Selects.end(),
+                                     [EntryBB](SelectInst *SI) {
+                                       return SI->getParent() == EntryBB;
+                                     }), Selects.end());
+        Unhoistables.clear();
+        InsertPoint = Branch;
+      }
+    }
+    CHR_DEBUG(dbgs() << "InsertPoint " << *InsertPoint << "\n");
+#ifndef NDEBUG
+    if (RI.HasBranch) {
+      assert(!DT.dominates(Branch, InsertPoint) &&
+             "Branch can't be already above the hoist point");
+      assert(checkHoistValue(Branch->getCondition(), InsertPoint,
+                             DT, Unhoistables, nullptr) &&
+             "checkHoistValue for branch");
+    }
+    for (auto *SI : Selects) {
+      assert(!DT.dominates(SI, InsertPoint) &&
+             "SI can't be already above the hoist point");
+      assert(checkHoistValue(SI->getCondition(), InsertPoint, DT,
+                             Unhoistables, nullptr) &&
+             "checkHoistValue for selects");
+    }
+    CHR_DEBUG(dbgs() << "Result\n");
+    if (RI.HasBranch) {
+      CHR_DEBUG(dbgs() << "BI " << *Branch << "\n");
+    }
+    for (auto *SI : Selects) {
+      CHR_DEBUG(dbgs() << "SI " << *SI << "\n");
+    }
+#endif
+  }
+}
+
+CHRScope * CHR::findScopes(Region *R, Region *NextRegion, Region *ParentRegion,
+                           SmallVectorImpl<CHRScope *> &Scopes) {
+  CHR_DEBUG(dbgs() << "findScopes " << R->getNameStr() << "\n");
+  CHRScope *Result = findScope(R);
+  // Visit subscopes.
+  if (R->begin() != R->end()) {
+    CHRScope *ConsecutiveSubscope = nullptr;
+    SmallVector<CHRScope *, 8> Subscopes;
+    for (auto It = R->begin(); It != R->end(); ++It) {
+      const std::unique_ptr<Region> &SubR = *It;
+      auto Next_It = std::next(It);
+      Region *NextSubR = Next_It != R->end() ? Next_It->get() : nullptr;
+      CHR_DEBUG(dbgs() << "Looking at subregion " << SubR.get()->getNameStr() << "\n");
+      CHRScope *SubCHRScope = findScopes(SubR.get(), NextSubR, R, Scopes);
+      if (SubCHRScope) {
+        CHR_DEBUG(dbgs() << "Subregion Scope " << *SubCHRScope << "\n");
+      } else {
+        CHR_DEBUG(dbgs() << "Subregion Scope null\n");
+      }
+      if (SubCHRScope) {
+        if (!ConsecutiveSubscope)
+          ConsecutiveSubscope = SubCHRScope;
+        else if (!ConsecutiveSubscope->appendable(SubCHRScope)) {
+          Subscopes.push_back(ConsecutiveSubscope);
+          ConsecutiveSubscope = SubCHRScope;
+        } else
+          ConsecutiveSubscope->append(SubCHRScope);
+      } else {
+        if (ConsecutiveSubscope) {
+          Subscopes.push_back(ConsecutiveSubscope);
+        }
+        ConsecutiveSubscope = nullptr;
+      }
+    }
+    if (ConsecutiveSubscope) {
+      Subscopes.push_back(ConsecutiveSubscope);
+    }
+    for (CHRScope *Sub : Subscopes) {
+      if (Result) {
+        // Combine it with the parent.
+        Result->addSub(Sub);
+      } else {
+        // Push Subscopes as they won't be combined with the parent.
+        Scopes.push_back(Sub);
+      }
+    }
+  }
+  return Result;
+}
+
+static DenseSet<Value *> getCHRConditionValuesForRegion(RegInfo &RI) {
+  DenseSet<Value *> ConditionValues;
+  if (RI.HasBranch) {
+    auto *BI = cast<BranchInst>(RI.R->getEntry()->getTerminator());
+    ConditionValues.insert(BI->getCondition());
+  }
+  for (SelectInst *SI : RI.Selects) {
+    ConditionValues.insert(SI->getCondition());
+  }
+  return ConditionValues;
+}
+
+
+// Determine whether to split a scope depending on the sets of the branch
+// condition values of the previous region and the current region. We split
+// (return true) it if 1) the condition values of the inner/lower scope can't be
+// hoisted up to the outer/upper scope, or 2) the two sets of the condition
+// values have an empty intersection (because the combined branch conditions
+// won't probably lead to a simpler combined condition).
+static bool shouldSplit(Instruction *InsertPoint,
+                        DenseSet<Value *> &PrevConditionValues,
+                        DenseSet<Value *> &ConditionValues,
+                        DominatorTree &DT,
+                        DenseSet<Instruction *> &Unhoistables) {
+  CHR_DEBUG(
+      dbgs() << "shouldSplit " << *InsertPoint << " PrevConditionValues ";
+      for (Value *V : PrevConditionValues) {
+        dbgs() << *V << ", ";
+      }
+      dbgs() << " ConditionValues ";
+      for (Value *V : ConditionValues) {
+        dbgs() << *V << ", ";
+      }
+      dbgs() << "\n");
+  assert(InsertPoint && "Null InsertPoint");
+  // If any of Bases isn't hoistable to the hoist point, split.
+  for (Value *V : ConditionValues) {
+    if (!checkHoistValue(V, InsertPoint, DT, Unhoistables, nullptr)) {
+      CHR_DEBUG(dbgs() << "Split. checkHoistValue false " << *V << "\n");
+      return true; // Not hoistable, split.
+    }
+  }
+  // If PrevConditionValues or ConditionValues is empty, don't split to avoid
+  // unnecessary splits at scopes with no branch/selects.  If
+  // PrevConditionValues and ConditionValues don't intersect at all, split.
+  if (!PrevConditionValues.empty() && !ConditionValues.empty()) {
+    // Use std::set as DenseSet doesn't work with set_intersection.
+    std::set<Value *> PrevBases, Bases;
+    for (Value *V : PrevConditionValues) {
+      std::set<Value *> BaseValues = getBaseValues(V, DT);
+      PrevBases.insert(BaseValues.begin(), BaseValues.end());
+    }
+    for (Value *V : ConditionValues) {
+      std::set<Value *> BaseValues = getBaseValues(V, DT);
+      Bases.insert(BaseValues.begin(), BaseValues.end());
+    }
+    CHR_DEBUG(
+        dbgs() << "PrevBases ";
+        for (Value *V : PrevBases) {
+          dbgs() << *V << ", ";
+        }
+        dbgs() << " Bases ";
+        for (Value *V : Bases) {
+          dbgs() << *V << ", ";
+        }
+        dbgs() << "\n");
+    std::set<Value *> Intersection;
+    std::set_intersection(PrevBases.begin(), PrevBases.end(),
+                          Bases.begin(), Bases.end(),
+                          std::inserter(Intersection, Intersection.begin()));
+    if (Intersection.empty()) {
+      // Empty intersection, split.
+      CHR_DEBUG(dbgs() << "Split. Intersection empty\n");
+      return true;
+    }
+  }
+  CHR_DEBUG(dbgs() << "No split\n");
+  return false;  // Don't split.
+}
+
+static void GetSelectsInScope(CHRScope *Scope,
+                              DenseSet<Instruction *> &Output) {
+  for (RegInfo &RI : Scope->RegInfos) {
+    for (SelectInst *SI : RI.Selects) {
+      Output.insert(SI);
+    }
+  }
+  for (CHRScope *Sub : Scope->Subs) {
+    GetSelectsInScope(Sub, Output);
+  }
+}
+
+void CHR::splitScopes(SmallVectorImpl<CHRScope *> &Input,
+                      SmallVectorImpl<CHRScope *> &Output) {
+  for (CHRScope *Scope : Input) {
+    assert(!Scope->BranchInsertPoint &&
+           "BranchInsertPoint must not be set");
+    DenseSet<Instruction *> Unhoistables;
+    GetSelectsInScope(Scope, Unhoistables);
+    splitScope(Scope, nullptr, nullptr, nullptr, Output, Unhoistables);
+  }
+#ifndef NDEBUG
+  for (CHRScope *Scope : Output) {
+    assert(Scope->BranchInsertPoint && "BranchInsertPoint must be set");
+  }
+#endif
+}
+
+SmallVector<CHRScope *, 8> CHR::splitScope(
+    CHRScope *Scope,
+    CHRScope *Outer,
+    DenseSet<Value *> *OuterConditionValues,
+    Instruction *OuterInsertPoint,
+    SmallVectorImpl<CHRScope *> &Output,
+    DenseSet<Instruction *> &Unhoistables) {
+  if (Outer) {
+    assert(OuterConditionValues && "Null OuterConditionValues");
+    assert(OuterInsertPoint && "Null OuterInsertPoint");
+  }
+  bool PrevSplitFromOuter = true;
+  DenseSet<Value *> PrevConditionValues;
+  Instruction *PrevInsertPoint = nullptr;
+  SmallVector<CHRScope *, 8> Splits;
+  SmallVector<bool, 8> SplitsSplitFromOuter;
+  SmallVector<DenseSet<Value *>, 8> SplitsConditionValues;
+  SmallVector<Instruction *, 8> SplitsInsertPoints;
+  SmallVector<RegInfo, 8> RegInfos(Scope->RegInfos);  // Copy
+  for (RegInfo &RI : RegInfos) {
+    Instruction *InsertPoint = getBranchInsertPoint(RI);
+    DenseSet<Value *> ConditionValues = getCHRConditionValuesForRegion(RI);
+    CHR_DEBUG(
+        dbgs() << "ConditionValues ";
+        for (Value *V : ConditionValues) {
+          dbgs() << *V << ", ";
+        }
+        dbgs() << "\n");
+    if (RI.R == RegInfos[0].R) {
+      // First iteration. Check to see if we should split from the outer.
+      if (Outer) {
+        CHR_DEBUG(dbgs() << "Outer " << *Outer << "\n");
+        CHR_DEBUG(dbgs() << "Should split from outer at "
+                  << RI.R->getNameStr() << "\n");
+        if (shouldSplit(OuterInsertPoint, *OuterConditionValues,
+                        ConditionValues, DT, Unhoistables)) {
+          PrevConditionValues = ConditionValues;
+          PrevInsertPoint = InsertPoint;
+        } else {
+          // Not splitting from the outer. Use the outer bases and insert
+          // point. Union the bases.
+          PrevSplitFromOuter = false;
+          PrevConditionValues = *OuterConditionValues;
+          PrevConditionValues.insert(ConditionValues.begin(),
+                                     ConditionValues.end());
+          PrevInsertPoint = OuterInsertPoint;
+        }
+      } else {
+        CHR_DEBUG(dbgs() << "Outer null\n");
+        PrevConditionValues = ConditionValues;
+        PrevInsertPoint = InsertPoint;
+      }
+    } else {
+      CHR_DEBUG(dbgs() << "Should split from prev at "
+                << RI.R->getNameStr() << "\n");
+      if (shouldSplit(PrevInsertPoint, PrevConditionValues, ConditionValues,
+                      DT, Unhoistables)) {
+        CHRScope *Tail = Scope->split(RI.R);
+        Scopes.insert(Tail);
+        Splits.push_back(Scope);
+        SplitsSplitFromOuter.push_back(PrevSplitFromOuter);
+        SplitsConditionValues.push_back(PrevConditionValues);
+        SplitsInsertPoints.push_back(PrevInsertPoint);
+        Scope = Tail;
+        PrevConditionValues = ConditionValues;
+        PrevInsertPoint = InsertPoint;
+        PrevSplitFromOuter = true;
+      } else {
+        // Not splitting. Union the bases. Keep the hoist point.
+        PrevConditionValues.insert(ConditionValues.begin(), ConditionValues.end());
+      }
+    }
+  }
+  Splits.push_back(Scope);
+  SplitsSplitFromOuter.push_back(PrevSplitFromOuter);
+  SplitsConditionValues.push_back(PrevConditionValues);
+  assert(PrevInsertPoint && "Null PrevInsertPoint");
+  SplitsInsertPoints.push_back(PrevInsertPoint);
+  assert(Splits.size() == SplitsConditionValues.size() &&
+         Splits.size() == SplitsSplitFromOuter.size() &&
+         Splits.size() == SplitsInsertPoints.size() && "Mismatching sizes");
+  for (size_t I = 0; I < Splits.size(); ++I) {
+    CHRScope *Split = Splits[I];
+    DenseSet<Value *> &SplitConditionValues = SplitsConditionValues[I];
+    Instruction *SplitInsertPoint = SplitsInsertPoints[I];
+    SmallVector<CHRScope *, 8> NewSubs;
+    DenseSet<Instruction *> SplitUnhoistables;
+    GetSelectsInScope(Split, SplitUnhoistables);
+    for (CHRScope *Sub : Split->Subs) {
+      SmallVector<CHRScope *, 8> SubSplits = splitScope(
+          Sub, Split, &SplitConditionValues, SplitInsertPoint, Output,
+          SplitUnhoistables);
+      NewSubs.insert(NewSubs.end(), SubSplits.begin(), SubSplits.end());
+    }
+    Split->Subs = NewSubs;
+  }
+  SmallVector<CHRScope *, 8> Result;
+  for (size_t I = 0; I < Splits.size(); ++I) {
+    CHRScope *Split = Splits[I];
+    if (SplitsSplitFromOuter[I]) {
+      // Split from the outer.
+      Output.push_back(Split);
+      Split->BranchInsertPoint = SplitsInsertPoints[I];
+      CHR_DEBUG(dbgs() << "BranchInsertPoint " << *SplitsInsertPoints[I]
+                << "\n");
+    } else {
+      // Connected to the outer.
+      Result.push_back(Split);
+    }
+  }
+  if (!Outer)
+    assert(Result.empty() &&
+           "If no outer (top-level), must return no nested ones");
+  return Result;
+}
+
+void CHR::setPerScopeBias(SmallVectorImpl<CHRScope *> &Scopes) {
+  for (CHRScope *Scope : Scopes) {
+    assert(Scope->TrueBiasedRegions.empty() && Scope->FalseBiasedRegions.empty() && "Empty");
+    setPerScopeBias(Scope, Scope);
+    CHR_DEBUG(
+        dbgs() << "setPerScopeBias " << *Scope << "\n";
+        dbgs() << "TrueBiasedRegions ";
+        for (Region *R : Scope->TrueBiasedRegions) {
+          dbgs() << R->getNameStr() << ", ";
+        }
+        dbgs() << "\n";
+        dbgs() << "FalseBiasedRegions ";
+        for (Region *R : Scope->FalseBiasedRegions) {
+          dbgs() << R->getNameStr() << ", ";
+        }
+        dbgs() << "\n";
+        dbgs() << "TrueBiasedSelects ";
+        for (SelectInst *SI : Scope->TrueBiasedSelects) {
+          dbgs() << *SI << ", ";
+        }
+        dbgs() << "\n";
+        dbgs() << "FalseBiasedSelects ";
+        for (SelectInst *SI : Scope->FalseBiasedSelects) {
+          dbgs() << *SI << ", ";
+        }
+        dbgs() << "\n";);
+  }
+}
+
+void CHR::setPerScopeBias(CHRScope *Scope, CHRScope *OutermostScope) {
+  for (RegInfo &RI : Scope->RegInfos) {
+    if (RI.HasBranch) {
+      Region *R = RI.R;
+      if (TrueBiasedRegionsGlobal.count(R) > 0)
+        OutermostScope->TrueBiasedRegions.insert(R);
+      else if (FalseBiasedRegionsGlobal.count(R) > 0)
+        OutermostScope->FalseBiasedRegions.insert(R);
+      else
+        llvm_unreachable("Must be biased");
+    }
+    for (SelectInst *SI : RI.Selects) {
+      if (TrueBiasedSelectsGlobal.count(SI) > 0)
+        OutermostScope->TrueBiasedSelects.insert(SI);
+      else if (FalseBiasedSelectsGlobal.count(SI) > 0)
+        OutermostScope->FalseBiasedSelects.insert(SI);
+      else
+        llvm_unreachable("Must be biased");
+    }
+  }
+  for (CHRScope *Sub : Scope->Subs) {
+    setPerScopeBias(Sub, OutermostScope);
+  }
+}
+
+static bool hasAtLeastTwoBiasedBranches(CHRScope *Scope) {
+  unsigned NumBiased = Scope->TrueBiasedRegions.size() +
+                       Scope->FalseBiasedRegions.size() +
+                       Scope->TrueBiasedSelects.size() +
+                       Scope->FalseBiasedSelects.size();
+  return NumBiased >= CHRMergeThreshold;
+}
+
+void CHR::filterScopes(SmallVectorImpl<CHRScope *> &Input,
+                       SmallVectorImpl<CHRScope *> &Output) {
+  for (CHRScope *Scope : Input) {
+    // Filter out the ones with only one region and no subs.
+    if (!hasAtLeastTwoBiasedBranches(Scope)) {
+      CHR_DEBUG(dbgs() << "Filtered out by biased branches truthy-regions "
+                << Scope->TrueBiasedRegions.size()
+                << " falsy-regions " << Scope->FalseBiasedRegions.size()
+                << " true-selects " << Scope->TrueBiasedSelects.size()
+                << " false-selects " << Scope->FalseBiasedSelects.size() << "\n");
+      continue;
+    }
+    Output.push_back(Scope);
+  }
+}
+
+void CHR::setCHRRegions(SmallVectorImpl<CHRScope *> &Input,
+                        SmallVectorImpl<CHRScope *> &Output) {
+  for (CHRScope *Scope : Input) {
+    assert(Scope->HoistStopMap.empty() && Scope->CHRRegions.empty() &&
+           "Empty");
+    setCHRRegions(Scope, Scope);
+    Output.push_back(Scope);
+    CHR_DEBUG(
+        dbgs() << "setCHRRegions HoistStopMap " << *Scope << "\n";
+        for (auto pair : Scope->HoistStopMap) {
+          Region *R = pair.first;
+          dbgs() << "Region " << R->getNameStr() << "\n";
+          for (Instruction *I : pair.second) {
+            dbgs() << "HoistStop " << *I << "\n";
+          }
+        }
+        dbgs() << "CHRRegions" << "\n";
+        for (RegInfo &RI : Scope->CHRRegions) {
+          dbgs() << RI.R->getNameStr() << "\n";
+        });
+  }
+}
+
+void CHR::setCHRRegions(CHRScope *Scope, CHRScope *OutermostScope) {
+  DenseSet<Instruction *> Unhoistables;
+  // Put the biased selects in Unhoistables because they should stay where they
+  // are and constant-folded after CHR (in case one biased select or a branch
+  // can depend on another biased select.)
+  for (RegInfo &RI : Scope->RegInfos) {
+    for (SelectInst *SI : RI.Selects) {
+      Unhoistables.insert(SI);
+    }
+  }
+  Instruction *InsertPoint = OutermostScope->BranchInsertPoint;
+  for (RegInfo &RI : Scope->RegInfos) {
+    Region *R = RI.R;
+    DenseSet<Instruction *> HoistStops;
+    bool IsHoisted = false;
+    if (RI.HasBranch) {
+      assert((OutermostScope->TrueBiasedRegions.count(R) > 0 ||
+              OutermostScope->FalseBiasedRegions.count(R) > 0) &&
+             "Must be truthy or falsy");
+      auto *BI = cast<BranchInst>(R->getEntry()->getTerminator());
+      // Note checkHoistValue fills in HoistStops.
+      bool IsHoistable = checkHoistValue(BI->getCondition(), InsertPoint, DT,
+                                         Unhoistables, &HoistStops);
+      assert(IsHoistable && "Must be hoistable");
+      (void)(IsHoistable);  // Unused in release build
+      IsHoisted = true;
+    }
+    for (SelectInst *SI : RI.Selects) {
+      assert((OutermostScope->TrueBiasedSelects.count(SI) > 0 ||
+              OutermostScope->FalseBiasedSelects.count(SI) > 0) &&
+             "Must be true or false biased");
+      // Note checkHoistValue fills in HoistStops.
+      bool IsHoistable = checkHoistValue(SI->getCondition(), InsertPoint, DT,
+                                         Unhoistables, &HoistStops);
+      assert(IsHoistable && "Must be hoistable");
+      (void)(IsHoistable);  // Unused in release build
+      IsHoisted = true;
+    }
+    if (IsHoisted) {
+      OutermostScope->CHRRegions.push_back(RI);
+      OutermostScope->HoistStopMap[R] = HoistStops;
+    }
+  }
+  for (CHRScope *Sub : Scope->Subs)
+    setCHRRegions(Sub, OutermostScope);
+}
+
+bool CHRScopeSorter(CHRScope *Scope1, CHRScope *Scope2) {
+  return Scope1->RegInfos[0].R->getDepth() < Scope2->RegInfos[0].R->getDepth();
+}
+
+void CHR::sortScopes(SmallVectorImpl<CHRScope *> &Input,
+                     SmallVectorImpl<CHRScope *> &Output) {
+  Output.resize(Input.size());
+  std::copy(Input.begin(), Input.end(), Output.begin());
+  std::stable_sort(Output.begin(), Output.end(), CHRScopeSorter);
+}
+
+// Return true if V is already hoisted or was hoisted (along with its operands)
+// to the insert point.
+static void hoistValue(Value *V, Instruction *HoistPoint, Region *R,
+                       HoistStopMapTy &HoistStopMap,
+                       DenseSet<Instruction *> &HoistedSet,
+                       DenseSet<PHINode *> &TrivialPHIs) {
+  auto IT = HoistStopMap.find(R);
+  assert(IT != HoistStopMap.end() && "Region must be in hoist stop map");
+  DenseSet<Instruction *> &HoistStops = IT->second;
+  if (auto *I = dyn_cast<Instruction>(V)) {
+    if (I == HoistPoint)
+      return;
+    if (HoistStops.count(I))
+      return;
+    if (auto *PN = dyn_cast<PHINode>(I))
+      if (TrivialPHIs.count(PN))
+        // The trivial phi inserted by the previous CHR scope could replace a
+        // non-phi in HoistStops. Note that since this phi is at the exit of a
+        // previous CHR scope, which dominates this scope, it's safe to stop
+        // hoisting there.
+        return;
+    if (HoistedSet.count(I))
+      // Already hoisted, return.
+      return;
+    assert(isHoistableInstructionType(I) && "Unhoistable instruction type");
+    for (Value *Op : I->operands()) {
+      hoistValue(Op, HoistPoint, R, HoistStopMap, HoistedSet, TrivialPHIs);
+    }
+    I->moveBefore(HoistPoint);
+    HoistedSet.insert(I);
+    CHR_DEBUG(dbgs() << "hoistValue " << *I << "\n");
+  }
+}
+
+// Hoist the dependent condition values of the branches and the selects in the
+// scope to the insert point.
+static void hoistScopeConditions(CHRScope *Scope, Instruction *HoistPoint,
+                                 DenseSet<PHINode *> &TrivialPHIs) {
+  DenseSet<Instruction *> HoistedSet;
+  for (const RegInfo &RI : Scope->CHRRegions) {
+    Region *R = RI.R;
+    bool IsTrueBiased = Scope->TrueBiasedRegions.count(R);
+    bool IsFalseBiased = Scope->FalseBiasedRegions.count(R);
+    if (RI.HasBranch && (IsTrueBiased || IsFalseBiased)) {
+      auto *BI = cast<BranchInst>(R->getEntry()->getTerminator());
+      hoistValue(BI->getCondition(), HoistPoint, R, Scope->HoistStopMap,
+                 HoistedSet, TrivialPHIs);
+    }
+    for (SelectInst *SI : RI.Selects) {
+      bool IsTrueBiased = Scope->TrueBiasedSelects.count(SI);
+      bool IsFalseBiased = Scope->FalseBiasedSelects.count(SI);
+      if (!(IsTrueBiased || IsFalseBiased))
+        continue;
+      hoistValue(SI->getCondition(), HoistPoint, R, Scope->HoistStopMap,
+                 HoistedSet, TrivialPHIs);
+    }
+  }
+}
+
+// Negate the predicate if an ICmp if it's used only by branches or selects by
+// swapping the operands of the branches or the selects. Returns true if success.
+static bool NegateICmpIfUsedByBranchOrSelectOnly(ICmpInst *ICmp,
+                                                 Instruction *ExcludedUser,
+                                                 CHRScope *Scope) {
+  for (User *U : ICmp->users()) {
+    if (U == ExcludedUser)
+      continue;
+    if (isa<BranchInst>(U) && cast<BranchInst>(U)->isConditional())
+      continue;
+    if (isa<SelectInst>(U) && cast<SelectInst>(U)->getCondition() == ICmp)
+      continue;
+    return false;
+  }
+  for (User *U : ICmp->users()) {
+    if (U == ExcludedUser)
+      continue;
+    if (auto *BI = dyn_cast<BranchInst>(U)) {
+      assert(BI->isConditional() && "Must be conditional");
+      BI->swapSuccessors();
+      // Don't need to swap this in terms of
+      // TrueBiasedRegions/FalseBiasedRegions because true-based/false-based
+      // mean whehter the branch is likely go into the if-then rather than
+      // successor0/successor1 and because we can tell which edge is the then or
+      // the else one by comparing the destination to the region exit block.
+      continue;
+    }
+    if (auto *SI = dyn_cast<SelectInst>(U)) {
+      // Swap operands
+      Value *TrueValue = SI->getTrueValue();
+      Value *FalseValue = SI->getFalseValue();
+      SI->setTrueValue(FalseValue);
+      SI->setFalseValue(TrueValue);
+      SI->swapProfMetadata();
+      if (Scope->TrueBiasedSelects.count(SI)) {
+        assert(Scope->FalseBiasedSelects.count(SI) == 0 &&
+               "Must not be already in");
+        Scope->FalseBiasedSelects.insert(SI);
+      } else if (Scope->FalseBiasedSelects.count(SI)) {
+        assert(Scope->TrueBiasedSelects.count(SI) == 0 &&
+               "Must not be already in");
+        Scope->TrueBiasedSelects.insert(SI);
+      }
+      continue;
+    }
+    llvm_unreachable("Must be a branch or a select");
+  }
+  ICmp->setPredicate(CmpInst::getInversePredicate(ICmp->getPredicate()));
+  return true;
+}
+
+// A helper for transformScopes. Insert a trivial phi at the scope exit block
+// for a value that's defined in the scope but used outside it (meaning it's
+// alive at the exit block).
+static void insertTrivialPHIs(CHRScope *Scope,
+                              BasicBlock *EntryBlock, BasicBlock *ExitBlock,
+                              DenseSet<PHINode *> &TrivialPHIs) {
+  DenseSet<BasicBlock *> BlocksInScopeSet;
+  SmallVector<BasicBlock *, 8> BlocksInScopeVec;
+  for (RegInfo &RI : Scope->RegInfos) {
+    for (BasicBlock *BB : RI.R->blocks()) { // This includes the blocks in the
+                                            // sub-Scopes.
+      BlocksInScopeSet.insert(BB);
+      BlocksInScopeVec.push_back(BB);
+    }
+  }
+  CHR_DEBUG(
+      dbgs() << "Inserting redudant phis\n";
+      for (BasicBlock *BB : BlocksInScopeVec) {
+        dbgs() << "BlockInScope " << BB->getName() << "\n";
+      });
+  for (BasicBlock *BB : BlocksInScopeVec) {
+    for (Instruction &I : *BB) {
+      SmallVector<Instruction *, 8> Users;
+      for (User *U : I.users()) {
+        if (auto *UI = dyn_cast<Instruction>(U)) {
+          if (BlocksInScopeSet.count(UI->getParent()) == 0 &&
+              // Unless there's already a phi for I at the exit block.
+              !(isa<PHINode>(UI) && UI->getParent() == ExitBlock)) {
+            CHR_DEBUG(dbgs() << "V " << I << "\n");
+            CHR_DEBUG(dbgs() << "Used outside scope by user " << *UI << "\n");
+            Users.push_back(UI);
+          } else if (UI->getParent() == EntryBlock && isa<PHINode>(UI)) {
+            // There's a loop backedge from a block that's dominated by this
+            // scope to the entry block.
+            CHR_DEBUG(dbgs() << "V " << I << "\n");
+            CHR_DEBUG(dbgs()
+                      << "Used at entry block (for a back edge) by a phi user "
+                      << *UI << "\n");
+            Users.push_back(UI);
+          }
+        }
+      }
+      if (Users.size() > 0) {
+        // Insert a trivial phi for I (phi [&I, P0], [&I, P1], ...) at
+        // ExitBlock. Replace I with the new phi in UI unless UI is another
+        // phi at ExitBlock.
+        unsigned PredCount = std::distance(pred_begin(ExitBlock),
+                                           pred_end(ExitBlock));
+        PHINode *PN = PHINode::Create(I.getType(), PredCount, "",
+                                      &ExitBlock->front());
+        for (BasicBlock *Pred : predecessors(ExitBlock)) {
+          PN->addIncoming(&I, Pred);
+        }
+        TrivialPHIs.insert(PN);
+        CHR_DEBUG(dbgs() << "Insert phi " << *PN << "\n");
+        for (Instruction *UI : Users) {
+          for (unsigned J = 0, NumOps = UI->getNumOperands(); J < NumOps; ++J) {
+            if (UI->getOperand(J) == &I) {
+              UI->setOperand(J, PN);
+            }
+          }
+          CHR_DEBUG(dbgs() << "Updated user " << *UI << "\n");
+        }
+      }
+    }
+  }
+}
+
+// Assert that all the CHR regions of the scope have a biased branch or select.
+static void assertCHRRegionsHaveBiasedBranchOrSelect(CHRScope *Scope) {
+#ifndef NDEBUG
+  auto HasBiasedBranchOrSelect = [](RegInfo &RI, CHRScope *Scope) {
+    if (Scope->TrueBiasedRegions.count(RI.R) ||
+        Scope->FalseBiasedRegions.count(RI.R))
+      return true;
+    for (SelectInst *SI : RI.Selects)
+      if (Scope->TrueBiasedSelects.count(SI) ||
+          Scope->FalseBiasedSelects.count(SI))
+        return true;
+    return false;
+  };
+  for (RegInfo &RI : Scope->CHRRegions) {
+    assert(HasBiasedBranchOrSelect(RI, Scope) &&
+           "Must have biased branch or select");
+  }
+#endif
+}
+
+// Assert that all the condition values of the biased branches and selects have
+// been hoisted to the pre-entry block or outside of the scope.
+static void assertBranchOrSelectConditionHoisted(CHRScope *Scope,
+                                                 BasicBlock *PreEntryBlock) {
+  CHR_DEBUG(dbgs() << "Biased regions condition values \n");
+  for (RegInfo &RI : Scope->CHRRegions) {
+    Region *R = RI.R;
+    bool IsTrueBiased = Scope->TrueBiasedRegions.count(R);
+    bool IsFalseBiased = Scope->FalseBiasedRegions.count(R);
+    if (RI.HasBranch && (IsTrueBiased || IsFalseBiased)) {
+      auto *BI = cast<BranchInst>(R->getEntry()->getTerminator());
+      Value *V = BI->getCondition();
+      CHR_DEBUG(dbgs() << *V << "\n");
+      if (auto *I = dyn_cast<Instruction>(V)) {
+        assert((I->getParent() == PreEntryBlock ||
+                !Scope->contains(I)) &&
+               "Must have been hoisted to PreEntryBlock or outside the scope");
+      }
+    }
+    for (SelectInst *SI : RI.Selects) {
+      bool IsTrueBiased = Scope->TrueBiasedSelects.count(SI);
+      bool IsFalseBiased = Scope->FalseBiasedSelects.count(SI);
+      if (!(IsTrueBiased || IsFalseBiased))
+        continue;
+      Value *V = SI->getCondition();
+      CHR_DEBUG(dbgs() << *V << "\n");
+      if (auto *I = dyn_cast<Instruction>(V)) {
+        assert((I->getParent() == PreEntryBlock ||
+                !Scope->contains(I)) &&
+               "Must have been hoisted to PreEntryBlock or outside the scope");
+      }
+    }
+  }
+}
+
+void CHR::transformScopes(CHRScope *Scope, DenseSet<PHINode *> &TrivialPHIs) {
+  CHR_DEBUG(dbgs() << "transformScopes " << *Scope << "\n");
+
+  assert(Scope->RegInfos.size() >= 1 && "Should have at least one Region");
+  Region *FirstRegion = Scope->RegInfos[0].R;
+  BasicBlock *EntryBlock = FirstRegion->getEntry();
+  Region *LastRegion = Scope->RegInfos[Scope->RegInfos.size() - 1].R;
+  BasicBlock *ExitBlock = LastRegion->getExit();
+
+  if (ExitBlock) {
+    // Insert a trivial phi at the exit block (where the CHR hot path and the
+    // cold path merges) for a value that's defined in the scope but used
+    // outside it (meaning it's alive at the exit block). We will add the
+    // incoming values for the CHR cold paths to it below. Without this, we'd
+    // miss updating phi's for such values unless there happens to already be a
+    // phi for that value there.
+    insertTrivialPHIs(Scope, EntryBlock, ExitBlock, TrivialPHIs);
+  }
+
+  // Split the entry block of the first region. The new block becomes the new
+  // entry block of the first region. The old entry block becomes the block to
+  // insert the CHR branch into. Note DT gets updated. Since DT gets updated
+  // through the split, we update the entry of the first region after the split,
+  // and Region only points to the entry and the exit blocks, rather than
+  // keeping everything in a list or set, the blocks membership and the
+  // entry/exit blocks of the region are still valid after the split.
+  CHR_DEBUG(dbgs() << "Splitting entry block " << EntryBlock->getName()
+            << " at " << *Scope->BranchInsertPoint << "\n");
+  BasicBlock *NewEntryBlock =
+      SplitBlock(EntryBlock, Scope->BranchInsertPoint, &DT);
+  assert(NewEntryBlock->getSinglePredecessor() == EntryBlock &&
+         "NewEntryBlock's only pred must be EntryBlock");
+  FirstRegion->replaceEntryRecursive(NewEntryBlock);
+  BasicBlock *PreEntryBlock = EntryBlock;
+
+  ValueToValueMapTy VMap;
+  // Clone the blocks in the scope (excluding the PreEntryBlock) to split into a
+  // hot path (originals) and a cold path (clones) and update the PHIs at the
+  // exit block.
+  cloneScopeBlocks(Scope, PreEntryBlock, ExitBlock, LastRegion, VMap);
+
+  // Replace the old (placeholder) branch with the new (merged) conditional
+  // branch.
+  BranchInst *MergedBr = createMergedBranch(PreEntryBlock, EntryBlock,
+                                            NewEntryBlock, VMap);
+
+#ifndef NDEBUG
+  assertCHRRegionsHaveBiasedBranchOrSelect(Scope);
+#endif
+
+  // Hoist the conditional values of the branches/selects.
+  hoistScopeConditions(Scope, PreEntryBlock->getTerminator(), TrivialPHIs);
+
+#ifndef NDEBUG
+  assertBranchOrSelectConditionHoisted(Scope, PreEntryBlock);
+#endif
+
+  // Create the combined branch condition and constant-fold the branches/selects
+  // in the hot path.
+  fixupBranchesAndSelects(Scope, PreEntryBlock, MergedBr);
+}
+
+// A helper for transformScopes. Clone the blocks in the scope (excluding the
+// PreEntryBlock) to split into a hot path and a cold path and update the PHIs
+// at the exit block.
+void CHR::cloneScopeBlocks(CHRScope *Scope,
+                           BasicBlock *PreEntryBlock,
+                           BasicBlock *ExitBlock,
+                           Region *LastRegion,
+                           ValueToValueMapTy &VMap) {
+  // Clone all the blocks. The original blocks will be the hot-path
+  // CHR-optimized code and the cloned blocks will be the original unoptimized
+  // code. This is so that the block pointers from the
+  // CHRScope/Region/RegionInfo can stay valid in pointing to the hot-path code
+  // which CHR should apply to.
+  SmallVector<BasicBlock*, 8> NewBlocks;
+  for (RegInfo &RI : Scope->RegInfos)
+    for (BasicBlock *BB : RI.R->blocks()) { // This includes the blocks in the
+                                            // sub-Scopes.
+      assert(BB != PreEntryBlock && "Don't copy the preetntry block");
+      BasicBlock *NewBB = CloneBasicBlock(BB, VMap, ".nonchr", &F);
+      NewBlocks.push_back(NewBB);
+      VMap[BB] = NewBB;
+    }
+
+  // Place the cloned blocks right after the original blocks (right before the
+  // exit block of.)
+  if (ExitBlock)
+    F.getBasicBlockList().splice(ExitBlock->getIterator(),
+                                 F.getBasicBlockList(),
+                                 NewBlocks[0]->getIterator(), F.end());
+
+  // Update the cloned blocks/instructions to refer to themselves.
+  for (unsigned i = 0, e = NewBlocks.size(); i != e; ++i)
+    for (Instruction &I : *NewBlocks[i])
+      RemapInstruction(&I, VMap,
+                       RF_NoModuleLevelChanges | RF_IgnoreMissingLocals);
+
+  // Add the cloned blocks to the PHIs of the exit blocks. ExitBlock is null for
+  // the top-level region but we don't need to add PHIs. The trivial PHIs
+  // inserted above will be updated here.
+  if (ExitBlock)
+    for (PHINode &PN : ExitBlock->phis())
+      for (unsigned I = 0, NumOps = PN.getNumIncomingValues(); I < NumOps;
+           ++I) {
+        BasicBlock *Pred = PN.getIncomingBlock(I);
+        if (LastRegion->contains(Pred)) {
+          Value *V = PN.getIncomingValue(I);
+          auto It = VMap.find(V);
+          if (It != VMap.end()) V = It->second;
+          assert(VMap.find(Pred) != VMap.end() && "Pred must have been cloned");
+          PN.addIncoming(V, cast<BasicBlock>(VMap[Pred]));
+        }
+      }
+}
+
+// A helper for transformScope. Replace the old (placeholder) branch with the
+// new (merged) conditional branch.
+BranchInst *CHR::createMergedBranch(BasicBlock *PreEntryBlock,
+                                    BasicBlock *EntryBlock,
+                                    BasicBlock *NewEntryBlock,
+                                    ValueToValueMapTy &VMap) {
+  BranchInst *OldBR = cast<BranchInst>(PreEntryBlock->getTerminator());
+  assert(OldBR->isUnconditional() && OldBR->getSuccessor(0) == NewEntryBlock &&
+         "SplitBlock did not work correctly!");
+  assert(NewEntryBlock->getSinglePredecessor() == EntryBlock &&
+         "NewEntryBlock's only pred must be EntryBlock");
+  assert(VMap.find(NewEntryBlock) != VMap.end() &&
+         "NewEntryBlock must have been copied");
+  OldBR->removeFromParent();
+  OldBR->dropAllReferences();
+  BranchInst *NewBR = BranchInst::Create(NewEntryBlock,
+                                         cast<BasicBlock>(VMap[NewEntryBlock]),
+                                         ConstantInt::getTrue(F.getContext()));
+  PreEntryBlock->getInstList().push_back(NewBR);
+  assert(NewEntryBlock->getSinglePredecessor() == EntryBlock &&
+         "NewEntryBlock's only pred must be EntryBlock");
+  return NewBR;
+}
+
+// A helper for transformScopes. Create the combined branch condition and
+// constant-fold the branches/selects in the hot path.
+void CHR::fixupBranchesAndSelects(CHRScope *Scope,
+                                  BasicBlock *PreEntryBlock,
+                                  BranchInst *MergedBR) {
+  Value *MergedCondition = ConstantInt::getTrue(F.getContext());
+  double CHRBranchBias = 1.0;
+  uint64_t NumCHRedBranches = 0;
+  for (RegInfo &RI : Scope->CHRRegions) {
+    Region *R = RI.R;
+    if (RI.HasBranch) {
+      fixupBranch(R, Scope, PreEntryBlock, MergedCondition, CHRBranchBias);
+      ++NumCHRedBranches;
+    }
+    for (SelectInst *SI : RI.Selects) {
+      fixupSelect(SI, Scope, PreEntryBlock, MergedCondition, CHRBranchBias);
+      ++NumCHRedBranches;
+    }
+  }
+  Stats.NumBranchesDelta += NumCHRedBranches - 1;
+  MergedBR->setCondition(MergedCondition);
+  SmallVector<uint32_t, 2> Weights;
+  Weights.push_back(static_cast<uint32_t>(CHRBranchBias * 1000.0));
+  Weights.push_back(static_cast<uint32_t>((1.0 - CHRBranchBias) * 1000.0));
+  MDBuilder MDB(F.getContext());
+  MergedBR->setMetadata(LLVMContext::MD_prof, MDB.createBranchWeights(Weights));
+  CHR_DEBUG(dbgs() << "CHR branch bias " << Weights[0] << ":" << Weights[1]
+            << "\n");
+}
+
+// A helper for fixupBranchesAndSelects. Add to the combined branch condition
+// and constant-fold a branch in the hot path.
+void CHR::fixupBranch(Region *R, CHRScope *Scope,
+                      BasicBlock *PreEntryBlock,
+                      Value *&MergedCondition, double &CHRBranchBias) {
+  bool IsTrueBiased = Scope->TrueBiasedRegions.count(R);
+  assert((IsTrueBiased || Scope->FalseBiasedRegions.count(R)) &&
+         "Must be truthy or falsy");
+  auto *BI = cast<BranchInst>(R->getEntry()->getTerminator());
+  assert(BranchBiasMap.find(R) != BranchBiasMap.end() &&
+         "Must be in the bias map");
+  double Bias = BranchBiasMap[R];
+  assert(Bias >= CHRBiasThreshold && "Must be highly biased");
+  CHRBranchBias *= Bias;
+  BasicBlock *IfThen = BI->getSuccessor(1);
+  BasicBlock *IfElse = BI->getSuccessor(0);
+  BasicBlock *RegionExitBlock = R->getExit();
+  assert(RegionExitBlock && "Null ExitBlock");
+  assert((IfThen == RegionExitBlock || IfElse == RegionExitBlock) &&
+         IfThen != IfElse && "Invariant from findScopes");
+  if (IfThen == RegionExitBlock) {
+    // Swap them so that IfThen means going into it and IfElse means skipping
+    // it.
+    std::swap(IfThen, IfElse);
+  }
+  CHR_DEBUG(dbgs() << "IfThen " << IfThen->getName()
+            << " IfElse " << IfElse->getName() << "\n");
+  Value *Cond = BI->getCondition();
+  BasicBlock *HotTarget = IsTrueBiased ? IfThen : IfElse;
+  bool ConditionTrue = HotTarget == BI->getSuccessor(0);
+  addToMergedCondition(ConditionTrue, Cond, BI, Scope, PreEntryBlock,
+                       MergedCondition);
+  // Constant-fold the branch at ClonedEntryBlock.
+  assert(ConditionTrue == (HotTarget == BI->getSuccessor(0)) &&
+         "The successor shouldn't change");
+  Value *NewCondition = ConditionTrue ?
+                        ConstantInt::getTrue(F.getContext()) :
+                        ConstantInt::getFalse(F.getContext());
+  BI->setCondition(NewCondition);
+}
+
+// A helper for fixupBranchesAndSelects. Add to the combined branch condition
+// and constant-fold a select in the hot path.
+void CHR::fixupSelect(SelectInst *SI, CHRScope *Scope,
+                      BasicBlock *PreEntryBlock,
+                      Value *&MergedCondition, double &CHRBranchBias) {
+  bool IsTrueBiased = Scope->TrueBiasedSelects.count(SI);
+  assert((IsTrueBiased ||
+          Scope->FalseBiasedSelects.count(SI)) && "Must be biased");
+  assert(SelectBiasMap.find(SI) != SelectBiasMap.end() &&
+         "Must be in the bias map");
+  double Bias = SelectBiasMap[SI];
+  assert(Bias >= CHRBiasThreshold && "Must be highly biased");
+  CHRBranchBias *= Bias;
+  Value *Cond = SI->getCondition();
+  addToMergedCondition(IsTrueBiased, Cond, SI, Scope, PreEntryBlock,
+                       MergedCondition);
+  Value *NewCondition = IsTrueBiased ?
+                        ConstantInt::getTrue(F.getContext()) :
+                        ConstantInt::getFalse(F.getContext());
+  SI->setCondition(NewCondition);
+}
+
+// A helper for fixupBranch/fixupSelect. Add a branch condition to the merged
+// condition.
+void CHR::addToMergedCondition(bool IsTrueBiased, Value *Cond,
+                               Instruction *BranchOrSelect,
+                               CHRScope *Scope,
+                               BasicBlock *PreEntryBlock,
+                               Value *&MergedCondition) {
+  if (IsTrueBiased) {
+    Instruction *And = BinaryOperator::Create(Instruction::And,
+                                              MergedCondition, Cond);
+    PreEntryBlock->getInstList().insert(
+        PreEntryBlock->getTerminator()->getIterator(), And);
+    MergedCondition = And;
+  } else {
+    // If Cond is an icmp and all users of V except for BranchOrSelect is a
+    // branch, negate the icmp predicate and swap the branch targets and avoid
+    // inserting an Xor to negate Cond.
+    bool Done = false;
+    if (auto *ICmp = dyn_cast<ICmpInst>(Cond))
+      if (NegateICmpIfUsedByBranchOrSelectOnly(ICmp, BranchOrSelect, Scope)) {
+        Instruction *And = BinaryOperator::Create(Instruction::And,
+                                                  MergedCondition, Cond);
+        PreEntryBlock->getInstList().insert(
+            PreEntryBlock->getTerminator()->getIterator(), And);
+        MergedCondition = And;
+        Done = true;
+      }
+    if (!Done) {
+      Instruction *Negate =
+          BinaryOperator::Create(Instruction::Xor,
+                                 ConstantInt::getTrue(F.getContext()), Cond);
+      Instruction *And =
+          BinaryOperator::Create(Instruction::And, MergedCondition, Negate);
+      PreEntryBlock->getInstList().insert(
+          PreEntryBlock->getTerminator()->getIterator(), Negate);
+      PreEntryBlock->getInstList().insert(
+          PreEntryBlock->getTerminator()->getIterator(), And);
+      MergedCondition = And;
+    }
+  }
+}
+
+void CHR::transformScopes(SmallVectorImpl<CHRScope *> &CHRScopes) {
+  unsigned i = 0;
+  (void)(i); // Unused in release build.
+  DenseSet<PHINode *> TrivialPHIs;
+  for (CHRScope *Scope : CHRScopes) {
+    transformScopes(Scope, TrivialPHIs);
+    CHR_DEBUG(
+        std::ostringstream oss;
+        oss << " after transformScopes " << i++;
+        dumpIR(F, oss.str().c_str(), nullptr));
+  }
+}
+
+static void dumpScopes(SmallVectorImpl<CHRScope *> &Scopes, const char * Label) {
+  dbgs() << Label << " " << Scopes.size() << "\n";
+  for (CHRScope *Scope : Scopes) {
+    dbgs() << *Scope << "\n";
+  }
+}
+
+bool CHR::run() {
+  if (!shouldApply(F, PSI))
+    return false;
+
+  CHR_DEBUG(dumpIR(F, "before", nullptr));
+
+  bool Changed = false;
+  {
+    CHR_DEBUG(
+        dbgs() << "RegionInfo:\n";
+        RI.print(dbgs()));
+
+    // Recursively traverse the region tree and find regions that have biased
+    // branches and/or selects and create scopes.
+    SmallVector<CHRScope *, 8> AllScopes;
+    findScopes(AllScopes);
+    CHR_DEBUG(dumpScopes(AllScopes, "All scopes"));
+
+    // Split the scopes if 1) the conditiona values of the biased
+    // branches/selects of the inner/lower scope can't be hoisted up to the
+    // outermost/uppermost scope entry, or 2) the condition values of the biased
+    // branches/selects in a scope (including subscopes) don't share at least
+    // one common value.
+    SmallVector<CHRScope *, 8> SplitScopes;
+    splitScopes(AllScopes, SplitScopes);
+    CHR_DEBUG(dumpScopes(SplitScopes, "Split scopes"));
+
+    // After splitting, set the biased regions and selects of a scope (a tree
+    // root) that include those of the subscopes.
+    setPerScopeBias(SplitScopes);
+    CHR_DEBUG(dbgs() << "Set per-scope bias " << SplitScopes.size() << "\n");
+
+    // Filter out the scopes that has only one biased region or select (CHR
+    // isn't useful in such a case).
+    SmallVector<CHRScope *, 8> FilteredScopes;
+    filterScopes(SplitScopes, FilteredScopes);
+    CHR_DEBUG(dumpScopes(FilteredScopes, "Filtered scopes"));
+
+    // Set the regions to be CHR'ed and their hoist stops for each scope.
+    SmallVector<CHRScope *, 8> SetScopes;
+    setCHRRegions(FilteredScopes, SetScopes);
+    CHR_DEBUG(dumpScopes(SetScopes, "Set CHR regions"));
+
+    // Sort CHRScopes by the depth so that outer CHRScopes comes before inner
+    // ones. We need to apply CHR from outer to inner so that we apply CHR only
+    // to the hot path, rather than both hot and cold paths.
+    SmallVector<CHRScope *, 8> SortedScopes;
+    sortScopes(SetScopes, SortedScopes);
+    CHR_DEBUG(dumpScopes(SortedScopes, "Sorted scopes"));
+
+    CHR_DEBUG(
+        dbgs() << "RegionInfo:\n";
+        RI.print(dbgs()));
+
+    // Apply the CHR transformation.
+    if (!SortedScopes.empty()) {
+      transformScopes(SortedScopes);
+      Changed = true;
+    }
+  }
+
+  if (Changed)
+    CHR_DEBUG(dumpIR(F, "after", &Stats));
+
+  return Changed;
+}
+
+bool ControlHeightReductionLegacyPass::runOnFunction(Function &F) {
+  DominatorTree &DT = getAnalysis<DominatorTreeWrapperPass>().getDomTree();
+  ProfileSummaryInfo &PSI =
+      *getAnalysis<ProfileSummaryInfoWrapperPass>().getPSI();
+  RegionInfo &RI = getAnalysis<RegionInfoPass>().getRegionInfo();
+  return CHR(F, DT, PSI, RI).run();
+}
+
+namespace llvm {
+
+ControlHeightReductionPass::ControlHeightReductionPass() {
+  ParseCHRFilterFiles();
+}
+
+PreservedAnalyses ControlHeightReductionPass::run(
+    Function &F,
+    FunctionAnalysisManager &FAM) {
+  auto &DT = FAM.getResult<DominatorTreeAnalysis>(F);
+  auto &MAMProxy = FAM.getResult<ModuleAnalysisManagerFunctionProxy>(F);
+  auto &MAM = MAMProxy.getManager();
+  auto &PSI = *MAM.getCachedResult<ProfileSummaryAnalysis>(*F.getParent());
+  auto &RI = FAM.getResult<RegionInfoAnalysis>(F);
+  bool Changed = CHR(F, DT, PSI, RI).run();
+  if (!Changed)
+    return PreservedAnalyses::all();
+  auto PA = PreservedAnalyses();
+  PA.preserve<GlobalsAA>();
+  return PA;
+}
+
+} // namespace llvm

lib/Transforms/Instrumentation/Instrumentation.cpp

 }
 
 /// initializeInstrumentation - Initialize all passes in the TransformUtils
 /// library.
 void llvm::initializeInstrumentation(PassRegistry &Registry) {
   initializeAddressSanitizerPass(Registry);
   initializeAddressSanitizerModulePass(Registry);
   initializeBoundsCheckingLegacyPassPass(Registry);
+  initializeControlHeightReductionLegacyPassPass(Registry);
   initializeGCOVProfilerLegacyPassPass(Registry);
   initializePGOInstrumentationGenLegacyPassPass(Registry);
   initializePGOInstrumentationUseLegacyPassPass(Registry);
   initializePGOIndirectCallPromotionLegacyPassPass(Registry);
   initializePGOMemOPSizeOptLegacyPassPass(Registry);
   initializeInstrProfilingLegacyPassPass(Registry);
   initializeMemorySanitizerPass(Registry);
   initializeHWAddressSanitizerPass(Registry);

test/Transforms/PGOProfile/chr.ll

+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt < %s -chr -instcombine -simplifycfg -S | FileCheck %s
+; RUN: opt < %s -passes='require<profile-summary>,function(chr,instcombine,simplify-cfg)' -S | FileCheck %s
+
+declare void @foo()
+declare void @bar()
+
+; Simple case.
+; Roughly,
+; t0 = *i
+; if ((t0 & 1) != 0) // Likely true
+;   foo()
+; if ((t0 & 2) != 0) // Likely true
+;   foo()
+; ->
+; t0 = *i
+; if ((t0 & 3) != 0) { // Likely true
+;   foo()
+;   foo()
+; } else {
+;   if ((t0 & 1) != 0)
+;     foo()
+;   if ((t0 & 2) != 0)
+;     foo()
+; }
+define void @test_chr_1(i32* %i) !prof !14 {
+; CHECK-LABEL: @test_chr_1(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[TMP0:%.*]] = load i32, i32* [[I:%.*]], align 4
+; CHECK-NEXT:    [[TMP1:%.*]] = and i32 [[TMP0]], 3
+; CHECK-NEXT:    [[TMP2:%.*]] = icmp eq i32 [[TMP1]], 3
+; CHECK-NEXT:    br i1 [[TMP2]], label [[BB0:%.*]], label [[ENTRY_SPLIT_NONCHR:%.*]], !prof !15
+; CHECK:       bb0:
+; CHECK-NEXT:    call void @foo()
+; CHECK-NEXT:    call void @foo()
+; CHECK-NEXT:    br label [[BB3:%.*]]
+; CHECK:       entry.split.nonchr:
+; CHECK-NEXT:    [[TMP3:%.*]] = and i32 [[TMP0]], 1
+; CHECK-NEXT:    [[TMP4:%.*]] = icmp eq i32 [[TMP3]], 0
+; CHECK-NEXT:    br i1 [[TMP4]], label [[BB1_NONCHR:%.*]], label [[BB0_NONCHR:%.*]], !prof !16
+; CHECK:       bb0.nonchr:
+; CHECK-NEXT:    call void @foo()
+; CHECK-NEXT:    br label [[BB1_NONCHR]]
+; CHECK:       bb1.nonchr:
+; CHECK-NEXT:    [[TMP5:%.*]] = and i32 [[TMP0]], 2
+; CHECK-NEXT:    [[TMP6:%.*]] = icmp eq i32 [[TMP5]], 0
+; CHECK-NEXT:    br i1 [[TMP6]], label [[BB3]], label [[BB2_NONCHR:%.*]], !prof !16
+; CHECK:       bb2.nonchr:
+; CHECK-NEXT:    call void @foo()
+; CHECK-NEXT:    br label [[BB3]]
+; CHECK:       bb3:
+; CHECK-NEXT:    ret void
+;
+entry:
+  %0 = load i32, i32* %i
+  %1 = and i32 %0, 1
+  %2 = icmp eq i32 %1, 0
+  br i1 %2, label %bb1, label %bb0, !prof !15
+
+bb0:
+  call void @foo()
+  br label %bb1
+
+bb1:
+  %3 = and i32 %0, 2
+  %4 = icmp eq i32 %3, 0
+  br i1 %4, label %bb3, label %bb2, !prof !15
+
+bb2:
+  call void @foo()
+  br label %bb3
+
+bb3:
+  ret void
+}
+
+; Simple case with a cold block.
+; Roughly,
+; t0 = *i
+; if ((t0 & 1) != 0) // Likely true
+;   foo()
+; if ((t0 & 2) == 0) // Likely false
+;   bar()
+; if ((t0 & 4) != 0) // Likely true
+;   foo()
+; ->
+; t0 = *i
+; if ((t0 & 7) == 7) { // Likely true
+;   foo()
+;   foo()
+; } else {
+;   if ((t0 & 1) != 0)
+;     foo()
+;   if ((t0 & 2) != 0)
+;     bar()
+;   if ((t0 & 4) != 0)
+;     foo()
+; }
+define void @test_chr_1_1(i32* %i) !prof !14 {
+; CHECK-LABEL: @test_chr_1_1(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[TMP0:%.*]] = load i32, i32* [[I:%.*]], align 4
+; CHECK-NEXT:    [[TMP1:%.*]] = and i32 [[TMP0]], 7
+; CHECK-NEXT:    [[TMP2:%.*]] = icmp eq i32 [[TMP1]], 7
+; CHECK-NEXT:    br i1 [[TMP2]], label [[BB0:%.*]], label [[ENTRY_SPLIT_NONCHR:%.*]], !prof !15
+; CHECK:       bb0:
+; CHECK-NEXT:    call void @foo()
+; CHECK-NEXT:    call void @foo()
+; CHECK-NEXT:    br label [[BB5:%.*]]
+; CHECK:       entry.split.nonchr:
+; CHECK-NEXT:    [[TMP3:%.*]] = and i32 [[TMP0]], 1
+; CHECK-NEXT:    [[TMP4:%.*]] = icmp eq i32 [[TMP3]], 0
+; CHECK-NEXT:    br i1 [[TMP4]], label [[BB1_NONCHR:%.*]], label [[BB0_NONCHR:%.*]], !prof !16
+; CHECK:       bb0.nonchr:
+; CHECK-NEXT:    call void @foo()
+; CHECK-NEXT:    br label [[BB1_NONCHR]]
+; CHECK:       bb1.nonchr:
+; CHECK-NEXT:    [[TMP5:%.*]] = and i32 [[TMP0]], 2
+; CHECK-NEXT:    [[TMP6:%.*]] = icmp eq i32 [[TMP5]], 0
+; CHECK-NEXT:    br i1 [[TMP6]], label [[BB2_NONCHR:%.*]], label [[BB3_NONCHR:%.*]], !prof !16
+; CHECK:       bb2.nonchr:
+; CHECK-NEXT:    call void @bar()
+; CHECK-NEXT:    br label [[BB3_NONCHR]]
+; CHECK:       bb3.nonchr:
+; CHECK-NEXT:    [[TMP7:%.*]] = and i32 [[TMP0]], 4
+; CHECK-NEXT:    [[TMP8:%.*]] = icmp eq i32 [[TMP7]], 0
+; CHECK-NEXT:    br i1 [[TMP8]], label [[BB5]], label [[BB4_NONCHR:%.*]], !prof !16
+; CHECK:       bb4.nonchr:
+; CHECK-NEXT:    call void @foo()
+; CHECK-NEXT:    br label [[BB5]]
+; CHECK:       bb5:
+; CHECK-NEXT:    ret void
+;
+entry:
+  %0 = load i32, i32* %i
+  %1 = and i32 %0, 1
+  %2 = icmp eq i32 %1, 0
+  br i1 %2, label %bb1, label %bb0, !prof !15
+
+bb0:
+  call void @foo()
+  br label %bb1
+
+bb1:
+  %3 = and i32 %0, 2
+  %4 = icmp eq i32 %3, 0
+  br i1 %4, label %bb2, label %bb3, !prof !15
+
+bb2:
+  call void @bar()
+  br label %bb3
+
+bb3:
+  %5 = and i32 %0, 4
+  %6 = icmp eq i32 %5, 0
+  br i1 %6, label %bb5, label %bb4, !prof !15
+
+bb4:
+  call void @foo()
+  br label %bb5
+
+bb5:
+  ret void
+}
+
+; With an aggregate bit check.
+; Roughly,
+; t0 = *i
+; if ((t0 & 255) != 0) // Likely true
+;   if ((t0 & 1) != 0) // Likely true
+;     foo()
+;   if ((t0 & 2) != 0) // Likely true
+;     foo()
+; ->
+; t0 = *i
+; if ((t0 & 3) != 0) { // Likely true
+;   foo()
+;   foo()
+; } else if ((t0 & 255) != 0)
+;   if ((t0 & 1) != 0)
+;     foo()
+;   if ((t0 & 2) != 0)
+;     foo()
+; }
+define void @test_chr_2(i32* %i) !prof !14 {
+; CHECK-LABEL: @test_chr_2(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[TMP0:%.*]] = load i32, i32* [[I:%.*]], align 4
+; CHECK-NEXT:    [[TMP1:%.*]] = and i32 [[TMP0]], 3
+; CHECK-NEXT:    [[TMP2:%.*]] = icmp eq i32 [[TMP1]], 3
+; CHECK-NEXT:    br i1 [[TMP2]], label [[BB1:%.*]], label [[ENTRY_SPLIT_NONCHR:%.*]], !prof !15
+; CHECK:       bb1:
+; CHECK-NEXT:    call void @foo()
+; CHECK-NEXT:    call void @foo()
+; CHECK-NEXT:    br label [[BB4:%.*]]
+; CHECK:       entry.split.nonchr:
+; CHECK-NEXT:    [[TMP3:%.*]] = and i32 [[TMP0]], 255
+; CHECK-NEXT:    [[TMP4:%.*]] = icmp eq i32 [[TMP3]], 0
+; CHECK-NEXT:    br i1 [[TMP4]], label [[BB4]], label [[BB0_NONCHR:%.*]], !prof !16
+; CHECK:       bb0.nonchr:
+; CHECK-NEXT:    [[TMP5:%.*]] = and i32 [[TMP0]], 1
+; CHECK-NEXT:    [[TMP6:%.*]] = icmp eq i32 [[TMP5]], 0
+; CHECK-NEXT:    br i1 [[TMP6]], label [[BB2_NONCHR:%.*]], label [[BB1_NONCHR:%.*]], !prof !16
+; CHECK:       bb2.nonchr:
+; CHECK-NEXT:    [[TMP7:%.*]] = and i32 [[TMP0]], 2
+; CHECK-NEXT:    [[TMP8:%.*]] = icmp eq i32 [[TMP7]], 0
+; CHECK-NEXT:    br i1 [[TMP8]], label [[BB4]], label [[BB3_NONCHR:%.*]], !prof !16
+; CHECK:       bb3.nonchr:
+; CHECK-NEXT:    call void @foo()
+; CHECK-NEXT:    br label [[BB4]]
+; CHECK:       bb1.nonchr:
+; CHECK-NEXT:    call void @foo()
+; CHECK-NEXT:    br label [[BB2_NONCHR]]
+; CHECK:       bb4:
+; CHECK-NEXT:    ret void
+;
+entry:
+  %0 = load i32, i32* %i
+  %1 = and i32 %0, 255
+  %2 = icmp eq i32 %1, 0
+  br i1 %2, label %bb4, label %bb0, !prof !15
+
+bb0:
+  %3 = and i32 %0, 1
+  %4 = icmp eq i32 %3, 0
+  br i1 %4, label %bb2, label %bb1, !prof !15
+
+bb1:
+  call void @foo()
+  br label %bb2
+
+bb2:
+  %5 = and i32 %0, 2
+  %6 = icmp eq i32 %5, 0
+  br i1 %6, label %bb4, label %bb3, !prof !15
+
+bb3:
+  call void @foo()
+  br label %bb4
+
+bb4:
+  ret void
+}
+
+; Split case.
+; Roughly,
+; t1 = *i
+; if ((t1 & 1) != 0) // Likely true
+;   foo()
+; if ((t1 & 2) != 0) // Likely true
+;   foo()
+; t2 = *i
+; if ((t2 & 4) != 0) // Likely true
+;   foo()
+; if ((t2 & 8) != 0) // Likely true
+;   foo()
+; ->
+; t1 = *i
+; if ((t1 & 3) != 0) { // Likely true
+;   foo()
+;   foo()
+; } else {
+;   if ((t1 & 1) != 0)
+;     foo()
+;   if ((t1 & 2) != 0)
+;     foo()
+; }
+; t2 = *i
+; if ((t2 & 12) != 0) { // Likely true
+;   foo()
+;   foo()
+; } else {
+;   if ((t2 & 4) != 0)
+;     foo()
+;   if ((t2 & 8) != 0)
+;     foo()
+; }
+define void @test_chr_3(i32* %i) !prof !14 {
+; CHECK-LABEL: @test_chr_3(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[TMP0:%.*]] = load i32, i32* [[I:%.*]], align 4
+; CHECK-NEXT:    [[TMP1:%.*]] = and i32 [[TMP0]], 3
+; CHECK-NEXT:    [[TMP2:%.*]] = icmp eq i32 [[TMP1]], 3
+; CHECK-NEXT:    br i1 [[TMP2]], label [[BB0:%.*]], label [[ENTRY_SPLIT_NONCHR:%.*]], !prof !15
+; CHECK:       bb0:
+; CHECK-NEXT:    call void @foo()
+; CHECK-NEXT:    call void @foo()
+; CHECK-NEXT:    br label [[BB3:%.*]]
+; CHECK:       entry.split.nonchr:
+; CHECK-NEXT:    [[TMP3:%.*]] = and i32 [[TMP0]], 1
+; CHECK-NEXT:    [[TMP4:%.*]] = icmp eq i32 [[TMP3]], 0
+; CHECK-NEXT:    br i1 [[TMP4]], label [[BB1_NONCHR:%.*]], label [[BB0_NONCHR:%.*]], !prof !16
+; CHECK:       bb0.nonchr:
+; CHECK-NEXT:    call void @foo()
+; CHECK-NEXT:    br label [[BB1_NONCHR]]
+; CHECK:       bb1.nonchr:
+; CHECK-NEXT:    [[TMP5:%.*]] = and i32 [[TMP0]], 2
+; CHECK-NEXT:    [[TMP6:%.*]] = icmp eq i32 [[TMP5]], 0
+; CHECK-NEXT:    br i1 [[TMP6]], label [[BB3]], label [[BB2_NONCHR:%.*]], !prof !16
+; CHECK:       bb2.nonchr:
+; CHECK-NEXT:    call void @foo()
+; CHECK-NEXT:    br label [[BB3]]
+; CHECK:       bb3:
+; CHECK-NEXT:    [[TMP7:%.*]] = load i32, i32* [[I]], align 4
+; CHECK-NEXT:    [[TMP8:%.*]] = and i32 [[TMP7]], 12
+; CHECK-NEXT:    [[TMP9:%.*]] = icmp eq i32 [[TMP8]], 12
+; CHECK-NEXT:    br i1 [[TMP9]], label [[BB4:%.*]], label [[BB3_SPLIT_NONCHR:%.*]], !prof !15
+; CHECK:       bb4:
+; CHECK-NEXT:    call void @foo()
+; CHECK-NEXT:    call void @foo()
+; CHECK-NEXT:    br label [[BB7:%.*]]
+; CHECK:       bb3.split.nonchr:
+; CHECK-NEXT:    [[TMP10:%.*]] = and i32 [[TMP7]], 4
+; CHECK-NEXT:    [[TMP11:%.*]] = icmp eq i32 [[TMP10]], 0
+; CHECK-NEXT:    br i1 [[TMP11]], label [[BB5_NONCHR:%.*]], label [[BB4_NONCHR:%.*]], !prof !16
+; CHECK:       bb4.nonchr:
+; CHECK-NEXT:    call void @foo()
+; CHECK-NEXT:    br label [[BB5_NONCHR]]
+; CHECK:       bb5.nonchr:
+; CHECK-NEXT:    [[TMP12:%.*]] = and i32 [[TMP7]], 8
+; CHECK-NEXT:    [[TMP13:%.*]] = icmp eq i32 [[TMP12]], 0
+; CHECK-NEXT:    br i1 [[TMP13]], label [[BB7]], label [[BB6_NONCHR:%.*]], !prof !16
+; CHECK:       bb6.nonchr:
+; CHECK-NEXT:    call void @foo()
+; CHECK-NEXT:    br label [[BB7]]
+; CHECK:       bb7:
+; CHECK-NEXT:    ret void
+;
+entry:
+  %0 = load i32, i32* %i
+  %1 = and i32 %0, 1
+  %2 = icmp eq i32 %1, 0
+  br i1 %2, label %bb1, label %bb0, !prof !15
+
+bb0:
+  call void @foo()
+  br label %bb1
+
+bb1:
+  %3 = and i32 %0, 2
+  %4 = icmp eq i32 %3, 0
+  br i1 %4, label %bb3, label %bb2, !prof !15
+
+bb2:
+  call void @foo()
+  br label %bb3
+
+bb3:
+  %5 = load i32, i32* %i
+  %6 = and i32 %5, 4
+  %7 = icmp eq i32 %6, 0
+  br i1 %7, label %bb5, label %bb4, !prof !15
+
+bb4:
+  call void @foo()
+  br label %bb5
+
+bb5:
+  %8 = and i32 %5, 8
+  %9 = icmp eq i32 %8, 0
+  br i1 %9, label %bb7, label %bb6, !prof !15
+
+bb6:
+  call void @foo()
+  br label %bb7
+
+bb7:
+  ret void
+}
+
+; Selects.
+; Roughly,
+; t0 = *i
+; sum1 = (t0 & 1) ? sum0 : (sum0 + 42) // Likely false
+; sum2 = (t0 & 2) ? sum1 : (sum1 + 43) // Likely false
+; return sum2
+; ->
+; t0 = *i
+; if ((t0 & 3) == 3)
+;   return sum0 + 85
+; else {
+;   sum1 = (t0 & 1) ? sum0 : (sum0 + 42)
+;   sum2 = (t0 & 2) ? sum1 : (sum1 + 43)
+;   return sum2
+; }
+define i32 @test_chr_4(i32* %i, i32 %sum0) !prof !14 {
+; CHECK-LABEL: @test_chr_4(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[TMP0:%.*]] = load i32, i32* [[I:%.*]], align 4
+; CHECK-NEXT:    [[TMP1:%.*]] = and i32 [[TMP0]], 3
+; CHECK-NEXT:    [[TMP2:%.*]] = icmp eq i32 [[TMP1]], 3
+; CHECK-NEXT:    br i1 [[TMP2]], label [[ENTRY_SPLIT:%.*]], label [[ENTRY_SPLIT_NONCHR:%.*]], !prof !15
+; CHECK:       entry.split:
+; CHECK-NEXT:    [[TMP3:%.*]] = add i32 [[SUM0:%.*]], 85
+; CHECK-NEXT:    ret i32 [[TMP3]]
+; CHECK:       entry.split.nonchr:
+; CHECK-NEXT:    [[TMP4:%.*]] = add i32 [[SUM0]], 42
+; CHECK-NEXT:    [[TMP5:%.*]] = and i32 [[TMP0]], 1
+; CHECK-NEXT:    [[TMP6:%.*]] = icmp eq i32 [[TMP5]], 0
+; CHECK-NEXT:    [[SUM1_NONCHR:%.*]] = select i1 [[TMP6]], i32 [[SUM0]], i32 [[TMP4]], !prof !16
+; CHECK-NEXT:    [[TMP7:%.*]] = and i32 [[TMP0]], 2
+; CHECK-NEXT:    [[TMP8:%.*]] = icmp eq i32 [[TMP7]], 0
+; CHECK-NEXT:    [[TMP9:%.*]] = add i32 [[SUM1_NONCHR]], 43
+; CHECK-NEXT:    [[SUM2_NONCHR:%.*]] = select i1 [[TMP8]], i32 [[SUM1_NONCHR]], i32 [[TMP9]], !prof !16
+; CHECK-NEXT:    ret i32 [[SUM2_NONCHR]]
+;
+entry:
+  %0 = load i32, i32* %i
+  %1 = and i32 %0, 1
+  %2 = icmp eq i32 %1, 0
+  %3 = add i32 %sum0, 42
+  %sum1 = select i1 %2, i32 %sum0, i32 %3, !prof !15
+  %4 = and i32 %0, 2
+  %5 = icmp eq i32 %4, 0
+  %6 = add i32 %sum1, 43
+  %sum2 = select i1 %5, i32 %sum1, i32 %6, !prof !15
+  ret i32 %sum2
+}
+
+; Selects + Brs
+; Roughly,
+; t0 = *i
+; if ((t0 & 255) != 0) { // Likely true
+;   sum = (t0 & 1) ? sum0 : (sum0 + 42) // Likely false
+;   sum = (t0 & 2) ? sum : (sum + 43) // Likely false
+;   if ((t0 & 4) != 0) { // Likely true
+;     sum3 = sum + 44
+;     sum = (t0 & 8) ? sum3 : (sum3 + 44) // Likely false
+;   }
+; }
+; return sum
+; ->
+; t0 = *i
+; if ((t0 & 15) != 15) { // Likely true
+;   sum = sum0 + 173
+; } else if ((t0 & 255) != 0) {
+;   sum = (t0 & 1) ? sum0 : (sum0 + 42)
+;   sum = (t0 & 2) ? sum : (sum + 43)
+;   if ((t0 & 4) != 0) {
+;     sum3 = sum + 44
+;     sum = (t0 & 8) ? sum3 : (sum3 + 44)
+;   }
+; }
+; return sum
+define i32 @test_chr_5(i32* %i, i32 %sum0) !prof !14 {
+; CHECK-LABEL: @test_chr_5(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[TMP0:%.*]] = load i32, i32* [[I:%.*]], align 4
+; CHECK-NEXT:    [[TMP1:%.*]] = and i32 [[TMP0]], 15
+; CHECK-NEXT:    [[TMP2:%.*]] = icmp eq i32 [[TMP1]], 15
+; CHECK-NEXT:    br i1 [[TMP2]], label [[BB0:%.*]], label [[ENTRY_SPLIT_NONCHR:%.*]], !prof !15
+; CHECK:       bb0:
+; CHECK-NEXT:    [[TMP3:%.*]] = add i32 [[SUM0:%.*]], 85
+; CHECK-NEXT:    [[TMP4:%.*]] = add i32 [[SUM0]], 173
+; CHECK-NEXT:    br label [[BB3:%.*]]
+; CHECK:       entry.split.nonchr:
+; CHECK-NEXT:    [[TMP5:%.*]] = and i32 [[TMP0]], 255
+; CHECK-NEXT:    [[TMP6:%.*]] = icmp eq i32 [[TMP5]], 0
+; CHECK-NEXT:    br i1 [[TMP6]], label [[BB3]], label [[BB0_NONCHR:%.*]], !prof !16
+; CHECK:       bb0.nonchr:
+; CHECK-NEXT:    [[TMP7:%.*]] = and i32 [[TMP0]], 1
+; CHECK-NEXT:    [[TMP8:%.*]] = icmp eq i32 [[TMP7]], 0
+; CHECK-NEXT:    [[TMP9:%.*]] = add i32 [[SUM0]], 42
+; CHECK-NEXT:    [[SUM1_NONCHR:%.*]] = select i1 [[TMP8]], i32 [[SUM0]], i32 [[TMP9]], !prof !16
+; CHECK-NEXT:    [[TMP10:%.*]] = and i32 [[TMP0]], 2
+; CHECK-NEXT:    [[TMP11:%.*]] = icmp eq i32 [[TMP10]], 0
+; CHECK-NEXT:    [[TMP12:%.*]] = add i32 [[SUM1_NONCHR]], 43
+; CHECK-NEXT:    [[SUM2_NONCHR:%.*]] = select i1 [[TMP11]], i32 [[SUM1_NONCHR]], i32 [[TMP12]], !prof !16
+; CHECK-NEXT:    [[TMP13:%.*]] = and i32 [[TMP0]], 4
+; CHECK-NEXT:    [[TMP14:%.*]] = icmp eq i32 [[TMP13]], 0
+; CHECK-NEXT:    br i1 [[TMP14]], label [[BB3]], label [[BB1_NONCHR:%.*]], !prof !16
+; CHECK:       bb1.nonchr:
+; CHECK-NEXT:    [[TMP15:%.*]] = and i32 [[TMP0]], 8
+; CHECK-NEXT:    [[TMP16:%.*]] = icmp eq i32 [[TMP15]], 0
+; CHECK-NEXT:    [[SUM4_NONCHR_V:%.*]] = select i1 [[TMP16]], i32 44, i32 88, !prof !16
+; CHECK-NEXT:    [[SUM4_NONCHR:%.*]] = add i32 [[SUM2_NONCHR]], [[SUM4_NONCHR_V]]
+; CHECK-NEXT:    br label [[BB3]]
+; CHECK:       bb3:
+; CHECK-NEXT:    [[SUM6:%.*]] = phi i32 [ [[TMP4]], [[BB0]] ], [ [[SUM0]], [[ENTRY_SPLIT_NONCHR]] ], [ [[SUM2_NONCHR]], [[BB0_NONCHR]] ], [ [[SUM4_NONCHR]], [[BB1_NONCHR]] ]
+; CHECK-NEXT:    ret i32 [[SUM6]]
+;
+entry:
+  %0 = load i32, i32* %i
+  %1 = and i32 %0, 255
+  %2 = icmp eq i32 %1, 0
+  br i1 %2, label %bb3, label %bb0, !prof !15
+
+bb0:
+  %3 = and i32 %0, 1
+  %4 = icmp eq i32 %3, 0
+  %5 = add i32 %sum0, 42
+  %sum1 = select i1 %4, i32 %sum0, i32 %5, !prof !15
+  %6 = and i32 %0, 2
+  %7 = icmp eq i32 %6, 0
+  %8 = add i32 %sum1, 43
+  %sum2 = select i1 %7, i32 %sum1, i32 %8, !prof !15
+  %9 = and i32 %0, 4
+  %10 = icmp eq i32 %9, 0
+  br i1 %10, label %bb2, label %bb1, !prof !15
+
+bb1:
+  %sum3 = add i32 %sum2, 44
+  %11 = and i32 %0, 8
+  %12 = icmp eq i32 %11, 0
+  %13 = add i32 %sum3, 44
+  %sum4 = select i1 %12, i32 %sum3, i32 %13, !prof !15
+  br label %bb2
+
+bb2:
+  %sum5 = phi i32 [ %sum2, %bb0 ], [ %sum4, %bb1 ]
+  br label %bb3
+
+bb3:
+  %sum6 = phi i32 [ %sum0, %entry ], [ %sum5, %bb2 ]
+  ret i32 %sum6
+}
+
+; Selects + Brs with a scope split in the middle
+; Roughly,
+; t0 = *i
+; if ((t0 & 255) != 0) { // Likely true
+;   sum = (t0 & 1) ? sum0 : (sum0 + 42) // Likely false
+;   sum = (t0 & 2) ? sum : (sum + 43) // Likely false
+;   if ((sum0 & 4) != 0) { // Likely true. The condition doesn't use v.
+;     sum3 = sum + 44
+;     sum = (t0 & 8) ? sum3 : (sum3 + 44) // Likely false
+;   }
+; }
+; return sum
+; ->
+; t0 = *i
+; if ((sum0 & 4) != 0 && (t0 & 11) != 11) { // Likely true
+;   sum = sum0 + 173
+; } else if ((t0 & 255) != 0) {
+;   sum = (t0 & 1) ? sum0 : (sum0 + 42)
+;   sum = (t0 & 2) ? sum : (sum + 43)
+;   if ((sum0 & 4) != 0) {
+;     sum3 = sum + 44
+;     sum = (t0 & 8) ? sum3 : (sum3 + 44)
+;   }
+; }
+; return sum
+define i32 @test_chr_5_1(i32* %i, i32 %sum0) !prof !14 {
+; CHECK-LABEL: @test_chr_5_1(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[TMP0:%.*]] = load i32, i32* [[I:%.*]], align 4
+; CHECK-NEXT:    [[TMP1:%.*]] = and i32 [[SUM0:%.*]], 4
+; CHECK-NEXT:    [[TMP2:%.*]] = icmp ne i32 [[TMP1]], 0
+; CHECK-NEXT:    [[TMP3:%.*]] = and i32 [[TMP0]], 11
+; CHECK-NEXT:    [[TMP4:%.*]] = icmp eq i32 [[TMP3]], 11
+; CHECK-NEXT:    [[TMP5:%.*]] = and i1 [[TMP4]], [[TMP2]]
+; CHECK-NEXT:    br i1 [[TMP5]], label [[BB0:%.*]], label [[ENTRY_SPLIT_NONCHR:%.*]], !prof !15
+; CHECK:       bb0:
+; CHECK-NEXT:    [[TMP6:%.*]] = add i32 [[SUM0]], 85
+; CHECK-NEXT:    [[TMP7:%.*]] = add i32 [[SUM0]], 173
+; CHECK-NEXT:    br label [[BB3:%.*]]
+; CHECK:       entry.split.nonchr:
+; CHECK-NEXT:    [[TMP8:%.*]] = and i32 [[TMP0]], 255
+; CHECK-NEXT:    [[TMP9:%.*]] = icmp eq i32 [[TMP8]], 0
+; CHECK-NEXT:    br i1 [[TMP9]], label [[BB3]], label [[BB0_NONCHR:%.*]], !prof !16
+; CHECK:       bb0.nonchr:
+; CHECK-NEXT:    [[TMP10:%.*]] = and i32 [[TMP0]], 1
+; CHECK-NEXT:    [[TMP11:%.*]] = icmp eq i32 [[TMP10]], 0
+; CHECK-NEXT:    [[TMP12:%.*]] = add i32 [[SUM0]], 42
+; CHECK-NEXT:    [[SUM1_NONCHR:%.*]] = select i1 [[TMP11]], i32 [[SUM0]], i32 [[TMP12]], !prof !16
+; CHECK-NEXT:    [[TMP13:%.*]] = and i32 [[TMP0]], 2
+; CHECK-NEXT:    [[TMP14:%.*]] = icmp eq i32 [[TMP13]], 0
+; CHECK-NEXT:    [[TMP15:%.*]] = add i32 [[SUM1_NONCHR]], 43
+; CHECK-NEXT:    [[SUM2_NONCHR:%.*]] = select i1 [[TMP14]], i32 [[SUM1_NONCHR]], i32 [[TMP15]], !prof !16
+; CHECK-NEXT:    [[TMP16:%.*]] = and i32 [[SUM0]], 4
+; CHECK-NEXT:    [[TMP17:%.*]] = icmp eq i32 [[TMP16]], 0
+; CHECK-NEXT:    br i1 [[TMP17]], label [[BB3]], label [[BB1_NONCHR:%.*]], !prof !16
+; CHECK:       bb1.nonchr:
+; CHECK-NEXT:    [[TMP18:%.*]] = and i32 [[TMP0]], 8
+; CHECK-NEXT:    [[TMP19:%.*]] = icmp eq i32 [[TMP18]], 0
+; CHECK-NEXT:    [[SUM4_NONCHR_V:%.*]] = select i1 [[TMP19]], i32 44, i32 88, !prof !16
+; CHECK-NEXT:    [[SUM4_NONCHR:%.*]] = add i32 [[SUM2_NONCHR]], [[SUM4_NONCHR_V]]
+; CHECK-NEXT:    br label [[BB3]]
+; CHECK:       bb3:
+; CHECK-NEXT:    [[SUM6:%.*]] = phi i32 [ [[TMP7]], [[BB0]] ], [ [[SUM0]], [[ENTRY_SPLIT_NONCHR]] ], [ [[SUM2_NONCHR]], [[BB0_NONCHR]] ], [ [[SUM4_NONCHR]], [[BB1_NONCHR]] ]
+; CHECK-NEXT:    ret i32 [[SUM6]]
+;
+entry:
+  %0 = load i32, i32* %i
+  %1 = and i32 %0, 255
+  %2 = icmp eq i32 %1, 0
+  br i1 %2, label %bb3, label %bb0, !prof !15
+
+bb0:
+  %3 = and i32 %0, 1
+  %4 = icmp eq i32 %3, 0
+  %5 = add i32 %sum0, 42
+  %sum1 = select i1 %4, i32 %sum0, i32 %5, !prof !15
+  %6 = and i32 %0, 2
+  %7 = icmp eq i32 %6, 0
+  %8 = add i32 %sum1, 43
+  %sum2 = select i1 %7, i32 %sum1, i32 %8, !prof !15
+  %9 = and i32 %sum0, 4                              ; Split
+  %10 = icmp eq i32 %9, 0
+  br i1 %10, label %bb2, label %bb1, !prof !15
+
+bb1:
+  %sum3 = add i32 %sum2, 44
+  %11 = and i32 %0, 8
+  %12 = icmp eq i32 %11, 0
+  %13 = add i32 %sum3, 44
+  %sum4 = select i1 %12, i32 %sum3, i32 %13, !prof !15
+  br label %bb2
+
+bb2:
+  %sum5 = phi i32 [ %sum2, %bb0 ], [ %sum4, %bb1 ]
+  br label %bb3
+
+bb3:
+  %sum6 = phi i32 [ %sum0, %entry ], [ %sum5, %bb2 ]
+  ret i32 %sum6
+}
+
+; Selects + Brs, non-matching bases
+; Roughly,
+; i0 = *i
+; j0 = *j
+; if ((i0 & 255) != 0) { // Likely true
+;   sum = (i0 & 2) ? sum0 : (sum0 + 43) // Likely false
+;   if ((j0 & 4) != 0) { // Likely true. The condition uses j0, not i0.
+;     sum3 = sum + 44
+;     sum = (i0 & 8) ? sum3 : (sum3 + 44) // Likely false
+;   }
+; }
+; return sum
+; ->
+; i0 = *i
+; j0 = *j
+; if ((j0 & 4) != 0 && (i0 & 10) != 10) { // Likely true
+;   sum = sum0 + 131
+; } else if ((i0 & 255) != 0) {
+;   sum = (i0 & 2) ? sum0 : (sum0 + 43)
+;   if ((j0 & 4) != 0) {
+;     sum3 = sum + 44
+;     sum = (i0 & 8) ? sum3 : (sum3 + 44)
+;   }
+; }
+; return sum
+define i32 @test_chr_6(i32* %i, i32* %j, i32 %sum0) !prof !14 {
+; CHECK-LABEL: @test_chr_6(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[I0:%.*]] = load i32, i32* [[I:%.*]], align 4
+; CHECK-NEXT:    [[J0:%.*]] = load i32, i32* [[J:%.*]], align 4
+; CHECK-NEXT:    [[V9:%.*]] = and i32 [[J0]], 4
+; CHECK-NEXT:    [[V10:%.*]] = icmp ne i32 [[V9]], 0
+; CHECK-NEXT:    [[TMP0:%.*]] = and i32 [[I0]], 10
+; CHECK-NEXT:    [[TMP1:%.*]] = icmp eq i32 [[TMP0]], 10
+; CHECK-NEXT:    [[TMP2:%.*]] = and i1 [[TMP1]], [[V10]]
+; CHECK-NEXT:    br i1 [[TMP2]], label [[BB0:%.*]], label [[ENTRY_SPLIT_NONCHR:%.*]], !prof !15
+; CHECK:       bb0:
+; CHECK-NEXT:    [[V8:%.*]] = add i32 [[SUM0:%.*]], 43
+; CHECK-NEXT:    [[V13:%.*]] = add i32 [[SUM0]], 131
+; CHECK-NEXT:    br label [[BB3:%.*]]
+; CHECK:       entry.split.nonchr:
+; CHECK-NEXT:    [[V1:%.*]] = and i32 [[I0]], 255
+; CHECK-NEXT:    [[V2:%.*]] = icmp eq i32 [[V1]], 0
+; CHECK-NEXT:    br i1 [[V2]], label [[BB3]], label [[BB0_NONCHR:%.*]], !prof !16
+; CHECK:       bb0.nonchr:
+; CHECK-NEXT:    [[V3_NONCHR:%.*]] = and i32 [[I0]], 2
+; CHECK-NEXT:    [[V4_NONCHR:%.*]] = icmp eq i32 [[V3_NONCHR]], 0
+; CHECK-NEXT:    [[V8_NONCHR:%.*]] = add i32 [[SUM0]], 43
+; CHECK-NEXT:    [[SUM2_NONCHR:%.*]] = select i1 [[V4_NONCHR]], i32 [[SUM0]], i32 [[V8_NONCHR]], !prof !16
+; CHECK-NEXT:    [[V9_NONCHR:%.*]] = and i32 [[J0]], 4
+; CHECK-NEXT:    [[V10_NONCHR:%.*]] = icmp eq i32 [[V9_NONCHR]], 0
+; CHECK-NEXT:    br i1 [[V10_NONCHR]], label [[BB3]], label [[BB1_NONCHR:%.*]], !prof !16
+; CHECK:       bb1.nonchr:
+; CHECK-NEXT:    [[V11_NONCHR:%.*]] = and i32 [[I0]], 8
+; CHECK-NEXT:    [[V12_NONCHR:%.*]] = icmp eq i32 [[V11_NONCHR]], 0
+; CHECK-NEXT:    [[SUM4_NONCHR_V:%.*]] = select i1 [[V12_NONCHR]], i32 44, i32 88, !prof !16
+; CHECK-NEXT:    [[SUM4_NONCHR:%.*]] = add i32 [[SUM2_NONCHR]], [[SUM4_NONCHR_V]]
+; CHECK-NEXT:    br label [[BB3]]
+; CHECK:       bb3:
+; CHECK-NEXT:    [[SUM6:%.*]] = phi i32 [ [[V13]], [[BB0]] ], [ [[SUM0]], [[ENTRY_SPLIT_NONCHR]] ], [ [[SUM2_NONCHR]], [[BB0_NONCHR]] ], [ [[SUM4_NONCHR]], [[BB1_NONCHR]] ]
+; CHECK-NEXT:    ret i32 [[SUM6]]
+;
+entry:
+  %i0 = load i32, i32* %i
+  %j0 = load i32, i32* %j
+  %v1 = and i32 %i0, 255
+  %v2 = icmp eq i32 %v1, 0
+  br i1 %v2, label %bb3, label %bb0, !prof !15
+
+bb0:
+  %v3 = and i32 %i0, 2
+  %v4 = icmp eq i32 %v3, 0
+  %v8 = add i32 %sum0, 43
+  %sum2 = select i1 %v4, i32 %sum0, i32 %v8, !prof !15
+  %v9 = and i32 %j0, 4
+  %v10 = icmp eq i32 %v9, 0
+  br i1 %v10, label %bb2, label %bb1, !prof !15
+
+bb1:
+  %sum3 = add i32 %sum2, 44
+  %v11 = and i32 %i0, 8
+  %v12 = icmp eq i32 %v11, 0
+  %v13 = add i32 %sum3, 44
+  %sum4 = select i1 %v12, i32 %sum3, i32 %v13, !prof !15
+  br label %bb2
+
+bb2:
+  %sum5 = phi i32 [ %sum2, %bb0 ], [ %sum4, %bb1 ]
+  br label %bb3
+
+bb3:
+  %sum6 = phi i32 [ %sum0, %entry ], [ %sum5, %bb2 ]
+  ret i32 %sum6
+}
+
+; Selects + Brs, the branch condition can't be hoisted to be merged with a
+; select. No CHR happens.
+; Roughly,
+; i0 = *i
+; sum = ((i0 & 2) == 0) ? sum0 : (sum0 + 43)  // Likely false
+; foo();
+; j0 = *j
+; if ((j0 & 4) != 0) { // Likely true
+;   foo();
+;   sum = sum + 44
+; }
+; return sum
+; ->
+; (no change)
+define i32 @test_chr_7(i32* %i, i32* %j, i32 %sum0) !prof !14 {
+; CHECK-LABEL: @test_chr_7(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[I0:%.*]] = load i32, i32* [[I:%.*]], align 4
+; CHECK-NEXT:    [[V3:%.*]] = and i32 [[I0]], 2
+; CHECK-NEXT:    [[V4:%.*]] = icmp eq i32 [[V3]], 0
+; CHECK-NEXT:    [[V8:%.*]] = add i32 [[SUM0:%.*]], 43
+; CHECK-NEXT:    [[SUM2:%.*]] = select i1 [[V4]], i32 [[SUM0]], i32 [[V8]], !prof !16
+; CHECK-NEXT:    call void @foo()
+; CHECK-NEXT:    [[J0:%.*]] = load i32, i32* [[J:%.*]], align 4
+; CHECK-NEXT:    [[V9:%.*]] = and i32 [[J0]], 4
+; CHECK-NEXT:    [[V10:%.*]] = icmp eq i32 [[V9]], 0
+; CHECK-NEXT:    br i1 [[V10]], label [[BB2:%.*]], label [[BB1:%.*]], !prof !16
+; CHECK:       bb1:
+; CHECK-NEXT:    call void @foo()
+; CHECK-NEXT:    [[SUM4:%.*]] = add i32 [[SUM2]], 44
+; CHECK-NEXT:    br label [[BB2]]
+; CHECK:       bb2:
+; CHECK-NEXT:    [[SUM5:%.*]] = phi i32 [ [[SUM2]], [[ENTRY:%.*]] ], [ [[SUM4]], [[BB1]] ]
+; CHECK-NEXT:    ret i32 [[SUM5]]
+;
+entry:
+  %i0 = load i32, i32* %i
+  %v3 = and i32 %i0, 2
+  %v4 = icmp eq i32 %v3, 0
+  %v8 = add i32 %sum0, 43
+  %sum2 = select i1 %v4, i32 %sum0, i32 %v8, !prof !15
+  call void @foo()
+  %j0 = load i32, i32* %j
+  %v9 = and i32 %j0, 4
+  %v10 = icmp eq i32 %v9, 0
+  br i1 %v10, label %bb2, label %bb1, !prof !15    ; %v10 can't be hoisted above the above select
+
+bb1:
+  call void @foo()
+  %sum4 = add i32 %sum2, 44
+  br label %bb2
+
+bb2:
+  %sum5 = phi i32 [ %sum2, %entry ], [ %sum4, %bb1 ]
+  ret i32 %sum5
+}
+
+; Selects + Brs, the branch condition can't be hoisted to be merged with the
+; selects. Dropping the select.
+; Roughly,
+; i0 = *i
+; sum = ((i0 & 2) == 0) ? sum0 : (sum0 + 43)  // Likely false
+; foo();
+; j0 = *j
+; if ((j0 & 4) != 0) // Likely true
+;   foo()
+; if ((j0 & 8) != 0) // Likely true
+;   foo()
+; return sum
+; ->
+; i0 = *i
+; sum = ((i0 & 2) == 0) ? sum0 : (sum0 + 43)  // Likely false
+; foo();
+; j0 = *j
+; if ((j0 & 12) != 12) { // Likely true
+;   foo()
+;   foo()
+; } else {
+;   if ((j0 & 4) != 0)
+;     foo()
+;   if ((j0 & 8) != 0)
+;     foo()
+; }
+; return sum
+define i32 @test_chr_7_1(i32* %i, i32* %j, i32 %sum0) !prof !14 {
+; CHECK-LABEL: @test_chr_7_1(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[I0:%.*]] = load i32, i32* [[I:%.*]], align 4
+; CHECK-NEXT:    [[V3:%.*]] = and i32 [[I0]], 2
+; CHECK-NEXT:    [[V4:%.*]] = icmp eq i32 [[V3]], 0
+; CHECK-NEXT:    [[V8:%.*]] = add i32 [[SUM0:%.*]], 43
+; CHECK-NEXT:    [[SUM2:%.*]] = select i1 [[V4]], i32 [[SUM0]], i32 [[V8]], !prof !16
+; CHECK-NEXT:    call void @foo()
+; CHECK-NEXT:    [[J0:%.*]] = load i32, i32* [[J:%.*]], align 4
+; CHECK-NEXT:    [[TMP0:%.*]] = and i32 [[J0]], 12
+; CHECK-NEXT:    [[TMP1:%.*]] = icmp eq i32 [[TMP0]], 12
+; CHECK-NEXT:    br i1 [[TMP1]], label [[BB0:%.*]], label [[ENTRY_SPLIT_NONCHR:%.*]], !prof !15
+; CHECK:       bb0:
+; CHECK-NEXT:    call void @foo()
+; CHECK-NEXT:    call void @foo()
+; CHECK-NEXT:    br label [[BB3:%.*]]
+; CHECK:       entry.split.nonchr:
+; CHECK-NEXT:    [[V9:%.*]] = and i32 [[J0]], 4
+; CHECK-NEXT:    [[V10:%.*]] = icmp eq i32 [[V9]], 0
+; CHECK-NEXT:    br i1 [[V10]], label [[BB1_NONCHR:%.*]], label [[BB0_NONCHR:%.*]], !prof !16
+; CHECK:       bb0.nonchr:
+; CHECK-NEXT:    call void @foo()
+; CHECK-NEXT:    br label [[BB1_NONCHR]]
+; CHECK:       bb1.nonchr:
+; CHECK-NEXT:    [[V11_NONCHR:%.*]] = and i32 [[J0]], 8
+; CHECK-NEXT:    [[V12_NONCHR:%.*]] = icmp eq i32 [[V11_NONCHR]], 0
+; CHECK-NEXT:    br i1 [[V12_NONCHR]], label [[BB3]], label [[BB2_NONCHR:%.*]], !prof !16
+; CHECK:       bb2.nonchr:
+; CHECK-NEXT:    call void @foo()
+; CHECK-NEXT:    br label [[BB3]]
+; CHECK:       bb3:
+; CHECK-NEXT:    ret i32 [[SUM2]]
+;
+entry:
+  %i0 = load i32, i32* %i
+  %v3 = and i32 %i0, 2
+  %v4 = icmp eq i32 %v3, 0
+  %v8 = add i32 %sum0, 43
+  %sum2 = select i1 %v4, i32 %sum0, i32 %v8, !prof !15
+  call void @foo()
+  %j0 = load i32, i32* %j
+  %v9 = and i32 %j0, 4
+  %v10 = icmp eq i32 %v9, 0
+  br i1 %v10, label %bb1, label %bb0, !prof !15    ; %v10 can't be hoisted above the above select
+
+bb0:
+  call void @foo()
+  br label %bb1
+
+bb1:
+  %v11 = and i32 %j0, 8
+  %v12 = icmp eq i32 %v11, 0
+  br i1 %v12, label %bb3, label %bb2, !prof !15
+
+bb2:
+  call void @foo()
+  br label %bb3
+
+bb3:
+  ret i32 %sum2
+}
+
+; Branches aren't biased enough. No CHR happens.
+; Roughly,
+; t0 = *i
+; if ((t0 & 1) != 0) // Not biased
+;   foo()
+; if ((t0 & 2) != 0) // Not biased
+;   foo()
+; ->
+; (no change)
+define void @test_chr_8(i32* %i) !prof !14 {
+; CHECK-LABEL: @test_chr_8(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[TMP0:%.*]] = load i32, i32* [[I:%.*]], align 4
+; CHECK-NEXT:    [[TMP1:%.*]] = and i32 [[TMP0]], 1
+; CHECK-NEXT:    [[TMP2:%.*]] = icmp eq i32 [[TMP1]], 0
+; CHECK-NEXT:    br i1 [[TMP2]], label [[BB1:%.*]], label [[BB0:%.*]], !prof !17
+; CHECK:       bb0:
+; CHECK-NEXT:    call void @foo()
+; CHECK-NEXT:    br label [[BB1]]
+; CHECK:       bb1:
+; CHECK-NEXT:    [[TMP3:%.*]] = and i32 [[TMP0]], 2
+; CHECK-NEXT:    [[TMP4:%.*]] = icmp eq i32 [[TMP3]], 0
+; CHECK-NEXT:    br i1 [[TMP4]], label [[BB3:%.*]], label [[BB2:%.*]], !prof !17
+; CHECK:       bb2:
+; CHECK-NEXT:    call void @foo()
+; CHECK-NEXT:    br label [[BB3]]
+; CHECK:       bb3:
+; CHECK-NEXT:    ret void
+;
+entry:
+  %0 = load i32, i32* %i
+  %1 = and i32 %0, 1
+  %2 = icmp eq i32 %1, 0
+  br i1 %2, label %bb1, label %bb0, !prof !16
+
+bb0:
+  call void @foo()
+  br label %bb1
+
+bb1:
+  %3 = and i32 %0, 2
+  %4 = icmp eq i32 %3, 0
+  br i1 %4, label %bb3, label %bb2, !prof !16
+
+bb2:
+  call void @foo()
+  br label %bb3
+
+bb3:
+  ret void
+}
+
+; With an existing phi at the exit.
+; Roughly,
+; t = *i
+; if ((t0 & 1) != 0) // Likely true
+;   foo()
+; if ((t0 & 2) != 0) { // Likely true
+;   t = *j
+;   foo()
+; }
+; // There's a phi for t here.
+; return t
+; ->
+; t = *i
+; if ((t & 3) == 3) { // Likely true
+;   foo()
+;   t = *j
+;   foo()
+; } else {
+;   if ((t & 1) != 0)
+;     foo()
+;   if ((t & 2) != 0) {
+;     t = *j
+;     foo()
+;   }
+; }
+; // There's a phi for t here.
+; return t
+define i32 @test_chr_9(i32* %i, i32* %j) !prof !14 {
+; CHECK-LABEL: @test_chr_9(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[TMP0:%.*]] = load i32, i32* [[I:%.*]], align 4
+; CHECK-NEXT:    [[TMP1:%.*]] = and i32 [[TMP0]], 3
+; CHECK-NEXT:    [[TMP2:%.*]] = icmp eq i32 [[TMP1]], 3
+; CHECK-NEXT:    br i1 [[TMP2]], label [[BB0:%.*]], label [[ENTRY_SPLIT_NONCHR:%.*]], !prof !15
+; CHECK:       bb0:
+; CHECK-NEXT:    call void @foo()
+; CHECK-NEXT:    [[TMP3:%.*]] = load i32, i32* [[J:%.*]], align 4
+; CHECK-NEXT:    call void @foo()
+; CHECK-NEXT:    br label [[BB3:%.*]]
+; CHECK:       entry.split.nonchr:
+; CHECK-NEXT:    [[TMP4:%.*]] = and i32 [[TMP0]], 1
+; CHECK-NEXT:    [[TMP5:%.*]] = icmp eq i32 [[TMP4]], 0
+; CHECK-NEXT:    br i1 [[TMP5]], label [[BB1_NONCHR:%.*]], label [[BB0_NONCHR:%.*]], !prof !16
+; CHECK:       bb0.nonchr:
+; CHECK-NEXT:    call void @foo()
+; CHECK-NEXT:    br label [[BB1_NONCHR]]
+; CHECK:       bb1.nonchr:
+; CHECK-NEXT:    [[TMP6:%.*]] = and i32 [[TMP0]], 2
+; CHECK-NEXT:    [[TMP7:%.*]] = icmp eq i32 [[TMP6]], 0
+; CHECK-NEXT:    br i1 [[TMP7]], label [[BB3]], label [[BB2_NONCHR:%.*]], !prof !16
+; CHECK:       bb2.nonchr:
+; CHECK-NEXT:    [[TMP8:%.*]] = load i32, i32* [[J]], align 4
+; CHECK-NEXT:    call void @foo()
+; CHECK-NEXT:    br label [[BB3]]
+; CHECK:       bb3:
+; CHECK-NEXT:    [[TMP9:%.*]] = phi i32 [ [[TMP3]], [[BB0]] ], [ [[TMP0]], [[BB1_NONCHR]] ], [ [[TMP8]], [[BB2_NONCHR]] ]
+; CHECK-NEXT:    ret i32 [[TMP9]]
+;
+entry:
+  %0 = load i32, i32* %i
+  %1 = and i32 %0, 1
+  %2 = icmp eq i32 %1, 0
+  br i1 %2, label %bb1, label %bb0, !prof !15
+
+bb0:
+  call void @foo()
+  br label %bb1
+
+bb1:
+  %3 = and i32 %0, 2
+  %4 = icmp eq i32 %3, 0
+  br i1 %4, label %bb3, label %bb2, !prof !15
+
+bb2:
+  %5 = load i32, i32* %j
+  call void @foo()
+  br label %bb3
+
+bb3:
+  %6 = phi i32 [ %0, %bb1 ], [ %5, %bb2 ]
+  ret i32 %6
+}
+
+; With no phi at the exit, but the exit needs a phi inserted after CHR.
+; Roughly,
+; t0 = *i
+; if ((t0 & 1) != 0) // Likely true
+;   foo()
+; t1 = *j
+; if ((t1 & 2) != 0) // Likely true
+;   foo()
+; return (t1 * 42) - (t1 - 99)
+; ->
+; t0 = *i
+; if ((t0 & 3) == 3) { // Likely true
+;   foo()
+;   t1 = *j
+;   foo()
+; } else {
+;   if ((t0 & 1) != 0)
+;     foo()
+;   if ((t0 & 2) != 0) {
+;     t1 = *j
+;     foo()
+;   }
+; }
+; // A new phi for t1 is inserted here.
+; return (t1 * 42) - (t1 - 99)
+define i32 @test_chr_10(i32* %i, i32* %j) !prof !14 {
+; CHECK-LABEL: @test_chr_10(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[TMP0:%.*]] = load i32, i32* [[I:%.*]], align 4
+; CHECK-NEXT:    [[TMP1:%.*]] = and i32 [[TMP0]], 3
+; CHECK-NEXT:    [[TMP2:%.*]] = icmp eq i32 [[TMP1]], 3
+; CHECK-NEXT:    br i1 [[TMP2]], label [[BB0:%.*]], label [[ENTRY_SPLIT_NONCHR:%.*]], !prof !15
+; CHECK:       bb0:
+; CHECK-NEXT:    call void @foo()
+; CHECK-NEXT:    [[TMP3:%.*]] = load i32, i32* [[J:%.*]], align 4
+; CHECK-NEXT:    call void @foo()
+; CHECK-NEXT:    br label [[BB3:%.*]]
+; CHECK:       entry.split.nonchr:
+; CHECK-NEXT:    [[TMP4:%.*]] = and i32 [[TMP0]], 1
+; CHECK-NEXT:    [[TMP5:%.*]] = icmp eq i32 [[TMP4]], 0
+; CHECK-NEXT:    br i1 [[TMP5]], label [[BB1_NONCHR:%.*]], label [[BB0_NONCHR:%.*]], !prof !16
+; CHECK:       bb0.nonchr:
+; CHECK-NEXT:    call void @foo()
+; CHECK-NEXT:    br label [[BB1_NONCHR]]
+; CHECK:       bb1.nonchr:
+; CHECK-NEXT:    [[TMP6:%.*]] = load i32, i32* [[J]], align 4
+; CHECK-NEXT:    [[TMP7:%.*]] = and i32 [[TMP0]], 2
+; CHECK-NEXT:    [[TMP8:%.*]] = icmp eq i32 [[TMP7]], 0
+; CHECK-NEXT:    br i1 [[TMP8]], label [[BB3]], label [[BB2_NONCHR:%.*]], !prof !16
+; CHECK:       bb2.nonchr:
+; CHECK-NEXT:    call void @foo()
+; CHECK-NEXT:    br label [[BB3]]
+; CHECK:       bb3:
+; CHECK-NEXT:    [[TMP9:%.*]] = phi i32 [ [[TMP3]], [[BB0]] ], [ [[TMP6]], [[BB2_NONCHR]] ], [ [[TMP6]], [[BB1_NONCHR]] ]
+; CHECK-NEXT:    [[TMP10:%.*]] = mul i32 [[TMP9]], 42
+; CHECK-NEXT:    [[TMP11:%.*]] = add i32 [[TMP9]], -99
+; CHECK-NEXT:    [[TMP12:%.*]] = add i32 [[TMP10]], [[TMP11]]
+; CHECK-NEXT:    ret i32 [[TMP12]]
+;
+entry:
+  %0 = load i32, i32* %i
+  %1 = and i32 %0, 1
+  %2 = icmp eq i32 %1, 0
+  br i1 %2, label %bb1, label %bb0, !prof !15
+
+bb0:
+  call void @foo()
+  br label %bb1
+
+bb1:
+  %3 = load i32, i32* %j
+  %4 = and i32 %0, 2
+  %5 = icmp eq i32 %4, 0
+  br i1 %5, label %bb3, label %bb2, !prof !15
+
+bb2:
+  call void @foo()
+  br label %bb3
+
+bb3:
+  %6 = mul i32 %3, 42
+  %7 = sub i32 %3, 99
+  %8 = add i32 %6, %7
+  ret i32 %8
+}
+
+; Hoisting a branch condition value whose dependencies reach the same value in
+; two paths and may cause a bad hoisting that hoists it twice and puts a use
+; ahead of its definition.
+; Roughly,
+; t0 = *i
+; if ((t0 & 1) != 0) // Likely true
+;   foo()
+; // there are two use-def paths from the branch condition to t0.
+; if ((1.0 / t0) * t0 < 1) // Likely true
+;   foo()
+; ->
+; t0 = *i
+; if ((t0 & 1) != 0 && (1.0 / t0) * t0 > 0) { // Likely true
+;   foo()
+;   foo()
+; } else {
+;   if ((t0 & 1) != 0)
+;     foo()
+;   if ((1.0 / t0) * t0 < 1) // Likely true
+;     foo()
+; }
+define void @test_chr_11(i32* %i, i32 %x) !prof !14 {
+; CHECK-LABEL: @test_chr_11(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[TMP0:%.*]] = load i32, i32* [[I:%.*]], align 4
+; CHECK-NEXT:    [[TMP1:%.*]] = and i32 [[TMP0]], 1
+; CHECK-NEXT:    [[TMP2:%.*]] = icmp ne i32 [[TMP1]], 0
+; CHECK-NEXT:    [[CONV:%.*]] = sitofp i32 [[TMP0]] to double
+; CHECK-NEXT:    [[DIV:%.*]] = fdiv double 1.000000e+00, [[CONV]]
+; CHECK-NEXT:    [[MUL16:%.*]] = fmul double [[DIV]], [[CONV]]
+; CHECK-NEXT:    [[CONV717:%.*]] = fptosi double [[MUL16]] to i32
+; CHECK-NEXT:    [[CMP18:%.*]] = icmp sgt i32 [[CONV717]], 0
+; CHECK-NEXT:    [[TMP3:%.*]] = and i1 [[TMP2]], [[CMP18]]
+; CHECK-NEXT:    br i1 [[TMP3]], label [[BB0:%.*]], label [[ENTRY_SPLIT_NONCHR:%.*]], !prof !15
+; CHECK:       bb0:
+; CHECK-NEXT:    call void @foo()
+; CHECK-NEXT:    call void @foo()
+; CHECK-NEXT:    br label [[BB3:%.*]]
+; CHECK:       entry.split.nonchr:
+; CHECK-NEXT:    br i1 [[TMP2]], label [[BB0_NONCHR:%.*]], label [[BB1_NONCHR:%.*]], !prof !18
+; CHECK:       bb0.nonchr:
+; CHECK-NEXT:    call void @foo()
+; CHECK-NEXT:    br label [[BB1_NONCHR]]
+; CHECK:       bb1.nonchr:
+; CHECK-NEXT:    [[CONV_NONCHR:%.*]] = sitofp i32 [[TMP0]] to double
+; CHECK-NEXT:    [[DIV_NONCHR:%.*]] = fdiv double 1.000000e+00, [[CONV_NONCHR]]
+; CHECK-NEXT:    [[MUL16_NONCHR:%.*]] = fmul double [[DIV_NONCHR]], [[CONV_NONCHR]]
+; CHECK-NEXT:    [[CONV717_NONCHR:%.*]] = fptosi double [[MUL16_NONCHR]] to i32
+; CHECK-NEXT:    [[CMP18_NONCHR:%.*]] = icmp slt i32 [[CONV717_NONCHR]], 1
+; CHECK-NEXT:    br i1 [[CMP18_NONCHR]], label [[BB3]], label [[BB2_NONCHR:%.*]], !prof !16
+; CHECK:       bb2.nonchr:
+; CHECK-NEXT:    call void @foo()
+; CHECK-NEXT:    br label [[BB3]]
+; CHECK:       bb3:
+; CHECK-NEXT:    ret void
+;
+entry:
+  %0 = load i32, i32* %i
+  %1 = and i32 %0, 1
+  %2 = icmp eq i32 %1, 0
+  br i1 %2, label %bb1, label %bb0, !prof !15
+
+bb0:
+  call void @foo()
+  br label %bb1
+
+bb1:
+  %conv = sitofp i32 %0 to double
+  %div = fdiv double 1.000000e+00, %conv
+  %mul16 = fmul double %div, %conv
+  %conv717 = fptosi double %mul16 to i32
+  %cmp18 = icmp slt i32 %conv717, 1
+  br i1 %cmp18, label %bb3, label %bb2, !prof !15
+
+bb2:
+  call void @foo()
+  br label %bb3
+
+bb3:
+  ret void
+}
+
+; Selects + unrelated br only
+define i32 @test_chr_12(i32* %i, i32 %sum0) !prof !14 {
+; CHECK-LABEL: @test_chr_12(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[TMP0:%.*]] = load i32, i32* [[I:%.*]], align 4
+; CHECK-NEXT:    [[TMP1:%.*]] = and i32 [[TMP0]], 255
+; CHECK-NEXT:    [[TMP2:%.*]] = icmp eq i32 [[TMP1]], 0
+; CHECK-NEXT:    br i1 [[TMP2]], label [[BB3:%.*]], label [[BB0:%.*]], !prof !16
+; CHECK:       bb0:
+; CHECK-NEXT:    [[TMP3:%.*]] = and i32 [[TMP0]], 1
+; CHECK-NEXT:    [[TMP4:%.*]] = icmp eq i32 [[TMP3]], 0
+; CHECK-NEXT:    [[TMP5:%.*]] = add i32 [[SUM0:%.*]], 42
+; CHECK-NEXT:    [[SUM1:%.*]] = select i1 [[TMP4]], i32 [[SUM0]], i32 [[TMP5]], !prof !16
+; CHECK-NEXT:    [[TMP6:%.*]] = and i32 [[TMP0]], 2
+; CHECK-NEXT:    [[TMP7:%.*]] = icmp eq i32 [[TMP6]], 0
+; CHECK-NEXT:    [[TMP8:%.*]] = add i32 [[SUM1]], 43
+; CHECK-NEXT:    [[SUM2:%.*]] = select i1 [[TMP7]], i32 [[SUM1]], i32 [[TMP8]], !prof !16
+; CHECK-NEXT:    [[TMP9:%.*]] = load i32, i32* [[I]], align 4
+; CHECK-NEXT:    [[TMP10:%.*]] = icmp ne i32 [[TMP9]], 0
+; CHECK-NEXT:    [[TMP11:%.*]] = and i32 [[TMP0]], 8
+; CHECK-NEXT:    [[TMP12:%.*]] = icmp ne i32 [[TMP11]], 0
+; CHECK-NEXT:    [[TMP13:%.*]] = and i1 [[TMP10]], [[TMP12]]
+; CHECK-NEXT:    br i1 [[TMP13]], label [[BB1:%.*]], label [[BB0_SPLIT_NONCHR:%.*]], !prof !15
+; CHECK:       bb1:
+; CHECK-NEXT:    [[TMP14:%.*]] = add i32 [[SUM2]], 88
+; CHECK-NEXT:    br label [[BB3]]
+; CHECK:       bb0.split.nonchr:
+; CHECK-NEXT:    br i1 [[TMP10]], label [[BB1_NONCHR:%.*]], label [[BB3]], !prof !18
+; CHECK:       bb1.nonchr:
+; CHECK-NEXT:    [[TMP15:%.*]] = and i32 [[TMP0]], 8
+; CHECK-NEXT:    [[TMP16:%.*]] = icmp eq i32 [[TMP15]], 0
+; CHECK-NEXT:    [[SUM4_NONCHR_V:%.*]] = select i1 [[TMP16]], i32 44, i32 88, !prof !16
+; CHECK-NEXT:    [[SUM4_NONCHR:%.*]] = add i32 [[SUM2]], [[SUM4_NONCHR_V]]
+; CHECK-NEXT:    br label [[BB3]]
+; CHECK:       bb3:
+; CHECK-NEXT:    [[SUM6:%.*]] = phi i32 [ [[SUM0]], [[ENTRY:%.*]] ], [ [[TMP14]], [[BB1]] ], [ [[SUM2]], [[BB0_SPLIT_NONCHR]] ], [ [[SUM4_NONCHR]], [[BB1_NONCHR]] ]
+; CHECK-NEXT:    ret i32 [[SUM6]]
+;
+entry:
+  %0 = load i32, i32* %i
+  %1 = and i32 %0, 255
+  %2 = icmp eq i32 %1, 0
+  br i1 %2, label %bb3, label %bb0, !prof !15
+
+bb0:
+  %3 = and i32 %0, 1
+  %4 = icmp eq i32 %3, 0
+  %5 = add i32 %sum0, 42
+  %sum1 = select i1 %4, i32 %sum0, i32 %5, !prof !15
+  %6 = and i32 %0, 2
+  %7 = icmp eq i32 %6, 0
+  %8 = add i32 %sum1, 43
+  %sum2 = select i1 %7, i32 %sum1, i32 %8, !prof !15
+  %9 = load i32, i32* %i
+  %10 = icmp eq i32 %9, 0
+  br i1 %10, label %bb2, label %bb1, !prof !15
+
+bb1:
+  %sum3 = add i32 %sum2, 44
+  %11 = and i32 %0, 8
+  %12 = icmp eq i32 %11, 0
+  %13 = add i32 %sum3, 44
+  %sum4 = select i1 %12, i32 %sum3, i32 %13, !prof !15
+  br label %bb2
+
+bb2:
+  %sum5 = phi i32 [ %sum2, %bb0 ], [ %sum4, %bb1 ]
+  br label %bb3
+
+bb3:
+  %sum6 = phi i32 [ %sum0, %entry ], [ %sum5, %bb2 ]
+  ret i32 %sum6
+}
+
+; In the second CHR, a condition value depends on a trivial phi that's inserted
+; by the first CHR.
+; Roughly,
+; i0 = *i
+; v2 = (z != 1) ? pred : true  // Likely false
+; if (z == 0 && pred)  // Likely false
+;   foo()
+; j0 = *j
+; sum2 = ((i0 & 2) == j0) ? sum0 : (sum0 + 43) // Likely false
+; sum3 = ((i0 == j0) ? sum0 : (sum0 + 43) // Likely false
+; foo()
+; if ((i0 & 4) == 0) // Unbiased
+;   foo()
+; return i0 + sum3
+; ->
+; i0 = *i
+; if (z != 1 && (z == 0 && pred)) // First CHR
+;   foo()
+; // A trivial phi for i0 is inserted here by the first CHR (which gets removed
+; // later) and the subsequent branch condition (for the second CHR) uses it.
+; j0 = *j
+; if ((i0 & 2) != j0 && i0 != j0) {  // Second CHR
+;   sum3 = sum0 + 43
+;   foo()
+;   if (i0 & 4) == 0)
+;     foo()
+; } else {
+;   sum3 = (i0 == j0) ? sum0 : (sum0 + 43)
+;   foo()
+;   if (i0 & 4) == 0)
+;     foo()
+; }
+; return i0 + sum3
+define i32 @test_chr_14(i32* %i, i32* %j, i32 %sum0, i1 %pred, i32 %z) !prof !14 {
+; CHECK-LABEL: @test_chr_14(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[I0:%.*]] = load i32, i32* [[I:%.*]], align 4
+; CHECK-NEXT:    [[V1:%.*]] = icmp ne i32 [[Z:%.*]], 1
+; CHECK-NEXT:    [[V0:%.*]] = icmp eq i32 [[Z]], 0
+; CHECK-NEXT:    [[V3_NONCHR:%.*]] = and i1 [[V0]], [[PRED:%.*]]
+; CHECK-NEXT:    [[OR_COND:%.*]] = and i1 [[V1]], [[V3_NONCHR]]
+; CHECK-NEXT:    br i1 [[OR_COND]], label [[BB0_NONCHR:%.*]], label [[BB1:%.*]], !prof !19
+; CHECK:       bb0.nonchr:
+; CHECK-NEXT:    call void @foo()
+; CHECK-NEXT:    br label [[BB1]]
+; CHECK:       bb1:
+; CHECK-NEXT:    [[J0:%.*]] = load i32, i32* [[J:%.*]], align 4
+; CHECK-NEXT:    [[V6:%.*]] = and i32 [[I0]], 2
+; CHECK-NEXT:    [[V4:%.*]] = icmp ne i32 [[V6]], [[J0]]
+; CHECK-NEXT:    [[V8:%.*]] = add i32 [[SUM0:%.*]], 43
+; CHECK-NEXT:    [[V5:%.*]] = icmp ne i32 [[I0]], [[J0]]
+; CHECK-NEXT:    [[TMP0:%.*]] = and i1 [[V4]], [[V5]]
+; CHECK-NEXT:    br i1 [[TMP0]], label [[BB1_SPLIT:%.*]], label [[BB1_SPLIT_NONCHR:%.*]], !prof !15
+; CHECK:       bb1.split:
+; CHECK-NEXT:    call void @foo()
+; CHECK-NEXT:    [[V9:%.*]] = and i32 [[I0]], 4
+; CHECK-NEXT:    [[V10:%.*]] = icmp eq i32 [[V9]], 0
+; CHECK-NEXT:    br i1 [[V10]], label [[BB3:%.*]], label [[BB2:%.*]]
+; CHECK:       bb2:
+; CHECK-NEXT:    call void @foo()
+; CHECK-NEXT:    br label [[BB3]]
+; CHECK:       bb1.split.nonchr:
+; CHECK-NEXT:    [[V5_NONCHR:%.*]] = icmp eq i32 [[I0]], [[J0]]
+; CHECK-NEXT:    [[SUM3_NONCHR:%.*]] = select i1 [[V5_NONCHR]], i32 [[SUM0]], i32 [[V8]], !prof !16
+; CHECK-NEXT:    call void @foo()
+; CHECK-NEXT:    [[V9_NONCHR:%.*]] = and i32 [[I0]], 4
+; CHECK-NEXT:    [[V10_NONCHR:%.*]] = icmp eq i32 [[V9_NONCHR]], 0
+; CHECK-NEXT:    br i1 [[V10_NONCHR]], label [[BB3]], label [[BB2_NONCHR:%.*]]
+; CHECK:       bb2.nonchr:
+; CHECK-NEXT:    call void @foo()
+; CHECK-NEXT:    br label [[BB3]]
+; CHECK:       bb3:
+; CHECK-NEXT:    [[TMP1:%.*]] = phi i32 [ [[V8]], [[BB2]] ], [ [[V8]], [[BB1_SPLIT]] ], [ [[SUM3_NONCHR]], [[BB2_NONCHR]] ], [ [[SUM3_NONCHR]], [[BB1_SPLIT_NONCHR]] ]
+; CHECK-NEXT:    [[V11:%.*]] = add i32 [[I0]], [[TMP1]]
+; CHECK-NEXT:    ret i32 [[V11]]
+;
+entry:
+  %i0 = load i32, i32* %i
+  %v0 = icmp eq i32 %z, 0
+  %v1 = icmp ne i32 %z, 1
+  %v2 = select i1 %v1, i1 %pred, i1 true, !prof !15
+  %v3 = and i1 %v0, %pred
+  br i1 %v3, label %bb0, label %bb1, !prof !15
+
+bb0:
+  call void @foo()
+  br label %bb1
+
+bb1:
+  %j0 = load i32, i32* %j
+  %v6 = and i32 %i0, 2
+  %v4 = icmp eq i32 %v6, %j0
+  %v8 = add i32 %sum0, 43
+  %sum2 = select i1 %v4, i32 %sum0, i32 %v8, !prof !15
+  %v5 = icmp eq i32 %i0, %j0
+  %sum3 = select i1 %v5, i32 %sum0, i32 %v8, !prof !15
+  call void @foo()
+  %v9 = and i32 %i0, 4
+  %v10 = icmp eq i32 %v9, 0
+  br i1 %v10, label %bb3, label %bb2
+
+bb2:
+  call void @foo()
+  br label %bb3
+
+bb3:
+  %v11 = add i32 %i0, %sum3
+  ret i32 %v11
+}
+
+; Branch or selects depends on another select. No CHR happens.
+; Roughly,
+; i0 = *i
+; if (z == 0 && ((z != 1) ? pred : true)) { // Likely false
+;   foo()
+; j0 = *j
+; sum2 = ((i0 & 2) == j0) ? sum0 : (sum0 + 43) // Likely false
+; sum3 = (i0 == sum2) ? sum2 : (sum0 + 43) // Likely false. This depends on the
+;                                          // previous select.
+; foo()
+; if ((i0 & 4) == 0) // Unbiased
+;   foo()
+; return i0 + sum3
+; ->
+; (no change)
+define i32 @test_chr_15(i32* %i, i32* %j, i32 %sum0, i1 %pred, i32 %z) !prof !14 {
+; CHECK-LABEL: @test_chr_15(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[I0:%.*]] = load i32, i32* [[I:%.*]], align 4
+; CHECK-NEXT:    [[V0:%.*]] = icmp eq i32 [[Z:%.*]], 0
+; CHECK-NEXT:    [[V3:%.*]] = and i1 [[V0]], [[PRED:%.*]]
+; CHECK-NEXT:    br i1 [[V3]], label [[BB0:%.*]], label [[BB1:%.*]], !prof !16
+; CHECK:       bb0:
+; CHECK-NEXT:    call void @foo()
+; CHECK-NEXT:    br label [[BB1]]
+; CHECK:       bb1:
+; CHECK-NEXT:    [[J0:%.*]] = load i32, i32* [[J:%.*]], align 4
+; CHECK-NEXT:    [[V6:%.*]] = and i32 [[I0]], 2
+; CHECK-NEXT:    [[V4:%.*]] = icmp eq i32 [[V6]], [[J0]]
+; CHECK-NEXT:    [[V8:%.*]] = add i32 [[SUM0:%.*]], 43
+; CHECK-NEXT:    [[SUM2:%.*]] = select i1 [[V4]], i32 [[SUM0]], i32 [[V8]], !prof !16
+; CHECK-NEXT:    [[V5:%.*]] = icmp eq i32 [[I0]], [[SUM2]]
+; CHECK-NEXT:    [[SUM3:%.*]] = select i1 [[V5]], i32 [[SUM2]], i32 [[V8]], !prof !16
+; CHECK-NEXT:    call void @foo()
+; CHECK-NEXT:    [[V9:%.*]] = and i32 [[I0]], 4
+; CHECK-NEXT:    [[V10:%.*]] = icmp eq i32 [[V9]], 0
+; CHECK-NEXT:    br i1 [[V10]], label [[BB3:%.*]], label [[BB2:%.*]]
+; CHECK:       bb2:
+; CHECK-NEXT:    call void @foo()
+; CHECK-NEXT:    br label [[BB3]]
+; CHECK:       bb3:
+; CHECK-NEXT:    [[V11:%.*]] = add i32 [[I0]], [[SUM3]]
+; CHECK-NEXT:    ret i32 [[V11]]
+;
+entry:
+  %i0 = load i32, i32* %i
+  %v0 = icmp eq i32 %z, 0
+  %v1 = icmp ne i32 %z, 1
+  %v2 = select i1 %v1, i1 %pred, i1 true, !prof !15
+  %v3 = and i1 %v0, %v2
+  br i1 %v3, label %bb0, label %bb1, !prof !15
+
+bb0:
+  call void @foo()
+  br label %bb1
+
+bb1:
+  %j0 = load i32, i32* %j
+  %v6 = and i32 %i0, 2
+  %v4 = icmp eq i32 %v6, %j0
+  %v8 = add i32 %sum0, 43
+  %sum2 = select i1 %v4, i32 %sum0, i32 %v8, !prof !15
+  %v5 = icmp eq i32 %i0, %sum2
+  %sum3 = select i1 %v5, i32 %sum2, i32 %v8, !prof !15
+  call void @foo()
+  %v9 = and i32 %i0, 4
+  %v10 = icmp eq i32 %v9, 0
+  br i1 %v10, label %bb3, label %bb2
+
+bb2:
+  call void @foo()
+  br label %bb3
+
+bb3:
+  %v11 = add i32 %i0, %sum3
+  ret i32 %v11
+}
+
+; With an existing phi at the exit but a value (%v40) is both alive and is an
+; operand to a phi at the exit block.
+; Roughly,
+; t0 = *i
+; if ((t0 & 1) != 0) // Likely true
+;   foo()
+; v40 = t0 + 44
+; if ((t0 & 2) != 0) // Likely true
+;   v41 = t0 + 99
+;   foo()
+; }
+; v42 = phi v40, v41
+; return v42 + v40
+; ->
+; t0 = *i
+; if ((t0 & 3) == 3) // Likely true
+;   foo()
+;   v40 = t0 + 44
+;   v41 = t0 + 99
+;   foo()
+; } else {
+;   if ((t0 & 1) != 0) // Likely true
+;     foo()
+;   v40_nc = t0 + 44
+;   if ((t0 & 2) != 0) // Likely true
+;     v41_nc = t0 + 99
+;     foo()
+;   }
+; }
+; t7 = phi v40, v40_nc
+; v42 = phi v41, v41_nc
+; v43 = v42 + t7
+; return v43
+define i32 @test_chr_16(i32* %i) !prof !14 {
+; CHECK-LABEL: @test_chr_16(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[TMP0:%.*]] = load i32, i32* [[I:%.*]], align 4
+; CHECK-NEXT:    [[TMP1:%.*]] = and i32 [[TMP0]], 3
+; CHECK-NEXT:    [[TMP2:%.*]] = icmp eq i32 [[TMP1]], 3
+; CHECK-NEXT:    br i1 [[TMP2]], label [[BB0:%.*]], label [[ENTRY_SPLIT_NONCHR:%.*]], !prof !15
+; CHECK:       bb0:
+; CHECK-NEXT:    call void @foo()
+; CHECK-NEXT:    [[V40:%.*]] = add i32 [[TMP0]], 44
+; CHECK-NEXT:    [[V41:%.*]] = add i32 [[TMP0]], 99
+; CHECK-NEXT:    call void @foo()
+; CHECK-NEXT:    br label [[BB3:%.*]]
+; CHECK:       entry.split.nonchr:
+; CHECK-NEXT:    [[TMP3:%.*]] = and i32 [[TMP0]], 1
+; CHECK-NEXT:    [[TMP4:%.*]] = icmp eq i32 [[TMP3]], 0
+; CHECK-NEXT:    br i1 [[TMP4]], label [[BB1_NONCHR:%.*]], label [[BB0_NONCHR:%.*]], !prof !16
+; CHECK:       bb0.nonchr:
+; CHECK-NEXT:    call void @foo()
+; CHECK-NEXT:    br label [[BB1_NONCHR]]
+; CHECK:       bb1.nonchr:
+; CHECK-NEXT:    [[V40_NONCHR:%.*]] = add i32 [[TMP0]], 44
+; CHECK-NEXT:    [[TMP5:%.*]] = and i32 [[TMP0]], 2
+; CHECK-NEXT:    [[TMP6:%.*]] = icmp eq i32 [[TMP5]], 0
+; CHECK-NEXT:    br i1 [[TMP6]], label [[BB3]], label [[BB2_NONCHR:%.*]], !prof !16
+; CHECK:       bb2.nonchr:
+; CHECK-NEXT:    [[V41_NONCHR:%.*]] = add i32 [[TMP0]], 99
+; CHECK-NEXT:    call void @foo()
+; CHECK-NEXT:    br label [[BB3]]
+; CHECK:       bb3:
+; CHECK-NEXT:    [[TMP7:%.*]] = phi i32 [ [[V40]], [[BB0]] ], [ [[V40_NONCHR]], [[BB2_NONCHR]] ], [ [[V40_NONCHR]], [[BB1_NONCHR]] ]
+; CHECK-NEXT:    [[V42:%.*]] = phi i32 [ [[V41]], [[BB0]] ], [ [[V41_NONCHR]], [[BB2_NONCHR]] ], [ [[V40_NONCHR]], [[BB1_NONCHR]] ]
+; CHECK-NEXT:    [[V43:%.*]] = add i32 [[V42]], [[TMP7]]
+; CHECK-NEXT:    ret i32 [[V43]]
+;
+entry:
+  %0 = load i32, i32* %i
+  %1 = and i32 %0, 1
+  %2 = icmp eq i32 %1, 0
+  br i1 %2, label %bb1, label %bb0, !prof !15
+
+bb0:
+  call void @foo()
+  br label %bb1
+
+bb1:
+  %v40 = add i32 %0, 44
+  %3 = and i32 %0, 2
+  %4 = icmp eq i32 %3, 0
+  br i1 %4, label %bb3, label %bb2, !prof !15
+
+bb2:
+  %v41 = add i32 %0, 99
+  call void @foo()
+  br label %bb3
+
+bb3:
+  %v42 = phi i32 [ %v41, %bb2 ], [ %v40, %bb1 ]
+  %v43 = add i32 %v42, %v40
+  ret i32 %v43
+}
+
+; Two consecutive regions have an entry in the middle of them. No CHR happens.
+; Roughly,
+; if ((i & 4) == 0) {
+;   if (!j)
+;     goto bb1
+; } else {
+;   t0 = (i & 1)
+;   if (t0 != 0) // Likely true
+;     foo()
+;     s = (i & 1) + i
+;   }
+;  bb1:
+;   p = phi i, t0, s
+;   if ((i & 2) != 0) // Likely true
+;     foo()
+;     q = p + 2
+; }
+; r = phi p, q, i
+; return r
+; ->
+; (no change)
+define i32 @test_chr_17(i32 %i, i1 %j) !prof !14 {
+; CHECK-LABEL: @test_chr_17(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[V0:%.*]] = and i32 [[I:%.*]], 4
+; CHECK-NEXT:    [[V1:%.*]] = icmp eq i32 [[V0]], 0
+; CHECK-NEXT:    br i1 [[V1]], label [[BBE:%.*]], label [[BBQ:%.*]]
+; CHECK:       bbq:
+; CHECK-NEXT:    br i1 [[J:%.*]], label [[BB3:%.*]], label [[BB1:%.*]]
+; CHECK:       bbe:
+; CHECK-NEXT:    [[TMP0:%.*]] = and i32 [[I]], 1
+; CHECK-NEXT:    [[TMP1:%.*]] = icmp eq i32 [[TMP0]], 0
+; CHECK-NEXT:    br i1 [[TMP1]], label [[BB1]], label [[BB0:%.*]], !prof !16
+; CHECK:       bb0:
+; CHECK-NEXT:    call void @foo()
+; CHECK-NEXT:    [[S:%.*]] = add i32 [[TMP0]], [[I]]
+; CHECK-NEXT:    br label [[BB1]]
+; CHECK:       bb1:
+; CHECK-NEXT:    [[P:%.*]] = phi i32 [ [[I]], [[BBQ]] ], [ [[TMP0]], [[BBE]] ], [ [[S]], [[BB0]] ]
+; CHECK-NEXT:    [[TMP2:%.*]] = and i32 [[I]], 2
+; CHECK-NEXT:    [[TMP3:%.*]] = icmp eq i32 [[TMP2]], 0
+; CHECK-NEXT:    br i1 [[TMP3]], label [[BB3]], label [[BB2:%.*]], !prof !16
+; CHECK:       bb2:
+; CHECK-NEXT:    call void @foo()
+; CHECK-NEXT:    [[Q:%.*]] = add i32 [[P]], [[TMP2]]
+; CHECK-NEXT:    br label [[BB3]]
+; CHECK:       bb3:
+; CHECK-NEXT:    [[R:%.*]] = phi i32 [ [[P]], [[BB1]] ], [ [[Q]], [[BB2]] ], [ [[I]], [[BBQ]] ]
+; CHECK-NEXT:    ret i32 [[R]]
+;
+entry:
+  %v0 = and i32 %i, 4
+  %v1 = icmp eq i32 %v0, 0
+  br i1 %v1, label %bbe, label %bbq
+
+bbq:
+  br i1 %j, label %bb3, label %bb1
+
+bbe:
+  %0 = and i32 %i, 1
+  %1 = icmp eq i32 %0, 0
+  br i1 %1, label %bb1, label %bb0, !prof !15
+
+bb0:
+  call void @foo()
+  %s = add i32 %0, %i
+  br label %bb1
+
+bb1:
+  %p = phi i32 [ %i, %bbq ], [ %0, %bbe ], [ %s, %bb0 ]
+  %2 = and i32 %i, 2
+  %3 = icmp eq i32 %2, 0
+  br i1 %3, label %bb3, label %bb2, !prof !15
+
+bb2:
+  call void @foo()
+  %q = add i32 %p, %2
+  br label %bb3
+
+bb3:
+  %r = phi i32 [ %p, %bb1 ], [ %q, %bb2 ], [ %i, %bbq ]
+  ret i32 %r
+}
+
+; Select + br, there's a loop and we need to update the user of an inserted phi
+; at the entry block. This is a regression test for a bug that's fixed.
+; Roughly,
+; do {
+;   inc1 = phi inc2, 0
+;   li = *i
+;   sum1 = sum0 + 42
+;   sum2 = ((li & 1) == 0) ? sum0 : sum1  // Likely false
+;   inc2 = inc1 + 1
+;   if ((li & 4) != 0) // Likely true
+;     sum3 = sum2 + 44
+;   sum4 = phi sum1, sum3
+; } while (inc2 != 100)  // Likely true (loop back)
+; return sum4
+; ->
+; do {
+;   inc1 = phi tmp2, 0  // The first operand needed to be updated
+;   li = *i
+;   sum1 = sum0 + 42
+;   if ((li & 5) == 5) { // Likely true
+;     inc2 = inc1 + 1
+;     sum3 = sum0 + 86
+;   } else {
+;     inc2_nc = inc1 + 1
+;     if ((li & 4) == 0)
+;       sum2_nc = ((li & 1) == 0) ? sum0 : sum1
+;       sum3_nc = sum2_nc + 44
+;     }
+;   tmp2 = phi inc2, in2c_nc
+;   sum4 = phi sum3, sum3_nc, sum1
+; } while (tmp2 != 100)
+; return sum4
+define i32 @test_chr_18(i32* %i, i32 %sum0) !prof !14 {
+; CHECK-LABEL: @test_chr_18(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    br label [[BB0:%.*]]
+; CHECK:       bb0:
+; CHECK-NEXT:    [[INC1:%.*]] = phi i32 [ [[TMP2:%.*]], [[BB2:%.*]] ], [ 0, [[ENTRY:%.*]] ]
+; CHECK-NEXT:    [[LI:%.*]] = load i32, i32* [[I:%.*]], align 4
+; CHECK-NEXT:    [[SUM1:%.*]] = add i32 [[SUM0:%.*]], 42
+; CHECK-NEXT:    [[TMP0:%.*]] = and i32 [[LI]], 5
+; CHECK-NEXT:    [[TMP1:%.*]] = icmp eq i32 [[TMP0]], 5
+; CHECK-NEXT:    br i1 [[TMP1]], label [[BB0_SPLIT:%.*]], label [[BB0_SPLIT_NONCHR:%.*]], !prof !15
+; CHECK:       bb0.split:
+; CHECK-NEXT:    [[INC2:%.*]] = add i32 [[INC1]], 1
+; CHECK-NEXT:    [[SUM3:%.*]] = add i32 [[SUM0]], 86
+; CHECK-NEXT:    br label [[BB2]]
+; CHECK:       bb0.split.nonchr:
+; CHECK-NEXT:    [[A4_NONCHR:%.*]] = and i32 [[LI]], 4
+; CHECK-NEXT:    [[CMP4_NONCHR:%.*]] = icmp eq i32 [[A4_NONCHR]], 0
+; CHECK-NEXT:    [[INC2_NONCHR:%.*]] = add i32 [[INC1]], 1
+; CHECK-NEXT:    br i1 [[CMP4_NONCHR]], label [[BB2]], label [[BB1_NONCHR:%.*]], !prof !16
+; CHECK:       bb1.nonchr:
+; CHECK-NEXT:    [[A1:%.*]] = and i32 [[LI]], 1
+; CHECK-NEXT:    [[CMP1:%.*]] = icmp eq i32 [[A1]], 0
+; CHECK-NEXT:    [[SUM2_NONCHR:%.*]] = select i1 [[CMP1]], i32 [[SUM0]], i32 [[SUM1]], !prof !16
+; CHECK-NEXT:    [[SUM3_NONCHR:%.*]] = add i32 [[SUM2_NONCHR]], 44
+; CHECK-NEXT:    br label [[BB2]]
+; CHECK:       bb2:
+; CHECK-NEXT:    [[TMP2]] = phi i32 [ [[INC2]], [[BB0_SPLIT]] ], [ [[INC2_NONCHR]], [[BB1_NONCHR]] ], [ [[INC2_NONCHR]], [[BB0_SPLIT_NONCHR]] ]
+; CHECK-NEXT:    [[SUM4:%.*]] = phi i32 [ [[SUM3]], [[BB0_SPLIT]] ], [ [[SUM3_NONCHR]], [[BB1_NONCHR]] ], [ [[SUM1]], [[BB0_SPLIT_NONCHR]] ]
+; CHECK-NEXT:    [[CMP:%.*]] = icmp eq i32 [[TMP2]], 100
+; CHECK-NEXT:    br i1 [[CMP]], label [[BB3:%.*]], label [[BB0]], !prof !16
+; CHECK:       bb3:
+; CHECK-NEXT:    ret i32 [[SUM4]]
+;
+entry:
+  br label %bb0
+
+bb0:
+  %inc1 = phi i32 [ %inc2, %bb2 ], [ 0, %entry ]
+  %li = load i32, i32* %i
+  %a1 = and i32 %li, 1
+  %cmp1 = icmp eq i32 %a1, 0
+  %sum1 = add i32 %sum0, 42
+  %sum2 = select i1 %cmp1, i32 %sum0, i32 %sum1, !prof !15
+  %a4 = and i32 %li, 4
+  %cmp4 = icmp eq i32 %a4, 0
+  %inc2 = add i32 %inc1, 1
+  br i1 %cmp4, label %bb2, label %bb1, !prof !15
+
+bb1:
+  %sum3 = add i32 %sum2, 44
+  br label %bb2
+
+bb2:
+  %sum4 = phi i32 [ %sum1, %bb0 ], [ %sum3, %bb1 ]
+  %cmp = icmp eq i32 %inc2, 100
+  br i1 %cmp, label %bb3, label %bb0, !prof !15
+
+bb3:
+  ret i32 %sum4
+}
+
+
+; Selects + Brs. Those share the condition value, which causes the
+; targets/operands of the branch/select to be flipped.
+; Roughly,
+; t0 = *i
+; if ((t0 & 255) != 0) {  // Likely true
+;   sum1 = ((t0 & 1) == 0) ? sum0 : (sum0 + 42)  // Likely false
+;   sum2 = ((t0 & 1) == 0) ? sum1 : (sum1 + 42)  // Likely false
+;   if ((t0 & 1) != 0) { // Likely true
+;     sum3 = sum2 + 44
+;     sum4 = ((t0 & 8) == 0) ? sum3 : (sum3 + 44) // Likely false
+;   }
+;   sum5 = phi sum2, sum4
+; }
+; sum6 = phi sum0, sum5
+; return sum6
+; ->
+; t0 = *i
+; if ((t0 & 9) == 9) { // Likely true
+;   tmp3 = sum0 + 85  // Dead
+;   tmp4 = sum0 + 173
+; } else {
+;   if ((t0 & 255) != 0) {
+;     sum2_nc = ((t0 & 1) == 0) ? sum0 : (sum0 + 85)
+;     sum4_nc_v = ((t0 & 8) == 0) ? 44 : 88
+;     sum4_nc = add sum2_nc + sum4_nc_v
+;   }
+; }
+; sum6 = phi tmp4, sum0, sum2_nc, sum4_nc
+; return sum6
+define i32 @test_chr_19(i32* %i, i32 %sum0) !prof !14 {
+; CHECK-LABEL: @test_chr_19(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[TMP0:%.*]] = load i32, i32* [[I:%.*]], align 4
+; CHECK-NEXT:    [[TMP1:%.*]] = and i32 [[TMP0]], 9
+; CHECK-NEXT:    [[TMP2:%.*]] = icmp eq i32 [[TMP1]], 9
+; CHECK-NEXT:    br i1 [[TMP2]], label [[BB0:%.*]], label [[ENTRY_SPLIT_NONCHR:%.*]], !prof !15
+; CHECK:       bb0:
+; CHECK-NEXT:    [[TMP3:%.*]] = add i32 [[SUM0:%.*]], 85
+; CHECK-NEXT:    [[TMP4:%.*]] = add i32 [[SUM0]], 173
+; CHECK-NEXT:    br label [[BB3:%.*]]
+; CHECK:       entry.split.nonchr:
+; CHECK-NEXT:    [[TMP5:%.*]] = and i32 [[TMP0]], 255
+; CHECK-NEXT:    [[TMP6:%.*]] = icmp eq i32 [[TMP5]], 0
+; CHECK-NEXT:    br i1 [[TMP6]], label [[BB3]], label [[BB0_NONCHR:%.*]], !prof !16
+; CHECK:       bb0.nonchr:
+; CHECK-NEXT:    [[TMP7:%.*]] = and i32 [[TMP0]], 1
+; CHECK-NEXT:    [[TMP8:%.*]] = icmp eq i32 [[TMP7]], 0
+; CHECK-NEXT:    [[TMP9:%.*]] = add i32 [[SUM0]], 85
+; CHECK-NEXT:    [[SUM2_NONCHR:%.*]] = select i1 [[TMP8]], i32 [[SUM0]], i32 [[TMP9]], !prof !16
+; CHECK-NEXT:    br i1 [[TMP8]], label [[BB3]], label [[BB1_NONCHR:%.*]], !prof !16
+; CHECK:       bb1.nonchr:
+; CHECK-NEXT:    [[TMP10:%.*]] = and i32 [[TMP0]], 8
+; CHECK-NEXT:    [[TMP11:%.*]] = icmp eq i32 [[TMP10]], 0
+; CHECK-NEXT:    [[SUM4_NONCHR_V:%.*]] = select i1 [[TMP11]], i32 44, i32 88, !prof !16
+; CHECK-NEXT:    [[SUM4_NONCHR:%.*]] = add i32 [[SUM2_NONCHR]], [[SUM4_NONCHR_V]]
+; CHECK-NEXT:    br label [[BB3]]
+; CHECK:       bb3:
+; CHECK-NEXT:    [[SUM6:%.*]] = phi i32 [ [[TMP4]], [[BB0]] ], [ [[SUM0]], [[ENTRY_SPLIT_NONCHR]] ], [ [[SUM2_NONCHR]], [[BB0_NONCHR]] ], [ [[SUM4_NONCHR]], [[BB1_NONCHR]] ]
+; CHECK-NEXT:    ret i32 [[SUM6]]
+;
+entry:
+  %0 = load i32, i32* %i
+  %1 = and i32 %0, 255
+  %2 = icmp eq i32 %1, 0
+  br i1 %2, label %bb3, label %bb0, !prof !15
+
+bb0:
+  %3 = and i32 %0, 1
+  %4 = icmp eq i32 %3, 0
+  %5 = add i32 %sum0, 42
+  %sum1 = select i1 %4, i32 %sum0, i32 %5, !prof !15
+  %6 = add i32 %sum1, 43
+  %sum2 = select i1 %4, i32 %sum1, i32 %6, !prof !15
+  br i1 %4, label %bb2, label %bb1, !prof !15
+
+bb1:
+  %sum3 = add i32 %sum2, 44
+  %7 = and i32 %0, 8
+  %8 = icmp eq i32 %7, 0
+  %9 = add i32 %sum3, 44
+  %sum4 = select i1 %8, i32 %sum3, i32 %9, !prof !15
+  br label %bb2
+
+bb2:
+  %sum5 = phi i32 [ %sum2, %bb0 ], [ %sum4, %bb1 ]
+  br label %bb3
+
+bb3:
+  %sum6 = phi i32 [ %sum0, %entry ], [ %sum5, %bb2 ]
+  ret i32 %sum6
+}
+
+; Selects. The exit block, which belongs to the top-level region, has a select
+; and causes the top-level region to be the outermost CHR scope with the
+; subscope that includes the entry block with two selects. The outermost CHR
+; scope doesn't see the selects in the entry block as the entry block is in the
+; subscope and incorrectly sets the CHR hoist point to the branch rather than
+; the first select in the entry block and causes the CHR'ed selects ("select i1
+; false...") to incorrectly position above the CHR branch. This is testing
+; against a quirk of how the region analysis handles the entry block.
+; Roughly,
+; i0 = *i
+; sum2 = ((i0 & 2) == 0) ? sum0 : (sum0 + 43) // Likely false
+; sum3 = ((i0 & 4) == 0) ? sum2 : (sum2 + 44) // Likely false
+; if (j)
+;   foo()
+; i5 = *i
+; v13 = (i5 == 44) ? i5 : sum3
+; return v13
+; ->
+; i0 = *i
+; if ((i0 & 6) != 6) { // Likely true
+;   v9 = sum0 + 87
+;   if (j)
+;     foo()
+; } else {
+;   sum2.nc = ((i0 & 2) == 0) ? sum0 : (sum0 + 43)
+;   sum3.nc = ((i0 & 4) == 0) ? sum2.nc : (sum2.nc + 44)
+;   if (j)
+;     foo()
+; }
+; t2 = phi v9, sum3.nc
+; i5 = *i
+; v13 = (i5 == 44) ? 44 : t2
+; return v13
+define i32 @test_chr_20(i32* %i, i32 %sum0, i1 %j) !prof !14 {
+; CHECK-LABEL: @test_chr_20(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[I0:%.*]] = load i32, i32* [[I:%.*]], align 4
+; CHECK-NEXT:    [[TMP0:%.*]] = and i32 [[I0]], 6
+; CHECK-NEXT:    [[TMP1:%.*]] = icmp eq i32 [[TMP0]], 6
+; CHECK-NEXT:    br i1 [[TMP1]], label [[ENTRY_SPLIT:%.*]], label [[ENTRY_SPLIT_NONCHR:%.*]], !prof !15
+; CHECK:       entry.split:
+; CHECK-NEXT:    [[V9:%.*]] = add i32 [[SUM0:%.*]], 87
+; CHECK-NEXT:    br i1 [[J:%.*]], label [[BB1:%.*]], label [[BB4:%.*]]
+; CHECK:       bb1:
+; CHECK-NEXT:    call void @foo()
+; CHECK-NEXT:    br label [[BB4]]
+; CHECK:       entry.split.nonchr:
+; CHECK-NEXT:    [[V8:%.*]] = add i32 [[SUM0]], 43
+; CHECK-NEXT:    [[V3:%.*]] = and i32 [[I0]], 2
+; CHECK-NEXT:    [[V4:%.*]] = icmp eq i32 [[V3]], 0
+; CHECK-NEXT:    [[SUM2_NONCHR:%.*]] = select i1 [[V4]], i32 [[SUM0]], i32 [[V8]], !prof !16
+; CHECK-NEXT:    [[V6_NONCHR:%.*]] = and i32 [[I0]], 4
+; CHECK-NEXT:    [[V5_NONCHR:%.*]] = icmp eq i32 [[V6_NONCHR]], 0
+; CHECK-NEXT:    [[V9_NONCHR:%.*]] = add i32 [[SUM2_NONCHR]], 44
+; CHECK-NEXT:    [[SUM3_NONCHR:%.*]] = select i1 [[V5_NONCHR]], i32 [[SUM2_NONCHR]], i32 [[V9_NONCHR]], !prof !16
+; CHECK-NEXT:    br i1 [[J]], label [[BB1_NONCHR:%.*]], label [[BB4]]
+; CHECK:       bb1.nonchr:
+; CHECK-NEXT:    call void @foo()
+; CHECK-NEXT:    br label [[BB4]]
+; CHECK:       bb4:
+; CHECK-NEXT:    [[TMP2:%.*]] = phi i32 [ [[V9]], [[BB1]] ], [ [[V9]], [[ENTRY_SPLIT]] ], [ [[SUM3_NONCHR]], [[BB1_NONCHR]] ], [ [[SUM3_NONCHR]], [[ENTRY_SPLIT_NONCHR]] ]
+; CHECK-NEXT:    [[I5:%.*]] = load i32, i32* [[I]], align 4
+; CHECK-NEXT:    [[V12:%.*]] = icmp eq i32 [[I5]], 44
+; CHECK-NEXT:    [[V13:%.*]] = select i1 [[V12]], i32 44, i32 [[TMP2]], !prof !16
+; CHECK-NEXT:    ret i32 [[V13]]
+;
+entry:
+  %i0 = load i32, i32* %i
+  %v3 = and i32 %i0, 2
+  %v4 = icmp eq i32 %v3, 0
+  %v8 = add i32 %sum0, 43
+  %sum2 = select i1 %v4, i32 %sum0, i32 %v8, !prof !15
+  %v6 = and i32 %i0, 4
+  %v5 = icmp eq i32 %v6, 0
+  %v9 = add i32 %sum2, 44
+  %sum3 = select i1 %v5, i32 %sum2, i32 %v9, !prof !15
+  br i1 %j, label %bb1, label %bb4
+
+bb1:
+  call void @foo()
+  br label %bb4
+
+bb4:
+  %i5 = load i32, i32* %i
+  %v12 = icmp eq i32 %i5, 44
+  %v13 = select i1 %v12, i32 %i5, i32 %sum3, !prof !15
+  ret i32 %v13
+}
+
+!llvm.module.flags = !{!0}
+!0 = !{i32 1, !"ProfileSummary", !1}
+!1 = !{!2, !3, !4, !5, !6, !7, !8, !9}
+!2 = !{!"ProfileFormat", !"InstrProf"}
+!3 = !{!"TotalCount", i64 10000}
+!4 = !{!"MaxCount", i64 10}
+!5 = !{!"MaxInternalCount", i64 1}
+!6 = !{!"MaxFunctionCount", i64 1000}
+!7 = !{!"NumCounts", i64 3}
+!8 = !{!"NumFunctions", i64 3}
+!9 = !{!"DetailedSummary", !10}
+!10 = !{!11, !12, !13}
+!11 = !{i32 10000, i64 100, i32 1}
+!12 = !{i32 999000, i64 100, i32 1}
+!13 = !{i32 999999, i64 1, i32 2}
+
+!14 = !{!"function_entry_count", i64 100}
+!15 = !{!"branch_weights", i32 0, i32 1}
+!16 = !{!"branch_weights", i32 1, i32 1}
+; CHECK: !15 = !{!"branch_weights", i32 1000, i32 0}
+; CHECK: !16 = !{!"branch_weights", i32 0, i32 1}
+; CHECK: !17 = !{!"branch_weights", i32 1, i32 1}
+; CHECK: !18 = !{!"branch_weights", i32 1, i32 0}
+; CHECK: !19 = !{!"branch_weights", i32 0, i32 1000}