Add instcombine pass if sampleprofile pass is enabled.

[danielcdh]

Summary

Sample profile pass need to have instcombine pass. A related change is http://reviews.llvm.org/D17742. But we should not explicitly add dependency between to non-analysis passes. So we add the dependency here.

[dnovillo]

Ah. I should'be read this one first :) Ignore my question on http://reviews.llvm.org/D17742, then.

LGTM

lib/CodeGen/BackendUtil.cpp

if (Builder.OptLevel > 0)
     PM.add(createObjCARCOptPass());
 }
 
 static void addAddDiscriminatorsPass(const PassManagerBuilder &Builder,
                                      legacy::PassManagerBase &PM) {
   PM.add(createAddDiscriminatorsPass());
 }
 
+static void addInstructionCombiningPass(const PassManagerBuilder &Builder,
+                                        legacy::PassManagerBase &PM) {
+  PM.add(createInstructionCombiningPass());
+}
+
 static void addBoundsCheckingPass(const PassManagerBuilder &Builder,
                                     legacy::PassManagerBase &PM) {
   PM.add(createBoundsCheckingPass());
 }
 
 static void addSanitizerCoveragePass(const PassManagerBuilder &Builder,
                                      legacy::PassManagerBase &PM) {
   const PassManagerBuilderWrapper &BuilderWrapper =
if (LangOpts.Sanitize.hasOneOf(SanitizerKind::Efficiency)) {
     PMBuilder.addExtension(PassManagerBuilder::EP_EnabledOnOptLevel0,
                            addEfficiencySanitizerPass);
   }
 
   // Set up the per-function pass manager.
   legacy::FunctionPassManager *FPM = getPerFunctionPasses();
   if (CodeGenOpts.VerifyModule)
     FPM->add(createVerifierPass());
-  PMBuilder.populateFunctionPassManager(*FPM);
 
   // Set up the per-module pass manager.
   if (!CodeGenOpts.RewriteMapFiles.empty())
     addSymbolRewriterPass(CodeGenOpts, MPM);
 
   if (!CodeGenOpts.DisableGCov &&
       (CodeGenOpts.EmitGcovArcs || CodeGenOpts.EmitGcovNotes)) {
     // Not using 'GCOVOptions::getDefault' allows us to avoid exiting if
if (CodeGenOpts.hasProfileIRInstr()) {
     if (!CodeGenOpts.InstrProfileOutput.empty())
       PMBuilder.PGOInstrGen = CodeGenOpts.InstrProfileOutput;
     else
       PMBuilder.PGOInstrGen = "default.profraw";
   }
   if (CodeGenOpts.hasProfileIRUse())
     PMBuilder.PGOInstrUse = CodeGenOpts.ProfileInstrumentUsePath;
 
-  if (!CodeGenOpts.SampleProfileFile.empty())
+  if (!CodeGenOpts.SampleProfileFile.empty()) {
     MPM->add(createSampleProfileLoaderPass(CodeGenOpts.SampleProfileFile));
+    PMBuilder.addExtension(PassManagerBuilder::EP_EarlyAsPossible,
+                           addInstructionCombiningPass);
+  }
 
+  PMBuilder.populateFunctionPassManager(*FPM);
   PMBuilder.populateModulePassManager(*MPM);
 }
 
 void EmitAssemblyHelper::setCommandLineOpts() {
   SmallVector<const char *, 16> BackendArgs;
   BackendArgs.push_back("clang"); // Fake program name.
   if (!CodeGenOpts.DebugPass.empty()) {
     BackendArgs.push_back("-debug-pass");