[PM] Add support for sample PGO in the new pass manager (clang-side)

[danielcdh]

Summary

This implements the clang bits of https://reviews.llvm.org/D34720, and add corresponding test to verify if it worked.

[danielcdh]

test/CodeGen/pgo-sample-thinlto-summary.c

4

This test will currently fail because PrepareForLLVM has not been passed down so that we do not know if it's in the thinlto compile phase.

Related discussion: http://lists.llvm.org/pipermail/llvm-commits/Week-of-Mon-20170626/464868.html

This patch needs to commit after that issue is fixed.

[tejohnson]

LGTM for when the dependent patches are in.

[chandlerc]

LGTM too, but no need to wait for me to land this. =D

lib/CodeGen/BackendUtil.cpp

void EmitAssemblyHelper::EmitAssemblyWithNewPassManager(
   if (PGOOpt.RunProfileGen)
     PGOOpt.ProfileGenFile = CodeGenOpts.InstrProfileOutput.empty() ?
       DefaultProfileGenName : CodeGenOpts.InstrProfileOutput;
 
   // -fprofile-use.
   if (CodeGenOpts.hasProfileIRUse())
     PGOOpt.ProfileUseFile = CodeGenOpts.ProfileInstrumentUsePath;
 
+  if (!CodeGenOpts.SampleProfileFile.empty())
+    PGOOpt.SampleProfileFile = CodeGenOpts.SampleProfileFile;
+
   // Only pass a PGO options struct if -fprofile-generate or
   // -fprofile-use were passed on the cmdline.
   PassBuilder PB(TM.get(),
     (PGOOpt.RunProfileGen ||
-      !PGOOpt.ProfileUseFile.empty()) ?
+      !PGOOpt.ProfileUseFile.empty() ||
+      !PGOOpt.SampleProfileFile.empty()) ?
         Optional<PGOOptions>(PGOOpt) : None);
 
   LoopAnalysisManager LAM;
   FunctionAnalysisManager FAM;
   CGSCCAnalysisManager CGAM;
   ModuleAnalysisManager MAM;
 
   // Register the AA manager first so that our version is the one used.

test/CodeGen/pgo-sample-thinlto-summary.c

 // RUN: %clang_cc1 -O2 -fprofile-sample-use=%S/Inputs/pgo-sample-thinlto-summary.prof %s -emit-llvm -o - 2>&1 | FileCheck %s -check-prefix=SAMPLEPGO
 // RUN: %clang_cc1 -O2 -fprofile-sample-use=%S/Inputs/pgo-sample-thinlto-summary.prof %s -emit-llvm -flto=thin -o - 2>&1 | FileCheck %s -check-prefix=THINLTO
+// RUN: %clang_cc1 -O2 -fexperimental-new-pass-manager -fprofile-sample-use=%S/Inputs/pgo-sample-thinlto-summary.prof %s -emit-llvm -o - 2>&1 | FileCheck %s -check-prefix=SAMPLEPGO
+// RUN: %clang_cc1 -O2 -fexperimental-new-pass-manager -fprofile-sample-use=%S/Inputs/pgo-sample-thinlto-summary.prof %s -emit-llvm -flto=thin -o - 2>&1 | FileCheck %s -check-prefix=THINLTO
 // Checks if hot call is inlined by normal compile, but not inlined by
 // thinlto compile.
 
 int baz(int);
 int g;
 
 void foo(int n) {
   for (int i = 0; i < n; i++)