[InstrProf] Allow CSIRPGO function entry coverage

[ellis]

Summary

The flag -fcs-profile-generate for enabling CSIRPGO moves the pass
pgo-instrumentation after inlining. Function entry coverage works fine
with this change, so remove the assert. I had originally left this
assert in because I had not tested this at the time.

[phosek]

Is there a test covering this?

[ellis]

In D129407#3642933, @phosek wrote:

Is there a test covering this?

The only different between -fprofile-generate and -fcs-profile-generate is when the pgo-instr-gen pass is added, so I don't think an explicit test is necessary. We have lots of tests in test/Transforms/PGOProfile that use opt < %s -passes=pgo-instr-gen that uses this code to inject the llvm.instrprof intrinsics, but I couldn't find test that trigger this using the frontend flags.

That being said, I would be happy to add some tests if that's what we want. I think it would need to be a clang test that checks if the instrumentation code is injected correctly.

[ellis]

Test CSIRPGO + function coverage and refactor substitutions in compiler-rt/test/profile.

[ellis]

Friendly ping

[davidxl]

lgtm

[MaskRay]

LGTM.

llvm/lib/Transforms/Instrumentation/PGOInstrumentation.cpp

static void instrumentOneFunc(
   FuncPGOInstrumentation<PGOEdge, BBInfo> FuncInfo(
       F, TLI, ComdatMembers, true, BPI, BFI, IsCS, PGOInstrumentEntry);
 
   Type *I8PtrTy = Type::getInt8PtrTy(M->getContext());
   auto Name = ConstantExpr::getBitCast(FuncInfo.FuncNameVar, I8PtrTy);
   auto CFGHash = ConstantInt::get(Type::getInt64Ty(M->getContext()),
                                   FuncInfo.FunctionHash);
   if (PGOFunctionEntryCoverage) {
-    assert(!IsCS &&
-           "entry coverge does not support context-sensitive instrumentation");
     auto &EntryBB = F.getEntryBlock();
     IRBuilder<> Builder(&EntryBB, EntryBB.getFirstInsertionPt());
     // llvm.instrprof.cover(i8* <name>, i64 <hash>, i32 <num-counters>,
     //                      i32 <index>)
     Builder.CreateCall(
         Intrinsic::getDeclaration(M, Intrinsic::instrprof_cover),
         {Name, CFGHash, Builder.getInt32(1), Builder.getInt32(0)});
     return;