[PGO] Print target md5sum in missed optimization message

[davidxl]

Summary

This is helpful for performance debugging. Ideally, the target name should be dumped, but creating instprof symtab for this purpose is expensive. A user can always use other ways to find the name (e.g, dumping the object symtab and compute the md5 hash for the mapping). The later can also be a feature added to llvm-profdata.

[xur]

Looks good to me.

test/Transforms/PGOProfile/icp_mismatch_msg.ll

5

s/with/with md5sum/?

lib/Transforms/Instrumentation/IndirectCallPromotion.cpp

       break;
     }
 
     Function *TargetFunction = Symtab->getFunction(Target);
     if (TargetFunction == nullptr) {
       LLVM_DEBUG(dbgs() << " Not promote: Cannot find the target\n");
       ORE.emit([&]() {
         return OptimizationRemarkMissed(DEBUG_TYPE, "UnableToFindTarget", Inst)
-               << "Cannot promote indirect call: target not found";
+               << "Cannot promote indirect call: target with md5sum "
+               << ore::NV("target md5sum", Target) << " not found";
       });
       break;
     }
 
     const char *Reason = nullptr;
     if (!isLegalToPromote(CallSite(Inst), TargetFunction, &Reason)) {
       using namespace ore;
 

test/Transforms/PGOProfile/icp_mismatch_msg.ll

 ; RUN: opt < %s -pgo-icall-prom -pass-remarks-missed=pgo-icall-prom -S 2>& 1 | FileCheck %s
 ; RUN: opt < %s -passes=pgo-icall-prom -pass-remarks-missed=pgo-icall-prom -S 2>& 1 | FileCheck %s
 
 ; CHECK: remark: <unknown>:0:0: Cannot promote indirect call to func4 with count of 1234: The number of arguments mismatch
-; CHECK: remark: <unknown>:0:0: Cannot promote indirect call: target not found
+; CHECK: remark: <unknown>:0:0: Cannot promote indirect call: target with {{.*}} not found
 ; CHECK: remark: <unknown>:0:0: Cannot promote indirect call to func2 with count of 7890: Return type mismatch
 
 target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
 target triple = "x86_64-unknown-linux-gnu"
 
 @foo = common global i32 ()* null, align 8
 @foo2 = common global i32 ()* null, align 8
 @foo3 = common global i32 ()* null, align 8