[compiler-rt] [llvm] [InstrPGO][TypeProf]Annotate vtable types when they are present in the profile (PR #99402)

[Mingming Liu via llvm-commits]

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@@ -1755,8 +1757,18 @@ void PGOUseFunc::annotateValueSites() {
 void PGOUseFunc::annotateValueSites(uint32_t Kind) {
   assert(Kind <= IPVK_Last);
   unsigned ValueSiteIndex = 0;
-  auto &ValueSites = FuncInfo.ValueSites[Kind];
   unsigned NumValueSites = ProfileRecord.getNumValueSites(Kind);
+  // FuncPGOInstrumentation ctor finds value sites for each kind. It runs on the
+  // common path of pgo-instr-gen and pgo-instr-use, and vtable kind path
+  // is gated by `-enable-vtable-value-profiling`. If vtable profiles are
+  // present, not explicitly discarded and vtable sites remain empty, try to
+  // find the sites again.
+  if (NumValueSites > 0 && Kind == IPVK_VTableTarget &&
+      FuncInfo.ValueSites[Kind].empty() &&
+      !(EnableVTableProfileUse.getNumOccurrences() &&
+        EnableVTableProfileUse == false))
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minglotus-6 wrote:

`EnableVTableProfileUse.getNumOccurrences() && EnableVTableProfileUse == false` meant to allow skipping `VPC.get(IPVK_VTableTarget`. Now this PR uses `-icp-max-num-vtables` to do that.

While adding TODOs to speed up optimized build by skipping `VPC.get(<value-profile-kind>)` if there are no value profiles of this kind in function profile record, I realized `VPC.get(<value-profile-kind>)` for optimized build is necessary to compute function cfg hash with IR and detect profile mismatch.

https://github.com/llvm/llvm-project/pull/99402