================
@@ -322,14 +796,133 @@ bool
IndirectCallPromoter::processFunction(ProfileSummaryInfo *PSI) {
if (!NumCandidates ||
(PSI && PSI->hasProfileSummary() && !PSI->isHotCount(TotalCount)))
continue;
+
auto PromotionCandidates = getPromotionCandidatesForCallSite(
*CB, ICallProfDataRef, TotalCount, NumCandidates);
- Changed |= tryToPromoteWithFuncCmp(*CB, PromotionCandidates, TotalCount,
- ICallProfDataRef, NumCandidates);
+
+ VTableGUIDCountsMap VTableGUIDCounts;
+ Instruction *VPtr =
+ computeVTableInfos(CB, VTableGUIDCounts, PromotionCandidates);
+
+ if (isProfitableToCompareVTables(*CB, PromotionCandidates, TotalCount))
+ Changed |= tryToPromoteWithVTableCmp(*CB, VPtr, PromotionCandidates,
+ TotalCount, NumCandidates,
+ ICallProfDataRef, VTableGUIDCounts);
+ else
+ Changed |= tryToPromoteWithFuncCmp(*CB, VPtr, PromotionCandidates,
+ TotalCount, ICallProfDataRef,
+ NumCandidates, VTableGUIDCounts);
}
return Changed;
}
+// TODO: Returns false if the function addressing and vtable load instructions
+// cannot sink to indirect fallback.
+bool IndirectCallPromoter::isProfitableToCompareVTables(
+ const CallBase &CB, const std::vector<PromotionCandidate> &Candidates,
+ uint64_t TotalCount) {
+ if (!EnableVTableProfileUse || Candidates.empty())
+ return false;
+ uint64_t RemainingVTableCount = TotalCount;
+ const size_t CandidateSize = Candidates.size();
+ for (size_t I = 0; I < CandidateSize; I++) {
+ auto &Candidate = Candidates[I];
+ uint64_t CandidateVTableCount = 0;
+ for (auto &[GUID, Count] : Candidate.VTableGUIDAndCounts)
+ CandidateVTableCount += Count;
+
+ if (CandidateVTableCount < Candidate.Count * ICPVTablePercentageThreshold)
{
+ LLVM_DEBUG(dbgs() << "For callsite #" << NumOfPGOICallsites << CB << I
+ << "-th candidate, function count " << Candidate.Count
+ << " and its vtable count " << CandidateVTableCount
+ << " have discrepancies\n");
+ return false;
+ }
+
+ RemainingVTableCount -= Candidate.Count;
+
+ // 'MaxNumVTable' limits the number of vtables to make vtable comparison
+ // profitable. Comparing multiple vtables for one function candidate will
+ // insert additional instructions on the hot path, and allowing more than
+ // one vtable for non last candidates may or may not elongates dependency
----------------
minglotus-6 wrote:
done.
https://github.com/llvm/llvm-project/pull/81442
_______________________________________________
cfe-commits mailing list
cfe-commits@lists.llvm.org
https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
