| //===-- IndirectCallPromotionAnalysis.cpp - Find promotion candidates ===// |
| // |
| // The LLVM Compiler Infrastructure |
| // |
| // This file is distributed under the University of Illinois Open Source |
| // License. See LICENSE.TXT for details. |
| // |
| //===----------------------------------------------------------------------===// |
| // |
| // Helper methods for identifying profitable indirect call promotion |
| // candidates for an instruction when the indirect-call value profile metadata |
| // is available. |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #include "llvm/Analysis/IndirectCallPromotionAnalysis.h" |
| #include "llvm/ADT/STLExtras.h" |
| #include "llvm/Analysis/IndirectCallSiteVisitor.h" |
| #include "llvm/IR/CallSite.h" |
| #include "llvm/IR/DiagnosticInfo.h" |
| #include "llvm/IR/InstIterator.h" |
| #include "llvm/IR/InstVisitor.h" |
| #include "llvm/IR/Instructions.h" |
| #include "llvm/IR/IntrinsicInst.h" |
| #include "llvm/ProfileData/InstrProf.h" |
| #include "llvm/Support/Debug.h" |
| #include <string> |
| #include <utility> |
| #include <vector> |
| |
| using namespace llvm; |
| |
| #define DEBUG_TYPE "pgo-icall-prom-analysis" |
| |
| // The minimum call count for the direct-call target to be considered as the |
| // promotion candidate. |
| static cl::opt<unsigned> |
| ICPCountThreshold("icp-count-threshold", cl::Hidden, cl::ZeroOrMore, |
| cl::init(1000), |
| cl::desc("The minimum count to the direct call target " |
| "for the promotion")); |
| |
| // The percent threshold for the direct-call target (this call site vs the |
| // total call count) for it to be considered as the promotion target. |
| static cl::opt<unsigned> |
| ICPPercentThreshold("icp-percent-threshold", cl::init(30), cl::Hidden, |
| cl::ZeroOrMore, |
| cl::desc("The percentage threshold for the promotion")); |
| |
| // Set the maximum number of targets to promote for a single indirect-call |
| // callsite. |
| static cl::opt<unsigned> |
| MaxNumPromotions("icp-max-prom", cl::init(2), cl::Hidden, cl::ZeroOrMore, |
| cl::desc("Max number of promotions for a single indirect " |
| "call callsite")); |
| |
| ICallPromotionAnalysis::ICallPromotionAnalysis() { |
| ValueDataArray = llvm::make_unique<InstrProfValueData[]>(MaxNumPromotions); |
| } |
| |
| bool ICallPromotionAnalysis::isPromotionProfitable(uint64_t Count, |
| uint64_t TotalCount) { |
| if (Count < ICPCountThreshold) |
| return false; |
| |
| unsigned Percentage = (Count * 100) / TotalCount; |
| return (Percentage >= ICPPercentThreshold); |
| } |
| |
| // Indirect-call promotion heuristic. The direct targets are sorted based on |
| // the count. Stop at the first target that is not promoted. Returns the |
| // number of candidates deemed profitable. |
| uint32_t ICallPromotionAnalysis::getProfitablePromotionCandidates( |
| const Instruction *Inst, uint32_t NumVals, uint64_t TotalCount) { |
| ArrayRef<InstrProfValueData> ValueDataRef(ValueDataArray.get(), NumVals); |
| |
| DEBUG(dbgs() << " \nWork on callsite " << *Inst << " Num_targets: " << NumVals |
| << "\n"); |
| |
| uint32_t I = 0; |
| for (; I < MaxNumPromotions && I < NumVals; I++) { |
| uint64_t Count = ValueDataRef[I].Count; |
| assert(Count <= TotalCount); |
| DEBUG(dbgs() << " Candidate " << I << " Count=" << Count |
| << " Target_func: " << ValueDataRef[I].Value << "\n"); |
| |
| if (!isPromotionProfitable(Count, TotalCount)) { |
| DEBUG(dbgs() << " Not promote: Cold target.\n"); |
| return I; |
| } |
| TotalCount -= Count; |
| } |
| return I; |
| } |
| |
| ArrayRef<InstrProfValueData> |
| ICallPromotionAnalysis::getPromotionCandidatesForInstruction( |
| const Instruction *I, uint32_t &NumVals, uint64_t &TotalCount, |
| uint32_t &NumCandidates) { |
| bool Res = |
| getValueProfDataFromInst(*I, IPVK_IndirectCallTarget, MaxNumPromotions, |
| ValueDataArray.get(), NumVals, TotalCount); |
| if (!Res) { |
| NumCandidates = 0; |
| return ArrayRef<InstrProfValueData>(); |
| } |
| NumCandidates = getProfitablePromotionCandidates(I, NumVals, TotalCount); |
| return ArrayRef<InstrProfValueData>(ValueDataArray.get(), NumVals); |
| } |