LCOV - code coverage report
Current view: top level - lib/Analysis - IndirectCallPromotionAnalysis.cpp (source / functions) Hit Total Coverage
Test: llvm-toolchain.info Lines: 33 33 100.0 %
Date: 2017-09-14 15:23:50 Functions: 6 6 100.0 %
Legend: Lines: hit not hit

          Line data    Source code
       1             : //===-- IndirectCallPromotionAnalysis.cpp - Find promotion candidates ===//
       2             : //
       3             : //                      The LLVM Compiler Infrastructure
       4             : //
       5             : // This file is distributed under the University of Illinois Open Source
       6             : // License. See LICENSE.TXT for details.
       7             : //
       8             : //===----------------------------------------------------------------------===//
       9             : //
      10             : // Helper methods for identifying profitable indirect call promotion
      11             : // candidates for an instruction when the indirect-call value profile metadata
      12             : // is available.
      13             : //
      14             : //===----------------------------------------------------------------------===//
      15             : 
      16             : #include "llvm/Analysis/IndirectCallPromotionAnalysis.h"
      17             : #include "llvm/ADT/STLExtras.h"
      18             : #include "llvm/Analysis/IndirectCallSiteVisitor.h"
      19             : #include "llvm/IR/CallSite.h"
      20             : #include "llvm/IR/DiagnosticInfo.h"
      21             : #include "llvm/IR/InstIterator.h"
      22             : #include "llvm/IR/InstVisitor.h"
      23             : #include "llvm/IR/Instructions.h"
      24             : #include "llvm/IR/IntrinsicInst.h"
      25             : #include "llvm/ProfileData/InstrProf.h"
      26             : #include "llvm/Support/Debug.h"
      27             : #include <string>
      28             : #include <utility>
      29             : #include <vector>
      30             : 
      31             : using namespace llvm;
      32             : 
      33             : #define DEBUG_TYPE "pgo-icall-prom-analysis"
      34             : 
      35             : // The percent threshold for the direct-call target (this call site vs the
      36             : // remaining call count) for it to be considered as the promotion target.
      37       72306 : static cl::opt<unsigned> ICPRemainingPercentThreshold(
      38      216918 :     "icp-remaining-percent-threshold", cl::init(30), cl::Hidden, cl::ZeroOrMore,
      39      216918 :     cl::desc("The percentage threshold against remaining unpromoted indirect "
      40      216918 :              "call count for the promotion"));
      41             : 
      42             : // The percent threshold for the direct-call target (this call site vs the
      43             : // total call count) for it to be considered as the promotion target.
      44             : static cl::opt<unsigned>
      45      289224 :     ICPTotalPercentThreshold("icp-total-percent-threshold", cl::init(5),
      46             :                              cl::Hidden, cl::ZeroOrMore,
      47      216918 :                              cl::desc("The percentage threshold against total "
      48      216918 :                                       "count for the promotion"));
      49             : 
      50             : // Set the maximum number of targets to promote for a single indirect-call
      51             : // callsite.
      52             : static cl::opt<unsigned>
      53      289224 :     MaxNumPromotions("icp-max-prom", cl::init(3), cl::Hidden, cl::ZeroOrMore,
      54      216918 :                      cl::desc("Max number of promotions for a single indirect "
      55      216918 :                               "call callsite"));
      56             : 
      57        2592 : ICallPromotionAnalysis::ICallPromotionAnalysis() {
      58        3888 :   ValueDataArray = llvm::make_unique<InstrProfValueData[]>(MaxNumPromotions);
      59        1296 : }
      60             : 
      61          53 : bool ICallPromotionAnalysis::isPromotionProfitable(uint64_t Count,
      62             :                                                    uint64_t TotalCount,
      63             :                                                    uint64_t RemainingCount) {
      64         159 :   return Count * 100 >= ICPRemainingPercentThreshold * RemainingCount &&
      65         159 :          Count * 100 >= ICPTotalPercentThreshold * TotalCount;
      66             : }
      67             : 
      68             : // Indirect-call promotion heuristic. The direct targets are sorted based on
      69             : // the count. Stop at the first target that is not promoted. Returns the
      70             : // number of candidates deemed profitable.
      71          38 : uint32_t ICallPromotionAnalysis::getProfitablePromotionCandidates(
      72             :     const Instruction *Inst, uint32_t NumVals, uint64_t TotalCount) {
      73         114 :   ArrayRef<InstrProfValueData> ValueDataRef(ValueDataArray.get(), NumVals);
      74             : 
      75             :   DEBUG(dbgs() << " \nWork on callsite " << *Inst << " Num_targets: " << NumVals
      76             :                << "\n");
      77             : 
      78          38 :   uint32_t I = 0;
      79          38 :   uint64_t RemainingCount = TotalCount;
      80         136 :   for (; I < MaxNumPromotions && I < NumVals; I++) {
      81         106 :     uint64_t Count = ValueDataRef[I].Count;
      82             :     assert(Count <= RemainingCount);
      83             :     DEBUG(dbgs() << " Candidate " << I << " Count=" << Count
      84             :                  << "  Target_func: " << ValueDataRef[I].Value << "\n");
      85             : 
      86          53 :     if (!isPromotionProfitable(Count, TotalCount, RemainingCount)) {
      87             :       DEBUG(dbgs() << " Not promote: Cold target.\n");
      88             :       return I;
      89             :     }
      90          49 :     RemainingCount -= Count;
      91             :   }
      92             :   return I;
      93             : }
      94             : 
      95             : ArrayRef<InstrProfValueData>
      96          67 : ICallPromotionAnalysis::getPromotionCandidatesForInstruction(
      97             :     const Instruction *I, uint32_t &NumVals, uint64_t &TotalCount,
      98             :     uint32_t &NumCandidates) {
      99             :   bool Res =
     100         201 :       getValueProfDataFromInst(*I, IPVK_IndirectCallTarget, MaxNumPromotions,
     101          67 :                                ValueDataArray.get(), NumVals, TotalCount);
     102          67 :   if (!Res) {
     103          29 :     NumCandidates = 0;
     104          29 :     return ArrayRef<InstrProfValueData>();
     105             :   }
     106          38 :   NumCandidates = getProfitablePromotionCandidates(I, NumVals, TotalCount);
     107          76 :   return ArrayRef<InstrProfValueData>(ValueDataArray.get(), NumVals);
     108      216918 : }

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