[PATCH] D16016: [PGO] instrumentation for indirect call value profiling

[Rong Xu via llvm-commits]

xur created this revision.
xur added reviewers: davidxl, silvas, bogner, betulb.
xur added a subscriber: llvm-commits.

This patch adds the instrumentation for indirect call value profiling. It just finds all the indirect call-sites and generates instrprof_value_profile intrinsic calls. A new opt level option -disable-vp is introduced to disable
the value profiling instrumentation.

This patch has dependence on http://reviews.llvm.org/D16015


http://reviews.llvm.org/D16016

Files:
  lib/Transforms/Instrumentation/PGOInstrumentation.cpp

Index: lib/Transforms/Instrumentation/PGOInstrumentation.cpp
===================================================================
--- lib/Transforms/Instrumentation/PGOInstrumentation.cpp
+++ lib/Transforms/Instrumentation/PGOInstrumentation.cpp
@@ -53,6 +53,7 @@
 #include "llvm/Analysis/BlockFrequencyInfo.h"
 #include "llvm/Analysis/BranchProbabilityInfo.h"
 #include "llvm/Analysis/CFG.h"
+#include "llvm/IR/CallSite.h"
 #include "llvm/IR/DiagnosticInfo.h"
 #include "llvm/IR/IRBuilder.h"
 #include "llvm/IR/InstIterator.h"
@@ -81,6 +82,7 @@
 STATISTIC(NumOfPGOFunc, "Number of functions having valid profile counts.");
 STATISTIC(NumOfPGOMismatch, "Number of functions having mismatch profile.");
 STATISTIC(NumOfPGOMissing, "Number of functions without profile.");
+STATISTIC(NumOfPGOICall, "Number of indirect call value instrumentation.");
 
 // Command line option to specify the file to read profile from. This is
 // mainly used for testing.
@@ -90,6 +92,12 @@
                        cl::desc("Specify the path of profile data file. This is"
                                 "mainly for test purpose."));
 
+// Command line options to disable value profiling. The default is false:
+// i.e. vaule profiling is enabled by default. This is for debug purpose.
+static cl::opt<bool>
+DisableValueProfiling("disable-vp", cl::init(false), cl::Hidden,
+                     cl::desc("Disable Value Profiling"));
+
 namespace {
 class PGOInstrumentationGen : public ModulePass {
 public:
@@ -305,7 +313,7 @@
   return InstrBB;
 }
 
-// Visit all edge and instrument the edges not in MST.
+// Visit all edge and instrument the edges not in MST, and do value profiling.
 // Critical edges will be split.
 static void instrumentOneFunc(Function &F, Module *M,
                               BranchProbabilityInfo *BPI,
@@ -318,21 +326,47 @@
   }
 
   uint32_t I = 0;
+  Type *I8PtrTy = Type::getInt8PtrTy(M->getContext());
   for (auto &E : FuncInfo.MST.AllEdges) {
     BasicBlock *InstrBB = FuncInfo.getInstrBB(E.get());
     if (!InstrBB)
       continue;
 
     IRBuilder<> Builder(InstrBB, InstrBB->getFirstInsertionPt());
     assert(Builder.GetInsertPoint() != InstrBB->end() &&
            "Cannot get the Instrumentation point");
-    Type *I8PtrTy = Type::getInt8PtrTy(M->getContext());
     Builder.CreateCall(
         Intrinsic::getDeclaration(M, Intrinsic::instrprof_increment),
         {llvm::ConstantExpr::getBitCast(FuncInfo.FuncNameVar, I8PtrTy),
          Builder.getInt64(FuncInfo.FunctionHash), Builder.getInt32(NumCounters),
          Builder.getInt32(I++)});
   }
+
+  if (DisableValueProfiling) return;
+
+  unsigned NumIndirectCallSites = 0;
+  for (auto &BB : F) {
+    for (auto &Inst : BB) {
+      CallSite CS(&Inst);
+      if (!CS || CS.getCalledFunction()) continue;
+      Value *Callee = CS.getCalledValue();
+      if (!Callee) continue;
+
+      DEBUG(dbgs() << "Instrument one indirect call: CallSite Index = "
+                   << NumIndirectCallSites<<"\n");
+      IRBuilder<> Builder(&Inst);
+      assert(Builder.GetInsertPoint() != BB.end() &&
+             "Cannot get the Instrumentation point");
+      Builder.CreateCall(
+        Intrinsic::getDeclaration(M, Intrinsic::instrprof_value_profile),
+        {llvm::ConstantExpr::getBitCast(FuncInfo.FuncNameVar, I8PtrTy),
+         Builder.getInt64(FuncInfo.FunctionHash),
+         Builder.CreatePtrToInt(Callee, Builder.getInt64Ty()),
+         Builder.getInt32(llvm::InstrProfValueKind::IPVK_IndirectCallTarget),
+         Builder.getInt32(NumIndirectCallSites++)});
+    }
+  }
+  NumOfPGOICall += NumIndirectCallSites;
 }
 
 // This class represents a CFG edge in profile use compilation.


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