[GCOV] Flush counters before to avoid counting the execution before fork twice and for exec** functions we must flush before the call
Summary:
This is replacement for patch in https://reviews.llvm.org/D49460.
When we fork, the counters are duplicate as they're and so the values are finally wrong when writing gcda for parent and child.
So just before to fork, we flush the counters and so the parent and the child have new counters set to zero.
For exec** functions, we need to flush before the call to have some data.
Reviewers: vsk, davidxl, marco-c
Reviewed By: marco-c
Subscribers: llvm-commits, sylvestre.ledru, marco-c
Differential Revision: https://reviews.llvm.org/D53593
llvm-svn: 346313
diff --git a/llvm/lib/Transforms/Instrumentation/GCOVProfiling.cpp b/llvm/lib/Transforms/Instrumentation/GCOVProfiling.cpp
index 01938a0..084e6b7 100644
--- a/llvm/lib/Transforms/Instrumentation/GCOVProfiling.cpp
+++ b/llvm/lib/Transforms/Instrumentation/GCOVProfiling.cpp
@@ -109,6 +109,8 @@
insertCounterWriteout(ArrayRef<std::pair<GlobalVariable *, MDNode *>>);
Function *insertFlush(ArrayRef<std::pair<GlobalVariable *, MDNode *>>);
+ void AddFlushBeforeForkAndExec();
+
enum class GCovFileType { GCNO, GCDA };
std::string mangleName(const DICompileUnit *CU, GCovFileType FileType);
@@ -468,6 +470,8 @@
this->TLI = &TLI;
Ctx = &M.getContext();
+ AddFlushBeforeForkAndExec();
+
if (Options.EmitNotes) emitProfileNotes();
if (Options.EmitData) return emitProfileArcs();
return false;
@@ -524,6 +528,38 @@
return false;
}
+void GCOVProfiler::AddFlushBeforeForkAndExec() {
+ SmallVector<Instruction *, 2> ForkAndExecs;
+ for (auto &F : M->functions()) {
+ for (auto &I : instructions(F)) {
+ if (CallInst *CI = dyn_cast<CallInst>(&I)) {
+ if (Function *Callee = CI->getCalledFunction()) {
+ LibFunc LF;
+ if (TLI->getLibFunc(*Callee, LF) &&
+ (LF == LibFunc_fork || LF == LibFunc_execl ||
+ LF == LibFunc_execle || LF == LibFunc_execlp ||
+ LF == LibFunc_execv || LF == LibFunc_execvp ||
+ LF == LibFunc_execve || LF == LibFunc_execvpe ||
+ LF == LibFunc_execvP)) {
+ ForkAndExecs.push_back(&I);
+ }
+ }
+ }
+ }
+ }
+
+ // We need to split the block after the fork/exec call
+ // because else the counters for the lines after will be
+ // the same as before the call.
+ for (auto I : ForkAndExecs) {
+ IRBuilder<> Builder(I);
+ FunctionType *FTy = FunctionType::get(Builder.getVoidTy(), {}, false);
+ Constant *GCOVFlush = M->getOrInsertFunction("__gcov_flush", FTy);
+ Builder.CreateCall(GCOVFlush);
+ I->getParent()->splitBasicBlock(I);
+ }
+}
+
void GCOVProfiler::emitProfileNotes() {
NamedMDNode *CU_Nodes = M->getNamedMetadata("llvm.dbg.cu");
if (!CU_Nodes) return;