Resubmit "[PGO] Turn off comdat renaming in IR PGO by default"
This patch resubmits the changes in r291588.
llvm-svn: 291696
diff --git a/llvm/lib/Transforms/Instrumentation/InstrProfiling.cpp b/llvm/lib/Transforms/Instrumentation/InstrProfiling.cpp
index 8da3e31..adea7e7 100644
--- a/llvm/lib/Transforms/Instrumentation/InstrProfiling.cpp
+++ b/llvm/lib/Transforms/Instrumentation/InstrProfiling.cpp
@@ -32,6 +32,11 @@
cl::desc("Enable name string compression"),
cl::init(true));
+cl::opt<bool> DoHashBasedCounterSplit(
+ "hash-based-counter-split",
+ cl::desc("Rename counter variable of a comdat function based on cfg hash"),
+ cl::init(true));
+
cl::opt<bool> ValueProfileStaticAlloc(
"vp-static-alloc",
cl::desc("Do static counter allocation for value profiler"),
@@ -272,7 +277,16 @@
static std::string getVarName(InstrProfIncrementInst *Inc, StringRef Prefix) {
StringRef NamePrefix = getInstrProfNameVarPrefix();
StringRef Name = Inc->getName()->getName().substr(NamePrefix.size());
- return (Prefix + Name).str();
+ Function *F = Inc->getParent()->getParent();
+ Module *M = F->getParent();
+ if (!DoHashBasedCounterSplit || !isIRPGOFlagSet(M) ||
+ !canRenameComdatFunc(*F))
+ return (Prefix + Name).str();
+ uint64_t FuncHash = Inc->getHash()->getZExtValue();
+ SmallVector<char, 24> HashPostfix;
+ if (Name.endswith((Twine(".") + Twine(FuncHash)).toStringRef(HashPostfix)))
+ return (Prefix + Name).str();
+ return (Prefix + Name + "." + Twine(FuncHash)).str();
}
static inline bool shouldRecordFunctionAddr(Function *F) {
diff --git a/llvm/lib/Transforms/Instrumentation/PGOInstrumentation.cpp b/llvm/lib/Transforms/Instrumentation/PGOInstrumentation.cpp
index 28f4f7e..04f9a64 100644
--- a/llvm/lib/Transforms/Instrumentation/PGOInstrumentation.cpp
+++ b/llvm/lib/Transforms/Instrumentation/PGOInstrumentation.cpp
@@ -119,7 +119,7 @@
// Command line option to control appending FunctionHash to the name of a COMDAT
// function. This is to avoid the hash mismatch caused by the preinliner.
static cl::opt<bool> DoComdatRenaming(
- "do-comdat-renaming", cl::init(true), cl::Hidden,
+ "do-comdat-renaming", cl::init(false), cl::Hidden,
cl::desc("Append function hash to the name of COMDAT function to avoid "
"function hash mismatch due to the preinliner"));
@@ -134,6 +134,12 @@
static cl::opt<bool> NoPGOWarnMismatch("no-pgo-warn-mismatch", cl::init(false),
cl::Hidden);
+// Command line option to enable/disable the warning about a hash mismatch in
+// the profile data for Comdat functions, which often turns out to be false
+// positive due to the pre-instrumentation inline.
+static cl::opt<bool> NoPGOWarnMismatchComdat("no-pgo-warn-mismatch-comdat",
+ cl::init(true), cl::Hidden);
+
// Command line option to enable/disable select instruction instrumentation.
static cl::opt<bool> PGOInstrSelect("pgo-instr-select", cl::init(true),
cl::Hidden);
@@ -407,20 +413,8 @@
static bool canRenameComdat(
Function &F,
std::unordered_multimap<Comdat *, GlobalValue *> &ComdatMembers) {
- if (F.getName().empty())
+ if (!DoComdatRenaming || !canRenameComdatFunc(F, true))
return false;
- if (!needsComdatForCounter(F, *(F.getParent())))
- return false;
- // Only safe to do if this function may be discarded if it is not used
- // in the compilation unit.
- if (!GlobalValue::isDiscardableIfUnused(F.getLinkage()))
- return false;
-
- // For AvailableExternallyLinkage functions.
- if (!F.hasComdat()) {
- assert(F.getLinkage() == GlobalValue::AvailableExternallyLinkage);
- return true;
- }
// FIXME: Current only handle those Comdat groups that only containing one
// function and function aliases.
@@ -803,7 +797,11 @@
} else if (Err == instrprof_error::hash_mismatch ||
Err == instrprof_error::malformed) {
NumOfPGOMismatch++;
- SkipWarning = NoPGOWarnMismatch;
+ SkipWarning =
+ NoPGOWarnMismatch ||
+ (NoPGOWarnMismatchComdat &&
+ (F.hasComdat() ||
+ F.getLinkage() == GlobalValue::AvailableExternallyLinkage));
}
if (SkipWarning)