[PATCH] D103717: [InstrProfiling][ELF] Make __profd_ private if the function does not use value profiling

[Fangrui Song via Phabricator via llvm-commits]

MaskRay updated this revision to Diff 352926.
MaskRay retitled this revision from "[InstrProfiling] Make __profd_ unconditionally private for ELF" to "[InstrProfiling][ELF] Make __profd_ private if the function does not use value profiling".
MaskRay edited the summary of this revision.
MaskRay added a comment.

I need to add a test case, but this is the sketch.

I am not sure whether this value profiling detection is correct.


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D103717/new/

https://reviews.llvm.org/D103717

Files:
  llvm/lib/Transforms/Instrumentation/InstrProfiling.cpp
  llvm/test/Transforms/PGOProfile/indirect_call_profile.ll


Index: llvm/test/Transforms/PGOProfile/indirect_call_profile.ll
===================================================================
--- llvm/test/Transforms/PGOProfile/indirect_call_profile.ll
+++ llvm/test/Transforms/PGOProfile/indirect_call_profile.ll
@@ -54,7 +54,7 @@
 }
 
 ; Test that comdat function's address is recorded.
-; LOWER: @__profd_foo3.[[FOO3_HASH:[0-9]+]] = linkonce_odr{{.*}}@__profc_foo3.[[FOO3_HASH]]
+; LOWER: @__profd_foo3.[[FOO3_HASH:[0-9]+]] = private {{.*}} @__profc_foo3.[[FOO3_HASH]]
 ; Function Attrs: nounwind uwtable
 define linkonce_odr i32 @foo3()  comdat  {
   ret i32 1
Index: llvm/lib/Transforms/Instrumentation/InstrProfiling.cpp
===================================================================
--- llvm/lib/Transforms/Instrumentation/InstrProfiling.cpp
+++ llvm/lib/Transforms/Instrumentation/InstrProfiling.cpp
@@ -887,10 +887,10 @@
   // Allocate statically the array of pointers to value profile nodes for
   // the current function.
   Constant *ValuesPtrExpr = ConstantPointerNull::get(Int8PtrTy);
+  uint64_t NS = 0;
+  for (uint32_t Kind = IPVK_First; Kind <= IPVK_Last; ++Kind)
+    NS += PD.NumValueSites[Kind];
   if (ValueProfileStaticAlloc && !needsRuntimeRegistrationOfSectionRange(TT)) {
-    uint64_t NS = 0;
-    for (uint32_t Kind = IPVK_First; Kind <= IPVK_Last; ++Kind)
-      NS += PD.NumValueSites[Kind];
     if (NS) {
       ArrayType *ValuesTy = ArrayType::get(Type::getInt64Ty(Ctx), NS);
 
@@ -929,10 +929,13 @@
 #define INSTR_PROF_DATA(Type, LLVMType, Name, Init) Init,
 #include "llvm/ProfileData/InstrProfData.inc"
   };
-  // If code never references data variables (the symbol is unneeded), and
-  // linker GC cannot discard data variables while the text section is retained,
-  // data variables can be private. This optimization applies on COFF and ELF.
-  if (!DataReferencedByCode && !TT.isOSBinFormatMachO()) {
+  // If the data variable is not referenced by code, and linker GC can retain
+  // the data variable if the associated counter is retained, the data variable
+  // can be private. This optimization applies on ELF. On COFF, when
+  // DataReferencedByCode is false, __profd_ is never a comdat leader, this is
+  // applicable as well.
+  if ((TT.isOSBinFormatELF() && NS == 0) || (!DataReferencedByCode &&
+      TT.isOSBinFormatCOFF())) {
     Linkage = GlobalValue::PrivateLinkage;
     Visibility = GlobalValue::DefaultVisibility;
   }


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