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As discussed in [0], this diff adds the `omitprofile` attribute to
prevent the function from being profiled while allowing profiled
functions to be inlined into it. The `noprofile` attribute remains
unchanged.
The `noprofile` attribute is used for functions where it is
dangerous to add instrumentation to while the `omitprofile` attribute is
used to reduce code size or performance overhead.
[0]
https://discourse.llvm.org/t/why-does-the-noprofile-attribute-restrict-inlining/64108
Repository:
rG LLVM Github Monorepo
https://reviews.llvm.org/D130807
Files:
clang/lib/CodeGen/CodeGenFunction.h
clang/lib/CodeGen/CodeGenPGO.cpp
clang/test/CodeGen/profile-function-groups.c
llvm/docs/LangRef.rst
llvm/include/llvm/Bitcode/LLVMBitCodes.h
llvm/include/llvm/IR/Attributes.td
llvm/lib/Bitcode/Reader/BitcodeReader.cpp
llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
llvm/lib/Transforms/Instrumentation/GCOVProfiling.cpp
llvm/lib/Transforms/Instrumentation/PGOInstrumentation.cpp
llvm/lib/Transforms/Utils/CodeExtractor.cpp
llvm/test/Bitcode/attributes.ll
llvm/test/Transforms/GCOVProfiling/noprofile.ll
llvm/test/Transforms/PGOProfile/noprofile.ll
Index: llvm/test/Transforms/PGOProfile/noprofile.ll
===================================================================
--- llvm/test/Transforms/PGOProfile/noprofile.ll
+++ llvm/test/Transforms/PGOProfile/noprofile.ll
@@ -21,4 +21,10 @@
ret i32 %sub
}
+define i32 @test3() omitprofile {
+entry:
+; CHECK-NOT: call void @llvm.instrprof.increment
+ ret i32 101
+}
+
attributes #0 = { noprofile }
Index: llvm/test/Transforms/GCOVProfiling/noprofile.ll
===================================================================
--- llvm/test/Transforms/GCOVProfiling/noprofile.ll
+++ llvm/test/Transforms/GCOVProfiling/noprofile.ll
@@ -10,6 +10,14 @@
ret i32 42, !dbg !27
}
+; Test that the omitprofile attribute disables profiling.
+define dso_local i32 @omit_instr(i32 %a) omitprofile {
+; CHECK-LABEL: @omit_instr(
+; CHECK-NEXT: ret i32 52
+;
+ ret i32 52
+}
+
define dso_local i32 @instr(i32 %a) !dbg !28 {
; CHECK-LABEL: @instr(
; CHECK-NEXT: [[GCOV_CTR:%.*]] = load i64, ptr @__llvm_gcov_ctr, align 4, !dbg [[DBG8:![0-9]+]]
Index: llvm/test/Bitcode/attributes.ll
===================================================================
--- llvm/test/Bitcode/attributes.ll
+++ llvm/test/Bitcode/attributes.ll
@@ -535,6 +535,9 @@
; CHECK: define void @f87() [[FNRETTHUNKEXTERN:#[0-9]+]]
define void @f87() fn_ret_thunk_extern { ret void }
+; CHECK: define void @f88() [[OMITPROFILE:#[0-9]+]]
+define void @f88() omitprofile { ret void }
+
; CHECK: attributes #0 = { noreturn }
; CHECK: attributes #1 = { nounwind }
; CHECK: attributes #2 = { readnone }
@@ -589,4 +592,5 @@
; CHECK: attributes #51 = { uwtable(sync) }
; CHECK: attributes #52 = { nosanitize_bounds }
; CHECK: attributes [[FNRETTHUNKEXTERN]] = { fn_ret_thunk_extern }
+; CHECK: attributes [[OMITPROFILE]] = { omitprofile }
; CHECK: attributes #[[NOBUILTIN]] = { nobuiltin }
Index: llvm/lib/Transforms/Utils/CodeExtractor.cpp
===================================================================
--- llvm/lib/Transforms/Utils/CodeExtractor.cpp
+++ llvm/lib/Transforms/Utils/CodeExtractor.cpp
@@ -963,6 +963,7 @@
case Attribute::NoCfCheck:
case Attribute::MustProgress:
case Attribute::NoProfile:
+ case Attribute::OmitProfile:
break;
// These attributes cannot be applied to functions.
case Attribute::Alignment:
Index: llvm/lib/Transforms/Instrumentation/PGOInstrumentation.cpp
===================================================================
--- llvm/lib/Transforms/Instrumentation/PGOInstrumentation.cpp
+++ llvm/lib/Transforms/Instrumentation/PGOInstrumentation.cpp
@@ -1573,6 +1573,8 @@
continue;
if (F.hasFnAttribute(llvm::Attribute::NoProfile))
continue;
+ if (F.hasFnAttribute(llvm::Attribute::OmitProfile))
+ continue;
auto &TLI = LookupTLI(F);
auto *BPI = LookupBPI(F);
auto *BFI = LookupBFI(F);
Index: llvm/lib/Transforms/Instrumentation/GCOVProfiling.cpp
===================================================================
--- llvm/lib/Transforms/Instrumentation/GCOVProfiling.cpp
+++ llvm/lib/Transforms/Instrumentation/GCOVProfiling.cpp
@@ -797,6 +797,8 @@
if (isUsingScopeBasedEH(F)) continue;
if (F.hasFnAttribute(llvm::Attribute::NoProfile))
continue;
+ if (F.hasFnAttribute(llvm::Attribute::OmitProfile))
+ continue;
// Add the function line number to the lines of the entry block
// to have a counter for the function definition.
Index: llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
===================================================================
--- llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
+++ llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
@@ -698,6 +698,8 @@
return bitc::ATTR_KIND_NOCF_CHECK;
case Attribute::NoProfile:
return bitc::ATTR_KIND_NO_PROFILE;
+ case Attribute::OmitProfile:
+ return bitc::ATTR_KIND_OMIT_PROFILE;
case Attribute::NoUnwind:
return bitc::ATTR_KIND_NO_UNWIND;
case Attribute::NoSanitizeBounds:
Index: llvm/lib/Bitcode/Reader/BitcodeReader.cpp
===================================================================
--- llvm/lib/Bitcode/Reader/BitcodeReader.cpp
+++ llvm/lib/Bitcode/Reader/BitcodeReader.cpp
@@ -1919,6 +1919,8 @@
return Attribute::NoCfCheck;
case bitc::ATTR_KIND_NO_PROFILE:
return Attribute::NoProfile;
+ case bitc::ATTR_KIND_OMIT_PROFILE:
+ return Attribute::OmitProfile;
case bitc::ATTR_KIND_NO_UNWIND:
return Attribute::NoUnwind;
case bitc::ATTR_KIND_NO_SANITIZE_BOUNDS:
Index: llvm/include/llvm/IR/Attributes.td
===================================================================
--- llvm/include/llvm/IR/Attributes.td
+++ llvm/include/llvm/IR/Attributes.td
@@ -187,6 +187,10 @@
/// inlined into it.
def NoProfile : EnumAttr<"noprofile", [FnAttr]>;
+/// This function should not be instrumented but it is ok to inline profiled
+// functions into it.
+def OmitProfile : EnumAttr<"omitprofile", [FnAttr]>;
+
/// Function doesn't unwind stack.
def NoUnwind : EnumAttr<"nounwind", [FnAttr]>;
Index: llvm/include/llvm/Bitcode/LLVMBitCodes.h
===================================================================
--- llvm/include/llvm/Bitcode/LLVMBitCodes.h
+++ llvm/include/llvm/Bitcode/LLVMBitCodes.h
@@ -689,6 +689,7 @@
ATTR_KIND_ALLOC_KIND = 82,
ATTR_KIND_PRESPLIT_COROUTINE = 83,
ATTR_KIND_FNRETTHUNK_EXTERN = 84,
+ ATTR_KIND_OMIT_PROFILE = 85,
};
enum ComdatSelectionKindCodes {
Index: llvm/docs/LangRef.rst
===================================================================
--- llvm/docs/LangRef.rst
+++ llvm/docs/LangRef.rst
@@ -1805,6 +1805,11 @@
This function attribute prevents instrumentation based profiling, used for
coverage or profile based optimization, from being added to a function. It
also prevents instrumented functions from being inlined into this function.
+``omitprofile``
+ This function attribute prevents instrumentation based profiling, used for
+ coverage or profile based optimization, from being added to a function. This
+ attribute does not restrict inlining, so instrumented instruction could end
+ up in this function.
``noredzone``
This attribute indicates that the code generator should not use a
red zone, even if the target-specific ABI normally permits it.
Index: clang/test/CodeGen/profile-function-groups.c
===================================================================
--- clang/test/CodeGen/profile-function-groups.c
+++ clang/test/CodeGen/profile-function-groups.c
@@ -1,24 +1,24 @@
-// RUN: %clang -fprofile-generate -fprofile-function-groups=3 -fprofile-selected-function-group=0 -emit-llvm -S %s -o - | FileCheck %s --check-prefixes=CHECK,SELECT0
-// RUN: %clang -fprofile-generate -fprofile-function-groups=3 -fprofile-selected-function-group=1 -emit-llvm -S %s -o - | FileCheck %s --check-prefixes=CHECK,SELECT1
-// RUN: %clang -fprofile-generate -fprofile-function-groups=3 -fprofile-selected-function-group=2 -emit-llvm -S %s -o - | FileCheck %s --check-prefixes=CHECK,SELECT2
+// RUN: %clang -fprofile-generate -fprofile-function-groups=3 -fprofile-selected-function-group=0 -emit-llvm -S %s -o - | FileCheck %s --implicit-check-not="; {{.* (noprofile|omitprofile)}}" --check-prefixes=CHECK,SELECT0
+// RUN: %clang -fprofile-generate -fprofile-function-groups=3 -fprofile-selected-function-group=1 -emit-llvm -S %s -o - | FileCheck %s --implicit-check-not="; {{.* (noprofile|omitprofile)}}" --check-prefixes=CHECK,SELECT1
+// RUN: %clang -fprofile-generate -fprofile-function-groups=3 -fprofile-selected-function-group=2 -emit-llvm -S %s -o - | FileCheck %s --implicit-check-not="; {{.* (noprofile|omitprofile)}}" --check-prefixes=CHECK,SELECT2
// Group 0
-// SELECT0-NOT: noprofile
-// SELECT1: noprofile
-// SELECT2: noprofile
+
+// SELECT1: omitprofile
+// SELECT2: omitprofile
// CHECK: define {{.*}} @hoo()
void hoo() {}
// Group 1
-// SELECT0: noprofile
-// SELECT1-NOT: noprofile
-// SELECT2: noprofile
+// SELECT0: omitprofile
+
+// SELECT2: omitprofile
// CHECK: define {{.*}} @goo()
void goo() {}
// Group 2
-// SELECT0: noprofile
-// SELECT1: noprofile
-// SELECT2-NOT: noprofile
+// SELECT0: omitprofile
+// SELECT1: omitprofile
+
// CHECK: define {{.*}} @boo()
void boo() {}
Index: clang/lib/CodeGen/CodeGenPGO.cpp
===================================================================
--- clang/lib/CodeGen/CodeGenPGO.cpp
+++ clang/lib/CodeGen/CodeGenPGO.cpp
@@ -822,6 +822,8 @@
CGM.ClearUnusedCoverageMapping(D);
if (Fn->hasFnAttribute(llvm::Attribute::NoProfile))
return;
+ if (Fn->hasFnAttribute(llvm::Attribute::OmitProfile))
+ return;
setFuncName(Fn);
Index: clang/lib/CodeGen/CodeGenFunction.h
===================================================================
--- clang/lib/CodeGen/CodeGenFunction.h
+++ clang/lib/CodeGen/CodeGenFunction.h
@@ -1522,7 +1522,8 @@
/// If \p StepV is null, the default increment is 1.
void incrementProfileCounter(const Stmt *S, llvm::Value *StepV = nullptr) {
if (CGM.getCodeGenOpts().hasProfileClangInstr() &&
- !CurFn->hasFnAttribute(llvm::Attribute::NoProfile))
+ !CurFn->hasFnAttribute(llvm::Attribute::NoProfile) &&
+ !CurFn->hasFnAttribute(llvm::Attribute::OmitProfile))
PGO.emitCounterIncrement(Builder, S, StepV);
PGO.setCurrentStmt(S);
}
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