[clang] Add flag to experiment with cold function attributes #89298
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To be removed and promoted to a proper driver flag if experiments turn out fruitful. For now, this can be experimented with `-mllvm -pgo-cold-func-opt=[optsize|minsize|optnone|default] -mllvm -enable-pgo-force-function-attrs`. Original LLVM patch for this functionality: llvm#69030
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@llvm/pr-subscribers-clang-codegen @llvm/pr-subscribers-clang Author: Arthur Eubanks (aeubanks) ChangesTo be removed and promoted to a proper driver flag if experiments turn out fruitful. For now, this can be experimented with Original LLVM patch for this functionality: #69030 Full diff: https://github.com/llvm/llvm-project/pull/89298.diff 2 Files Affected:
diff --git a/clang/lib/CodeGen/BackendUtil.cpp b/clang/lib/CodeGen/BackendUtil.cpp
index 6cc00b85664f41..22c3f8642ad8eb 100644
--- a/clang/lib/CodeGen/BackendUtil.cpp
+++ b/clang/lib/CodeGen/BackendUtil.cpp
@@ -104,6 +104,21 @@ static cl::opt<bool> ClSanitizeOnOptimizerEarlyEP(
"sanitizer-early-opt-ep", cl::Optional,
cl::desc("Insert sanitizers on OptimizerEarlyEP."));
+// Experiment to mark cold functions as optsize/minsize/optnone.
+// TODO: remove once this is exposed as a proper driver flag.
+static cl::opt<PGOOptions::ColdFuncOpt> ClPGOColdFuncAttr(
+ "pgo-cold-func-opt", cl::init(PGOOptions::ColdFuncOpt::Default), cl::Hidden,
+ cl::desc(
+ "Function attribute to apply to cold functions as determined by PGO"),
+ cl::values(clEnumValN(PGOOptions::ColdFuncOpt::Default, "default",
+ "Default (no attribute)"),
+ clEnumValN(PGOOptions::ColdFuncOpt::OptSize, "optsize",
+ "Mark cold functions with optsize."),
+ clEnumValN(PGOOptions::ColdFuncOpt::MinSize, "minsize",
+ "Mark cold functions with minsize."),
+ clEnumValN(PGOOptions::ColdFuncOpt::OptNone, "optnone",
+ "Mark cold functions with optnone.")));
+
extern cl::opt<InstrProfCorrelator::ProfCorrelatorKind> ProfileCorrelate;
// Re-link builtin bitcodes after optimization
@@ -768,42 +783,41 @@ void EmitAssemblyHelper::RunOptimizationPipeline(
CodeGenOpts.InstrProfileOutput.empty() ? getDefaultProfileGenName()
: CodeGenOpts.InstrProfileOutput,
"", "", CodeGenOpts.MemoryProfileUsePath, nullptr, PGOOptions::IRInstr,
- PGOOptions::NoCSAction, PGOOptions::ColdFuncOpt::Default,
+ PGOOptions::NoCSAction, ClPGOColdFuncAttr,
CodeGenOpts.DebugInfoForProfiling,
/*PseudoProbeForProfiling=*/false, CodeGenOpts.AtomicProfileUpdate);
else if (CodeGenOpts.hasProfileIRUse()) {
// -fprofile-use.
auto CSAction = CodeGenOpts.hasProfileCSIRUse() ? PGOOptions::CSIRUse
: PGOOptions::NoCSAction;
- PGOOpt = PGOOptions(
- CodeGenOpts.ProfileInstrumentUsePath, "",
- CodeGenOpts.ProfileRemappingFile, CodeGenOpts.MemoryProfileUsePath, VFS,
- PGOOptions::IRUse, CSAction, PGOOptions::ColdFuncOpt::Default,
- CodeGenOpts.DebugInfoForProfiling);
+ PGOOpt = PGOOptions(CodeGenOpts.ProfileInstrumentUsePath, "",
+ CodeGenOpts.ProfileRemappingFile,
+ CodeGenOpts.MemoryProfileUsePath, VFS,
+ PGOOptions::IRUse, CSAction, ClPGOColdFuncAttr,
+ CodeGenOpts.DebugInfoForProfiling);
} else if (!CodeGenOpts.SampleProfileFile.empty())
// -fprofile-sample-use
PGOOpt = PGOOptions(
CodeGenOpts.SampleProfileFile, "", CodeGenOpts.ProfileRemappingFile,
CodeGenOpts.MemoryProfileUsePath, VFS, PGOOptions::SampleUse,
- PGOOptions::NoCSAction, PGOOptions::ColdFuncOpt::Default,
+ PGOOptions::NoCSAction, ClPGOColdFuncAttr,
CodeGenOpts.DebugInfoForProfiling, CodeGenOpts.PseudoProbeForProfiling);
else if (!CodeGenOpts.MemoryProfileUsePath.empty())
// -fmemory-profile-use (without any of the above options)
PGOOpt = PGOOptions("", "", "", CodeGenOpts.MemoryProfileUsePath, VFS,
PGOOptions::NoAction, PGOOptions::NoCSAction,
- PGOOptions::ColdFuncOpt::Default,
- CodeGenOpts.DebugInfoForProfiling);
+ ClPGOColdFuncAttr, CodeGenOpts.DebugInfoForProfiling);
else if (CodeGenOpts.PseudoProbeForProfiling)
// -fpseudo-probe-for-profiling
- PGOOpt = PGOOptions("", "", "", /*MemoryProfile=*/"", nullptr,
- PGOOptions::NoAction, PGOOptions::NoCSAction,
- PGOOptions::ColdFuncOpt::Default,
- CodeGenOpts.DebugInfoForProfiling, true);
+ PGOOpt =
+ PGOOptions("", "", "", /*MemoryProfile=*/"", nullptr,
+ PGOOptions::NoAction, PGOOptions::NoCSAction,
+ ClPGOColdFuncAttr, CodeGenOpts.DebugInfoForProfiling, true);
else if (CodeGenOpts.DebugInfoForProfiling)
// -fdebug-info-for-profiling
PGOOpt = PGOOptions("", "", "", /*MemoryProfile=*/"", nullptr,
PGOOptions::NoAction, PGOOptions::NoCSAction,
- PGOOptions::ColdFuncOpt::Default, true);
+ ClPGOColdFuncAttr, true);
// Check to see if we want to generate a CS profile.
if (CodeGenOpts.hasProfileCSIRInstr()) {
@@ -820,14 +834,13 @@ void EmitAssemblyHelper::RunOptimizationPipeline(
: CodeGenOpts.InstrProfileOutput;
PGOOpt->CSAction = PGOOptions::CSIRInstr;
} else
- PGOOpt =
- PGOOptions("",
- CodeGenOpts.InstrProfileOutput.empty()
- ? getDefaultProfileGenName()
- : CodeGenOpts.InstrProfileOutput,
- "", /*MemoryProfile=*/"", nullptr, PGOOptions::NoAction,
- PGOOptions::CSIRInstr, PGOOptions::ColdFuncOpt::Default,
- CodeGenOpts.DebugInfoForProfiling);
+ PGOOpt = PGOOptions("",
+ CodeGenOpts.InstrProfileOutput.empty()
+ ? getDefaultProfileGenName()
+ : CodeGenOpts.InstrProfileOutput,
+ "", /*MemoryProfile=*/"", nullptr,
+ PGOOptions::NoAction, PGOOptions::CSIRInstr,
+ ClPGOColdFuncAttr, CodeGenOpts.DebugInfoForProfiling);
}
if (TM)
TM->setPGOOption(PGOOpt);
diff --git a/clang/test/CodeGen/pgo-force-function-attrs.ll b/clang/test/CodeGen/pgo-force-function-attrs.ll
new file mode 100644
index 00000000000000..3e9ea95e4df410
--- /dev/null
+++ b/clang/test/CodeGen/pgo-force-function-attrs.ll
@@ -0,0 +1,12 @@
+; RUN: %clang_cc1 -O2 -mllvm -pgo-cold-func-opt=optsize -mllvm -enable-pgo-force-function-attrs -fprofile-sample-use=%S/Inputs/pgo-sample.prof %s -emit-llvm -o - | FileCheck %s --check-prefix=OPTSIZE
+; Check that no profile means no optsize
+; RUN: %clang_cc1 -O2 -mllvm -pgo-cold-func-opt=optsize -mllvm -enable-pgo-force-function-attrs %s -emit-llvm -o - | FileCheck %s --check-prefix=NONE
+; Check that no -pgo-cold-func-opt=optsize means no optsize
+; RUN: %clang_cc1 -O2 -mllvm -enable-pgo-force-function-attrs -fprofile-sample-use=%S/Inputs/pgo-sample.prof %s -emit-llvm -o - | FileCheck %s --check-prefix=NONE
+
+; NONE-NOT: optsize
+; OPTSIZE: optsize
+
+define void @f() cold {
+ ret void
+}
|
mtrofin
approved these changes
Apr 18, 2024
| CodeGenOpts.ProfileRemappingFile, CodeGenOpts.MemoryProfileUsePath, VFS, | ||
| PGOOptions::IRUse, CSAction, PGOOptions::ColdFuncOpt::Default, | ||
| CodeGenOpts.DebugInfoForProfiling); | ||
| PGOOpt = PGOOptions(CodeGenOpts.ProfileInstrumentUsePath, "", |
There was a problem hiding this comment.
could you do a clang-format, commit and rebase? This and the stuff at line 812 seems mostly that. Or does adding the ClPGOCouldFuncAttr mess up formatting?
There was a problem hiding this comment.
running clang-format on this file at main doesn't change these lines, so it seems like it is ClPGOCouldFuncAttr
aniplcc
pushed a commit
to aniplcc/llvm-project
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Apr 21, 2024
) To be removed and promoted to a proper driver flag if experiments turn out fruitful. For now, this can be experimented with `-mllvm -pgo-cold-func-opt=[optsize|minsize|optnone|default] -mllvm -enable-pgo-force-function-attrs`. Original LLVM patch for this functionality: llvm#69030
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To be removed and promoted to a proper driver flag if experiments turn out fruitful.
For now, this can be experimented with
-mllvm -pgo-cold-func-opt=[optsize|minsize|optnone|default] -mllvm -enable-pgo-force-function-attrs.Original LLVM patch for this functionality: #69030