[clang] [llvm] [InstrPGO] Instrument sampling profile based cold function (PR #109837)
Lei Wang via cfe-commits
cfe-commits at lists.llvm.org
Tue Sep 24 10:28:33 PDT 2024
https://github.com/wlei-llvm created https://github.com/llvm/llvm-project/pull/109837
None
>From b693ff3c33dcf21c1343d9d3432b1d7410a8b579 Mon Sep 17 00:00:00 2001
From: wlei <wlei at fb.com>
Date: Sun, 22 Sep 2024 20:23:20 -0700
Subject: [PATCH] [InstrPGO] Instrument sampling profile based cold function
---
clang/include/clang/Driver/Options.td | 6 +++++
clang/lib/Driver/ToolChain.cpp | 4 +++-
clang/lib/Driver/ToolChains/Clang.cpp | 14 +++++++++++
llvm/lib/Passes/PassBuilderPipelines.cpp | 16 +++++++++++++
.../Instrumentation/PGOInstrumentation.cpp | 14 +++++++++++
.../PGOProfile/instr-gen-cold-function.ll | 24 +++++++++++++++++++
6 files changed, 77 insertions(+), 1 deletion(-)
create mode 100644 llvm/test/Transforms/PGOProfile/instr-gen-cold-function.ll
diff --git a/clang/include/clang/Driver/Options.td b/clang/include/clang/Driver/Options.td
index 002f60350543d9..0ac289089839d2 100644
--- a/clang/include/clang/Driver/Options.td
+++ b/clang/include/clang/Driver/Options.td
@@ -1784,6 +1784,12 @@ defm debug_info_for_profiling : BoolFOption<"debug-info-for-profiling",
PosFlag<SetTrue, [], [ClangOption, CC1Option],
"Emit extra debug info to make sample profile more accurate">,
NegFlag<SetFalse>>;
+def fprofile_sample_cold_function : Flag<["-"], "fprofile-sample-cold-function">,
+ Group<f_Group>, Visibility<[ClangOption, CLOption]>,
+ HelpText<"Generate instrumented code to cold functions guided by sampling-based profile into default.profraw file (overridden by '=' form of option or LLVM_PROFILE_FILE env var)">;
+def fprofile_sample_cold_function_EQ : Joined<["-"], "fprofile-sample-cold-function=">,
+ Group<f_Group>, Visibility<[ClangOption, CLOption]>, MetaVarName<"<file>">,
+ HelpText<"Generate instrumented code to cold functions guided by sampling-based profile into <file> (overridden by LLVM_PROFILE_FILE env var)">;
def fprofile_instr_generate : Flag<["-"], "fprofile-instr-generate">,
Group<f_Group>, Visibility<[ClangOption, CLOption]>,
HelpText<"Generate instrumented code to collect execution counts into default.profraw file (overridden by '=' form of option or LLVM_PROFILE_FILE env var)">;
diff --git a/clang/lib/Driver/ToolChain.cpp b/clang/lib/Driver/ToolChain.cpp
index 16f9b629fc538c..5cd821cfe780c4 100644
--- a/clang/lib/Driver/ToolChain.cpp
+++ b/clang/lib/Driver/ToolChain.cpp
@@ -889,7 +889,9 @@ bool ToolChain::needsProfileRT(const ArgList &Args) {
Args.hasArg(options::OPT_fprofile_instr_generate) ||
Args.hasArg(options::OPT_fprofile_instr_generate_EQ) ||
Args.hasArg(options::OPT_fcreate_profile) ||
- Args.hasArg(options::OPT_forder_file_instrumentation);
+ Args.hasArg(options::OPT_forder_file_instrumentation) ||
+ Args.hasArg(options::OPT_fprofile_sample_cold_function) ||
+ Args.hasArg(options::OPT_fprofile_sample_cold_function_EQ);
}
bool ToolChain::needsGCovInstrumentation(const llvm::opt::ArgList &Args) {
diff --git a/clang/lib/Driver/ToolChains/Clang.cpp b/clang/lib/Driver/ToolChains/Clang.cpp
index 0bab48caf1a5e2..85e9e02ca8a4ee 100644
--- a/clang/lib/Driver/ToolChains/Clang.cpp
+++ b/clang/lib/Driver/ToolChains/Clang.cpp
@@ -649,6 +649,20 @@ static void addPGOAndCoverageFlags(const ToolChain &TC, Compilation &C,
}
}
+ if (auto *SampleColdArg =
+ Args.getLastArg(options::OPT_fprofile_sample_cold_function,
+ options::OPT_fprofile_sample_cold_function_EQ)) {
+ SmallString<128> Path;
+ if (SampleColdArg->getOption().matches(options::OPT_fprofile_sample_cold_function_EQ))
+ Path.append(SampleColdArg->getValue());
+ else
+ Path.append("default_%m.profraw");
+
+ CmdArgs.push_back("-mllvm");
+ CmdArgs.push_back(Args.MakeArgString(
+ Twine("--instrument-sample-cold-function-path=") + Path));
+ }
+
Arg *PGOGenArg = nullptr;
if (PGOGenerateArg) {
assert(!CSPGOGenerateArg);
diff --git a/llvm/lib/Passes/PassBuilderPipelines.cpp b/llvm/lib/Passes/PassBuilderPipelines.cpp
index 8f151a99b11709..5d1d8480b1472d 100644
--- a/llvm/lib/Passes/PassBuilderPipelines.cpp
+++ b/llvm/lib/Passes/PassBuilderPipelines.cpp
@@ -296,7 +296,13 @@ static cl::opt<bool> UseLoopVersioningLICM(
"enable-loop-versioning-licm", cl::init(false), cl::Hidden,
cl::desc("Enable the experimental Loop Versioning LICM pass"));
+static cl::opt<std::string> InstrumentSampleColdFuncPath(
+ "instrument-sample-cold-function-path", cl::init(""),
+ cl::desc("File path for instrumenting sampling PGO guided cold functions"),
+ cl::Hidden);
+
extern cl::opt<std::string> UseCtxProfile;
+extern cl::opt<bool> InstrumentColdFunction;
namespace llvm {
extern cl::opt<bool> EnableMemProfContextDisambiguation;
@@ -1119,6 +1125,16 @@ PassBuilder::buildModuleSimplificationPipeline(OptimizationLevel Level,
// removed.
MPM.addPass(
PGOIndirectCallPromotion(true /* IsInLTO */, true /* SamplePGO */));
+
+ if (InstrumentSampleColdFuncPath.getNumOccurrences() && Phase != ThinOrFullLTOPhase::ThinLTOPostLink) {
+ assert(!InstrumentSampleColdFuncPath.empty() &&
+ "File path is requeired for instrumentation generation");
+ InstrumentColdFunction = true;
+ addPreInlinerPasses(MPM, Level, Phase);
+ addPGOInstrPasses(MPM, Level, /* RunProfileGen */ true,
+ /* IsCS */ false, /* AtomicCounterUpdate */ false,
+ InstrumentSampleColdFuncPath, "", PGOOpt->FS);
+ }
}
// Try to perform OpenMP specific optimizations on the module. This is a
diff --git a/llvm/lib/Transforms/Instrumentation/PGOInstrumentation.cpp b/llvm/lib/Transforms/Instrumentation/PGOInstrumentation.cpp
index 10442fa0bb9003..cbd14567d97c95 100644
--- a/llvm/lib/Transforms/Instrumentation/PGOInstrumentation.cpp
+++ b/llvm/lib/Transforms/Instrumentation/PGOInstrumentation.cpp
@@ -319,6 +319,16 @@ static cl::opt<unsigned> PGOFunctionCriticalEdgeThreshold(
cl::desc("Do not instrument functions with the number of critical edges "
" greater than this threshold."));
+cl::opt<bool> InstrumentColdFunction(
+ "instrument-cold-function", cl::init(false), cl::Hidden,
+ cl::desc("Instrument cold functions (currently only used under sampling "
+ " PGO pipeline))"));
+
+static cl::opt<uint64_t> InstrumentColdFuncMaxEntryCount(
+ "instrument-cold-function-max-entry-count", cl::init(0), cl::Hidden,
+ cl::desc("When using --instrument-cold-function, skip instrumenting the "
+ "function whose entry count is above the given value"));
+
extern cl::opt<unsigned> MaxNumVTableAnnotations;
namespace llvm {
@@ -1891,6 +1901,10 @@ static bool skipPGOGen(const Function &F) {
return true;
if (F.getInstructionCount() < PGOFunctionSizeThreshold)
return true;
+ if (InstrumentColdFunction &&
+ (!F.getEntryCount() ||
+ F.getEntryCount()->getCount() > InstrumentColdFuncMaxEntryCount))
+ return true;
return false;
}
diff --git a/llvm/test/Transforms/PGOProfile/instr-gen-cold-function.ll b/llvm/test/Transforms/PGOProfile/instr-gen-cold-function.ll
new file mode 100644
index 00000000000000..14d3b3c7e9b6fa
--- /dev/null
+++ b/llvm/test/Transforms/PGOProfile/instr-gen-cold-function.ll
@@ -0,0 +1,24 @@
+; RUN: opt < %s --passes=pgo-instr-gen -instrument-cold-function -S | FileCheck --check-prefixes=COLD %s
+; RUN: opt < %s --passes=pgo-instr-gen -instrument-cold-function -instrument-cold-function-max-entry-count=1 -S | FileCheck --check-prefixes=ENTRY-COUNT %s
+
+; COLD: call void @llvm.instrprof.increment(ptr @__profn_foo, i64 [[#]], i32 1, i32 0)
+; COLD-NOT: __profn_main
+
+; ENTRY-COUNT: call void @llvm.instrprof.increment(ptr @__profn_foo, i64 [[#]], i32 1, i32 0)
+; ENTRY-COUNT: call void @llvm.instrprof.increment(ptr @__profn_main, i64 [[#]], i32 1, i32 0)
+
+target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-i128:128-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+define void @foo() !prof !0 {
+entry:
+ ret void
+}
+
+define i32 @main() !prof !1 {
+entry:
+ ret i32 0
+}
+
+!0 = !{!"function_entry_count", i64 0}
+!1 = !{!"function_entry_count", i64 1}
More information about the cfe-commits
mailing list