[clang] bef3b54 - [InstrPGO] Avoid using global variable to fix potential data race (#114364)
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cfe-commits at lists.llvm.org
Thu Oct 31 21:28:16 PDT 2024
Author: Lei Wang
Date: 2024-10-31T21:28:13-07:00
New Revision: bef3b54ea10a564a2de72f658f2efd64f537c079
URL: https://github.com/llvm/llvm-project/commit/bef3b54ea10a564a2de72f658f2efd64f537c079
DIFF: https://github.com/llvm/llvm-project/commit/bef3b54ea10a564a2de72f658f2efd64f537c079.diff
LOG: [InstrPGO] Avoid using global variable to fix potential data race (#114364)
In https://github.com/llvm/llvm-project/pull/109837, it sets a global
variable(`PGOInstrumentColdFunctionOnly`) in PassBuilderPipelines.cpp
which introduced a data race detected by TSan. To fix this, I decouple
the flag setting, the flags are now set
separately(`instrument-cold-function-only-path` is required to be used
with `--pgo-instrument-cold-function-only`).
Added:
clang/test/CodeGen/pgo-cold-function-coverage.c
clang/test/Driver/fprofile-generate-cold-function-coverage.c
llvm/test/Transforms/PGOProfile/instr-gen-cold-function.ll
Modified:
clang/include/clang/Driver/Options.td
clang/lib/Driver/ToolChain.cpp
clang/lib/Driver/ToolChains/Clang.cpp
llvm/lib/Passes/PassBuilderPipelines.cpp
llvm/lib/Transforms/Instrumentation/PGOInstrumentation.cpp
Removed:
################################################################################
diff --git a/clang/include/clang/Driver/Options.td b/clang/include/clang/Driver/Options.td
index 7a05cc03353ac1..3434f2e7e305ca 100644
--- a/clang/include/clang/Driver/Options.td
+++ b/clang/include/clang/Driver/Options.td
@@ -1786,6 +1786,12 @@ 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_generate_cold_function_coverage : Flag<["-"], "fprofile-generate-cold-function-coverage">,
+ Group<f_Group>, Visibility<[ClangOption, CLOption]>,
+ HelpText<"Generate instrumented code to collect coverage info for cold functions into default.profraw file (overridden by '=' form of option or LLVM_PROFILE_FILE env var)">;
+def fprofile_generate_cold_function_coverage_EQ : Joined<["-"], "fprofile-generate-cold-function-coverage=">,
+ Group<f_Group>, Visibility<[ClangOption, CLOption]>, MetaVarName<"<directory>">,
+ HelpText<"Generate instrumented code to collect coverage info for cold functions into <directory>/default.profraw (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 6d3ede40691093..bdf3da0c96adca 100644
--- a/clang/lib/Driver/ToolChain.cpp
+++ b/clang/lib/Driver/ToolChain.cpp
@@ -899,7 +899,9 @@ 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_generate_cold_function_coverage) ||
+ Args.hasArg(options::OPT_fprofile_generate_cold_function_coverage_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 db2a4c4d6ff974..dca8d3fd7b3eaf 100644
--- a/clang/lib/Driver/ToolChains/Clang.cpp
+++ b/clang/lib/Driver/ToolChains/Clang.cpp
@@ -632,6 +632,28 @@ static void addPGOAndCoverageFlags(const ToolChain &TC, Compilation &C,
}
}
+ if (auto *ColdFuncCoverageArg = Args.getLastArg(
+ options::OPT_fprofile_generate_cold_function_coverage,
+ options::OPT_fprofile_generate_cold_function_coverage_EQ)) {
+ SmallString<128> Path(
+ ColdFuncCoverageArg->getOption().matches(
+ options::OPT_fprofile_generate_cold_function_coverage_EQ)
+ ? ColdFuncCoverageArg->getValue()
+ : "");
+ llvm::sys::path::append(Path, "default_%m.profraw");
+ // FIXME: Idealy the file path should be passed through
+ // `-fprofile-instrument-path=`(InstrProfileOutput), however, this field is
+ // shared with other profile use path(see PGOOptions), we need to refactor
+ // PGOOptions to make it work.
+ CmdArgs.push_back("-mllvm");
+ CmdArgs.push_back(Args.MakeArgString(
+ Twine("--instrument-cold-function-only-path=") + Path));
+ CmdArgs.push_back("-mllvm");
+ CmdArgs.push_back("--pgo-instrument-cold-function-only");
+ CmdArgs.push_back("-mllvm");
+ CmdArgs.push_back("--pgo-function-entry-coverage");
+ }
+
Arg *PGOGenArg = nullptr;
if (PGOGenerateArg) {
assert(!CSPGOGenerateArg);
diff --git a/clang/test/CodeGen/pgo-cold-function-coverage.c b/clang/test/CodeGen/pgo-cold-function-coverage.c
new file mode 100644
index 00000000000000..3003cdc3e15e02
--- /dev/null
+++ b/clang/test/CodeGen/pgo-cold-function-coverage.c
@@ -0,0 +1,19 @@
+// Test -fprofile-generate-cold-function-coverage
+
+// RUN: rm -rf %t && split-file %s %t
+// RUN: %clang --target=x86_64 -O2 -fprofile-generate-cold-function-coverage=/xxx/yyy/ -fprofile-sample-accurate -fprofile-sample-use=%t/pgo-cold-func.prof -S -emit-llvm -o - %t/pgo-cold-func.c | FileCheck %s
+
+// CHECK: @__llvm_profile_filename = {{.*}} c"/xxx/yyy/default_%m.profraw\00"
+
+// CHECK: store i8 0, ptr @__profc_bar, align 1
+// CHECK-NOT: @__profc_foo
+
+//--- pgo-cold-func.prof
+foo:1:1
+ 1: 1
+
+//--- pgo-cold-func.c
+int bar(int x) { return x;}
+int foo(int x) {
+ return x;
+}
diff --git a/clang/test/Driver/fprofile-generate-cold-function-coverage.c b/clang/test/Driver/fprofile-generate-cold-function-coverage.c
new file mode 100644
index 00000000000000..135acf2e736f79
--- /dev/null
+++ b/clang/test/Driver/fprofile-generate-cold-function-coverage.c
@@ -0,0 +1,9 @@
+// RUN: %clang -### -c -fprofile-generate-cold-function-coverage %s 2>&1 | FileCheck %s
+// CHECK: "--instrument-cold-function-only-path=default_%m.profraw"
+// CHECK: "--pgo-instrument-cold-function-only"
+// CHECK: "--pgo-function-entry-coverage"
+// CHECK-NOT: "-fprofile-instrument"
+// CHECK-NOT: "-fprofile-instrument-path=
+
+// RUN: %clang -### -c -fprofile-generate-cold-function-coverage=dir %s 2>&1 | FileCheck %s --check-prefix=CHECK-EQ
+// CHECK-EQ: "--instrument-cold-function-only-path=dir{{/|\\\\}}default_%m.profraw"
diff --git a/llvm/lib/Passes/PassBuilderPipelines.cpp b/llvm/lib/Passes/PassBuilderPipelines.cpp
index 0585e83e59a9ab..3f28dd39911f79 100644
--- a/llvm/lib/Passes/PassBuilderPipelines.cpp
+++ b/llvm/lib/Passes/PassBuilderPipelines.cpp
@@ -296,7 +296,14 @@ 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> InstrumentColdFuncOnlyPath(
+ "instrument-cold-function-only-path", cl::init(""),
+ cl::desc("File path for cold function only instrumentation(requires use "
+ "with --pgo-instrument-cold-function-only)"),
+ cl::Hidden);
+
extern cl::opt<std::string> UseCtxProfile;
+extern cl::opt<bool> PGOInstrumentColdFunctionOnly;
namespace llvm {
extern cl::opt<bool> EnableMemProfContextDisambiguation;
@@ -1183,8 +1190,16 @@ PassBuilder::buildModuleSimplificationPipeline(OptimizationLevel Level,
const bool IsCtxProfUse =
!UseCtxProfile.empty() && Phase == ThinOrFullLTOPhase::ThinLTOPreLink;
+ assert(
+ (InstrumentColdFuncOnlyPath.empty() || PGOInstrumentColdFunctionOnly) &&
+ "--instrument-cold-function-only-path is provided but "
+ "--pgo-instrument-cold-function-only is not enabled");
+ const bool IsColdFuncOnlyInstrGen = PGOInstrumentColdFunctionOnly &&
+ IsPGOPreLink &&
+ !InstrumentColdFuncOnlyPath.empty();
+
if (IsPGOInstrGen || IsPGOInstrUse || IsMemprofUse || IsCtxProfGen ||
- IsCtxProfUse)
+ IsCtxProfUse || IsColdFuncOnlyInstrGen)
addPreInlinerPasses(MPM, Level, Phase);
// Add all the requested passes for instrumentation PGO, if requested.
@@ -1206,6 +1221,11 @@ PassBuilder::buildModuleSimplificationPipeline(OptimizationLevel Level,
return MPM;
addPostPGOLoopRotation(MPM, Level);
MPM.addPass(PGOCtxProfLoweringPass());
+ } else if (IsColdFuncOnlyInstrGen) {
+ addPGOInstrPasses(
+ MPM, Level, /* RunProfileGen */ true, /* IsCS */ false,
+ /* AtomicCounterUpdate */ false, InstrumentColdFuncOnlyPath,
+ /* ProfileRemappingFile */ "", IntrusiveRefCntPtr<vfs::FileSystem>());
}
if (IsPGOInstrGen || IsPGOInstrUse || IsCtxProfGen)
diff --git a/llvm/lib/Transforms/Instrumentation/PGOInstrumentation.cpp b/llvm/lib/Transforms/Instrumentation/PGOInstrumentation.cpp
index bceb6135cc1f92..4d8141431a0c19 100644
--- a/llvm/lib/Transforms/Instrumentation/PGOInstrumentation.cpp
+++ b/llvm/lib/Transforms/Instrumentation/PGOInstrumentation.cpp
@@ -319,6 +319,20 @@ static cl::opt<unsigned> PGOFunctionCriticalEdgeThreshold(
cl::desc("Do not instrument functions with the number of critical edges "
" greater than this threshold."));
+static cl::opt<uint64_t> PGOColdInstrumentEntryThreshold(
+ "pgo-cold-instrument-entry-threshold", cl::init(0), cl::Hidden,
+ cl::desc("For cold function instrumentation, skip instrumenting functions "
+ "whose entry count is above the given value."));
+
+static cl::opt<bool> PGOTreatUnknownAsCold(
+ "pgo-treat-unknown-as-cold", cl::init(false), cl::Hidden,
+ cl::desc("For cold function instrumentation, treat count unknown(e.g. "
+ "unprofiled) functions as cold."));
+
+cl::opt<bool> PGOInstrumentColdFunctionOnly(
+ "pgo-instrument-cold-function-only", cl::init(false), cl::Hidden,
+ cl::desc("Enable cold function only instrumentation."));
+
extern cl::opt<unsigned> MaxNumVTableAnnotations;
namespace llvm {
@@ -1897,6 +1911,11 @@ static bool skipPGOGen(const Function &F) {
return true;
if (F.getInstructionCount() < PGOFunctionSizeThreshold)
return true;
+ if (PGOInstrumentColdFunctionOnly) {
+ if (auto EntryCount = F.getEntryCount())
+ return EntryCount->getCount() > PGOColdInstrumentEntryThreshold;
+ return !PGOTreatUnknownAsCold;
+ }
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..ab8cf8c010812b
--- /dev/null
+++ b/llvm/test/Transforms/PGOProfile/instr-gen-cold-function.ll
@@ -0,0 +1,35 @@
+; RUN: opt < %s --passes=pgo-instr-gen -pgo-instrument-cold-function-only -pgo-function-entry-coverage -S | FileCheck --check-prefixes=COLD %s
+; RUN: opt < %s --passes=pgo-instr-gen -pgo-instrument-cold-function-only -pgo-function-entry-coverage -pgo-cold-instrument-entry-threshold=1 -S | FileCheck --check-prefixes=ENTRY-COUNT %s
+; RUN: opt < %s --passes=pgo-instr-gen -pgo-instrument-cold-function-only -pgo-function-entry-coverage -pgo-treat-unknown-as-cold -S | FileCheck --check-prefixes=UNKNOWN-FUNC %s
+
+; COLD: call void @llvm.instrprof.cover(ptr @__profn_foo, i64 [[#]], i32 1, i32 0)
+; COLD-NOT: __profn_main
+; COLD-NOT: __profn_bar
+
+; ENTRY-COUNT: call void @llvm.instrprof.cover(ptr @__profn_foo, i64 [[#]], i32 1, i32 0)
+; ENTRY-COUNT: call void @llvm.instrprof.cover(ptr @__profn_main, i64 [[#]], i32 1, i32 0)
+
+; UNKNOWN-FUNC: call void @llvm.instrprof.cover(ptr @__profn_bar, i64 [[#]], i32 1, i32 0)
+; UNKNOWN-FUNC: call void @llvm.instrprof.cover(ptr @__profn_foo, 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 @bar() {
+entry:
+ ret void
+}
+
+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}
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