[PGO] Generate __llvm_profile_raw_version only when instrumented #93917
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The 'PGOInstrumentationGen' pass should preserve all analysis results when nothing was actually instrumented. Currently, only modules that contain at least a single function definition are instrumented. When a module contains only function declarations and, optionally, global variable definitions (a module for the regular-LTO phase for thin-LTO when LTOUnit splitting is enabled, for example), such module is not instrumented (yet?) and there is no reason to invalidate any analysis results. NFC.
Currently, only modules that contain at least a single function definition are instrumented. When a module contains no function definitions at all, the module is not instrumented (yet?) and there is no reason to introduce the '__llvm_profile_raw_version' variable into the module.
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@llvm/pr-subscribers-llvm-transforms @llvm/pr-subscribers-pgo Author: Pavel Samolysov (samolisov) ChangesCurrently, only modules that contain at least a single function Full diff: https://github.com/llvm/llvm-project/pull/93917.diff 5 Files Affected:
diff --git a/llvm/lib/Transforms/Instrumentation/PGOInstrumentation.cpp b/llvm/lib/Transforms/Instrumentation/PGOInstrumentation.cpp
index 2269c2e0fffae..ff94fc98d0117 100644
--- a/llvm/lib/Transforms/Instrumentation/PGOInstrumentation.cpp
+++ b/llvm/lib/Transforms/Instrumentation/PGOInstrumentation.cpp
@@ -405,9 +405,14 @@ static GlobalVariable *createIRLevelProfileFlagVar(Module &M, bool IsCS) {
ProfileVersion |= VARIANT_MASK_BYTE_COVERAGE;
if (PGOTemporalInstrumentation)
ProfileVersion |= VARIANT_MASK_TEMPORAL_PROF;
- auto IRLevelVersionVariable = new GlobalVariable(
+ assert(!M.global_empty() &&
+ "If a module was instrumented, there must be defined global variables "
+ "at least for the counters.");
+ auto *InsertionPoint = &*M.global_begin();
+ auto *IRLevelVersionVariable = new GlobalVariable(
M, IntTy64, true, GlobalValue::WeakAnyLinkage,
- Constant::getIntegerValue(IntTy64, APInt(64, ProfileVersion)), VarName);
+ Constant::getIntegerValue(IntTy64, APInt(64, ProfileVersion)), VarName,
+ InsertionPoint);
IRLevelVersionVariable->setVisibility(GlobalValue::HiddenVisibility);
Triple TT(M.getTargetTriple());
if (TT.supportsCOMDAT()) {
@@ -1829,11 +1834,6 @@ static bool InstrumentAllFunctions(
Module &M, function_ref<TargetLibraryInfo &(Function &)> LookupTLI,
function_ref<BranchProbabilityInfo *(Function &)> LookupBPI,
function_ref<BlockFrequencyInfo *(Function &)> LookupBFI, bool IsCS) {
- // For the context-sensitve instrumentation, we should have a separated pass
- // (before LTO/ThinLTO linking) to create these variables.
- if (!IsCS && !PGOCtxProfLoweringPass::isContextualIRPGOEnabled())
- createIRLevelProfileFlagVar(M, /*IsCS=*/false);
-
Triple TT(M.getTargetTriple());
LLVMContext &Ctx = M.getContext();
if (!TT.isOSBinFormatELF() && EnableVTableValueProfiling)
@@ -1845,6 +1845,7 @@ static bool InstrumentAllFunctions(
std::unordered_multimap<Comdat *, GlobalValue *> ComdatMembers;
collectComdatMembers(M, ComdatMembers);
+ bool AnythingInstrumented = false;
for (auto &F : M) {
if (skipPGOGen(F))
continue;
@@ -1852,7 +1853,17 @@ static bool InstrumentAllFunctions(
auto *BPI = LookupBPI(F);
auto *BFI = LookupBFI(F);
instrumentOneFunc(F, &M, TLI, BPI, BFI, ComdatMembers, IsCS);
+ AnythingInstrumented = true;
}
+
+ if (!AnythingInstrumented)
+ return false;
+
+ // For the context-sensitve instrumentation, we should have a separated pass
+ // (before LTO/ThinLTO linking) to create these variables.
+ if (!IsCS && !PGOCtxProfLoweringPass::isContextualIRPGOEnabled())
+ createIRLevelProfileFlagVar(M, /*IsCS=*/false);
+
return true;
}
diff --git a/llvm/test/Transforms/PGOProfile/declarations_only.ll b/llvm/test/Transforms/PGOProfile/declarations_only.ll
index e7208fc264c7c..7a975725410c9 100644
--- a/llvm/test/Transforms/PGOProfile/declarations_only.ll
+++ b/llvm/test/Transforms/PGOProfile/declarations_only.ll
@@ -1,13 +1,8 @@
-; RUN: opt < %s -passes=pgo-instr-gen -S | FileCheck %s --check-prefix=GEN --check-prefix=GEN-COMDAT
+; RUN: opt < %s -passes=pgo-instr-gen -S | FileCheck %s --implicit-check-not='__llvm_profile_raw_version'
target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
target triple = "x86_64-unknown-linux-gnu"
-; GEN-COMDAT: $__llvm_profile_raw_version = comdat any
-; GEN-COMDAT: @__llvm_profile_raw_version = hidden constant i64 {{[0-9]+}}, comdat
-; GEN-NOT: @__profn_test_1 = private constant [6 x i8] c"test_1"
-; GEN-NOT: @__profn_test_2 = private constant [6 x i8] c"test_2"
-
declare i32 @test_1(i32 %i)
declare i32 @test_2(i32 %i)
diff --git a/llvm/test/Transforms/PGOProfile/global_variables_only.ll b/llvm/test/Transforms/PGOProfile/global_variables_only.ll
index 3bfa29af5d34f..46628bfafe534 100644
--- a/llvm/test/Transforms/PGOProfile/global_variables_only.ll
+++ b/llvm/test/Transforms/PGOProfile/global_variables_only.ll
@@ -1,9 +1,6 @@
-; RUN: opt < %s -passes=pgo-instr-gen -S | FileCheck %s --check-prefix=GEN-COMDAT
+; RUN: opt < %s -passes=pgo-instr-gen -S | FileCheck %s --implicit-check-not='__llvm_profile_raw_version'
target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
target triple = "x86_64-unknown-linux-gnu"
-; GEN-COMDAT: $__llvm_profile_raw_version = comdat any
-; GEN-COMDAT: @__llvm_profile_raw_version = hidden constant i64 {{[0-9]+}}, comdat
-
@var = internal unnamed_addr global [35 x ptr] zeroinitializer, align 16
diff --git a/llvm/test/Transforms/PGOProfile/no_global_variables.ll b/llvm/test/Transforms/PGOProfile/no_global_variables.ll
new file mode 100644
index 0000000000000..0faa2f35274c9
--- /dev/null
+++ b/llvm/test/Transforms/PGOProfile/no_global_variables.ll
@@ -0,0 +1,15 @@
+; RUN: opt < %s -passes=pgo-instr-gen -S | FileCheck %s --check-prefix=GEN-COMDAT
+target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+; GEN-COMDAT: $__llvm_profile_raw_version = comdat any
+; GEN-COMDAT: @__llvm_profile_raw_version = hidden constant i64 {{[0-9]+}}, comdat
+
+define i32 @test_1(i32 %i) {
+entry:
+ ret i32 0
+}
+
+define i32 @test_2(i32 %i) {
+entry:
+ ret i32 1
+}
diff --git a/llvm/unittests/Transforms/Instrumentation/PGOInstrumentationTest.cpp b/llvm/unittests/Transforms/Instrumentation/PGOInstrumentationTest.cpp
index 02c2df2a138b0..01d17c5059a1a 100644
--- a/llvm/unittests/Transforms/Instrumentation/PGOInstrumentationTest.cpp
+++ b/llvm/unittests/Transforms/Instrumentation/PGOInstrumentationTest.cpp
@@ -104,9 +104,13 @@ class MockModuleAnalysisHandle
ModuleAnalysisManager::Invalidator &));
};
-struct PGOInstrumentationGenTest
- : public Test,
- WithParamInterface<std::tuple<StringRef, StringRef>> {
+template <typename ParamType> struct PGOTestName {
+ std::string operator()(const TestParamInfo<ParamType> &Info) const {
+ return std::get<1>(Info.param).str();
+ }
+};
+
+struct PGOInstrumentationGenTest : public Test {
LLVMContext Ctx;
ModulePassManager MPM;
PassBuilder PB;
@@ -143,12 +147,47 @@ struct PGOInstrumentationGenTest
}
};
+struct PGOInstrumentationGenInstrumentTest
+ : PGOInstrumentationGenTest,
+ WithParamInterface<std::tuple<StringRef, StringRef>> {};
+
static constexpr StringRef CodeWithFuncDefs = R"(
define i32 @f(i32 %n) {
entry:
ret i32 0
})";
+INSTANTIATE_TEST_SUITE_P(
+ PGOInstrumetationGenTestSuite, PGOInstrumentationGenInstrumentTest,
+ Values(std::make_tuple(CodeWithFuncDefs, "instrument_function_defs")),
+ PGOTestName<PGOInstrumentationGenInstrumentTest::ParamType>());
+
+TEST_P(PGOInstrumentationGenInstrumentTest, Instrumented) {
+ const StringRef Code = std::get<0>(GetParam());
+ parseAssembly(Code);
+
+ ASSERT_THAT(M, NotNull());
+
+ Sequence PassSequence;
+ EXPECT_CALL(MMAHandle, run(Ref(*M), _))
+ .InSequence(PassSequence)
+ .WillOnce(DoDefault());
+ EXPECT_CALL(MMAHandle, invalidate(Ref(*M), _, _))
+ .InSequence(PassSequence)
+ .WillOnce(DoDefault());
+
+ MPM.run(*M, MAM);
+
+ const auto *IRInstrVar =
+ M->getNamedGlobal(INSTR_PROF_QUOTE(INSTR_PROF_RAW_VERSION_VAR));
+ EXPECT_THAT(IRInstrVar, NotNull());
+ EXPECT_FALSE(IRInstrVar->isDeclaration());
+}
+
+struct PGOInstrumentationGenIgnoreTest
+ : PGOInstrumentationGenTest,
+ WithParamInterface<std::tuple<StringRef, StringRef>> {};
+
static constexpr StringRef CodeWithFuncDecls = R"(
declare i32 @f(i32);
)";
@@ -159,34 +198,26 @@ static constexpr StringRef CodeWithGlobals = R"(
)";
INSTANTIATE_TEST_SUITE_P(
- PGOInstrumetationGenTestSuite, PGOInstrumentationGenTest,
- Values(std::make_tuple(CodeWithFuncDefs, "instrument_function_defs"),
- std::make_tuple(CodeWithFuncDecls, "instrument_function_decls"),
+ PGOInstrumetationGenIgnoreTestSuite, PGOInstrumentationGenIgnoreTest,
+ Values(std::make_tuple(CodeWithFuncDecls, "instrument_function_decls"),
std::make_tuple(CodeWithGlobals, "instrument_globals")),
- [](const TestParamInfo<PGOInstrumentationGenTest::ParamType> &Info) {
- return std::get<1>(Info.param).str();
- });
+ PGOTestName<PGOInstrumentationGenIgnoreTest::ParamType>());
-TEST_P(PGOInstrumentationGenTest, Instrumented) {
+TEST_P(PGOInstrumentationGenIgnoreTest, NotInstrumented) {
const StringRef Code = std::get<0>(GetParam());
+
parseAssembly(Code);
ASSERT_THAT(M, NotNull());
- Sequence PassSequence;
- EXPECT_CALL(MMAHandle, run(Ref(*M), _))
- .InSequence(PassSequence)
- .WillOnce(DoDefault());
- EXPECT_CALL(MMAHandle, invalidate(Ref(*M), _, _))
- .InSequence(PassSequence)
- .WillOnce(DoDefault());
+ EXPECT_CALL(MMAHandle, run(Ref(*M), _)).WillOnce(DoDefault());
+ EXPECT_CALL(MMAHandle, invalidate(Ref(*M), _, _)).Times(0);
MPM.run(*M, MAM);
const auto *IRInstrVar =
M->getNamedGlobal(INSTR_PROF_QUOTE(INSTR_PROF_RAW_VERSION_VAR));
- EXPECT_THAT(IRInstrVar, NotNull());
- EXPECT_FALSE(IRInstrVar->isDeclaration());
+ EXPECT_THAT(IRInstrVar, IsNull());
}
} // end anonymous namespace
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It seems, github doesn't allow to modify the source branch for a PR, so I cannot convert an already opened PR #93421 into a stacked one. I've pushed exactly the same commits into the https://github.com/llvm/llvm-project/tree/users/psamolysov/pgo-instrument-when-at-least-one-definition branch and opened this PR into that branch. There are some conflicts but I believe they will be solved after landing the changes from #93421 into main. This commit is reviewable: 5d5ead1 |
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What's the benefit to this change? From a compile time perspective, files containing no functions are essentially negligible. From a consistency perspective, not adding |
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@aeubanks my intent is to get no |
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Currently, only modules that contain at least a single function
definition are instrumented. When a module contains no function
definitions at all, the module is not instrumented (yet?) and there is
no reason to introduce the '__llvm_profile_raw_version' variable into
the module.