diff --git a/llvm/include/llvm/Analysis/StaticDataProfileInfo.h b/llvm/include/llvm/Analysis/StaticDataProfileInfo.h index fa21eba1377df..f06e7ceaa74ce 100644 --- a/llvm/include/llvm/Analysis/StaticDataProfileInfo.h +++ b/llvm/include/llvm/Analysis/StaticDataProfileInfo.h @@ -10,6 +10,24 @@ namespace llvm { +namespace memprof { +// Represents the eligibility status of a global variable for section prefix +// annotation. Other than AnnotationOk, each enum value indicates a specific +// reason for ineligibility. +enum class AnnotationKind : uint8_t { + AnnotationOK, + DeclForLinker, + ExplicitSection, + ReservedName, +}; +/// Returns the annotation kind of the global variable \p GV. +AnnotationKind getAnnotationKind(const GlobalVariable &GV); + +/// Returns true if the annotation kind of the global variable \p GV is +/// AnnotationOK. +bool IsAnnotationOK(const GlobalVariable &GV); +} // namespace memprof + /// A class that holds the constants that represent static data and their /// profile information and provides methods to operate on them. class StaticDataProfileInfo { diff --git a/llvm/lib/Analysis/StaticDataProfileInfo.cpp b/llvm/lib/Analysis/StaticDataProfileInfo.cpp index b036b2dde770e..1f751ee5e09d9 100644 --- a/llvm/lib/Analysis/StaticDataProfileInfo.cpp +++ b/llvm/lib/Analysis/StaticDataProfileInfo.cpp @@ -6,6 +6,46 @@ #include "llvm/ProfileData/InstrProf.h" using namespace llvm; + +namespace llvm { +namespace memprof { +// Returns true iff the global variable has custom section either by +// __attribute__((section("name"))) +// (https://clang.llvm.org/docs/AttributeReference.html#section-declspec-allocate) +// or #pragma clang section directives +// (https://clang.llvm.org/docs/LanguageExtensions.html#specifying-section-names-for-global-objects-pragma-clang-section). +static bool hasExplicitSectionName(const GlobalVariable &GVar) { + if (GVar.hasSection()) + return true; + + auto Attrs = GVar.getAttributes(); + if (Attrs.hasAttribute("bss-section") || Attrs.hasAttribute("data-section") || + Attrs.hasAttribute("relro-section") || + Attrs.hasAttribute("rodata-section")) + return true; + return false; +} + +AnnotationKind getAnnotationKind(const GlobalVariable &GV) { + if (GV.isDeclarationForLinker()) + return AnnotationKind::DeclForLinker; + // Skip 'llvm.'-prefixed global variables conservatively because they are + // often handled specially, + StringRef Name = GV.getName(); + if (Name.starts_with("llvm.")) + return AnnotationKind::ReservedName; + // Respect user-specified custom data sections. + if (hasExplicitSectionName(GV)) + return AnnotationKind::ExplicitSection; + return AnnotationKind::AnnotationOK; +} + +bool IsAnnotationOK(const GlobalVariable &GV) { + return getAnnotationKind(GV) == AnnotationKind::AnnotationOK; +} +} // namespace memprof +} // namespace llvm + void StaticDataProfileInfo::addConstantProfileCount( const Constant *C, std::optional Count) { if (!Count) { diff --git a/llvm/lib/CodeGen/StaticDataAnnotator.cpp b/llvm/lib/CodeGen/StaticDataAnnotator.cpp index 53a9ab4dbda02..9b737751c4a98 100644 --- a/llvm/lib/CodeGen/StaticDataAnnotator.cpp +++ b/llvm/lib/CodeGen/StaticDataAnnotator.cpp @@ -75,7 +75,7 @@ bool StaticDataAnnotator::runOnModule(Module &M) { bool Changed = false; for (auto &GV : M.globals()) { - if (GV.isDeclarationForLinker()) + if (!llvm::memprof::IsAnnotationOK(GV)) continue; // The implementation below assumes prior passes don't set section prefixes, diff --git a/llvm/lib/CodeGen/StaticDataSplitter.cpp b/llvm/lib/CodeGen/StaticDataSplitter.cpp index e22dc2507d548..1593a401bcb24 100644 --- a/llvm/lib/CodeGen/StaticDataSplitter.cpp +++ b/llvm/lib/CodeGen/StaticDataSplitter.cpp @@ -130,10 +130,8 @@ StaticDataSplitter::getConstant(const MachineOperand &Op, if (Op.isGlobal()) { // Find global variables with local linkage. const GlobalVariable *GV = getLocalLinkageGlobalVariable(Op.getGlobal()); - // Skip 'llvm.'-prefixed global variables conservatively because they are - // often handled specially, and skip those not in static data - // sections. - if (!GV || GV->getName().starts_with("llvm.") || + // Skip those not eligible for annotation or not in static data sections. + if (!GV || !llvm::memprof::IsAnnotationOK(*GV) || !inStaticDataSection(*GV, TM)) return nullptr; return GV; diff --git a/llvm/lib/Transforms/Instrumentation/MemProfUse.cpp b/llvm/lib/Transforms/Instrumentation/MemProfUse.cpp index d86fcf268ce4f..a6ec6c1207767 100644 --- a/llvm/lib/Transforms/Instrumentation/MemProfUse.cpp +++ b/llvm/lib/Transforms/Instrumentation/MemProfUse.cpp @@ -17,6 +17,7 @@ #include "llvm/ADT/StringRef.h" #include "llvm/Analysis/MemoryProfileInfo.h" #include "llvm/Analysis/OptimizationRemarkEmitter.h" +#include "llvm/Analysis/StaticDataProfileInfo.h" #include "llvm/Analysis/TargetLibraryInfo.h" #include "llvm/IR/DiagnosticInfo.h" #include "llvm/IR/Function.h" @@ -194,6 +195,30 @@ static bool isAllocationWithHotColdVariant(const Function *Callee, } } +static void HandleUnsupportedAnnotationKinds(GlobalVariable &GVar, + AnnotationKind Kind) { + assert(Kind != llvm::memprof::AnnotationKind::AnnotationOK && + "Should not handle AnnotationOK here"); + SmallString<32> Reason; + switch (Kind) { + case llvm::memprof::AnnotationKind::ExplicitSection: + ++NumOfMemProfExplicitSectionGlobalVars; + Reason.append("explicit section name"); + break; + case llvm::memprof::AnnotationKind::DeclForLinker: + Reason.append("linker declaration"); + break; + case llvm::memprof::AnnotationKind::ReservedName: + Reason.append("name starts with `llvm.`"); + break; + default: + llvm_unreachable("Unexpected annotation kind"); + } + LLVM_DEBUG(dbgs() << "Skip annotation for " << GVar.getName() << " due to " + << Reason << ".\n"); + return; +} + struct AllocMatchInfo { uint64_t TotalSize = 0; AllocationType AllocType = AllocationType::None; @@ -775,23 +800,6 @@ PreservedAnalyses MemProfUsePass::run(Module &M, ModuleAnalysisManager &AM) { return PreservedAnalyses::none(); } -// Returns true iff the global variable has custom section either by -// __attribute__((section("name"))) -// (https://clang.llvm.org/docs/AttributeReference.html#section-declspec-allocate) -// or #pragma clang section directives -// (https://clang.llvm.org/docs/LanguageExtensions.html#specifying-section-names-for-global-objects-pragma-clang-section). -static bool hasExplicitSectionName(const GlobalVariable &GVar) { - if (GVar.hasSection()) - return true; - - auto Attrs = GVar.getAttributes(); - if (Attrs.hasAttribute("bss-section") || Attrs.hasAttribute("data-section") || - Attrs.hasAttribute("relro-section") || - Attrs.hasAttribute("rodata-section")) - return true; - return false; -} - bool MemProfUsePass::annotateGlobalVariables( Module &M, const memprof::DataAccessProfData *DataAccessProf) { if (!AnnotateStaticDataSectionPrefix || M.globals().empty()) @@ -817,13 +825,9 @@ bool MemProfUsePass::annotateGlobalVariables( for (GlobalVariable &GVar : M.globals()) { assert(!GVar.getSectionPrefix().has_value() && "GVar shouldn't have section prefix yet"); - if (GVar.isDeclarationForLinker()) - continue; - - if (hasExplicitSectionName(GVar)) { - ++NumOfMemProfExplicitSectionGlobalVars; - LLVM_DEBUG(dbgs() << "Global variable " << GVar.getName() - << " has explicit section name. Skip annotating.\n"); + auto Kind = llvm::memprof::getAnnotationKind(GVar); + if (Kind != llvm::memprof::AnnotationKind::AnnotationOK) { + HandleUnsupportedAnnotationKinds(GVar, Kind); continue; } @@ -833,7 +837,6 @@ bool MemProfUsePass::annotateGlobalVariables( // TODO: Track string content hash in the profiles and compute it inside the // compiler to categeorize the hotness string literals. if (Name.starts_with(".str")) { - LLVM_DEBUG(dbgs() << "Skip annotating string literal " << Name << "\n"); continue; } diff --git a/llvm/test/CodeGen/X86/global-variable-partition.ll b/llvm/test/CodeGen/X86/global-variable-partition.ll index ce06d1712f840..604b4fd5a96ed 100644 --- a/llvm/test/CodeGen/X86/global-variable-partition.ll +++ b/llvm/test/CodeGen/X86/global-variable-partition.ll @@ -106,23 +106,31 @@ target triple = "x86_64-unknown-linux-gnu" ; UNIQ-NEXT: .section .data.unlikely.,"aw",@progbits,unique,8 ; AGG-NEXT: .section .data.unlikely.,"aw",@progbits +;; The `.section` directive is omitted for .data with -unique-section-names=false. +; See MCSectionELF::shouldOmitSectionDirective for the implementation details. + ; For @data_with_unknown_hotness ; SYM: .type .Ldata_with_unknown_hotness,@object # @data_with_unknown_hotness ; SYM: .section .data..Ldata_with_unknown_hotness,"aw",@progbits ; UNIQ: .section .data,"aw",@progbits,unique,9 -; The `.section` directive is omitted for .data with -unique-section-names=false. -; See MCSectionELF::shouldOmitSectionDirective for the implementation details. + ; AGG: .data ; COMMON: .Ldata_with_unknown_hotness: -; For @hot_data_custom_bar_section -; It has an explicit section attribute 'var' and shouldn't have hot or unlikely suffix. +; For variables that are not eligible for section prefix annotation ; COMMON: .type hot_data_custom_bar_section,@object ; SYM-NEXT: .section bar,"aw",@progbits ; SYM: hot_data_custom_bar_section ; UNIQ: .section bar,"aw",@progbits ; AGG: .section bar,"aw",@progbits +; SYM: .section .data.llvm.fake_var,"aw" +; UNIQ: .section .data,"aw" +; AGG: .data + +;; No section for linker declaration +; COMMON-NOT: qux + @.str = private unnamed_addr constant [5 x i8] c"hot\09\00", align 1 @.str.1 = private unnamed_addr constant [10 x i8] c"%d\09%d\09%d\0A\00", align 1 @hot_relro_array = internal constant [2 x ptr] [ptr @bss2, ptr @data3] @@ -137,6 +145,8 @@ target triple = "x86_64-unknown-linux-gnu" @data3 = internal global i32 3 @data_with_unknown_hotness = private global i32 5 @hot_data_custom_bar_section = internal global i32 101 #0 +@llvm.fake_var = internal global i32 123 +@qux = external global i64 define void @cold_func(i32 %0) !prof !15 { %2 = load i32, ptr @cold_bss diff --git a/llvm/test/Transforms/PGOProfile/data-access-profile.ll b/llvm/test/Transforms/PGOProfile/data-access-profile.ll index d9976a9d23755..205184bdd7156 100644 --- a/llvm/test/Transforms/PGOProfile/data-access-profile.ll +++ b/llvm/test/Transforms/PGOProfile/data-access-profile.ll @@ -31,8 +31,10 @@ ; LOG: Global variable var2.llvm.125 is annotated as hot ; LOG: Global variable bar is not annotated ; LOG: Global variable foo is annotated as unlikely -; LOG: Global variable var3 has explicit section name. Skip annotating. -; LOG: Global variable var4 has explicit section name. Skip annotating. +; LOG: Skip annotation for var3 due to explicit section name. +; LOG: Skip annotation for var4 due to explicit section name. +; LOG: Skip annotation for llvm.fake_var due to name starts with `llvm.`. +; LOG: Skip annotation for qux due to linker declaration. ;; String literals are not annotated. ; IR: @.str = unnamed_addr constant [5 x i8] c"abcde" @@ -54,6 +56,11 @@ ; IR-NEXT: @var3 = constant [2 x i32] [i32 12345, i32 6789], section "sec1" ; IR-NEXT: @var4 = constant [1 x i64] [i64 98765] #0 +; IR: @llvm.fake_var = global i32 123 +; IR-NOT: !section_prefix +; IR: @qux = external global i64 +; IR-NOT: !section_prefix + ; IR: attributes #0 = { "rodata-section"="sec2" } ; IR: !0 = !{!"section_prefix", !"hot"} @@ -112,11 +119,14 @@ target triple = "x86_64-unknown-linux-gnu" @foo = global i8 2 @var3 = constant [2 x i32][i32 12345, i32 6789], section "sec1" @var4 = constant [1 x i64][i64 98765] #0 +@llvm.fake_var = global i32 123 +@qux = external global i64 define i32 @func() { %a = load i32, ptr @var1 %b = load i32, ptr @var2.llvm.125 - %ret = call i32 (...) @func_taking_arbitrary_param(i32 %a, i32 %b) + %c = load i32, ptr @llvm.fake_var + %ret = call i32 (...) @func_taking_arbitrary_param(i32 %a, i32 %b, i32 %c) ret i32 %ret } @@ -136,5 +146,8 @@ target triple = "x86_64-unknown-linux-gnu" @foo = global i8 2 @var3 = constant [2 x i32][i32 12345, i32 6789], section "sec1" @var4 = constant [1 x i64][i64 98765] #0 +@llvm.fake_var = global i32 123 +@qux = external global i64 + attributes #0 = { "rodata-section"="sec2" }