akhuang created this revision. Herald added subscribers: dexonsmith, fedor.sergeev. akhuang requested review of this revision. Herald added projects: clang, LLDB. Herald added subscribers: lldb-commits, cfe-commits.
Constructor homing reduces the amount of class type info that is emitted by emitting conmplete type info for a class only when a constructor for that class is emitted. This will mainly reduce the amount of duplicate debug info in object files. In Chrome enabling ctor homing decreased total build directory sizes by about 30%. It's also expected that some class types (such as unused classes) will no longer be emitted in the debug info. This is fine, since we wouldn't expect to need these types when debugging. In some cases (e.g. libc++, https://reviews.llvm.org/D98750), classes are used without calling the constructor. Since this is technically undefined behavior, enabling constructor homing should be fine. However Clang now has an attribute `__attribute__((standalone_debug))` that can be used on classes to ignore ctor homing. Bug: https://bugs.llvm.org/show_bug.cgi?id=46537 Repository: rG LLVM Github Monorepo https://reviews.llvm.org/D106084 Files: clang/include/clang/Basic/DebugInfoOptions.h clang/lib/Driver/ToolChains/Clang.cpp clang/test/CodeGenCXX/debug-info-template-deduction-guide.cpp clang/test/Driver/cl-options.c clang/test/Driver/clang-g-opts.c clang/test/Driver/cuda-dwarf-2.cu clang/test/Driver/debug-options-as.c clang/test/Driver/debug-options.c clang/test/Driver/integrated-as.s clang/test/Driver/myriad-toolchain.c clang/test/Driver/openmp-offload-gpu.c clang/test/Driver/split-debug.c lldb/test/Shell/SymbolFile/PDB/Inputs/ClassLayoutTest.cpp
Index: lldb/test/Shell/SymbolFile/PDB/Inputs/ClassLayoutTest.cpp =================================================================== --- lldb/test/Shell/SymbolFile/PDB/Inputs/ClassLayoutTest.cpp +++ lldb/test/Shell/SymbolFile/PDB/Inputs/ClassLayoutTest.cpp @@ -106,6 +106,9 @@ int main() { MemberTest::Base B1; B1.Get(); + // Create instance of C1 so that it has debug info (due to constructor + // homing). + MemberTest::Class C1; MemberTest::Class::StaticMemberFunc(1, 10, 2); return 0; } Index: clang/test/Driver/split-debug.c =================================================================== --- clang/test/Driver/split-debug.c +++ clang/test/Driver/split-debug.c @@ -9,7 +9,7 @@ // INLINE: "-fsplit-dwarf-inlining" // NOINLINE-NOT: "-fsplit-dwarf-inlining" -// SPLIT: "-debug-info-kind=limited" +// SPLIT: "-debug-info-kind=constructor" // SPLIT-SAME: "-ggnu-pubnames" // SPLIT-SAME: "-split-dwarf-file" "split-debug.dwo" "-split-dwarf-output" "split-debug.dwo" @@ -38,14 +38,14 @@ // RUN: %clang -### -c -target x86_64 -gsplit-dwarf=single -g -gno-split-dwarf %s 2>&1 | FileCheck %s --check-prefix=NOSPLIT // RUN: %clang -### -c -target x86_64 -gno-split-dwarf -g -gsplit-dwarf %s 2>&1 | FileCheck %s --check-prefixes=NOINLINE,SPLIT -// NOSPLIT: "-debug-info-kind=limited" +// NOSPLIT: "-debug-info-kind=constructor" // NOSPLIT-NOT: "-ggnu-pubnames" // NOSPLIT-NOT: "-split-dwarf /// Test -gsplit-dwarf=single. // RUN: %clang -### -c -target x86_64 -gsplit-dwarf=single -g %s 2>&1 | FileCheck %s --check-prefix=SINGLE -// SINGLE: "-debug-info-kind=limited" +// SINGLE: "-debug-info-kind=constructor" // SINGLE: "-split-dwarf-file" "split-debug.o" // SINGLE-NOT: "-split-dwarf-output" @@ -62,7 +62,7 @@ // RUN: %clang -### -c -target x86_64 -gsplit-dwarf=split -g -gno-pubnames %s 2>&1 | FileCheck %s --check-prefixes=NOPUBNAMES // RUN: %clang -### -c -target x86_64 -gsplit-dwarf=split -g -gno-gnu-pubnames %s 2>&1 | FileCheck %s --check-prefixes=NOPUBNAMES -// NOPUBNAMES: "-debug-info-kind=limited" +// NOPUBNAMES: "-debug-info-kind=constructor" // NOPUBNAMES-NOT: "-ggnu-pubnames" // NOPUBNAMES-SAME: "-split-dwarf-file" "split-debug.dwo" "-split-dwarf-output" "split-debug.dwo" Index: clang/test/Driver/openmp-offload-gpu.c =================================================================== --- clang/test/Driver/openmp-offload-gpu.c +++ clang/test/Driver/openmp-offload-gpu.c @@ -248,7 +248,7 @@ // HAS_DEBUG-NOT: warning: debug // HAS_DEBUG: "-triple" "nvptx64-nvidia-cuda" -// HAS_DEBUG-SAME: "-debug-info-kind={{limited|line-tables-only}}" +// HAS_DEBUG-SAME: "-debug-info-kind={{constructor|line-tables-only}}" // HAS_DEBUG-SAME: "-dwarf-version=2" // HAS_DEBUG-SAME: "-fopenmp-is-device" // HAS_DEBUG: ptxas Index: clang/test/Driver/myriad-toolchain.c =================================================================== --- clang/test/Driver/myriad-toolchain.c +++ clang/test/Driver/myriad-toolchain.c @@ -83,7 +83,7 @@ // NOSTDLIB-NOT: "-lc" // RUN: %clang -### -c -g %s -target sparc-myriad 2>&1 | FileCheck -check-prefix=G_SPARC %s -// G_SPARC: "-debug-info-kind=limited" "-dwarf-version=2" +// G_SPARC: "-debug-info-kind=constructor" "-dwarf-version=2" // RUN: %clang -### -c %s -target sparc-myriad-rtems -fuse-init-array 2>&1 \ // RUN: | FileCheck -check-prefix=USE-INIT-ARRAY %s Index: clang/test/Driver/integrated-as.s =================================================================== --- clang/test/Driver/integrated-as.s +++ clang/test/Driver/integrated-as.s @@ -27,19 +27,19 @@ // XA_INCLUDE2: "-Ifoo_dir" // RUN: %clang -### -target x86_64--- -c -integrated-as %s -gdwarf-4 -gdwarf-2 2>&1 | FileCheck --check-prefix=DWARF2 %s -// DWARF2: "-debug-info-kind=limited" "-dwarf-version=2" +// DWARF2: "-debug-info-kind=constructor" "-dwarf-version=2" // RUN: %clang -### -target x86_64--- -c -integrated-as %s -gdwarf-3 2>&1 | FileCheck --check-prefix=DWARF3 %s -// DWARF3: "-debug-info-kind=limited" "-dwarf-version=3" +// DWARF3: "-debug-info-kind=constructor" "-dwarf-version=3" // RUN: %clang -### -target x86_64--- -c -integrated-as %s -gdwarf-4 2>&1 | FileCheck --check-prefix=DWARF4 %s -// DWARF4: "-debug-info-kind=limited" "-dwarf-version=4" +// DWARF4: "-debug-info-kind=constructor" "-dwarf-version=4" // RUN: %clang -### -target x86_64--- -c -integrated-as %s -Xassembler -gdwarf-2 2>&1 | FileCheck --check-prefix=DWARF2XASSEMBLER %s -// DWARF2XASSEMBLER: "-debug-info-kind=limited" "-dwarf-version=2" +// DWARF2XASSEMBLER: "-debug-info-kind=constructor" "-dwarf-version=2" // RUN: %clang -### -target x86_64--- -c -integrated-as %s -Wa,-gdwarf-2 2>&1 | FileCheck --check-prefix=DWARF2WA %s -// DWARF2WA: "-debug-info-kind=limited" "-dwarf-version=2" +// DWARF2WA: "-debug-info-kind=constructor" "-dwarf-version=2" // A dwarf version number that driver can't parse is just stuffed in. // RUN: %clang -### -target x86_64--- -c -integrated-as %s -Wa,-gdwarf-huh 2>&1 | FileCheck --check-prefix=BOGODWARF %s Index: clang/test/Driver/debug-options.c =================================================================== --- clang/test/Driver/debug-options.c +++ clang/test/Driver/debug-options.c @@ -306,18 +306,18 @@ // GLIO_ONLY_DWARF2: "-dwarf-version=2" // // G_ONLY: "-cc1" -// G_ONLY: "-debug-info-kind=limited" +// G_ONLY: "-debug-info-kind=constructor" // // These tests assert that "-gline-tables-only" "-g" uses the latter, // but otherwise not caring about the DebugInfoKind. // G_ONLY_DWARF2: "-cc1" -// G_ONLY_DWARF2: "-debug-info-kind={{standalone|limited}}" +// G_ONLY_DWARF2: "-debug-info-kind={{standalone|constructor}}" // G_ONLY_DWARF2: "-dwarf-version=2" // // G_STANDALONE: "-cc1" // G_STANDALONE: "-debug-info-kind=standalone" // G_LIMITED: "-cc1" -// G_LIMITED: "-debug-info-kind=limited" +// G_LIMITED: "-debug-info-kind=constructor" // G_DWARF2: "-dwarf-version=2" // G_DWARF4: "-dwarf-version=4" // @@ -375,7 +375,7 @@ // NOCI: "-gno-column-info" // // GEXTREFS: "-dwarf-ext-refs" "-fmodule-format=obj" -// GEXTREFS: "-debug-info-kind={{standalone|limited}}" +// GEXTREFS: "-debug-info-kind={{standalone|constructor}}" // RUN: not %clang -cc1 -debug-info-kind=watkind 2>&1 | FileCheck -check-prefix=BADSTRING1 %s // BADSTRING1: error: invalid value 'watkind' in '-debug-info-kind=watkind' @@ -406,7 +406,7 @@ // RUN: | FileCheck -check-prefix=NO_DEBUG_UNUSED_TYPES %s // RUN: %clang -### -fno-eliminate-unused-debug-types -g1 -c %s 2>&1 \ // RUN: | FileCheck -check-prefix=NO_DEBUG_UNUSED_TYPES %s -// NO_DEBUG_UNUSED_TYPES: "-debug-info-kind={{limited|line-tables-only|standalone}}" +// NO_DEBUG_UNUSED_TYPES: "-debug-info-kind={{constructor|line-tables-only|standalone}}" // NO_DEBUG_UNUSED_TYPES-NOT: "-debug-info-kind=unused-types" // // RUN: %clang -### -c -gdwarf-5 -gdwarf64 -target x86_64 %s 2>&1 | FileCheck -check-prefix=GDWARF64_ON %s Index: clang/test/Driver/debug-options-as.c =================================================================== --- clang/test/Driver/debug-options-as.c +++ clang/test/Driver/debug-options-as.c @@ -23,7 +23,7 @@ // RUN: | FileCheck %s // // CHECK: "-cc1as" -// CHECK: "-debug-info-kind=limited" +// CHECK: "-debug-info-kind=constructor" // Check to make sure clang with -g on a .s file gets passed -dwarf-debug-producer. // rdar://12955296 Index: clang/test/Driver/cuda-dwarf-2.cu =================================================================== --- clang/test/Driver/cuda-dwarf-2.cu +++ clang/test/Driver/cuda-dwarf-2.cu @@ -49,7 +49,7 @@ // HAS_DEBUG-NOT: warning: debug // HAS_DEBUG: "-fcuda-is-device" -// HAS_DEBUG-SAME: "-debug-info-kind={{limited|line-tables-only}}" +// HAS_DEBUG-SAME: "-debug-info-kind={{constructor|line-tables-only}}" // HAS_DEBUG-SAME: "-dwarf-version=2" // HAS_DEBUG: ptxas // HAS_DEBUG-SAME: "-g" Index: clang/test/Driver/clang-g-opts.c =================================================================== --- clang/test/Driver/clang-g-opts.c +++ clang/test/Driver/clang-g-opts.c @@ -31,7 +31,7 @@ // RUN: | FileCheck --check-prefix=CHECK-WITH-G-DWARF2 %s // CHECK-WITHOUT-G-NOT: -debug-info-kind -// CHECK-WITH-G: "-debug-info-kind=limited" +// CHECK-WITH-G: "-debug-info-kind=constructor" // CHECK-WITH-G: "-dwarf-version=4" // CHECK-WITH-G-DWARF2: "-dwarf-version=2" Index: clang/test/Driver/cl-options.c =================================================================== --- clang/test/Driver/cl-options.c +++ clang/test/Driver/cl-options.c @@ -563,11 +563,11 @@ // RUN: %clang_cl /Zi /c -### -- %s 2>&1 | FileCheck -check-prefix=Zi %s // Zi: "-gcodeview" -// Zi: "-debug-info-kind=limited" +// Zi: "-debug-info-kind=constructor" // RUN: %clang_cl /Z7 /c -### -- %s 2>&1 | FileCheck -check-prefix=Z7 %s // Z7: "-gcodeview" -// Z7: "-debug-info-kind=limited" +// Z7: "-debug-info-kind=constructor" // RUN: %clang_cl -gline-tables-only /c -### -- %s 2>&1 | FileCheck -check-prefix=ZGMLT %s // ZGMLT: "-gcodeview" @@ -592,7 +592,7 @@ // which made it "win". This test could not detect that bug. // RUN: %clang_cl /Z7 -gdwarf /c -### -- %s 2>&1 | FileCheck -check-prefix=Z7_gdwarf %s // Z7_gdwarf: "-gcodeview" -// Z7_gdwarf: "-debug-info-kind=limited" +// Z7_gdwarf: "-debug-info-kind=constructor" // Z7_gdwarf: "-dwarf-version=4" // RUN: %clang_cl -fmsc-version=1800 -TP -### -- %s 2>&1 | FileCheck -check-prefix=CXX11 %s Index: clang/test/CodeGenCXX/debug-info-template-deduction-guide.cpp =================================================================== --- clang/test/CodeGenCXX/debug-info-template-deduction-guide.cpp +++ clang/test/CodeGenCXX/debug-info-template-deduction-guide.cpp @@ -8,10 +8,8 @@ S(T) {} }; -// CHECK: !DIGlobalVariable(name: "s1" -// CHECK-SAME: type: [[TYPE_NUM:![0-9]+]] -// CHECK: !DIGlobalVariable(name: "s2" -// CHECK-SAME: type: [[TYPE_NUM]] -// CHECK: [[TYPE_NUM]] = distinct !DICompositeType(tag: DW_TAG_structure_type, name: "S<int>", +// CHECK-DAG: !DIGlobalVariable(name: "s1"{{.*}} type: [[TYPE_NUM:![0-9]+]] +// CHECK-DAG: !DIGlobalVariable(name: "s2"{{.*}} type: [[TYPE_NUM]] +// CHECK-DAG: [[TYPE_NUM]] = distinct !DICompositeType(tag: DW_TAG_structure_type, name: "S<int>", S s1(42); S<int> s2(42); Index: clang/lib/Driver/ToolChains/Clang.cpp =================================================================== --- clang/lib/Driver/ToolChains/Clang.cpp +++ clang/lib/Driver/ToolChains/Clang.cpp @@ -503,7 +503,7 @@ return codegenoptions::DebugLineTablesOnly; if (A.getOption().matches(options::OPT_gline_directives_only)) return codegenoptions::DebugDirectivesOnly; - return codegenoptions::LimitedDebugInfo; + return codegenoptions::DebugInfoConstructor; } static bool mustUseNonLeafFramePointerForTarget(const llvm::Triple &Triple) { @@ -2544,7 +2544,7 @@ CmdArgs.push_back(Value.data()); } else { RenderDebugEnablingArgs(Args, CmdArgs, - codegenoptions::LimitedDebugInfo, + codegenoptions::DebugInfoConstructor, DwarfVersion, llvm::DebuggerKind::Default); } } else if (Value.startswith("-mcpu") || Value.startswith("-mfpu") || @@ -3913,7 +3913,7 @@ } } if (const Arg *A = Args.getLastArg(options::OPT_g_Group)) { - DebugInfoKind = codegenoptions::LimitedDebugInfo; + DebugInfoKind = codegenoptions::DebugInfoConstructor; // If the last option explicitly specified a debug-info level, use it. if (checkDebugInfoOption(A, Args, D, TC) && @@ -4035,7 +4035,7 @@ if (checkDebugInfoOption(A, Args, D, TC)) { if (DebugInfoKind != codegenoptions::DebugLineTablesOnly && DebugInfoKind != codegenoptions::DebugDirectivesOnly) { - DebugInfoKind = codegenoptions::LimitedDebugInfo; + DebugInfoKind = codegenoptions::DebugInfoConstructor; CmdArgs.push_back("-dwarf-ext-refs"); CmdArgs.push_back("-fmodule-format=obj"); } @@ -4056,7 +4056,8 @@ if (const Arg *A = Args.getLastArg(options::OPT_fstandalone_debug)) (void)checkDebugInfoOption(A, Args, D, TC); - if (DebugInfoKind == codegenoptions::LimitedDebugInfo) { + if (DebugInfoKind == codegenoptions::LimitedDebugInfo || + DebugInfoKind == codegenoptions::DebugInfoConstructor) { if (Args.hasFlag(options::OPT_fno_eliminate_unused_debug_types, options::OPT_feliminate_unused_debug_types, false)) DebugInfoKind = codegenoptions::UnusedTypeInfo; @@ -7163,7 +7164,7 @@ options::OPT_gline_tables_only)) { *EmitCodeView = true; if (DebugInfoArg->getOption().matches(options::OPT__SLASH_Z7)) - *DebugInfoKind = codegenoptions::LimitedDebugInfo; + *DebugInfoKind = codegenoptions::DebugInfoConstructor; else *DebugInfoKind = codegenoptions::DebugLineTablesOnly; } else { @@ -7447,7 +7448,7 @@ // the guard for source type, however there is a test which asserts // that some assembler invocation receives no -debug-info-kind, // and it's not clear whether that test is just overly restrictive. - DebugInfoKind = (WantDebug ? codegenoptions::LimitedDebugInfo + DebugInfoKind = (WantDebug ? codegenoptions::DebugInfoConstructor : codegenoptions::NoDebugInfo); // Add the -fdebug-compilation-dir flag if needed. addDebugCompDirArg(Args, CmdArgs, C.getDriver().getVFS()); Index: clang/include/clang/Basic/DebugInfoOptions.h =================================================================== --- clang/include/clang/Basic/DebugInfoOptions.h +++ clang/include/clang/Basic/DebugInfoOptions.h @@ -37,6 +37,7 @@ /// Limit generated debug info for classes to reduce size. This emits class /// type info only where the constructor is emitted, if it is a class that /// has a constructor. + /// FIXME: Consider combining this with LimitedDebugInfo. DebugInfoConstructor, /// Limit generated debug info to reduce size (-fno-standalone-debug). This
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