From: Fangrui Song Date: Sat, 6 Feb 2021 05:45:21 +0000 (-0800) Subject: .gcc_except_table: Set SHF_LINK_ORDER if binutils>=2.36, and drop unneeded unique... X-Git-Tag: llvmorg-14-init~15856 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=e44a1009428304d2203ab5b99d479ab2a0abf53a;p=platform%2Fupstream%2Fllvm.git .gcc_except_table: Set SHF_LINK_ORDER if binutils>=2.36, and drop unneeded unique ID for -fno-unique-section-names GNU ld>=2.36 supports mixed SHF_LINK_ORDER and non-SHF_LINK_ORDER sections in an output section, so we can set SHF_LINK_ORDER if -fbinutils-version=2.36 or above. If -fno-function-sections or older binutils, drop unique ID for -fno-unique-section-names. The users can just specify -fbinutils-version=2.36 or above to allow GC with both GNU ld and LLD. (LLD does not support garbage collection of non-group non-SHF_LINK_ORDER .gcc_except_table sections.) --- diff --git a/llvm/include/llvm/CodeGen/TargetLoweringObjectFileImpl.h b/llvm/include/llvm/CodeGen/TargetLoweringObjectFileImpl.h index 31e08b7..98a0207 100644 --- a/llvm/include/llvm/CodeGen/TargetLoweringObjectFileImpl.h +++ b/llvm/include/llvm/CodeGen/TargetLoweringObjectFileImpl.h @@ -63,7 +63,7 @@ public: MCSection *getSectionForJumpTable(const Function &F, const TargetMachine &TM) const override; - MCSection *getSectionForLSDA(const Function &F, + MCSection *getSectionForLSDA(const Function &F, const MCSymbol &FnSym, const TargetMachine &TM) const override; MCSection * diff --git a/llvm/include/llvm/Target/TargetLoweringObjectFile.h b/llvm/include/llvm/Target/TargetLoweringObjectFile.h index cad43f5..921063b 100644 --- a/llvm/include/llvm/Target/TargetLoweringObjectFile.h +++ b/llvm/include/llvm/Target/TargetLoweringObjectFile.h @@ -125,8 +125,8 @@ public: virtual MCSection *getSectionForJumpTable(const Function &F, const TargetMachine &TM) const; - virtual MCSection *getSectionForLSDA(const Function &F, - const TargetMachine &TM) const { + virtual MCSection *getSectionForLSDA(const Function &, const MCSymbol &, + const TargetMachine &) const { return LSDASection; } diff --git a/llvm/lib/CodeGen/AsmPrinter/EHStreamer.cpp b/llvm/lib/CodeGen/AsmPrinter/EHStreamer.cpp index 2ffe8a7..6fb00793 100644 --- a/llvm/lib/CodeGen/AsmPrinter/EHStreamer.cpp +++ b/llvm/lib/CodeGen/AsmPrinter/EHStreamer.cpp @@ -420,8 +420,8 @@ MCSymbol *EHStreamer::emitExceptionTable() { bool HaveTTData = !TypeInfos.empty() || !FilterIds.empty(); // Type infos. - MCSection *LSDASection = - Asm->getObjFileLowering().getSectionForLSDA(MF->getFunction(), Asm->TM); + MCSection *LSDASection = Asm->getObjFileLowering().getSectionForLSDA( + MF->getFunction(), *Asm->CurrentFnSym, Asm->TM); unsigned TTypeEncoding; if (!HaveTTData) { diff --git a/llvm/lib/CodeGen/TargetLoweringObjectFileImpl.cpp b/llvm/lib/CodeGen/TargetLoweringObjectFileImpl.cpp index fe64b38..cccac07 100644 --- a/llvm/lib/CodeGen/TargetLoweringObjectFileImpl.cpp +++ b/llvm/lib/CodeGen/TargetLoweringObjectFileImpl.cpp @@ -834,9 +834,8 @@ MCSection *TargetLoweringObjectFileELF::getSectionForJumpTable( /* AssociatedSymbol */ nullptr); } -MCSection * -TargetLoweringObjectFileELF::getSectionForLSDA(const Function &F, - const TargetMachine &TM) const { +MCSection *TargetLoweringObjectFileELF::getSectionForLSDA( + const Function &F, const MCSymbol &FnSym, const TargetMachine &TM) const { // If neither COMDAT nor function sections, use the monolithic LSDA section. // Re-use this path if LSDASection is null as in the Arm EHABI. if (!LSDASection || (!F.hasComdat() && !TM.getFunctionSections())) @@ -845,30 +844,26 @@ TargetLoweringObjectFileELF::getSectionForLSDA(const Function &F, const auto *LSDA = cast(LSDASection); unsigned Flags = LSDA->getFlags(); StringRef Group; + const MCSymbolELF *LinkedToSym = nullptr; if (F.hasComdat()) { Group = F.getComdat()->getName(); Flags |= ELF::SHF_GROUP; } + // Use SHF_LINK_ORDER to facilitate --gc-sections if we can use GNU ld>=2.36 + // or LLD, which support mixed SHF_LINK_ORDER & non-SHF_LINK_ORDER. + if (TM.getFunctionSections() && + (getContext().getAsmInfo()->useIntegratedAssembler() && + getContext().getAsmInfo()->binutilsIsAtLeast(2, 36))) { + Flags |= ELF::SHF_LINK_ORDER; + LinkedToSym = cast(&FnSym); + } // Append the function name as the suffix like GCC, assuming // -funique-section-names applies to .gcc_except_table sections. - if (TM.getUniqueSectionNames()) - return getContext().getELFSection(LSDA->getName() + "." + F.getName(), - LSDA->getType(), Flags, 0, Group, - MCSection::NonUniqueID, nullptr); - - // Allocate a unique ID if function sections && (integrated assembler or GNU - // as>=2.35). Note we could use SHF_LINK_ORDER to facilitate --gc-sections but - // that would require that we know the linker is a modern LLD (12.0 or later). - // GNU ld as of 2.35 does not support mixed SHF_LINK_ORDER & - // non-SHF_LINK_ORDER components in an output section - // https://sourceware.org/bugzilla/show_bug.cgi?id=26256 - unsigned ID = TM.getFunctionSections() && - getContext().getAsmInfo()->useIntegratedAssembler() - ? NextUniqueID++ - : MCSection::NonUniqueID; - return getContext().getELFSection(LSDA->getName(), LSDA->getType(), Flags, 0, - Group, ID, nullptr); + return getContext().getELFSection( + (TM.getUniqueSectionNames() ? LSDA->getName() + "." + F.getName() + : LSDA->getName()), + LSDA->getType(), Flags, 0, Group, MCSection::NonUniqueID, LinkedToSym); } bool TargetLoweringObjectFileELF::shouldPutJumpTableInFunctionSection( diff --git a/llvm/test/CodeGen/X86/gcc_except_table-multi.ll b/llvm/test/CodeGen/X86/gcc_except_table-multi.ll index 2538a34..c1bd86e 100644 --- a/llvm/test/CodeGen/X86/gcc_except_table-multi.ll +++ b/llvm/test/CodeGen/X86/gcc_except_table-multi.ll @@ -1,10 +1,10 @@ -; RUN: llc -simplifycfg-require-and-preserve-domtree=1 < %s -mtriple=x86_64 | FileCheck %s --check-prefixes=CHECK,NORMAL -; RUN: llc -simplifycfg-require-and-preserve-domtree=1 < %s -mtriple=x86_64 -unique-section-names=false | FileCheck %s --check-prefixes=CHECK,NOUNIQUE -; RUN: llc -simplifycfg-require-and-preserve-domtree=1 < %s -mtriple=x86_64 -function-sections | FileCheck %s --check-prefixes=CHECK,SEP -; RUN: llc -simplifycfg-require-and-preserve-domtree=1 < %s -mtriple=x86_64 -function-sections -unique-section-names=false | FileCheck %s --check-prefixes=CHECK,SEP_NOUNIQUE +; RUN: llc -simplifycfg-require-and-preserve-domtree=1 < %s -mtriple=x86_64 -binutils-version=2.35 | FileCheck %s --check-prefixes=CHECK,NORMAL +; RUN: llc -simplifycfg-require-and-preserve-domtree=1 < %s -mtriple=x86_64 -binutils-version=2.36 | FileCheck %s --check-prefixes=CHECK,NORMAL +; RUN: llc -simplifycfg-require-and-preserve-domtree=1 < %s -mtriple=x86_64 -function-sections -binutils-version=2.35 | FileCheck %s --check-prefixes=CHECK,SEP_BFD +; RUN: llc -simplifycfg-require-and-preserve-domtree=1 < %s -mtriple=x86_64 -function-sections -binutils-version=2.36 | FileCheck %s --check-prefixes=CHECK,SEP -;; Don't use `,unique` if GNU as<2.35. -; RUN: llc -simplifycfg-require-and-preserve-domtree=1 < %s -mtriple=x86_64 -function-sections -unique-section-names=false -no-integrated-as | FileCheck %s --check-prefixes=CHECK,SEP_NOUNIQUE_GAS +; RUN: llc -simplifycfg-require-and-preserve-domtree=1 < %s -mtriple=x86_64 -function-sections -unique-section-names=false | FileCheck %s --check-prefixes=CHECK,SEP_NOUNIQUE +; RUN: llc -simplifycfg-require-and-preserve-domtree=1 < %s -mtriple=x86_64 -unique-section-names=false | FileCheck %s --check-prefixes=CHECK,NOUNIQUE @_ZTIi = external constant i8* @@ -16,10 +16,10 @@ define i32 @group() uwtable comdat personality i8* bitcast (i32 (...)* @__gxx_pe ; CHECK-LABEL: group: ; CHECK: .cfi_endproc ; NORMAL-NEXT: .section .gcc_except_table.group,"aG",@progbits,group,comdat{{$}} +; SEP_BFD-NEXT: .section .gcc_except_table.group,"aG",@progbits,group,comdat{{$}} +; SEP-NEXT: .section .gcc_except_table.group,"aGo",@progbits,group,comdat,group{{$}} +; SEP_NOUNIQUE-NEXT: .section .gcc_except_table,"aG",@progbits,group,comdat{{$}} ; NOUNIQUE-NEXT: .section .gcc_except_table,"aG",@progbits,group,comdat{{$}} -; SEP-NEXT: .section .gcc_except_table.group,"aG",@progbits,group,comdat{{$}} -; SEP_NOUNIQUE-NEXT: .section .gcc_except_table,"aG",@progbits,group,comdat,unique,2 -; SEP_NOUNIQUE_GAS-NEXT: .section .gcc_except_table,"aG",@progbits,group,comdat{{$}} entry: invoke void @ext() to label %try.cont unwind label %lpad lpad: @@ -38,10 +38,10 @@ define i32 @foo() uwtable personality i8* bitcast (i32 (...)* @__gxx_personality ; CHECK-LABEL: foo: ; CHECK: .cfi_endproc ; NORMAL-NEXT: .section .gcc_except_table,"a",@progbits{{$}} +; SEP_BFD-NEXT: .section .gcc_except_table.foo,"a",@progbits{{$}} +; SEP-NEXT: .section .gcc_except_table.foo,"ao",@progbits,foo{{$}} +; SEP_NOUNIQUE-NEXT: .section .gcc_except_table,"a",@progbits{{$}} ; NOUNIQUE-NEXT: .section .gcc_except_table,"a",@progbits{{$}} -; SEP-NEXT: .section .gcc_except_table.foo,"a",@progbits{{$}} -; SEP_NOUNIQUE-NEXT: .section .gcc_except_table,"a",@progbits,unique,4 -; SEP_NOUNIQUE_GAS-NEXT: .section .gcc_except_table,"a",@progbits{{$}} entry: invoke void @ext() to label %try.cont unwind label %lpad lpad: