Author: Jez Ng Date: 2020-12-17T08:49:17-05:00 New Revision: 4c8276cdc120c24410dcd62a9986f04e7327fc2f
URL: https://github.com/llvm/llvm-project/commit/4c8276cdc120c24410dcd62a9986f04e7327fc2f DIFF: https://github.com/llvm/llvm-project/commit/4c8276cdc120c24410dcd62a9986f04e7327fc2f.diff LOG: [lld-macho] Use LC_LOAD_WEAK_DYLIB for dylibs with only weakrefs Note that dylibs without *any* refs will still be loaded in the usual (strong) fashion. Reviewed By: #lld-macho, thakis Differential Revision: https://reviews.llvm.org/D93435 Added: Modified: lld/MachO/InputFiles.cpp lld/MachO/InputFiles.h lld/MachO/Symbols.h lld/MachO/Writer.cpp lld/test/MachO/weak-import.s Removed: ################################################################################ diff --git a/lld/MachO/InputFiles.cpp b/lld/MachO/InputFiles.cpp index a32e8caf3d29..ce66c9650446 100644 --- a/lld/MachO/InputFiles.cpp +++ b/lld/MachO/InputFiles.cpp @@ -527,7 +527,7 @@ void loadReexport(StringRef path, DylibFile *umbrella) { } DylibFile::DylibFile(MemoryBufferRef mb, DylibFile *umbrella) - : InputFile(DylibKind, mb) { + : InputFile(DylibKind, mb), refState(RefState::Unreferenced) { if (umbrella == nullptr) umbrella = this; @@ -580,7 +580,7 @@ DylibFile::DylibFile(MemoryBufferRef mb, DylibFile *umbrella) } DylibFile::DylibFile(const InterfaceFile &interface, DylibFile *umbrella) - : InputFile(DylibKind, interface) { + : InputFile(DylibKind, interface), refState(RefState::Unreferenced) { if (umbrella == nullptr) umbrella = this; diff --git a/lld/MachO/InputFiles.h b/lld/MachO/InputFiles.h index f48fc1f8c232..ef573145f594 100644 --- a/lld/MachO/InputFiles.h +++ b/lld/MachO/InputFiles.h @@ -38,6 +38,7 @@ namespace macho { class InputSection; class Symbol; struct Reloc; +enum class RefState : uint8_t; // If --reproduce option is given, all input files are written // to this tar archive. @@ -135,6 +136,7 @@ class DylibFile : public InputFile { uint32_t compatibilityVersion = 0; uint32_t currentVersion = 0; uint64_t ordinal = 0; // Ordinal numbering starts from 1, so 0 is a sentinel + RefState refState; bool reexport = false; bool forceWeakImport = false; }; diff --git a/lld/MachO/Symbols.h b/lld/MachO/Symbols.h index 80898e085818..80be27dd1c1f 100644 --- a/lld/MachO/Symbols.h +++ b/lld/MachO/Symbols.h @@ -116,7 +116,11 @@ class Defined : public Symbol { const bool external : 1; }; -// Indicates whether & how a dylib symbol is referenced. +// This enum does double-duty: as a symbol property, it indicates whether & how +// a dylib symbol is referenced. As a DylibFile property, it indicates the kind +// of referenced symbols contained within the file. If there are both weak +// and strong references to the same file, we will count the file as +// strongly-referenced. enum class RefState : uint8_t { Unreferenced = 0, Weak = 1, Strong = 2 }; class Undefined : public Symbol { diff --git a/lld/MachO/Writer.cpp b/lld/MachO/Writer.cpp index 29c8fd6ed1fa..a4c677a4b288 100644 --- a/lld/MachO/Writer.cpp +++ b/lld/MachO/Writer.cpp @@ -43,6 +43,7 @@ class Writer { Writer() : buffer(errorHandler().outputBuffer) {} void scanRelocations(); + void scanSymbols(); void createOutputSections(); void createLoadCommands(); void assignAddresses(OutputSegment *); @@ -424,6 +425,17 @@ void Writer::scanRelocations() { } } +void Writer::scanSymbols() { + for (const macho::Symbol *sym : symtab->getSymbols()) { + if (const auto *defined = dyn_cast<Defined>(sym)) { + if (defined->overridesWeakDef) + in.weakBinding->addNonWeakDefinition(defined); + } else if (const auto *dysym = dyn_cast<DylibSymbol>(sym)) { + dysym->file->refState = std::max(dysym->file->refState, dysym->refState); + } + } +} + void Writer::createLoadCommands() { in.header->addLoadCommand(make<LCDyldInfo>( in.rebase, in.binding, in.weakBinding, in.lazyBinding, in.exports)); @@ -463,10 +475,10 @@ void Writer::createLoadCommands() { uint64_t dylibOrdinal = 1; for (InputFile *file : inputFiles) { if (auto *dylibFile = dyn_cast<DylibFile>(file)) { - // TODO: dylibs that are only referenced by weak refs should also be - // loaded via LC_LOAD_WEAK_DYLIB. LoadCommandType lcType = - dylibFile->forceWeakImport ? LC_LOAD_WEAK_DYLIB : LC_LOAD_DYLIB; + dylibFile->forceWeakImport || dylibFile->refState == RefState::Weak + ? LC_LOAD_WEAK_DYLIB + : LC_LOAD_DYLIB; in.header->addLoadCommand(make<LCDylib>(lcType, dylibFile->dylibName, dylibFile->compatibilityVersion, dylibFile->currentVersion)); @@ -699,11 +711,7 @@ void Writer::run() { scanRelocations(); if (in.stubHelper->isNeeded()) in.stubHelper->setup(); - - for (const macho::Symbol *sym : symtab->getSymbols()) - if (const auto *defined = dyn_cast<Defined>(sym)) - if (defined->overridesWeakDef) - in.weakBinding->addNonWeakDefinition(defined); + scanSymbols(); // Sort and assign sections to their respective segments. No more sections nor // segments may be created after these methods run. diff --git a/lld/test/MachO/weak-import.s b/lld/test/MachO/weak-import.s index 51736edd5499..a47bfb8df3c5 100644 --- a/lld/test/MachO/weak-import.s +++ b/lld/test/MachO/weak-import.s @@ -1,35 +1,72 @@ # REQUIRES: x86 # RUN: split-file %s %t # RUN: llvm-mc -filetype=obj -triple=x86_64-apple-darwin %t/test.s -o %t/test.o +# RUN: llvm-mc -filetype=obj -triple=x86_64-apple-darwin %t/weak-ref-only.s -o %t/weak-ref-only.o +# RUN: llvm-mc -filetype=obj -triple=x86_64-apple-darwin %t/weak-ref-sub-library.s -o %t/weak-ref-sub-library.o +# RUN: llvm-mc -filetype=obj -triple=x86_64-apple-darwin %t/mixed-ref.s -o %t/mixed-ref.o # RUN: llvm-mc -filetype=obj -triple=x86_64-apple-darwin %t/foo.s -o %t/foo.o -# RUN: %lld -lSystem -dylib %t/foo.o -o %t/libfoo.dylib +# RUN: llvm-mc -filetype=obj -triple=x86_64-apple-darwin %t/bar.s -o %t/bar.o +# RUN: %lld -lSystem -dylib %t/bar.o -o %t/libbar.dylib +# RUN: %lld -lSystem -dylib %t/foo.o %t/libbar.dylib -sub_library libbar -o %t/libfoo.dylib # RUN: %lld -weak-lSystem %t/test.o -weak_framework CoreFoundation -weak_library %t/libfoo.dylib -o %t/test -# RUN: llvm-objdump --macho --all-headers %t/test | FileCheck %s -DDIR=%t +# RUN: llvm-objdump --macho --all-headers %t/test | FileCheck %s -DDIR=%t --check-prefixes=WEAK-SYS,WEAK-FOO # RUN: %lld -weak-lSystem %t/test.o \ # RUN: -framework CoreFoundation -weak_framework CoreFoundation -framework CoreFoundation \ # RUN: %t/libfoo.dylib -weak_library %t/libfoo.dylib %t/libfoo.dylib -o %t/test -# RUN: llvm-objdump --macho --all-headers %t/test | FileCheck %s -DDIR=%t +# RUN: llvm-objdump --macho --all-headers %t/test | FileCheck %s -DDIR=%t --check-prefixes=WEAK-SYS,WEAK-FOO +# RUN: %lld -lSystem -dylib %t/libfoo.dylib %t/weak-ref-only.o -o %t/weak-ref-only +# RUN: llvm-objdump --macho --all-headers %t/weak-ref-only | FileCheck %s -DDIR=%t --check-prefixes=SYS,WEAK-FOO +# RUN: %lld -lSystem -dylib %t/libfoo.dylib %t/weak-ref-sub-library.o -o %t/weak-ref-sub-library +# RUN: llvm-objdump --macho --all-headers %t/weak-ref-sub-library | FileCheck %s -DDIR=%t --check-prefixes=SYS,WEAK-FOO +# RUN: %lld -lSystem -dylib %t/libfoo.dylib %t/mixed-ref.o -o %t/mixed-ref +# RUN: llvm-objdump --macho --all-headers %t/mixed-ref | FileCheck %s -DDIR=%t --check-prefixes=SYS,FOO -# CHECK: cmd LC_LOAD_WEAK_DYLIB -# CHECK-NEXT: cmdsize -# CHECK-NEXT: name /usr/lib/libSystem.B.dylib +# WEAK-SYS: cmd LC_LOAD_WEAK_DYLIB +# WEAK-SYS-NEXT: cmdsize +# WEAK-SYS-NEXT: name /usr/lib/libSystem.B.dylib -# CHECK: cmd LC_LOAD_WEAK_DYLIB -# CHECK-NEXT: cmdsize -# CHECK-NEXT: name /System/Library/Frameworks/CoreFoundation.framework/CoreFoundation +# WEAK-SYS: cmd LC_LOAD_WEAK_DYLIB +# WEAK-SYS-NEXT: cmdsize +# WEAK-SYS-NEXT: name /System/Library/Frameworks/CoreFoundation.framework/CoreFoundation -# CHECK: cmd LC_LOAD_WEAK_DYLIB -# CHECK-NEXT: cmdsize -# CHECK-NEXT: name [[DIR]]/libfoo.dylib +# SYS: cmd LC_LOAD_DYLIB +# SYS-NEXT: cmdsize +# SYS-NEXT: name /usr/lib/libSystem.B.dylib + +# WEAK-FOO: cmd LC_LOAD_WEAK_DYLIB +# WEAK-FOO-NEXT: cmdsize +# WEAK-FOO-NEXT: name [[DIR]]/libfoo.dylib + +# FOO: cmd LC_LOAD_DYLIB +# FOO-NEXT: cmdsize +# FOO-NEXT: name [[DIR]]/libfoo.dylib #--- foo.s .globl _foo _foo: - ret + +#--- bar.s +.globl _bar +_bar: + +#--- weak-ref-only.s +.weak_reference _foo +.data +.quad _foo + +#--- weak-ref-sub-library.s +.weak_reference _bar +.data +.quad _bar + +#--- mixed-ref.s +.weak_definition _foo +.data +.quad _foo +.quad _bar #--- test.s .globl _main -.text _main: ret _______________________________________________ llvm-branch-commits mailing list llvm-branch-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-branch-commits