From b7e12ca7aab73a00d7a7a2fbbd5214dde9353335 Mon Sep 17 00:00:00 2001 From: Jez Ng Date: Wed, 27 Oct 2021 14:58:15 -0400 Subject: [PATCH] [lld-macho] If export_size is zero, export_off must be zero Otherwise tools like codesign_allocate will choke. We were already handling this correctly for the other DYLD_INFO sections. Doing this correctly is a bit subtle: we don't know if export_size will be zero until we have run `ExportSection::finalizeContents()`. However, we must still add the ExportSection to the `__LINKEDIT` segment in order that it gets sorted during `sortSectionsAndSegments()`. Reviewed By: #lld-macho, oontvoo Differential Revision: https://reviews.llvm.org/D112589 --- lld/MachO/SyntheticSections.h | 1 + lld/MachO/Writer.cpp | 7 ++++++- lld/test/MachO/no-unneeded-dyld-info.s | 9 +++++---- 3 files changed, 12 insertions(+), 5 deletions(-) diff --git a/lld/MachO/SyntheticSections.h b/lld/MachO/SyntheticSections.h index cc7af64..49b68c7 100644 --- a/lld/MachO/SyntheticSections.h +++ b/lld/MachO/SyntheticSections.h @@ -345,6 +345,7 @@ public: ExportSection(); void finalizeContents() override; uint64_t getRawSize() const override { return size; } + bool isNeeded() const override { return size; } void writeTo(uint8_t *buf) const override; bool hasWeakSymbol = false; diff --git a/lld/MachO/Writer.cpp b/lld/MachO/Writer.cpp index 27ad7b2..c2aef4d 100644 --- a/lld/MachO/Writer.cpp +++ b/lld/MachO/Writer.cpp @@ -968,7 +968,12 @@ template void Writer::createOutputSections() { for (SyntheticSection *ssec : syntheticSections) { auto it = concatOutputSections.find({ssec->segname, ssec->name}); - if (ssec->isNeeded()) { + // We add all LinkEdit sections here because we don't know if they are + // needed until their finalizeContents() methods get called later. While + // this means that we add some redundant sections to __LINKEDIT, there is + // is no redundancy in the output, as we do not emit section headers for + // any LinkEdit sections. + if (ssec->isNeeded() || ssec->segname == segment_names::linkEdit) { if (it == concatOutputSections.end()) { getOrCreateOutputSegment(ssec->segname)->addOutputSection(ssec); } else { diff --git a/lld/test/MachO/no-unneeded-dyld-info.s b/lld/test/MachO/no-unneeded-dyld-info.s index b69950f..cf92adf 100644 --- a/lld/test/MachO/no-unneeded-dyld-info.s +++ b/lld/test/MachO/no-unneeded-dyld-info.s @@ -1,6 +1,6 @@ # REQUIRES: x86 # RUN: llvm-mc -filetype=obj -triple=x86_64-apple-darwin %s -o %t.o -# RUN: %lld -o %t %t.o +# RUN: %lld -dylib -o %t %t.o # RUN: llvm-objdump --macho --all-headers %t | FileCheck %s # CHECK: cmd LC_DYLD_INFO_ONLY @@ -13,7 +13,8 @@ # CHECK-NEXT: weak_bind_size 0 # CHECK-NEXT: lazy_bind_off 0 # CHECK-NEXT: lazy_bind_size 0 +# CHECK-NEXT: export_off 0 +# CHECK-NEXT: export_size 0 -.globl _main -_main: - ret +_not_exported: + .space 1 -- 2.7.4