Author: Reid Kleckner Date: 2020-04-13T13:48:04-07:00 New Revision: edbe962459da6e3b7b4168118f93a77847b54e02
URL: https://github.com/llvm/llvm-project/commit/edbe962459da6e3b7b4168118f93a77847b54e02 DIFF: https://github.com/llvm/llvm-project/commit/edbe962459da6e3b7b4168118f93a77847b54e02.diff LOG: [COFF] Don't treat DWARF sections as GC roots DWARF sections are typically live and not COMDAT, so they would be treated as GC roots. Enabling DWARF would essentially keep all code with debug info alive, preventing any section GC. Fixes PR45273 Reviewed By: mstorsjo, MaskRay Differential Revision: https://reviews.llvm.org/D76935 (cherry picked from commit c579a5b1d92a9bc2046d00ee2d427832e0f5ddec) Added: lld/test/COFF/gc-dwarf.s Modified: lld/COFF/MarkLive.cpp Removed: ################################################################################ diff --git a/lld/COFF/MarkLive.cpp b/lld/COFF/MarkLive.cpp index 6d34cb864e3c..0afa615a1933 100644 --- a/lld/COFF/MarkLive.cpp +++ b/lld/COFF/MarkLive.cpp @@ -28,10 +28,12 @@ void markLive(ArrayRef<Chunk *> chunks) { // as we push, so sections never appear twice in the list. SmallVector<SectionChunk *, 256> worklist; - // COMDAT section chunks are dead by default. Add non-COMDAT chunks. + // COMDAT section chunks are dead by default. Add non-COMDAT chunks. Do not + // traverse DWARF sections. They are live, but they should not keep other + // sections alive. for (Chunk *c : chunks) if (auto *sc = dyn_cast<SectionChunk>(c)) - if (sc->live) + if (sc->live && !sc->isDWARF()) worklist.push_back(sc); auto enqueue = [&](SectionChunk *c) { diff --git a/lld/test/COFF/gc-dwarf.s b/lld/test/COFF/gc-dwarf.s new file mode 100644 index 000000000000..56b866f4a4ac --- /dev/null +++ b/lld/test/COFF/gc-dwarf.s @@ -0,0 +1,60 @@ +# REQUIRES: x86 + +# RUN: llvm-mc -triple=x86_64-windows-msvc %s -filetype=obj -o %t.obj +# RUN: lld-link -lldmap:%t.map -out:%t.exe -opt:ref -entry:main %t.obj -verbose 2>&1 | FileCheck %s +# RUN: FileCheck %s --check-prefix=MAP --input-file=%t.map + +# CHECK: Discarded unused1 +# CHECK-NEXT: Discarded unused2 +# CHECK-NOT: Discarded + +# MAP: In Symbol +# MAP: gc-dwarf.s.tmp.obj:(.text) +# MAP: {{ main$}} +# MAP: gc-dwarf.s.tmp.obj:(.text) +# MAP: {{ used$}} + + .def @feat.00; .scl 3; .type 0; .endef + .globl @feat.00 +.set @feat.00, 0 + + .def main; .scl 2; .type 32; .endef + .section .text,"xr",one_only,main + .globl main +main: + callq used + xorl %eax, %eax + retq + + .def used; .scl 2; .type 32; .endef + .section .text,"xr",one_only,used + .globl used +used: + retq + + + .def unused1; .scl 2; .type 32; .endef + .section .text,"xr",one_only,unused1 + .globl unused1 +unused1: + retq + + .def unused2; .scl 2; .type 32; .endef + .section .text,"xr",one_only,unused2 + .globl unused2 +unused2: + retq + +# This isn't valid DWARF, but LLD doesn't care. Make up some data that +# references the functions above. +.section .debug_info,"r" +.long main@IMGREL +.long unused1@IMGREL +.long unused2@IMGREL + +# Similarly, .eh_frame unwind info should not keep functions alive. Again, this +# is not valid unwind info, but it doesn't matter for testing purposes. +.section .eh_frame,"r" +.long main@IMGREL +.long unused1@IMGREL +.long unused2@IMGREL _______________________________________________ llvm-branch-commits mailing list llvm-branch-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-branch-commits
