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lld-link: Allow backward references between associated comdats 

References between associated comdats are invalid per COFF spec, but the newest
Windows SDK contains obj files that have these references
(https://bugs.chromium.org/p/chromium/issues/detail?id=925943#c13). So add back
support for them and add tests for them. The old code handled them fine.

This makes lld-link match the behavior of newer link.exe versions as far as I
can tell. (The behavior before this change matched the behavior of older
link.exe versions.)

This mostly reverts r352254.

Differential Revision: https://reviews.llvm.org/D57387

llvm-svn: 352508
This commit is contained in:
Nico Weber 2019-01-29 15:50:31 +00:00
parent b1f28579ac
commit 5b04e0a3fd
2 changed files with 16 additions and 14 deletions
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12
lld/COFF/InputFiles.cpp
View File

@ -250,16 +250,12 @@ void ObjFile::readAssociativeDefinition(COFFSymbolRef Sym,
// Check whether the parent is prevailing. If it is, so are we, and we read
// the section; otherwise mark it as discarded.
if (Parent) {
if (Parent->Selection == IMAGE_COMDAT_SELECT_ASSOCIATIVE) {
Diag();
return;
}
SectionChunk *C = readSection(SectionNumber, Def, "");
C->Selection = IMAGE_COMDAT_SELECT_ASSOCIATIVE;
SparseChunks[SectionNumber] = C;
if (SparseChunks[SectionNumber])
Parent->addAssociative(SparseChunks[SectionNumber]);
if (C) {
C->Selection = IMAGE_COMDAT_SELECT_ASSOCIATIVE;
Parent->addAssociative(C);
}
} else {
SparseChunks[SectionNumber] = nullptr;
}

18
lld/test/COFF/associative-comdat-order.test
View File

@ -6,11 +6,17 @@
# FORWARD-NOT: lld-link: error:
# Tests that an associative comdat being associated with another
# associated comdat earlier in the file produces an error.
# associated comdat earlier in the file works.
# RUN: sed -e s/ASSOC1/3/ -e s/ASSOC2/1/ %s | yaml2obj > %t.obj
# RUN: not lld-link /include:symbol /dll /noentry /nodefaultlib %t.obj /out:%t.exe 2>&1 | FileCheck --check-prefix=BACKWARD %s
# BACKWARD: lld-link: error: {{.*}}: associative comdat .text$ac2 (sec 2) has invalid reference to section .text$ac1 (sec 1)
# BACKWARD-NOT: lld-link: error:
# RUN: lld-link /include:symbol /dll /noentry /nodefaultlib %t.obj /out:%t.exe
# RUN: llvm-objdump -s %t.exe | FileCheck --check-prefix=BACKWARD %s
# BACKWARD: Contents of section .text:
# BACKWARD: 180001000 01000000 02000000 03000000 ............
# RUN: lld-link /dll /noentry /nodefaultlib %t.obj /out:%t.exe
# RUN: llvm-objdump -s %t.exe | FileCheck --check-prefix=BACKWARDDROP %s
# BACKWARDDROP-NOT: Contents of section .text:
--- !COFF
header:
@ -24,11 +30,11 @@ sections:
- Name: '.text$ac2'
Characteristics: [ IMAGE_SCN_CNT_INITIALIZED_DATA, IMAGE_SCN_LNK_COMDAT, IMAGE_SCN_MEM_READ, IMAGE_SCN_MEM_WRITE ]
Alignment: 1
SectionData: '01000000'
SectionData: '02000000'
- Name: '.text$nm'
Characteristics: [ IMAGE_SCN_CNT_INITIALIZED_DATA, IMAGE_SCN_LNK_COMDAT, IMAGE_SCN_MEM_READ, IMAGE_SCN_MEM_WRITE ]
Alignment: 1
SectionData: '01000000'
SectionData: '03000000'
symbols:
- Name: '.text$ac1'
Value: 0