[lld] df8f3bf - [LLD] [COFF] Check the aux section definition size for IMAGE_COMDAT_SELECT_SAME_SIZE
Martin Storsjö via llvm-commits
llvm-commits at lists.llvm.org
Thu Aug 27 05:11:07 PDT 2020
Author: Martin Storsjö
Date: 2020-08-27T15:08:57+03:00
New Revision: df8f3bf6266569545b0b80eccbd990fecb94b3ee
URL: https://github.com/llvm/llvm-project/commit/df8f3bf6266569545b0b80eccbd990fecb94b3ee
DIFF: https://github.com/llvm/llvm-project/commit/df8f3bf6266569545b0b80eccbd990fecb94b3ee.diff
LOG: [LLD] [COFF] Check the aux section definition size for IMAGE_COMDAT_SELECT_SAME_SIZE
Binutils generated sections seem to be padded to a multiple of 16 bytes,
but the aux section definition contains the original, unpadded section
length.
The size check used for IMAGE_COMDAT_SELECT_SAME_SIZE previously
only checked the size of the section itself. When checking the
currently processed object file against the previously chosen
comdat section, we easily have access to the aux section definition
of the currently processed section, but we have to iterate over the
symbols of the previously selected object file to find the section
definition of the previously picked section. (We don't want to
inflate SectionChunk to carry more data, for something that is only
needed in corner cases.) Only do this when the mingw flag is set.
This fixes statically linking clang-built C++ object files against
libstdc++ built with GCC, if the object files contain e.g. typeinfo.
Differential Revision: https://reviews.llvm.org/D86659
Added:
lld/test/COFF/Inputs/comdat-binutils.yaml
lld/test/COFF/Inputs/comdat-llvm.yaml
lld/test/COFF/comdat-gcc-compatibility-size.test
Modified:
lld/COFF/InputFiles.cpp
lld/COFF/InputFiles.h
Removed:
################################################################################
diff --git a/lld/COFF/InputFiles.cpp b/lld/COFF/InputFiles.cpp
index 0bcc6c940bba..a692dfe95d6d 100644
--- a/lld/COFF/InputFiles.cpp
+++ b/lld/COFF/InputFiles.cpp
@@ -472,8 +472,23 @@ Symbol *ObjFile::createUndefined(COFFSymbolRef sym) {
return symtab->addUndefined(name, this, sym.isWeakExternal());
}
-void ObjFile::handleComdatSelection(COFFSymbolRef sym, COMDATType &selection,
- bool &prevailing, DefinedRegular *leader) {
+static const coff_aux_section_definition *findSectionDef(COFFObjectFile *obj,
+ int32_t section) {
+ uint32_t numSymbols = obj->getNumberOfSymbols();
+ for (uint32_t i = 0; i < numSymbols; ++i) {
+ COFFSymbolRef sym = check(obj->getSymbol(i));
+ if (sym.getSectionNumber() != section)
+ continue;
+ if (const coff_aux_section_definition *def = sym.getSectionDefinition())
+ return def;
+ }
+ return nullptr;
+}
+
+void ObjFile::handleComdatSelection(
+ COFFSymbolRef sym, COMDATType &selection, bool &prevailing,
+ DefinedRegular *leader,
+ const llvm::object::coff_aux_section_definition *def) {
if (prevailing)
return;
// There's already an existing comdat for this symbol: `Leader`.
@@ -540,8 +555,16 @@ void ObjFile::handleComdatSelection(COFFSymbolRef sym, COMDATType &selection,
break;
case IMAGE_COMDAT_SELECT_SAME_SIZE:
- if (leaderChunk->getSize() != getSection(sym)->SizeOfRawData)
- symtab->reportDuplicate(leader, this);
+ if (leaderChunk->getSize() != getSection(sym)->SizeOfRawData) {
+ if (!config->mingw) {
+ symtab->reportDuplicate(leader, this);
+ } else {
+ const coff_aux_section_definition *leaderDef = findSectionDef(
+ leaderChunk->file->getCOFFObj(), leaderChunk->getSectionNumber());
+ if (!leaderDef || leaderDef->Length != def->Length)
+ symtab->reportDuplicate(leader, this);
+ }
+ }
break;
case IMAGE_COMDAT_SELECT_EXACT_MATCH: {
@@ -657,7 +680,7 @@ Optional<Symbol *> ObjFile::createDefined(
COMDATType selection = (COMDATType)def->Selection;
if (leader->isCOMDAT)
- handleComdatSelection(sym, selection, prevailing, leader);
+ handleComdatSelection(sym, selection, prevailing, leader, def);
if (prevailing) {
SectionChunk *c = readSection(sectionNumber, def, getName());
diff --git a/lld/COFF/InputFiles.h b/lld/COFF/InputFiles.h
index 1e0b97a82be2..0a5114b165f0 100644
--- a/lld/COFF/InputFiles.h
+++ b/lld/COFF/InputFiles.h
@@ -255,9 +255,10 @@ class ObjFile : public InputFile {
// match the existing symbol and its selection. If either old or new
// symbol have selection IMAGE_COMDAT_SELECT_LARGEST, Sym might replace
// the existing leader. In that case, Prevailing is set to true.
- void handleComdatSelection(COFFSymbolRef sym,
- llvm::COFF::COMDATType &selection,
- bool &prevailing, DefinedRegular *leader);
+ void
+ handleComdatSelection(COFFSymbolRef sym, llvm::COFF::COMDATType &selection,
+ bool &prevailing, DefinedRegular *leader,
+ const llvm::object::coff_aux_section_definition *def);
llvm::Optional<Symbol *>
createDefined(COFFSymbolRef sym,
diff --git a/lld/test/COFF/Inputs/comdat-binutils.yaml b/lld/test/COFF/Inputs/comdat-binutils.yaml
new file mode 100644
index 000000000000..70fff87e1a44
--- /dev/null
+++ b/lld/test/COFF/Inputs/comdat-binutils.yaml
@@ -0,0 +1,30 @@
+--- !COFF
+header:
+ Machine: IMAGE_FILE_MACHINE_AMD64
+ Characteristics: [ IMAGE_FILE_RELOCS_STRIPPED, IMAGE_FILE_LINE_NUMS_STRIPPED ]
+sections:
+ - Name: '.rdata$mysymbol'
+ Characteristics: [ IMAGE_SCN_CNT_INITIALIZED_DATA, IMAGE_SCN_LNK_COMDAT, IMAGE_SCN_MEM_READ ]
+ Alignment: 16
+ SectionData: 2A000000000000000000000000000000
+symbols:
+ - Name: '.rdata$mysymbol'
+ Value: 0
+ SectionNumber: 1
+ SimpleType: IMAGE_SYM_TYPE_NULL
+ ComplexType: IMAGE_SYM_DTYPE_NULL
+ StorageClass: IMAGE_SYM_CLASS_STATIC
+ SectionDefinition:
+ Length: 1
+ NumberOfRelocations: 0
+ NumberOfLinenumbers: 0
+ CheckSum: 0
+ Number: 0
+ Selection: IMAGE_COMDAT_SELECT_SAME_SIZE
+ - Name: mysymbol
+ Value: 0
+ SectionNumber: 1
+ SimpleType: IMAGE_SYM_TYPE_NULL
+ ComplexType: IMAGE_SYM_DTYPE_NULL
+ StorageClass: IMAGE_SYM_CLASS_EXTERNAL
+...
diff --git a/lld/test/COFF/Inputs/comdat-llvm.yaml b/lld/test/COFF/Inputs/comdat-llvm.yaml
new file mode 100644
index 000000000000..eef117a92334
--- /dev/null
+++ b/lld/test/COFF/Inputs/comdat-llvm.yaml
@@ -0,0 +1,30 @@
+--- !COFF
+header:
+ Machine: IMAGE_FILE_MACHINE_AMD64
+ Characteristics: [ ]
+sections:
+ - Name: '.rdata$mysymbol'
+ Characteristics: [ IMAGE_SCN_CNT_INITIALIZED_DATA, IMAGE_SCN_LNK_COMDAT, IMAGE_SCN_MEM_READ ]
+ Alignment: 1
+ SectionData: 2A
+symbols:
+ - Name: '.rdata$mysymbol'
+ Value: 0
+ SectionNumber: 1
+ SimpleType: IMAGE_SYM_TYPE_NULL
+ ComplexType: IMAGE_SYM_DTYPE_NULL
+ StorageClass: IMAGE_SYM_CLASS_STATIC
+ SectionDefinition:
+ Length: 1
+ NumberOfRelocations: 0
+ NumberOfLinenumbers: 0
+ CheckSum: 3686517206
+ Number: 1
+ Selection: IMAGE_COMDAT_SELECT_SAME_SIZE
+ - Name: mysymbol
+ Value: 0
+ SectionNumber: 1
+ SimpleType: IMAGE_SYM_TYPE_NULL
+ ComplexType: IMAGE_SYM_DTYPE_NULL
+ StorageClass: IMAGE_SYM_CLASS_EXTERNAL
+...
diff --git a/lld/test/COFF/comdat-gcc-compatibility-size.test b/lld/test/COFF/comdat-gcc-compatibility-size.test
new file mode 100644
index 000000000000..493867646362
--- /dev/null
+++ b/lld/test/COFF/comdat-gcc-compatibility-size.test
@@ -0,0 +1,15 @@
+# RUN: yaml2obj %p/Inputs/comdat-llvm.yaml > %t.llvm.o
+# RUN: yaml2obj %p/Inputs/comdat-binutils.yaml > %t.binutils.o
+# RUN: lld-link -lldmingw -noentry -dll %t.llvm.o %t.binutils.o -out:%t.dll
+# RUN: lld-link -lldmingw -noentry -dll %t.binutils.o %t.llvm.o -out:%t.dll
+# RUN: not lld-link -noentry -dll %t.llvm.o %t.binutils.o -out:%t.dll
+# RUN: not lld-link -noentry -dll %t.binutils.o %t.llvm.o -out:%t.dll
+
+# The test object files have been generated by assembling the following
+# snippet using binutils and llvm.
+
+# .section .rdata$mysymbol, "dr"
+# .linkonce same_size
+# .globl mysymbol
+#mysymbol:
+# .byte 42
More information about the llvm-commits
mailing list