forked from OSchip/llvm-project
[PECOFF] Support a new type of weak symbol.
Summary: COMDAT_SELECT_SAME_SIZE is a COMDAT type that I presume exist only in COFF. The semantics of the type is that linker should merge such COMDAT sections if their sizes are the same. Otherwise it's an error. Reviewers: Bigcheese, shankarke, kledzik CC: llvm-commits Differential Revision: http://llvm-reviews.chandlerc.com/D2996 llvm-svn: 203308
This commit is contained in:
Rui Ueyama
parent
1d6d1c88bd
commit
c79dd2f80a
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@ -93,12 +93,13 @@ public:
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enum Merge {
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mergeNo, // Another atom with same name is error
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mergeAsTentative, // Is ANSI C tentative definition, can be coalesced
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mergeAsWeak, // is C++ inline definition that was not inlined,
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mergeAsWeak, // Is C++ inline definition that was not inlined,
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// but address was not taken, so atom can be hidden
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// by linker
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mergeAsWeakAndAddressUsed,// is C++ definition inline definition whose
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// address was taken.
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mergeByContent // merge with other constants with same content
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mergeAsWeakAndAddressUsed, // Is C++ definition inline definition whose
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// address was taken.
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mergeByContent, // Merge with other constants with same content
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mergeSameNameAndSize, // Another atom with different size is error
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};
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enum ContentType {
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@ -98,27 +98,17 @@ enum MergeResolution {
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MCR_First,
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MCR_Second,
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MCR_Largest,
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MCR_SameSize,
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MCR_Error
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};
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static MergeResolution mergeCases[4][4] = {
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// no tentative weak weakAddressUsed
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{
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// first is no
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MCR_Error, MCR_First, MCR_First, MCR_First
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},
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{
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// first is tentative
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MCR_Second, MCR_Largest, MCR_Second, MCR_Second
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},
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{
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// first is weak
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MCR_Second, MCR_First, MCR_First, MCR_Second
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},
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{
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// first is weakAddressUsed
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MCR_Second, MCR_First, MCR_First, MCR_First
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}
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static MergeResolution mergeCases[][5] = {
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// no tentative weak weakAddress sameNameAndSize
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{MCR_Error, MCR_First, MCR_First, MCR_First, MCR_SameSize}, // no
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{MCR_Second, MCR_Largest, MCR_Second, MCR_Second, MCR_SameSize}, // tentative
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{MCR_Second, MCR_First, MCR_First, MCR_Second, MCR_SameSize}, // weak
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{MCR_Second, MCR_First, MCR_First, MCR_First, MCR_SameSize}, // weakAddress
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{MCR_SameSize, MCR_SameSize, MCR_SameSize, MCR_SameSize, MCR_SameSize}, // sameSize
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};
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static MergeResolution mergeSelect(DefinedAtom::Merge first,
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@ -126,7 +116,7 @@ static MergeResolution mergeSelect(DefinedAtom::Merge first,
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return mergeCases[first][second];
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}
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void SymbolTable::addByName(const Atom & newAtom) {
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void SymbolTable::addByName(const Atom &newAtom) {
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StringRef name = newAtom.name();
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assert(!name.empty());
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const Atom *existing = this->findByName(name);
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@ -149,7 +139,7 @@ void SymbolTable::addByName(const Atom & newAtom) {
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assert(existing->definition() == Atom::definitionRegular);
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assert(newAtom.definition() == Atom::definitionRegular);
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switch (mergeSelect(((DefinedAtom*)existing)->merge(),
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((DefinedAtom*)(&newAtom))->merge())) {
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((DefinedAtom*)&newAtom)->merge())) {
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case MCR_First:
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useNew = false;
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break;
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@ -159,6 +149,18 @@ void SymbolTable::addByName(const Atom & newAtom) {
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case MCR_Largest:
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useNew = true;
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break;
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case MCR_SameSize: {
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uint64_t sa = ((DefinedAtom*)existing)->size();
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uint64_t sb = ((DefinedAtom*)&newAtom)->size();
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if (sa == sb) {
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useNew = true;
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break;
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}
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llvm::errs() << "Size mismatch: "
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<< existing->name() << " (" << sa << ") "
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<< newAtom.name() << " (" << sb << ")\n";
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// fallthrough
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}
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case MCR_Error:
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llvm::errs() << "Duplicate symbols: "
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<< existing->name()
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@ -249,8 +249,10 @@ DefinedAtom::Merge getMerge(const coff_aux_section_definition *auxsym) {
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return DefinedAtom::mergeNo;
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case llvm::COFF::IMAGE_COMDAT_SELECT_ANY:
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return DefinedAtom::mergeAsWeakAndAddressUsed;
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case llvm::COFF::IMAGE_COMDAT_SELECT_SAME_SIZE:
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case llvm::COFF::IMAGE_COMDAT_SELECT_EXACT_MATCH:
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return DefinedAtom::mergeByContent;
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case llvm::COFF::IMAGE_COMDAT_SELECT_SAME_SIZE:
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return DefinedAtom::mergeSameNameAndSize;
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case llvm::COFF::IMAGE_COMDAT_SELECT_ASSOCIATIVE:
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case llvm::COFF::IMAGE_COMDAT_SELECT_LARGEST:
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case llvm::COFF::IMAGE_COMDAT_SELECT_NEWEST:
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@ -337,7 +337,9 @@ template <> struct ScalarEnumerationTraits<lld::DefinedAtom::Merge> {
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io.enumCase(value, "as-weak", lld::DefinedAtom::mergeAsWeak);
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io.enumCase(value, "as-addressed-weak",
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lld::DefinedAtom::mergeAsWeakAndAddressUsed);
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io.enumCase(value, "by-content", lld::DefinedAtom::mergeByContent);
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io.enumCase(value, "by-content", lld::DefinedAtom::mergeByContent);
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io.enumCase(value, "same-name-and-size",
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lld::DefinedAtom::mergeSameNameAndSize);
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}
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};
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@ -0,0 +1,25 @@
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---
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header:
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Machine: IMAGE_FILE_MACHINE_I386
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Characteristics: [ ]
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sections:
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- Name: .text
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Characteristics: [ IMAGE_SCN_CNT_CODE, IMAGE_SCN_LNK_COMDAT, IMAGE_SCN_MEM_EXECUTE, IMAGE_SCN_MEM_READ ]
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Alignment: 16
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SectionData: FFFFFFFFFFFFFF
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symbols:
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- Name: .text
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Value: 0
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SectionNumber: 1
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SimpleType: IMAGE_SYM_TYPE_NULL
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ComplexType: IMAGE_SYM_DTYPE_NULL
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StorageClass: IMAGE_SYM_CLASS_STATIC
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NumberOfAuxSymbols: 1
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AuxiliaryData: 0700000000000000C979F796000003000000
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- Name: "_foo"
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Value: 0
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SectionNumber: 1
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SimpleType: IMAGE_SYM_TYPE_NULL
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ComplexType: IMAGE_SYM_DTYPE_FUNCTION
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StorageClass: IMAGE_SYM_CLASS_EXTERNAL
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...
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@ -0,0 +1,25 @@
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---
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header:
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Machine: IMAGE_FILE_MACHINE_I386
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Characteristics: [ ]
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sections:
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- Name: .text
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Characteristics: [ IMAGE_SCN_CNT_CODE, IMAGE_SCN_LNK_COMDAT, IMAGE_SCN_MEM_EXECUTE, IMAGE_SCN_MEM_READ ]
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Alignment: 16
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SectionData: AAAAAAAAAAAAAA
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symbols:
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- Name: .text
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Value: 0
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SectionNumber: 1
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SimpleType: IMAGE_SYM_TYPE_NULL
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ComplexType: IMAGE_SYM_DTYPE_NULL
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StorageClass: IMAGE_SYM_CLASS_STATIC
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NumberOfAuxSymbols: 1
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AuxiliaryData: 0700000000000000C979F796000003000000
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- Name: "_foo"
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Value: 0
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SectionNumber: 1
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SimpleType: IMAGE_SYM_TYPE_NULL
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ComplexType: IMAGE_SYM_DTYPE_FUNCTION
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StorageClass: IMAGE_SYM_CLASS_EXTERNAL
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...
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@ -0,0 +1,24 @@
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# RUN: yaml2obj %p/Inputs/merge-same-size1.obj.yaml > %t1.obj
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# RUN: yaml2obj %p/Inputs/merge-same-size2.obj.yaml > %t2.obj
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#
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# RUN: lld -flavor link /out:%t.exe /subsystem:console /opt:noref /force \
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# RUN: -- %t1.obj %t2.obj 2>&1 > %t.log
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#
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# FileCheck complains if the input files is empty, so add a dummy line.
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# RUN: echo foo >> %t.log
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# RUN: FileCheck -check-prefix=STDERR %s < %t.log
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#
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# RUN: llvm-readobj -sections %t.exe | FileCheck -check-prefix=READOBJ %s
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STDERR-NOT: duplicate symbol error
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READOBJ: Format: COFF-i386
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READOBJ-NEXT: Arch: i386
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READOBJ-NEXT: AddressSize: 32bit
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READOBJ-NEXT: Sections [
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READOBJ-NEXT: Section {
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READOBJ-NEXT: Number: 1
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READOBJ-NEXT: Name: .text (2E 74 65 78 74 00 00 00)
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READOBJ-NEXT: VirtualSize: 0x7
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READOBJ-NEXT: VirtualAddress: 0x1000
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READOBJ-NEXT: RawDataSize: 7
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