[PATCH] [PECOFF] Support a new type of weak symbol.
Rui Ueyama
ruiu at google.com
Thu Mar 6 16:29:17 PST 2014
Hi Bigcheese, shankarke, kledzik,
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.
http://llvm-reviews.chandlerc.com/D2996
Files:
include/lld/Core/DefinedAtom.h
lib/Core/SymbolTable.cpp
lib/ReaderWriter/PECOFF/ReaderCOFF.cpp
lib/ReaderWriter/YAML/ReaderWriterYAML.cpp
test/pecoff/Inputs/merge-same-size1.obj.yaml
test/pecoff/Inputs/merge-same-size2.obj.yaml
test/pecoff/merge-same-size.test
Index: include/lld/Core/DefinedAtom.h
===================================================================
--- include/lld/Core/DefinedAtom.h
+++ include/lld/Core/DefinedAtom.h
@@ -93,12 +93,13 @@
enum Merge {
mergeNo, // Another atom with same name is error
mergeAsTentative, // Is ANSI C tentative definition, can be coalesced
- mergeAsWeak, // is C++ inline definition that was not inlined,
+ mergeAsWeak, // Is C++ inline definition that was not inlined,
// but address was not taken, so atom can be hidden
// by linker
- mergeAsWeakAndAddressUsed,// is C++ definition inline definition whose
- // address was taken.
- mergeByContent // merge with other constants with same content
+ mergeAsWeakAndAddressUsed, // Is C++ definition inline definition whose
+ // address was taken.
+ mergeByContent, // Merge with other constants with same content
+ mergeSameSize, // Another atom with different size is error
};
enum ContentType {
Index: lib/Core/SymbolTable.cpp
===================================================================
--- lib/Core/SymbolTable.cpp
+++ lib/Core/SymbolTable.cpp
@@ -121,12 +121,28 @@
}
};
-static MergeResolution mergeSelect(DefinedAtom::Merge first,
- DefinedAtom::Merge second) {
- return mergeCases[first][second];
+static MergeResolution mergeSelect(const DefinedAtom *first,
+ const DefinedAtom *second) {
+ DefinedAtom::Merge mf = first->merge();
+ DefinedAtom::Merge ms = second->merge();
+
+ // Check if they are merged by szie. If their sizes are equal, merge as if
+ // they are weak symbols.
+ if (mf == DefinedAtom::mergeSameSize) {
+ if (first->size() != second->size())
+ return MCR_Error;
+ mf = DefinedAtom::mergeAsWeak;
+ }
+ if (ms == DefinedAtom::mergeSameSize) {
+ if (first->size() != second->size())
+ return MCR_Error;
+ ms = DefinedAtom::mergeAsWeak;
+ }
+
+ return mergeCases[mf][ms];
}
-void SymbolTable::addByName(const Atom & newAtom) {
+void SymbolTable::addByName(const Atom &newAtom) {
StringRef name = newAtom.name();
assert(!name.empty());
const Atom *existing = this->findByName(name);
@@ -148,8 +164,7 @@
case NCR_DupDef:
assert(existing->definition() == Atom::definitionRegular);
assert(newAtom.definition() == Atom::definitionRegular);
- switch (mergeSelect(((DefinedAtom*)existing)->merge(),
- ((DefinedAtom*)(&newAtom))->merge())) {
+ switch (mergeSelect((DefinedAtom*)existing, (DefinedAtom*)&newAtom)) {
case MCR_First:
useNew = false;
break;
Index: lib/ReaderWriter/PECOFF/ReaderCOFF.cpp
===================================================================
--- lib/ReaderWriter/PECOFF/ReaderCOFF.cpp
+++ lib/ReaderWriter/PECOFF/ReaderCOFF.cpp
@@ -249,8 +249,10 @@
return DefinedAtom::mergeNo;
case llvm::COFF::IMAGE_COMDAT_SELECT_ANY:
return DefinedAtom::mergeAsWeakAndAddressUsed;
- case llvm::COFF::IMAGE_COMDAT_SELECT_SAME_SIZE:
case llvm::COFF::IMAGE_COMDAT_SELECT_EXACT_MATCH:
+ return DefinedAtom::mergeByContent;
+ case llvm::COFF::IMAGE_COMDAT_SELECT_SAME_SIZE:
+ return DefinedAtom::mergeSameSize;
case llvm::COFF::IMAGE_COMDAT_SELECT_ASSOCIATIVE:
case llvm::COFF::IMAGE_COMDAT_SELECT_LARGEST:
case llvm::COFF::IMAGE_COMDAT_SELECT_NEWEST:
Index: lib/ReaderWriter/YAML/ReaderWriterYAML.cpp
===================================================================
--- lib/ReaderWriter/YAML/ReaderWriterYAML.cpp
+++ lib/ReaderWriter/YAML/ReaderWriterYAML.cpp
@@ -337,7 +337,8 @@
io.enumCase(value, "as-weak", lld::DefinedAtom::mergeAsWeak);
io.enumCase(value, "as-addressed-weak",
lld::DefinedAtom::mergeAsWeakAndAddressUsed);
- io.enumCase(value, "by-content", lld::DefinedAtom::mergeByContent);
+ io.enumCase(value, "by-content", lld::DefinedAtom::mergeByContent);
+ io.enumCase(value, "same-size", lld::DefinedAtom::mergeSameSize);
}
};
Index: test/pecoff/Inputs/merge-same-size1.obj.yaml
===================================================================
--- /dev/null
+++ test/pecoff/Inputs/merge-same-size1.obj.yaml
@@ -0,0 +1,25 @@
+---
+header:
+ Machine: IMAGE_FILE_MACHINE_I386
+ Characteristics: [ ]
+sections:
+ - Name: .text
+ Characteristics: [ IMAGE_SCN_CNT_CODE, IMAGE_SCN_LNK_COMDAT, IMAGE_SCN_MEM_EXECUTE, IMAGE_SCN_MEM_READ ]
+ Alignment: 16
+ SectionData: FFFFFFFFFFFFFF
+symbols:
+ - Name: .text
+ Value: 0
+ SectionNumber: 1
+ SimpleType: IMAGE_SYM_TYPE_NULL
+ ComplexType: IMAGE_SYM_DTYPE_NULL
+ StorageClass: IMAGE_SYM_CLASS_STATIC
+ NumberOfAuxSymbols: 1
+ AuxiliaryData: 0700000000000000C979F796000003000000
+ - Name: "_foo"
+ Value: 0
+ SectionNumber: 1
+ SimpleType: IMAGE_SYM_TYPE_NULL
+ ComplexType: IMAGE_SYM_DTYPE_FUNCTION
+ StorageClass: IMAGE_SYM_CLASS_EXTERNAL
+...
Index: test/pecoff/Inputs/merge-same-size2.obj.yaml
===================================================================
--- /dev/null
+++ test/pecoff/Inputs/merge-same-size2.obj.yaml
@@ -0,0 +1,25 @@
+---
+header:
+ Machine: IMAGE_FILE_MACHINE_I386
+ Characteristics: [ ]
+sections:
+ - Name: .text
+ Characteristics: [ IMAGE_SCN_CNT_CODE, IMAGE_SCN_LNK_COMDAT, IMAGE_SCN_MEM_EXECUTE, IMAGE_SCN_MEM_READ ]
+ Alignment: 16
+ SectionData: AAAAAAAAAAAAAA
+symbols:
+ - Name: .text
+ Value: 0
+ SectionNumber: 1
+ SimpleType: IMAGE_SYM_TYPE_NULL
+ ComplexType: IMAGE_SYM_DTYPE_NULL
+ StorageClass: IMAGE_SYM_CLASS_STATIC
+ NumberOfAuxSymbols: 1
+ AuxiliaryData: 0700000000000000C979F796000003000000
+ - Name: "_foo"
+ Value: 0
+ SectionNumber: 1
+ SimpleType: IMAGE_SYM_TYPE_NULL
+ ComplexType: IMAGE_SYM_DTYPE_FUNCTION
+ StorageClass: IMAGE_SYM_CLASS_EXTERNAL
+...
Index: test/pecoff/merge-same-size.test
===================================================================
--- /dev/null
+++ test/pecoff/merge-same-size.test
@@ -0,0 +1,12 @@
+# RUN: yaml2obj %p/Inputs/merge-same-size1.obj.yaml > %t1.obj
+# RUN: yaml2obj %p/Inputs/merge-same-size2.obj.yaml > %t2.obj
+#
+# RUN: lld -flavor link /out:%t.exe /subsystem:console /opt:noref /force \
+# RUN: -- %t1.obj %t2.obj 2>&1 > %t.log
+#
+# FileCheck complains if the input files is empty, so add a dummy line.
+# RUN: echo foo >> %t.log
+#
+# RUN: FileCheck %s < %t.log
+
+CHECK-NOT: duplicate symbol error
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