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[WebAssembly] Fix local references to weak aliases 

When weak aliases are used with in same translation
unit we need to be able to directly reference to alias
and not just the thing it is aliases.  We do this by
defining both a wasm import and a wasm export in this
case that result in a single Symbol.  This change is
a partial revert of rL314245.  A corresponding lld
change address the previous issues we had with this.

See: https://github.com/WebAssembly/tool-conventions/issues/34

Differential Revision: https://reviews.llvm.org/D41472

llvm-svn: 321242
This commit is contained in:
Sam Clegg 2017-12-21 02:30:38 +00:00
parent c6e4d73f31
commit b6a429842e
4 changed files with 74 additions and 35 deletions
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21
llvm/include/llvm/Object/Wasm.h
View File

@ -43,9 +43,9 @@ public:
};
WasmSymbol(StringRef Name, SymbolType Type, uint32_t Section,
uint32_t ElementIndex, uint32_t ImportIndex = 0)
uint32_t ElementIndex, uint32_t FunctionType = 0)
: Name(Name), Type(Type), Section(Section), ElementIndex(ElementIndex),
ImportIndex(ImportIndex) {}
FunctionType(FunctionType) {}
StringRef Name;
SymbolType Type;
@ -55,8 +55,18 @@ public:
// Index into either the function or global index space.
uint32_t ElementIndex;
// For imports, the index into the import table
uint32_t ImportIndex;
// For function, the type index
uint32_t FunctionType;
// Symbols can be both exported and imported (in the case of the weakly
// defined symbol). In this the import index is stored as AltIndex.
uint32_t AltIndex = 0;
bool HasAltIndex = false;
void setAltIndex(uint32_t Index) {
HasAltIndex = true;
AltIndex = Index;
}
bool isFunction() const {
return Type == WasmSymbol::SymbolType::FUNCTION_IMPORT ||
@ -91,8 +101,7 @@ public:
void print(raw_ostream &Out) const {
Out << "Name=" << Name << ", Type=" << static_cast<int>(Type)
<< ", Flags=" << Flags << " ElemIndex=" << ElementIndex
<< ", ImportIndex=" << ImportIndex;
<< ", Flags=" << Flags << " ElemIndex=" << ElementIndex;
}
#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)

4
llvm/lib/MC/WasmObjectWriter.cpp
View File

@ -1116,7 +1116,7 @@ void WasmObjectWriter::writeObject(MCAssembler &Asm,
continue;
// If the symbol is not defined in this translation unit, import it.
if (!WS.isDefined(/*SetUsed=*/false)) {
if (!WS.isDefined(/*SetUsed=*/false) || WS.isVariable()) {
WasmImport Import;
Import.ModuleName = WS.getModuleName();
Import.FieldName = WS.getName();
@ -1288,7 +1288,7 @@ void WasmObjectWriter::writeObject(MCAssembler &Asm,
uint32_t Index = SymbolIndices.find(ResolvedSym)->second;
DEBUG(dbgs() << " -> index:" << Index << "\n");
SymbolIndices[&WS] = Index;
//SymbolIndices[&WS] = Index;
WasmExport Export;
Export.FieldName = WS.getName();
Export.Index = Index;

27
llvm/lib/Object/WasmObjectFile.cpp
View File

@ -303,7 +303,6 @@ Error WasmObjectFile::parseNameSection(const uint8_t *Ptr, const uint8_t *End) {
void WasmObjectFile::populateSymbolTable() {
// Add imports to symbol table
size_t ImportIndex = 0;
size_t GlobalIndex = 0;
size_t FunctionIndex = 0;
for (const wasm::WasmImport& Import : Imports) {
@ -312,7 +311,7 @@ void WasmObjectFile::populateSymbolTable() {
assert(Import.Global.Type == wasm::WASM_TYPE_I32);
SymbolMap.try_emplace(Import.Field, Symbols.size());
Symbols.emplace_back(Import.Field, WasmSymbol::SymbolType::GLOBAL_IMPORT,
ImportSection, GlobalIndex++, ImportIndex);
ImportSection, GlobalIndex++);
DEBUG(dbgs() << "Adding import: " << Symbols.back()
<< " sym index:" << Symbols.size() << "\n");
break;
@ -320,14 +319,13 @@ void WasmObjectFile::populateSymbolTable() {
SymbolMap.try_emplace(Import.Field, Symbols.size());
Symbols.emplace_back(Import.Field,
WasmSymbol::SymbolType::FUNCTION_IMPORT,
ImportSection, FunctionIndex++, ImportIndex);
ImportSection, FunctionIndex++, Import.SigIndex);
DEBUG(dbgs() << "Adding import: " << Symbols.back()
<< " sym index:" << Symbols.size() << "\n");
break;
default:
break;
}
ImportIndex++;
}
// Add exports to symbol table
@ -338,11 +336,22 @@ void WasmObjectFile::populateSymbolTable() {
Export.Kind == wasm::WASM_EXTERNAL_FUNCTION
? WasmSymbol::SymbolType::FUNCTION_EXPORT
: WasmSymbol::SymbolType::GLOBAL_EXPORT;
SymbolMap.try_emplace(Export.Name, Symbols.size());
Symbols.emplace_back(Export.Name, ExportType,
ExportSection, Export.Index);
DEBUG(dbgs() << "Adding export: " << Symbols.back()
<< " sym index:" << Symbols.size() << "\n");
auto Pair = SymbolMap.try_emplace(Export.Name, Symbols.size());
if (Pair.second) {
Symbols.emplace_back(Export.Name, ExportType,
ExportSection, Export.Index);
DEBUG(dbgs() << "Adding export: " << Symbols.back()
<< " sym index:" << Symbols.size() << "\n");
} else {
uint32_t SymIndex = Pair.first->second;
const WasmSymbol &OldSym = Symbols[SymIndex];
WasmSymbol NewSym(Export.Name, ExportType, ExportSection, Export.Index);
NewSym.setAltIndex(OldSym.ElementIndex);
Symbols[SymIndex] = NewSym;
DEBUG(dbgs() << "Replacing existing symbol: " << NewSym
<< " sym index:" << SymIndex << "\n");
}
}
}
}

57
llvm/test/MC/WebAssembly/weak-alias.ll
View File

@ -43,6 +43,15 @@ entry:
; CHECK-NEXT: ElemType: ANYFUNC
; CHECK-NEXT: Limits:
; CHECK-NEXT: Initial: 0x00000000
; CHECK-NEXT: - Module: env
; CHECK-NEXT: Field: foo_alias
; CHECK-NEXT: Kind: FUNCTION
; CHECK-NEXT: SigIndex: 0
; CHECK-NEXT: - Module: env
; CHECK-NEXT: Field: bar_alias
; CHECK-NEXT: Kind: GLOBAL
; CHECK-NEXT: GlobalType: I32
; CHECK-NEXT: GlobalMutable: false
; CHECK-NEXT: - Type: FUNCTION
; CHECK-NEXT: FunctionTypes: [ 0, 0 ]
; CHECK-NEXT: - Type: GLOBAL
@ -61,24 +70,33 @@ entry:
; CHECK-NEXT: Exports:
; CHECK-NEXT: - Name: call_alias
; CHECK-NEXT: Kind: FUNCTION
; CHECK-NEXT: Index: 0
; CHECK-NEXT: Index: 1
; CHECK-NEXT: - Name: foo
; CHECK-NEXT: Kind: FUNCTION
; CHECK-NEXT: Index: 1
; CHECK-NEXT: Index: 2
; CHECK-NEXT: - Name: bar
; CHECK-NEXT: Kind: GLOBAL
; CHECK-NEXT: Index: 0
; CHECK-NEXT: Index: 1
; CHECK-NEXT: - Name: bar_alias_address
; CHECK-NEXT: Kind: GLOBAL
; CHECK-NEXT: Index: 1
; CHECK-NEXT: Index: 2
; CHECK-NEXT: - Name: foo_alias
; CHECK-NEXT: Kind: FUNCTION
; CHECK-NEXT: Index: 1
; CHECK-NEXT: Index: 2
; CHECK-NEXT: - Name: bar_alias
; CHECK-NEXT: Kind: GLOBAL
; CHECK-NEXT: Index: 1
; CHECK-NEXT: - Type: CODE
; CHECK-NEXT: Relocations:
; CHECK-NEXT: - Type: R_WEBASSEMBLY_FUNCTION_INDEX_LEB
; CHECK-NEXT: Index: 0
; CHECK: - Type: DATA
; CHECK-NEXT: Offset: 0x00000004
; CHECK-NEXT: Functions:
; CHECK-NEXT: - Locals:
; CHECK-NEXT: Body: 1080808080000B
; CHECK-NEXT: - Locals:
; CHECK-NEXT: Body: 41000B
; CHECK-NEXT: - Type: DATA
; CHECK-NEXT: Relocations:
; CHECK-NEXT: - Type: R_WEBASSEMBLY_MEMORY_ADDR_I32
; CHECK-NEXT: Index: 0
@ -101,21 +119,23 @@ entry:
; CHECK-NEXT: Name: name
; CHECK-NEXT: FunctionNames:
; CHECK-NEXT: - Index: 0
; CHECK-NEXT: Name: call_alias
; CHECK-NEXT: Name: foo_alias
; CHECK-NEXT: - Index: 1
; CHECK-NEXT: Name: call_alias
; CHECK-NEXT: - Index: 2
; CHECK-NEXT: Name: foo
; CHECK-NEXT: - Type: CUSTOM
; CHECK-NEXT: Name: linking
; CHECK-NEXT: DataSize: 12
; CHECK-NEXT: SymbolInfo:
; CHECK-NEXT: - Name: call_alias
; CHECK-NEXT: Flags: [ VISIBILITY_HIDDEN ]
; CHECK-NEXT: - Name: foo
; CHECK-NEXT: Flags: [ VISIBILITY_HIDDEN ]
; CHECK-NEXT: - Name: foo_alias
; CHECK-NEXT: Flags: [ BINDING_WEAK, VISIBILITY_HIDDEN ]
; CHECK-NEXT: - Name: bar_alias
; CHECK-NEXT: Flags: [ BINDING_WEAK, VISIBILITY_HIDDEN ]
; CHECK-NEXT: - Name: call_alias
; CHECK-NEXT: Flags: [ VISIBILITY_HIDDEN ]
; CHECK-NEXT: - Name: foo
; CHECK-NEXT: Flags: [ VISIBILITY_HIDDEN ]
; CHECK-NEXT: SegmentInfo:
; CHECK-NEXT: - Index: 0
; CHECK-NEXT: Name: .data.bar
@ -128,11 +148,12 @@ entry:
; CHECK-NEXT: ...
; CHECK-SYMS: SYMBOL TABLE:
; CHECK-SYMS-NEXT: 00000000 g F name call_alias
; CHECK-SYMS-NEXT: 00000001 g F name foo
; CHECK-SYMS-NEXT: 00000000 g F EXPORT .hidden call_alias
; CHECK-SYMS-NEXT: 00000001 g F EXPORT .hidden foo
; CHECK-SYMS-NEXT: 00000000 g F name foo_alias
; CHECK-SYMS-NEXT: 00000001 g F name call_alias
; CHECK-SYMS-NEXT: 00000002 g F name foo
; CHECK-SYMS-NEXT: 00000002 gw F EXPORT .hidden foo_alias
; CHECK-SYMS-NEXT: 00000000 gw EXPORT .hidden bar_alias
; CHECK-SYMS-NEXT: 00000001 g F EXPORT .hidden call_alias
; CHECK-SYMS-NEXT: 00000002 g F EXPORT .hidden foo
; CHECK-SYMS-NEXT: 00000000 g EXPORT bar
; CHECK-SYMS-NEXT: 00000008 g EXPORT bar_alias_address
; CHECK-SYMS-NEXT: 00000001 gw F EXPORT .hidden foo_alias
; CHECK-SYMS-NEXT: 00000000 gw EXPORT .hidden bar_alias