From ba9fa9fd168f3cb74be749c77df73ada3ee0c27d Mon Sep 17 00:00:00 2001 From: Sam Clegg Date: Tue, 26 Sep 2017 21:10:09 +0000 Subject: [PATCH] [WebAssembly] Model weakly defined symbols as wasm exports Previously these were being included as both imports and exports, with the import being satisfied by the export (or some strong symbol) at runtime. However proved unnecessary and actually complicated linking as it meant there was not a 1-to-1 mapping between a wasm function /global index and a linker symbol. Differential Revision: https://reviews.llvm.org/D38246 llvm-svn: 314245 --- llvm/lib/MC/WasmObjectWriter.cpp | 3 +- llvm/lib/Object/WasmObjectFile.cpp | 18 +++------ llvm/test/MC/WebAssembly/weak-alias.ll | 67 ++++++++++++++++++---------------- 3 files changed, 42 insertions(+), 46 deletions(-) diff --git a/llvm/lib/MC/WasmObjectWriter.cpp b/llvm/lib/MC/WasmObjectWriter.cpp index f17801a..d7a9895 100644 --- a/llvm/lib/MC/WasmObjectWriter.cpp +++ b/llvm/lib/MC/WasmObjectWriter.cpp @@ -1036,7 +1036,7 @@ void WasmObjectWriter::writeObject(MCAssembler &Asm, registerFunctionType(WS); // If the symbol is not defined in this translation unit, import it. - if (!WS.isDefined(/*SetUsed=*/false) || WS.isVariable()) { + if (!WS.isDefined(/*SetUsed=*/false)) { WasmImport Import; Import.ModuleName = WS.getModuleName(); Import.FieldName = WS.getName(); @@ -1268,6 +1268,7 @@ void WasmObjectWriter::writeObject(MCAssembler &Asm, uint32_t Index = SymbolIndices.find(ResolvedSym)->second; DEBUG(dbgs() << " -> index:" << Index << "\n"); + SymbolIndices[&WS] = Index; WasmExport Export; Export.FieldName = WS.getName(); Export.Index = Index; diff --git a/llvm/lib/Object/WasmObjectFile.cpp b/llvm/lib/Object/WasmObjectFile.cpp index c320b91..1954335 100644 --- a/llvm/lib/Object/WasmObjectFile.cpp +++ b/llvm/lib/Object/WasmObjectFile.cpp @@ -337,19 +337,11 @@ void WasmObjectFile::populateSymbolTable() { Export.Kind == wasm::WASM_EXTERNAL_FUNCTION ? WasmSymbol::SymbolType::FUNCTION_EXPORT : WasmSymbol::SymbolType::GLOBAL_EXPORT; - 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; - Symbols[SymIndex] = - WasmSymbol(Export.Name, ExportType, ExportSection, Export.Index); - DEBUG(dbgs() << "Replacing existing symbol: " << Symbols[SymIndex] - << " sym index:" << SymIndex << "\n"); - } + 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"); } } } diff --git a/llvm/test/MC/WebAssembly/weak-alias.ll b/llvm/test/MC/WebAssembly/weak-alias.ll index 8db83e4..bdaaef7 100644 --- a/llvm/test/MC/WebAssembly/weak-alias.ll +++ b/llvm/test/MC/WebAssembly/weak-alias.ll @@ -29,42 +29,48 @@ entry: ; CHECK-NEXT: - Index: 0 ; CHECK-NEXT: ReturnType: I32 ; CHECK-NEXT: ParamTypes: - -; CHECK: - Type: IMPORT -; CHECK-NEXT: Imports: -; 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: - Type: FUNCTION +; CHECK-NEXT: - Type: FUNCTION ; CHECK-NEXT: FunctionTypes: [ 0, 0 ] - -; CHECK: - Type: EXPORT +; CHECK-NEXT: - Type: TABLE +; CHECK-NEXT: Tables: +; CHECK-NEXT: - ElemType: ANYFUNC +; CHECK-NEXT: Limits: +; CHECK-NEXT: Initial: 0x00000000 +; CHECK-NEXT: - Type: MEMORY +; CHECK-NEXT: Memories: +; CHECK-NEXT: - Initial: 0x00000001 +; CHECK-NEXT: - Type: GLOBAL +; CHECK-NEXT: Globals: +; CHECK-NEXT: - Type: I32 +; CHECK-NEXT: Mutable: false +; CHECK-NEXT: InitExpr: +; CHECK-NEXT: Opcode: I32_CONST +; CHECK-NEXT: Value: 0 +; CHECK-NEXT: - Type: I32 +; CHECK-NEXT: Mutable: false +; CHECK-NEXT: InitExpr: +; CHECK-NEXT: Opcode: I32_CONST +; CHECK-NEXT: Value: 8 +; CHECK-NEXT: - Type: EXPORT ; CHECK-NEXT: Exports: ; CHECK-NEXT: - Name: call_alias ; CHECK-NEXT: Kind: FUNCTION -; CHECK-NEXT: Index: 1 +; CHECK-NEXT: Index: 0 ; CHECK-NEXT: - Name: foo ; CHECK-NEXT: Kind: FUNCTION -; CHECK-NEXT: Index: 2 +; CHECK-NEXT: Index: 1 ; CHECK-NEXT: - Name: bar ; CHECK-NEXT: Kind: GLOBAL -; CHECK-NEXT: Index: 1 +; CHECK-NEXT: Index: 0 ; CHECK-NEXT: - Name: bar_alias_address ; CHECK-NEXT: Kind: GLOBAL -; CHECK-NEXT: Index: 2 +; CHECK-NEXT: Index: 1 ; CHECK-NEXT: - Name: foo_alias ; CHECK-NEXT: Kind: FUNCTION -; CHECK-NEXT: Index: 2 +; CHECK-NEXT: Index: 1 ; CHECK-NEXT: - Name: bar_alias ; CHECK-NEXT: Kind: GLOBAL -; CHECK-NEXT: Index: 1 +; CHECK-NEXT: Index: 0 ; CHECK: - Type: DATA ; CHECK-NEXT: Relocations: @@ -89,10 +95,8 @@ entry: ; CHECK-NEXT: Name: name ; CHECK-NEXT: FunctionNames: ; CHECK-NEXT: - Index: 0 -; CHECK-NEXT: Name: foo_alias -; CHECK-NEXT: - Index: 1 ; CHECK-NEXT: Name: call_alias -; CHECK-NEXT: - Index: 2 +; CHECK-NEXT: - Index: 1 ; CHECK-NEXT: Name: foo ; CHECK-NEXT: - Type: CUSTOM ; CHECK-NEXT: Name: linking @@ -111,12 +115,11 @@ entry: ; CHECK-NEXT: ... ; CHECK-SYMS: SYMBOL TABLE: -; 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 foo_alias -; CHECK-SYMS-NEXT: 00000000 gw EXPORT bar_alias -; CHECK-SYMS-NEXT: 00000001 g F EXPORT call_alias -; CHECK-SYMS-NEXT: 00000002 g F EXPORT foo +; CHECK-SYMS-NEXT: 00000000 g F name call_alias +; CHECK-SYMS-NEXT: 00000001 g F name foo +; CHECK-SYMS-NEXT: 00000000 g F EXPORT call_alias +; CHECK-SYMS-NEXT: 00000001 g F EXPORT foo ; CHECK-SYMS-NEXT: 00000000 g EXPORT bar ; CHECK-SYMS-NEXT: 00000008 g EXPORT bar_alias_address +; CHECK-SYMS-NEXT: 00000001 gw F EXPORT foo_alias +; CHECK-SYMS-NEXT: 00000000 gw EXPORT bar_alias -- 2.7.4