[WebAssembly] Add new `export_name` clang attribute for controlling wasm export names
This is equivalent to the existing `import_name` and `import_module`
attributes which control the import names in the final wasm binary
produced by lld.
This maps the existing
This attribute currently requires a string rather than using the
symbol name for a couple of reasons:
1. Avoid confusion with static and dynamic linking which is
based on symbol name. Exporting a function from a wasm module using
this directive is orthogonal to both static and dynamic linking.
2. Avoids name mangling.
Differential Revision: https://reviews.llvm.org/D70520
diff --git a/llvm/lib/Target/WebAssembly/AsmParser/WebAssemblyAsmParser.cpp b/llvm/lib/Target/WebAssembly/AsmParser/WebAssemblyAsmParser.cpp
index 138ce85..1f0bdde 100644
--- a/llvm/lib/Target/WebAssembly/AsmParser/WebAssemblyAsmParser.cpp
+++ b/llvm/lib/Target/WebAssembly/AsmParser/WebAssemblyAsmParser.cpp
@@ -712,6 +712,18 @@
return expect(AsmToken::EndOfStatement, "EOL");
}
+ if (DirectiveID.getString() == ".export_name") {
+ auto SymName = expectIdent();
+ if (SymName.empty())
+ return true;
+ if (expect(AsmToken::Comma, ","))
+ return true;
+ auto ExportName = expectIdent();
+ auto WasmSym = cast<MCSymbolWasm>(Ctx.getOrCreateSymbol(SymName));
+ WasmSym->setExportName(ExportName);
+ TOut.emitExportName(WasmSym, ExportName);
+ }
+
if (DirectiveID.getString() == ".import_module") {
auto SymName = expectIdent();
if (SymName.empty())
diff --git a/llvm/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyTargetStreamer.cpp b/llvm/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyTargetStreamer.cpp
index 4092620..7c21ed5 100644
--- a/llvm/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyTargetStreamer.cpp
+++ b/llvm/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyTargetStreamer.cpp
@@ -94,6 +94,12 @@
<< ImportName << '\n';
}
+void WebAssemblyTargetAsmStreamer::emitExportName(const MCSymbolWasm *Sym,
+ StringRef ExportName) {
+ OS << "\t.export_name\t" << Sym->getName() << ", "
+ << ExportName << '\n';
+}
+
void WebAssemblyTargetAsmStreamer::emitIndIdx(const MCExpr *Value) {
OS << "\t.indidx \t" << *Value << '\n';
}
diff --git a/llvm/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyTargetStreamer.h b/llvm/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyTargetStreamer.h
index 0164f8e..9aee1a0 100644
--- a/llvm/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyTargetStreamer.h
+++ b/llvm/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyTargetStreamer.h
@@ -48,6 +48,9 @@
/// .import_name
virtual void emitImportName(const MCSymbolWasm *Sym,
StringRef ImportName) = 0;
+ /// .export_name
+ virtual void emitExportName(const MCSymbolWasm *Sym,
+ StringRef ExportName) = 0;
protected:
void emitValueType(wasm::ValType Type);
@@ -68,6 +71,7 @@
void emitEventType(const MCSymbolWasm *Sym) override;
void emitImportModule(const MCSymbolWasm *Sym, StringRef ImportModule) override;
void emitImportName(const MCSymbolWasm *Sym, StringRef ImportName) override;
+ void emitExportName(const MCSymbolWasm *Sym, StringRef ExportName) override;
};
/// This part is for Wasm object output
@@ -85,6 +89,8 @@
StringRef ImportModule) override {}
void emitImportName(const MCSymbolWasm *Sym,
StringRef ImportName) override {}
+ void emitExportName(const MCSymbolWasm *Sym,
+ StringRef ExportName) override {}
};
/// This part is for null output
@@ -101,6 +107,7 @@
void emitEventType(const MCSymbolWasm *) override {}
void emitImportModule(const MCSymbolWasm *, StringRef) override {}
void emitImportName(const MCSymbolWasm *, StringRef) override {}
+ void emitExportName(const MCSymbolWasm *, StringRef) override {}
};
} // end namespace llvm
diff --git a/llvm/lib/Target/WebAssembly/WebAssemblyAsmPrinter.cpp b/llvm/lib/Target/WebAssembly/WebAssemblyAsmPrinter.cpp
index 5d8b873..cb95d5d 100644
--- a/llvm/lib/Target/WebAssembly/WebAssemblyAsmPrinter.cpp
+++ b/llvm/lib/Target/WebAssembly/WebAssemblyAsmPrinter.cpp
@@ -96,8 +96,11 @@
}
for (const auto &F : M) {
+ if (F.isIntrinsic())
+ continue;
+
// Emit function type info for all undefined functions
- if (F.isDeclarationForLinker() && !F.isIntrinsic()) {
+ if (F.isDeclarationForLinker()) {
SmallVector<MVT, 4> Results;
SmallVector<MVT, 4> Params;
computeSignatureVTs(F.getFunctionType(), F, TM, Params, Results);
@@ -130,6 +133,13 @@
getTargetStreamer()->emitImportName(Sym, Name);
}
}
+
+ if (F.hasFnAttribute("wasm-export-name")) {
+ auto *Sym = cast<MCSymbolWasm>(getSymbol(&F));
+ StringRef Name = F.getFnAttribute("wasm-export-name").getValueAsString();
+ Sym->setExportName(Name);
+ getTargetStreamer()->emitExportName(Sym, Name);
+ }
}
for (const auto &G : M.globals()) {