[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
GitOrigin-RevId: 881d877846e2904c731d616731969421ce8cc825
diff --git a/include/llvm/BinaryFormat/Wasm.h b/include/llvm/BinaryFormat/Wasm.h
index f550d88..59f99cc 100644
--- a/include/llvm/BinaryFormat/Wasm.h
+++ b/include/llvm/BinaryFormat/Wasm.h
@@ -131,6 +131,7 @@
uint32_t CodeSectionOffset;
uint32_t Size;
uint32_t CodeOffset; // start of Locals and Body
+ StringRef ExportName; // from the "export" section
StringRef SymbolName; // from the "linking" section
StringRef DebugName; // from the "name" section
uint32_t Comdat; // from the "comdat info" section
@@ -179,6 +180,7 @@
uint32_t Flags;
StringRef ImportModule; // For undefined symbols the module of the import
StringRef ImportName; // For undefined symbols the name of the import
+ StringRef ExportName; // For symbols to be exported from the final module
union {
// For function or global symbols, the index in function or global index
// space.
diff --git a/include/llvm/MC/MCSymbolWasm.h b/include/llvm/MC/MCSymbolWasm.h
index c60d406..ba2068a 100644
--- a/include/llvm/MC/MCSymbolWasm.h
+++ b/include/llvm/MC/MCSymbolWasm.h
@@ -21,6 +21,7 @@
mutable bool IsUsedInGOT = false;
Optional<std::string> ImportModule;
Optional<std::string> ImportName;
+ Optional<std::string> ExportName;
wasm::WasmSignature *Signature = nullptr;
Optional<wasm::WasmGlobalType> GlobalType;
Optional<wasm::WasmEventType> EventType;
@@ -87,6 +88,10 @@
}
void setImportName(StringRef Name) { ImportName = Name; }
+ bool hasExportName() const { return ExportName.hasValue(); }
+ const StringRef getExportName() const { return ExportName.getValue(); }
+ void setExportName(StringRef Name) { ExportName = Name; }
+
void setUsedInGOT() const { IsUsedInGOT = true; }
bool isUsedInGOT() const { return IsUsedInGOT; }
diff --git a/include/llvm/Object/Wasm.h b/include/llvm/Object/Wasm.h
index e130ea3..8af94c4 100644
--- a/include/llvm/Object/Wasm.h
+++ b/include/llvm/Object/Wasm.h
@@ -280,6 +280,7 @@
uint32_t StartFunction = -1;
bool HasLinkingSection = false;
bool HasDylinkSection = false;
+ bool SeenCodeSection = false;
wasm::WasmLinkingData LinkingData;
uint32_t NumImportedGlobals = 0;
uint32_t NumImportedFunctions = 0;
diff --git a/lib/MC/WasmObjectWriter.cpp b/lib/MC/WasmObjectWriter.cpp
index b22a393..321f93d 100644
--- a/lib/MC/WasmObjectWriter.cpp
+++ b/lib/MC/WasmObjectWriter.cpp
@@ -1324,6 +1324,14 @@
Comdats[C->getName()].emplace_back(
WasmComdatEntry{wasm::WASM_COMDAT_FUNCTION, Index});
}
+
+ if (WS.hasExportName()) {
+ wasm::WasmExport Export;
+ Export.Name = WS.getExportName();
+ Export.Kind = wasm::WASM_EXTERNAL_FUNCTION;
+ Export.Index = Index;
+ Exports.push_back(Export);
+ }
} else {
// An import; the index was assigned above.
Index = WasmIndices.find(&WS)->second;
@@ -1454,6 +1462,8 @@
}
if (WS.hasImportName())
Flags |= wasm::WASM_SYMBOL_EXPLICIT_NAME;
+ if (WS.hasExportName())
+ Flags |= wasm::WASM_SYMBOL_EXPORTED;
wasm::WasmSymbolInfo Info;
Info.Name = WS.getName();
diff --git a/lib/Object/WasmObjectFile.cpp b/lib/Object/WasmObjectFile.cpp
index 014b403..ab8918c 100644
--- a/lib/Object/WasmObjectFile.cpp
+++ b/lib/Object/WasmObjectFile.cpp
@@ -343,7 +343,7 @@
Error WasmObjectFile::parseNameSection(ReadContext &Ctx) {
llvm::DenseSet<uint64_t> Seen;
- if (Functions.size() != FunctionTypes.size()) {
+ if (FunctionTypes.size() && !SeenCodeSection) {
return make_error<GenericBinaryError>("Names must come after code section",
object_error::parse_failed);
}
@@ -389,7 +389,7 @@
Error WasmObjectFile::parseLinkingSection(ReadContext &Ctx) {
HasLinkingSection = true;
- if (Functions.size() != FunctionTypes.size()) {
+ if (FunctionTypes.size() && !SeenCodeSection) {
return make_error<GenericBinaryError>(
"Linking data must come after code section",
object_error::parse_failed);
@@ -940,6 +940,7 @@
Error WasmObjectFile::parseFunctionSection(ReadContext &Ctx) {
uint32_t Count = readVaruint32(Ctx);
FunctionTypes.reserve(Count);
+ Functions.resize(Count);
uint32_t NumTypes = Signatures.size();
while (Count--) {
uint32_t Type = readVaruint32(Ctx);
@@ -1029,9 +1030,11 @@
Ex.Index = readVaruint32(Ctx);
switch (Ex.Kind) {
case wasm::WASM_EXTERNAL_FUNCTION:
- if (!isValidFunctionIndex(Ex.Index))
+
+ if (!isDefinedFunctionIndex(Ex.Index))
return make_error<GenericBinaryError>("Invalid function export",
object_error::parse_failed);
+ getDefinedFunction(Ex.Index).ExportName = Ex.Name;
break;
case wasm::WASM_EXTERNAL_GLOBAL:
if (!isValidGlobalIndex(Ex.Index))
@@ -1132,6 +1135,7 @@
}
Error WasmObjectFile::parseCodeSection(ReadContext &Ctx) {
+ SeenCodeSection = true;
CodeSection = Sections.size();
uint32_t FunctionCount = readVaruint32(Ctx);
if (FunctionCount != FunctionTypes.size()) {
@@ -1139,14 +1143,14 @@
object_error::parse_failed);
}
- while (FunctionCount--) {
- wasm::WasmFunction Function;
+ for (uint32_t i = 0; i < FunctionCount; i++) {
+ wasm::WasmFunction& Function = Functions[i];
const uint8_t *FunctionStart = Ctx.Ptr;
uint32_t Size = readVaruint32(Ctx);
const uint8_t *FunctionEnd = Ctx.Ptr + Size;
Function.CodeOffset = Ctx.Ptr - FunctionStart;
- Function.Index = NumImportedFunctions + Functions.size();
+ Function.Index = NumImportedFunctions + i;
Function.CodeSectionOffset = FunctionStart - Ctx.Start;
Function.Size = FunctionEnd - FunctionStart;
@@ -1165,7 +1169,6 @@
Function.Comdat = UINT32_MAX;
Ctx.Ptr += BodySize;
assert(Ctx.Ptr == FunctionEnd);
- Functions.push_back(Function);
}
if (Ctx.Ptr != Ctx.End)
return make_error<GenericBinaryError>("Code section ended prematurely",
diff --git a/lib/Target/WebAssembly/AsmParser/WebAssemblyAsmParser.cpp b/lib/Target/WebAssembly/AsmParser/WebAssemblyAsmParser.cpp
index 138ce85..1f0bdde 100644
--- a/lib/Target/WebAssembly/AsmParser/WebAssemblyAsmParser.cpp
+++ b/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/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyTargetStreamer.cpp b/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyTargetStreamer.cpp
index 4092620..7c21ed5 100644
--- a/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyTargetStreamer.cpp
+++ b/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/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyTargetStreamer.h b/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyTargetStreamer.h
index 0164f8e..9aee1a0 100644
--- a/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyTargetStreamer.h
+++ b/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/lib/Target/WebAssembly/WebAssemblyAsmPrinter.cpp b/lib/Target/WebAssembly/WebAssemblyAsmPrinter.cpp
index 5d8b873..cb95d5d 100644
--- a/lib/Target/WebAssembly/WebAssemblyAsmPrinter.cpp
+++ b/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()) {
diff --git a/test/CodeGen/WebAssembly/export-name.ll b/test/CodeGen/WebAssembly/export-name.ll
new file mode 100644
index 0000000..d1d4c21
--- /dev/null
+++ b/test/CodeGen/WebAssembly/export-name.ll
@@ -0,0 +1,17 @@
+; RUN: llc < %s -asm-verbose=false -wasm-keep-registers | FileCheck %s
+
+target datalayout = "e-m:e-p:32:32-i64:64-n32:64-S128"
+target triple = "wasm32-unknown-unknown"
+
+define void @test() #0 {
+ ret void
+}
+
+declare void @test2() #1
+
+
+attributes #0 = { "wasm-export-name"="foo" }
+attributes #1 = { "wasm-export-name"="bar" }
+
+; CHECK: .export_name test, foo
+; CHECK: .export_name test2, bar
diff --git a/test/MC/WebAssembly/export-name.s b/test/MC/WebAssembly/export-name.s
new file mode 100644
index 0000000..51e1bcf
--- /dev/null
+++ b/test/MC/WebAssembly/export-name.s
@@ -0,0 +1,26 @@
+# RUN: llvm-mc -triple=wasm32-unknown-unknown < %s | FileCheck %s
+# Check that it also comiled to object for format.
+# RUN: llvm-mc -triple=wasm32-unknown-unknown -filetype=obj -o - < %s | obj2yaml | FileCheck -check-prefix=CHECK-OBJ %s
+
+foo:
+ .globl foo
+ .functype foo () -> ()
+ .export_name foo, bar
+ end_function
+
+# CHECK: .export_name foo, bar
+
+# CHECK-OBJ: - Type: EXPORT
+# CHECK-OBJ-NEXT: Exports:
+# CHECK-OBJ-NEXT: - Name: bar
+# CHECK-OBJ-NEXT: Kind: FUNCTION
+# CHECK-OBJ-NEXT: Index: 0
+
+# CHECK-OBJ: Name: linking
+# CHECK-OBJ-NEXT: Version: 2
+# CHECK-OBJ-NEXT: SymbolTable:
+# CHECK-OBJ-NEXT: - Index: 0
+# CHECK-OBJ-NEXT: Kind: FUNCTION
+# CHECK-OBJ-NEXT: Name: foo
+# CHECK-OBJ-NEXT: Flags: [ EXPORTED ]
+# CHECK-OBJ-NEXT: Function: 0
