[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/clang/include/clang/Basic/Attr.td b/clang/include/clang/Basic/Attr.td
index 40e180f..47d9e64 100644 (file)
--- a/clang/include/clang/Basic/Attr.td
+++ b/clang/include/clang/Basic/Attr.td
@@ -1600,6 +1600,14 @@ def BPFPreserveAccessIndex : InheritableAttr,
   let LangOpts = [COnly];
 }
 
+def WebAssemblyExportName : InheritableAttr,
+                            TargetSpecificAttr<TargetWebAssembly> {
+  let Spellings = [Clang<"export_name">];
+  let Args = [StringArgument<"ExportName">];
+  let Documentation = [WebAssemblyExportNameDocs];
+  let Subjects = SubjectList<[Function], ErrorDiag>;
+}
+
 def WebAssemblyImportModule : InheritableAttr,
                               TargetSpecificAttr<TargetWebAssembly> {
   let Spellings = [Clang<"import_module">];

diff --git a/clang/include/clang/Basic/AttrDocs.td b/clang/include/clang/Basic/AttrDocs.td
index 764ac24..c632e52 100644 (file)
--- a/clang/include/clang/Basic/AttrDocs.td
+++ b/clang/include/clang/Basic/AttrDocs.td
@@ -4101,6 +4101,21 @@ For more information see
 or `msvc documentation <https://docs.microsoft.com/pl-pl/cpp/cpp/selectany>`_.
 }]; }
 
+def WebAssemblyExportNameDocs : Documentation {
+  let Category = DocCatFunction;
+  let Content = [{
+Clang supports the ``__attribute__((export_name(<name>)))``
+attribute for the WebAssembly target. This attribute may be attached to a
+function declaration, where it modifies how the symbol is to be exported
+from the linked WebAssembly.
+
+WebAssembly functions are exported via string name. By default when a symbol
+is exported, the export name for C/C++ symbols are the same as their C/C++
+symbol names. This attribute can be used to override the default behavior, and
+request a specific string name be used instead.
+  }];
+}
+
 def WebAssemblyImportModuleDocs : Documentation {
   let Category = DocCatFunction;
   let Content = [{

diff --git a/clang/lib/CodeGen/TargetInfo.cpp b/clang/lib/CodeGen/TargetInfo.cpp
index 33e7b18..9fd4a5f 100644 (file)
--- a/clang/lib/CodeGen/TargetInfo.cpp
+++ b/clang/lib/CodeGen/TargetInfo.cpp
@@ -779,6 +779,12 @@ public:
         B.addAttribute("wasm-import-name", Attr->getImportName());
         Fn->addAttributes(llvm::AttributeList::FunctionIndex, B);
       }
+      if (const auto *Attr = FD->getAttr<WebAssemblyExportNameAttr>()) {
+        llvm::Function *Fn = cast<llvm::Function>(GV);
+        llvm::AttrBuilder B;
+        B.addAttribute("wasm-export-name", Attr->getExportName());
+        Fn->addAttributes(llvm::AttributeList::FunctionIndex, B);
+      }
     }
 
     if (auto *FD = dyn_cast_or_null<FunctionDecl>(D)) {

diff --git a/clang/lib/Sema/SemaDeclAttr.cpp b/clang/lib/Sema/SemaDeclAttr.cpp
index 60a9980..e83688c 100644 (file)
--- a/clang/lib/Sema/SemaDeclAttr.cpp
+++ b/clang/lib/Sema/SemaDeclAttr.cpp
@@ -5754,6 +5754,28 @@ static void handleBPFPreserveAccessIndexAttr(Sema &S, Decl *D,
   Rec->addAttr(::new (S.Context) BPFPreserveAccessIndexAttr(S.Context, AL));
 }
 
+static void handleWebAssemblyExportNameAttr(Sema &S, Decl *D, const ParsedAttr &AL) {
+  if (!isFunctionOrMethod(D)) {
+    S.Diag(D->getLocation(), diag::warn_attribute_wrong_decl_type)
+        << "'export_name'" << ExpectedFunction;
+    return;
+  }
+
+  auto *FD = cast<FunctionDecl>(D);
+  if (FD->isThisDeclarationADefinition()) {
+    S.Diag(D->getLocation(), diag::err_alias_is_definition) << FD << 0;
+    return;
+  }
+
+  StringRef Str;
+  SourceLocation ArgLoc;
+  if (!S.checkStringLiteralArgumentAttr(AL, 0, Str, &ArgLoc))
+    return;
+
+  FD->addAttr(::new (S.Context)
+                  WebAssemblyExportNameAttr(S.Context, AL, Str));
+}
+
 static void handleWebAssemblyImportModuleAttr(Sema &S, Decl *D, const ParsedAttr &AL) {
   if (!isFunctionOrMethod(D)) {
     S.Diag(D->getLocation(), diag::warn_attribute_wrong_decl_type)
@@ -6672,6 +6694,9 @@ static void ProcessDeclAttribute(Sema &S, Scope *scope, Decl *D,
   case ParsedAttr::AT_BPFPreserveAccessIndex:
     handleBPFPreserveAccessIndexAttr(S, D, AL);
     break;
+  case ParsedAttr::AT_WebAssemblyExportName:
+    handleWebAssemblyExportNameAttr(S, D, AL);
+    break;
   case ParsedAttr::AT_WebAssemblyImportModule:
     handleWebAssemblyImportModuleAttr(S, D, AL);
     break;

diff --git a/clang/test/CodeGen/wasm-export-name.c b/clang/test/CodeGen/wasm-export-name.c
new file mode 100644 (file)
index 0000000..b662a27
--- /dev/null
+++ b/clang/test/CodeGen/wasm-export-name.c
@@ -0,0 +1,11 @@
+// RUN: %clang_cc1 -triple wasm32-unknown-unknown-wasm -emit-llvm -o - %s | FileCheck %s
+
+int __attribute__((export_name("bar"))) foo(void);
+
+int foo(void) {
+  return 43;
+}
+
+// CHECK: define i32 @foo() [[A:#[0-9]+]]
+
+// CHECK: attributes [[A]] = {{{.*}} "wasm-export-name"="bar" {{.*}}}

diff --git a/clang/test/Misc/pragma-attribute-supported-attributes-list.test b/clang/test/Misc/pragma-attribute-supported-attributes-list.test
index 2effc52..dc2d668 100644 (file)
--- a/clang/test/Misc/pragma-attribute-supported-attributes-list.test
+++ b/clang/test/Misc/pragma-attribute-supported-attributes-list.test
@@ -151,6 +151,7 @@
 // CHECK-NEXT: WarnUnusedResult (SubjectMatchRule_objc_method, SubjectMatchRule_enum, SubjectMatchRule_record, SubjectMatchRule_hasType_functionType)
 // CHECK-NEXT: Weak (SubjectMatchRule_variable, SubjectMatchRule_function, SubjectMatchRule_record)
 // CHECK-NEXT: WeakRef (SubjectMatchRule_variable, SubjectMatchRule_function)
+// CHECK-NEXT: WebAssemblyExportName (SubjectMatchRule_function)
 // CHECK-NEXT: WebAssemblyImportModule (SubjectMatchRule_function)
 // CHECK-NEXT: WebAssemblyImportName (SubjectMatchRule_function)
 // CHECK-NEXT: WorkGroupSizeHint (SubjectMatchRule_function)

diff --git a/lld/docs/WebAssembly.rst b/lld/docs/WebAssembly.rst
index 6384a92..92bae2a 100644 (file)
--- a/lld/docs/WebAssembly.rst
+++ b/lld/docs/WebAssembly.rst
@@ -42,8 +42,8 @@ WebAssembly-specific options:
 .. option:: --export-dynamic
 
   When building an executable, export any non-hidden symbols.  By default only
-  the entry point and any symbols marked with --export/--export-all are
-  exported.
+  the entry point and any symbols marked as exports (either via the command line
+  or via the `export-name` source attribute) are exported.
 
 .. option:: --global-base=<value>
 
@@ -116,16 +116,18 @@ Imports and Exports
 ~~~~~~~~~~~~~~~~~~~
 
 When building a shared library any symbols marked as ``visibility=default`` will
-be exported.  When building an executable, only the entry point and symbols
-flagged as ``WASM_SYMBOL_EXPORTED`` are exported by default.  In LLVM the
-``WASM_SYMBOL_EXPORTED`` flag is applied to any symbol in the ``llvm.used`` list
-which corresponds to ``__attribute__((used))`` in C/C++ sources.
+be exported.
+
+When building an executable, only the entry point (``_start``) and symbols with
+the ``WASM_SYMBOL_EXPORTED`` flag are exported by default.  In LLVM the
+``WASM_SYMBOL_EXPORTED`` flag is set by the ``wasm-export-name`` attribute which
+in turn can be set using ``__attribute__((export_name))`` clang attribute.
 
 In addition, symbols can be exported via the linker command line using
 ``--export``.
 
 Finally, just like with native ELF linker the ``--export-dynamic`` flag can be
-used to export symbol in the executable which are marked as
+used to export symbols in the executable which are marked as
 ``visibility=default``.
 
 Garbage Collection

diff --git a/lld/test/wasm/export-name.ll b/lld/test/wasm/export-name.ll
new file mode 100644 (file)
index 0000000..83a8bd9
--- /dev/null
+++ b/lld/test/wasm/export-name.ll
@@ -0,0 +1,28 @@
+; RUN: llc -filetype=obj %s -o %t.o
+; RUN: wasm-ld -o %t.wasm %t.o
+; RUN: obj2yaml %t.wasm | FileCheck %s
+
+target triple = "wasm32-unknown-unknown"
+
+define void @foo() #0 {
+    ret void
+}
+
+define void @_start() {
+    call void @foo()
+    ret void
+}
+
+attributes #0 = { "wasm-export-name"="bar" }
+
+; CHECK:       - Type:            EXPORT
+; CHECK-NEXT:    Exports:
+; CHECK-NEXT:      - Name:            memory
+; CHECK-NEXT:        Kind:            MEMORY
+; CHECK-NEXT:        Index:           0
+; CHECK-NEXT:      - Name:            bar
+; CHECK-NEXT:        Kind:            FUNCTION
+; CHECK-NEXT:        Index:           0
+; CHECK-NEXT:      - Name:            _start
+; CHECK-NEXT:        Kind:            FUNCTION
+; CHECK-NEXT:        Index:           1

diff --git a/lld/wasm/InputChunks.h b/lld/wasm/InputChunks.h
index 2d3eb40..5d4aebd 100644 (file)
--- a/lld/wasm/InputChunks.h
+++ b/lld/wasm/InputChunks.h
@@ -130,6 +130,9 @@ public:
   void writeTo(uint8_t *sectionStart) const override;
   StringRef getName() const override { return function->SymbolName; }
   StringRef getDebugName() const override { return function->DebugName; }
+  StringRef getExportName() const {
+    return function ? function->ExportName : "";
+  }
   uint32_t getComdat() const override { return function->Comdat; }
   uint32_t getFunctionInputOffset() const { return getInputSectionOffset(); }
   uint32_t getFunctionCodeOffset() const { return function->CodeOffset; }

diff --git a/lld/wasm/Writer.cpp b/lld/wasm/Writer.cpp
index 5df3ae6..bd7bd7e 100644 (file)
--- a/lld/wasm/Writer.cpp
+++ b/lld/wasm/Writer.cpp
@@ -519,6 +519,10 @@ void Writer::calculateExports() {
     StringRef name = sym->getName();
     WasmExport export_;
     if (auto *f = dyn_cast<DefinedFunction>(sym)) {
+      StringRef exportName = f->function->getExportName();
+      if (!exportName.empty()) {
+        name = exportName;
+      }
       export_ = {name, WASM_EXTERNAL_FUNCTION, f->getFunctionIndex()};
     } else if (auto *g = dyn_cast<DefinedGlobal>(sym)) {
       // TODO(sbc): Remove this check once to mutable global proposal is

diff --git a/llvm/include/llvm/BinaryFormat/Wasm.h b/llvm/include/llvm/BinaryFormat/Wasm.h
index f550d88..59f99cc 100644 (file)
--- a/llvm/include/llvm/BinaryFormat/Wasm.h
+++ b/llvm/include/llvm/BinaryFormat/Wasm.h
@@ -131,6 +131,7 @@ struct WasmFunction {
   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 @@ struct WasmSymbolInfo {
   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/llvm/include/llvm/MC/MCSymbolWasm.h b/llvm/include/llvm/MC/MCSymbolWasm.h
index c60d406..ba2068a 100644 (file)
--- a/llvm/include/llvm/MC/MCSymbolWasm.h
+++ b/llvm/include/llvm/MC/MCSymbolWasm.h
@@ -21,6 +21,7 @@ class MCSymbolWasm : public MCSymbol {
   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 @@ public:
   }
   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/llvm/include/llvm/Object/Wasm.h b/llvm/include/llvm/Object/Wasm.h
index e130ea3..8af94c4 100644 (file)
--- a/llvm/include/llvm/Object/Wasm.h
+++ b/llvm/include/llvm/Object/Wasm.h
@@ -280,6 +280,7 @@ private:
   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/llvm/lib/MC/WasmObjectWriter.cpp b/llvm/lib/MC/WasmObjectWriter.cpp
index b22a393..321f93d 100644 (file)
--- a/llvm/lib/MC/WasmObjectWriter.cpp
+++ b/llvm/lib/MC/WasmObjectWriter.cpp
@@ -1324,6 +1324,14 @@ uint64_t WasmObjectWriter::writeObject(MCAssembler &Asm,
           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 @@ uint64_t WasmObjectWriter::writeObject(MCAssembler &Asm,
     }
     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/llvm/lib/Object/WasmObjectFile.cpp b/llvm/lib/Object/WasmObjectFile.cpp
index 014b403..ab8918c 100644 (file)
--- a/llvm/lib/Object/WasmObjectFile.cpp
+++ b/llvm/lib/Object/WasmObjectFile.cpp
@@ -343,7 +343,7 @@ Error WasmObjectFile::parseDylinkSection(ReadContext &Ctx) {
 
 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::parseNameSection(ReadContext &Ctx) {
 
 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::parseImportSection(ReadContext &Ctx) {
 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 @@ Error WasmObjectFile::parseExportSection(ReadContext &Ctx) {
     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::parseStartSection(ReadContext &Ctx) {
 }
 
 Error WasmObjectFile::parseCodeSection(ReadContext &Ctx) {
+  SeenCodeSection = true;
   CodeSection = Sections.size();
   uint32_t FunctionCount = readVaruint32(Ctx);
   if (FunctionCount != FunctionTypes.size()) {
@@ -1139,14 +1143,14 @@ Error WasmObjectFile::parseCodeSection(ReadContext &Ctx) {
                                           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 @@ Error WasmObjectFile::parseCodeSection(ReadContext &Ctx) {
     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/llvm/lib/Target/WebAssembly/AsmParser/WebAssemblyAsmParser.cpp b/llvm/lib/Target/WebAssembly/AsmParser/WebAssemblyAsmParser.cpp
index 138ce85..1f0bdde 100644 (file)
--- a/llvm/lib/Target/WebAssembly/AsmParser/WebAssemblyAsmParser.cpp
+++ b/llvm/lib/Target/WebAssembly/AsmParser/WebAssemblyAsmParser.cpp
@@ -712,6 +712,18 @@ public:
       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 (file)
--- a/llvm/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyTargetStreamer.cpp
+++ b/llvm/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyTargetStreamer.cpp
@@ -94,6 +94,12 @@ void WebAssemblyTargetAsmStreamer::emitImportName(const MCSymbolWasm *Sym,
                            << 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 (file)
--- a/llvm/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyTargetStreamer.h
+++ b/llvm/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyTargetStreamer.h
@@ -48,6 +48,9 @@ public:
   /// .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 @@ public:
   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 @@ public:
                         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 @@ public:
   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 (file)
--- a/llvm/lib/Target/WebAssembly/WebAssemblyAsmPrinter.cpp
+++ b/llvm/lib/Target/WebAssembly/WebAssemblyAsmPrinter.cpp
@@ -96,8 +96,11 @@ void WebAssemblyAsmPrinter::EmitEndOfAsmFile(Module &M) {
   }
 
   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 @@ void WebAssemblyAsmPrinter::EmitEndOfAsmFile(Module &M) {
         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/llvm/test/CodeGen/WebAssembly/export-name.ll b/llvm/test/CodeGen/WebAssembly/export-name.ll
new file mode 100644 (file)
index 0000000..d1d4c21
--- /dev/null
+++ b/llvm/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/llvm/test/MC/WebAssembly/export-name.s b/llvm/test/MC/WebAssembly/export-name.s
new file mode 100644 (file)
index 0000000..51e1bcf
--- /dev/null
+++ b/llvm/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