sbc100 updated this revision to Diff 231620.
sbc100 added a comment.

- rebase


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D70520/new/

https://reviews.llvm.org/D70520

Files:
  clang/include/clang/Basic/Attr.td
  clang/include/clang/Basic/AttrDocs.td
  clang/lib/CodeGen/TargetInfo.cpp
  clang/lib/Sema/SemaDeclAttr.cpp
  clang/test/CodeGen/wasm-export-name.c
  lld/test/wasm/export-name.ll
  lld/wasm/InputChunks.h
  lld/wasm/Writer.cpp
  llvm/include/llvm/BinaryFormat/Wasm.h
  llvm/include/llvm/MC/MCSymbolWasm.h
  llvm/include/llvm/Object/Wasm.h
  llvm/lib/MC/WasmObjectWriter.cpp
  llvm/lib/Object/WasmObjectFile.cpp
  llvm/lib/Target/WebAssembly/AsmParser/WebAssemblyAsmParser.cpp
  llvm/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyTargetStreamer.cpp
  llvm/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyTargetStreamer.h
  llvm/lib/Target/WebAssembly/WebAssemblyAsmPrinter.cpp
  llvm/test/CodeGen/WebAssembly/export-name.ll
  llvm/test/MC/WebAssembly/export-name.s

Index: llvm/test/MC/WebAssembly/export-name.s
===================================================================
--- /dev/null
+++ 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
Index: llvm/test/CodeGen/WebAssembly/export-name.ll
===================================================================
--- /dev/null
+++ 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
Index: llvm/lib/Target/WebAssembly/WebAssemblyAsmPrinter.cpp
===================================================================
--- llvm/lib/Target/WebAssembly/WebAssemblyAsmPrinter.cpp
+++ 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()) {
Index: llvm/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyTargetStreamer.h
===================================================================
--- llvm/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyTargetStreamer.h
+++ 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
Index: llvm/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyTargetStreamer.cpp
===================================================================
--- llvm/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyTargetStreamer.cpp
+++ 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';
 }
Index: llvm/lib/Target/WebAssembly/AsmParser/WebAssemblyAsmParser.cpp
===================================================================
--- llvm/lib/Target/WebAssembly/AsmParser/WebAssemblyAsmParser.cpp
+++ 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())
Index: llvm/lib/Object/WasmObjectFile.cpp
===================================================================
--- llvm/lib/Object/WasmObjectFile.cpp
+++ llvm/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",
Index: llvm/lib/MC/WasmObjectWriter.cpp
===================================================================
--- llvm/lib/MC/WasmObjectWriter.cpp
+++ llvm/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();
Index: llvm/include/llvm/Object/Wasm.h
===================================================================
--- llvm/include/llvm/Object/Wasm.h
+++ llvm/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;
Index: llvm/include/llvm/MC/MCSymbolWasm.h
===================================================================
--- llvm/include/llvm/MC/MCSymbolWasm.h
+++ llvm/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; }
 
Index: llvm/include/llvm/BinaryFormat/Wasm.h
===================================================================
--- llvm/include/llvm/BinaryFormat/Wasm.h
+++ llvm/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.
Index: lld/wasm/Writer.cpp
===================================================================
--- lld/wasm/Writer.cpp
+++ lld/wasm/Writer.cpp
@@ -519,6 +519,10 @@
     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
Index: lld/wasm/InputChunks.h
===================================================================
--- lld/wasm/InputChunks.h
+++ lld/wasm/InputChunks.h
@@ -130,6 +130,9 @@
   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; }
Index: lld/test/wasm/export-name.ll
===================================================================
--- /dev/null
+++ 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
Index: clang/test/CodeGen/wasm-export-name.c
===================================================================
--- /dev/null
+++ 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" {{.*}}}
Index: clang/lib/Sema/SemaDeclAttr.cpp
===================================================================
--- clang/lib/Sema/SemaDeclAttr.cpp
+++ clang/lib/Sema/SemaDeclAttr.cpp
@@ -5754,6 +5754,28 @@
   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)
@@ -6633,6 +6655,9 @@
   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;
Index: clang/lib/CodeGen/TargetInfo.cpp
===================================================================
--- clang/lib/CodeGen/TargetInfo.cpp
+++ clang/lib/CodeGen/TargetInfo.cpp
@@ -778,6 +778,12 @@
         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)) {
Index: clang/include/clang/Basic/AttrDocs.td
===================================================================
--- clang/include/clang/Basic/AttrDocs.td
+++ clang/include/clang/Basic/AttrDocs.td
@@ -4023,6 +4023,21 @@
 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 = [{
Index: clang/include/clang/Basic/Attr.td
===================================================================
--- clang/include/clang/Basic/Attr.td
+++ clang/include/clang/Basic/Attr.td
@@ -1587,6 +1587,14 @@
   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">];
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