[WebAssembly] Added visibility and ident directives to WasmAsmParser.

[aardappel]

Summary

These are output by clang -S, so can now be roundtripped thru clang.

(partially) fixes: https://bugs.llvm.org/show_bug.cgi?id=34544

[aardappel]

Reviewers: the code parsing these directives is from ELFAsmParser. We decided in the past that WASM should have its own container format parser, since it is a very different format from ELF, but copying code is never fun. Any suggestions here? Inherit from ELFAsmParser or take it as a member (may have unintended consequences). Pull into new base class for both (ELF people may not be happy with that). Or just ignore it?

[dschuff]

lib/MC/MCParser/WasmAsmParser.cpp

233

@sbc100 do we support exactly the same set of visibility types as ELF? I think the answer is no, right? In that case it probably also answers the question of whether we can share code with ELF too.

[sbc100]

I'm sad to see more code duplication but OK with adding along with the TODO to find a better way.

lib/MC/MCParser/WasmAsmParser.cpp

233

Technically we don't support "protected" yet, but there is no reason why we shouldn't in the future. Even though we don't support it its not clear to me if we should generate an error here, or perhaps in EmitSymbolAttribute?

[sbc100]

test/MC/WebAssembly/basic-assembly.s

91

Align second column with line above?

179

Indentation looks great than directives below?

[aardappel]

lib/MC/MCParser/WasmAsmParser.cpp

233

I will comment out "protected" for now, which will make it error.

test/MC/WebAssembly/basic-assembly.s

91

File had mixed tabs and spaces, which makes it look different in code review.. removing tabs.

179

I'll make indentation in this file more consistent..

[aardappel]

Removed "protected" and fixed indentation in tests.

lib/MC/MCParser/WasmAsmParser.cpp

void Initialize(MCAsmParser &P) override {
     Lexer = &Parser->getLexer();
     // Call the base implementation.
     this->MCAsmParserExtension::Initialize(*Parser);
 
     addDirectiveHandler<&WasmAsmParser::parseSectionDirectiveText>(".text");
     addDirectiveHandler<&WasmAsmParser::parseSectionDirective>(".section");
     addDirectiveHandler<&WasmAsmParser::parseDirectiveSize>(".size");
     addDirectiveHandler<&WasmAsmParser::parseDirectiveType>(".type");
+    addDirectiveHandler<&WasmAsmParser::ParseDirectiveIdent>(".ident");
+    addDirectiveHandler<
+      &WasmAsmParser::ParseDirectiveSymbolAttribute>(".weak");
+    addDirectiveHandler<
+      &WasmAsmParser::ParseDirectiveSymbolAttribute>(".local");
+    addDirectiveHandler<
+      &WasmAsmParser::ParseDirectiveSymbolAttribute>(".protected");
+    addDirectiveHandler<
+      &WasmAsmParser::ParseDirectiveSymbolAttribute>(".internal");
+    addDirectiveHandler<
+      &WasmAsmParser::ParseDirectiveSymbolAttribute>(".hidden");
   }
 
   bool error(const StringRef &Msg, const AsmToken &Tok) {
     return Parser->Error(Tok.getLoc(), Msg + Tok.getString());
   }
 
   bool isNext(AsmToken::TokenKind Kind) {
     auto Ok = Lexer->is(Kind);
if (TypeName == "function")
       WasmSym->setType(wasm::WASM_SYMBOL_TYPE_FUNCTION);
     else if (TypeName == "global")
       WasmSym->setType(wasm::WASM_SYMBOL_TYPE_GLOBAL);
     else
       return error("Unknown WASM symbol type: ", Lexer->getTok());
     Lex();
     return expect(AsmToken::EndOfStatement, "EOL");
   }
+
+  // FIXME: Shared with ELF.
+  /// ParseDirectiveIdent
+  ///  ::= .ident string
+  bool ParseDirectiveIdent(StringRef, SMLoc) {
+    if (getLexer().isNot(AsmToken::String))
+      return TokError("unexpected token in '.ident' directive");
+    StringRef Data = getTok().getIdentifier();
+    Lex();
+    if (getLexer().isNot(AsmToken::EndOfStatement))
+      return TokError("unexpected token in '.ident' directive");
+    Lex();
+    getStreamer().EmitIdent(Data);
+    return false;
+  }
+
+  // FIXME: Shared with ELF.
+  /// ParseDirectiveSymbolAttribute
+  ///  ::= { ".local", ".weak", ... } [ identifier ( , identifier )* ]
+  bool ParseDirectiveSymbolAttribute(StringRef Directive, SMLoc) {
+    MCSymbolAttr Attr = StringSwitch<MCSymbolAttr>(Directive)
+      .Case(".weak", MCSA_Weak)
+      .Case(".local", MCSA_Local)
+      .Case(".hidden", MCSA_Hidden)
+      .Case(".internal", MCSA_Internal)
+      .Case(".protected", MCSA_Protected)
+      .Default(MCSA_Invalid);
+    assert(Attr != MCSA_Invalid && "unexpected symbol attribute directive!");
+    if (getLexer().isNot(AsmToken::EndOfStatement)) {
+      while (true) {
+        StringRef Name;
+        if (getParser().parseIdentifier(Name))
+          return TokError("expected identifier in directive");
+        MCSymbol *Sym = getContext().getOrCreateSymbol(Name);
+        getStreamer().EmitSymbolAttribute(Sym, Attr);
+        if (getLexer().is(AsmToken::EndOfStatement))
+          break;
+        if (getLexer().isNot(AsmToken::Comma))
+          return TokError("unexpected token in directive");
+        Lex();
+      }
+    }
+    Lex();
+    return false;
+  }
 };
 
 } // end anonymous namespace
 
 namespace llvm {
 
 MCAsmParserExtension *createWasmAsmParser() {
   return new WasmAsmParser;
 }
 
 } // end namespace llvm

test/MC/WebAssembly/basic-assembly.s

.LBB0_4:
     i32.const .L.str
     throw 0
 .LBB0_5:
     #i32.trunc_sat_f32_s
     global.get  __stack_pointer
     end_function
 
     .section  .rodata..L.str,"",@
+    .hidden     .L.str
 .L.str:
     .int8 'H'
     .asciz  "ello, World!"
     .size .L.str, 14
 
+    .ident  "clang version 9.0.0 (trunk 364502) (llvm/trunk 364571)"
     .globaltype __stack_pointer, i32
 
 # CHECK:           .text
 # CHECK-LABEL: test0:
 # CHECK-NEXT:      .functype test0 (i32, i64) -> (i32)
 # CHECK-NEXT:      .eventtype  __cpp_exception i32
 # CHECK-NEXT:      .local      f32, f64
 # CHECK-NEXT:      local.get   2

 # CHECK-NEXT:      end_try
 # CHECK-NEXT:      i32.const .L.str
 # CHECK-NEXT:      throw 0
 # CHECK-NEXT:  .LBB0_5:
 # CHECK-NEXT:      global.get  __stack_pointer
 # CHECK-NEXT:      end_function
 
 # CHECK:      .section  .rodata..L.str,"",@
+# CHECK-NEXT:   .hidden     .L.str
 # CHECK-NEXT:.L.str:
 # CHECK-NEXT: .int8 72
 # CHECK-NEXT: .asciz  "ello, World!"
 
 # CHECK:           .globaltype  __stack_pointer, i32