[WebAssembly] Added WasmAsmParser.

Summary:
This is to replace the ELFAsmParser that WebAssembly was using, which
so far was a stub that didn't do anything, and couldn't work correctly
with wasm.

This new class is there to implement generic directives related to
wasm as a binary format. Wasm target specific directives are still
parsed in WebAssemblyAsmParser as before. The two classes now
cooperate more correctly too.

Also implemented .result which was missing. Any unknown directives
will now result in errors.

Reviewers: dschuff, sbc100

Subscribers: mgorny, jgravelle-google, eraman, aheejin, sunfish, llvm-commits

Differential Revision: https://reviews.llvm.org/D54360

llvm-svn: 346700

1 files changed, 31 insertions, 74 deletions

diff --git a/llvm/lib/Target/WebAssembly/AsmParser/WebAssemblyAsmParser.cpp b/llvm/lib/Target/WebAssembly/AsmParser/WebAssemblyAsmParser.cpp
index efa6793cff2..703ea2d7d02 100644
--- a/llvm/lib/Target/WebAssembly/AsmParser/WebAssemblyAsmParser.cpp
+++ b/llvm/lib/Target/WebAssembly/AsmParser/WebAssemblyAsmParser.cpp
@@ -132,13 +132,12 @@ struct WebAssemblyOperand : public MCParsedAsmOperand {
 class WebAssemblyAsmParser final : public MCTargetAsmParser {
   MCAsmParser &Parser;
   MCAsmLexer &Lexer;
-  MCSymbolWasm *LastSymbol;
 
 public:
   WebAssemblyAsmParser(const MCSubtargetInfo &STI, MCAsmParser &Parser,
                        const MCInstrInfo &MII, const MCTargetOptions &Options)
       : MCTargetAsmParser(Options, STI, MII), Parser(Parser),
-        Lexer(Parser.getLexer()), LastSymbol(nullptr) {
+        Lexer(Parser.getLexer()) {
     setAvailableFeatures(ComputeAvailableFeatures(STI.getFeatureBits()));
   }
 
@@ -191,6 +190,19 @@ public:
         .Default({MVT::INVALID_SIMPLE_VALUE_TYPE, wasm::WASM_TYPE_NORESULT});
   }
 
+  bool ParseRegTypeList(std::vector<MVT> &Types) {
+    while (Lexer.is(AsmToken::Identifier)) {
+      auto RegType = ParseRegType(Lexer.getTok().getString()).first;
+      if (RegType == MVT::INVALID_SIMPLE_VALUE_TYPE)
+        return true;
+      Types.push_back(RegType);
+      Parser.Lex();
+      if (!IsNext(AsmToken::Comma))
+        break;
+    }
+    return Expect(AsmToken::EndOfStatement, "EOL");
+  }
+
   void ParseSingleInteger(bool IsNegative, OperandVector &Operands) {
     auto &Int = Lexer.getTok();
     int64_t Val = Int.getIntVal();
@@ -314,10 +326,9 @@ public:
     return false;
   }
 
-  void onLabelParsed(MCSymbol *Symbol) override {
-    LastSymbol = cast<MCSymbolWasm>(Symbol);
-  }
-
+  // This function processes wasm-specific directives streamed to
+  // WebAssemblyTargetStreamer, all others go to the generic parser
+  // (see WasmAsmParser).
   bool ParseDirective(AsmToken DirectiveID) override {
     // This function has a really weird return value behavior that is different
     // from all the other parsing functions:
@@ -331,44 +342,7 @@ public:
         reinterpret_cast<WebAssemblyTargetStreamer &>(*Out.getTargetStreamer());
     // TODO: any time we return an error, at least one token must have been
     // consumed, otherwise this will not signal an error to the caller.
-    if (DirectiveID.getString() == ".type") {
-      // This could be the start of a function, check if followed by
-      // "label,@function"
-      if (!Lexer.is(AsmToken::Identifier))
-        return Error("Expected label after .type directive, got: ",
-                     Lexer.getTok());
-      auto WasmSym = cast<MCSymbolWasm>(
-                       TOut.getStreamer().getContext().getOrCreateSymbol(
-                         Lexer.getTok().getString()));
-      Parser.Lex();
-      if (!(IsNext(AsmToken::Comma) && IsNext(AsmToken::At) &&
-            Lexer.is(AsmToken::Identifier)))
-        return Error("Expected label,@type declaration, got: ", Lexer.getTok());
-      auto TypeName = Lexer.getTok().getString();
-      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());
-      Parser.Lex();
-      return Expect(AsmToken::EndOfStatement, "EOL");
-    } else if (DirectiveID.getString() == ".size") {
-      if (!Lexer.is(AsmToken::Identifier))
-        return Error("Expected label after .size directive, got: ",
-                     Lexer.getTok());
-      auto WasmSym = cast<MCSymbolWasm>(
-                       TOut.getStreamer().getContext().getOrCreateSymbol(
-                         Lexer.getTok().getString()));
-      Parser.Lex();
-      if (!IsNext(AsmToken::Comma))
-        return Error("Expected `,`, got: ", Lexer.getTok());
-      const MCExpr *Exp;
-      if (Parser.parseExpression(Exp))
-        return Error("Cannot parse .size expression: ", Lexer.getTok());
-      WasmSym->setSize(Exp);
-      return Expect(AsmToken::EndOfStatement, "EOL");
-    } else if (DirectiveID.getString() == ".globaltype") {
+    if (DirectiveID.getString() == ".globaltype") {
       if (!Lexer.is(AsmToken::Identifier))
         return Error("Expected symbol name after .globaltype directive, got: ",
                      Lexer.getTok());
@@ -392,40 +366,23 @@ public:
       // And emit the directive again.
       TOut.emitGlobalType(WasmSym);
       return Expect(AsmToken::EndOfStatement, "EOL");
-    } else if (DirectiveID.getString() == ".param" ||
-               DirectiveID.getString() == ".local") {
-      // Track the number of locals, needed for correct virtual register
-      // assignment elsewhere.
-      // Also output a directive to the streamer.
+    } else if (DirectiveID.getString() == ".param") {
       std::vector<MVT> Params;
+      if (ParseRegTypeList(Params)) return true;
+      TOut.emitParam(nullptr /* unused */, Params);
+      return false;
+    } else if (DirectiveID.getString() == ".result") {
+      std::vector<MVT> Results;
+      if (ParseRegTypeList(Results)) return true;
+      TOut.emitResult(nullptr /* unused */, Results);
+      return false;
+    } else if (DirectiveID.getString() == ".local") {
       std::vector<MVT> Locals;
-      while (Lexer.is(AsmToken::Identifier)) {
-        auto RegType = ParseRegType(Lexer.getTok().getString()).first;
-        if (RegType == MVT::INVALID_SIMPLE_VALUE_TYPE)
-          return true;
-        if (DirectiveID.getString() == ".param") {
-          Params.push_back(RegType);
-        } else {
-          Locals.push_back(RegType);
-        }
-        Parser.Lex();
-        if (!IsNext(AsmToken::Comma))
-          break;
-      }
-      assert(LastSymbol);
-      // TODO: LastSymbol isn't even used by emitParam, so could be removed.
-      TOut.emitParam(LastSymbol, Params);
+      if (ParseRegTypeList(Locals)) return true;
       TOut.emitLocal(Locals);
-      return Expect(AsmToken::EndOfStatement, "EOL");
-    } else {
-      // TODO: remove.
-      while (Lexer.isNot(AsmToken::EndOfStatement))
-        Parser.Lex();
-      return Expect(AsmToken::EndOfStatement, "EOL");
+      return false;
     }
-    // TODO: current ELF directive parsing is broken, fix this is a followup.
-    //return true;  // We didn't process this directive.
-    return false;
+    return true;  // We didn't process this directive.
   }
 
   bool MatchAndEmitInstruction(SMLoc IDLoc, unsigned & /*Opcode*/,