Revert "[WebAssembly] Added default stack-only instruction mode for MC."

This reverts commit 917a99b71ce21c975be7bfbf66f4040f965d9f3c.

llvm-svn: 339630

Author: aardappel

llvm/lib/Target/WebAssembly/AsmParser/WebAssemblyAsmParser.cpp

@@ -34,17 +34,47 @@ using namespace llvm;
 
 namespace {
 
+// We store register types as SimpleValueType to retain SIMD layout
+// information, but must also be able to supply them as the (unnamed)
+// register enum from WebAssemblyRegisterInfo.td/.inc.
+static unsigned MVTToWasmReg(MVT::SimpleValueType Type) {
+  switch(Type) {
+    case MVT::i32: return WebAssembly::I32_0;
+    case MVT::i64: return WebAssembly::I64_0;
+    case MVT::f32: return WebAssembly::F32_0;
+    case MVT::f64: return WebAssembly::F64_0;
+    case MVT::v16i8: return WebAssembly::V128_0;
+    case MVT::v8i16: return WebAssembly::V128_0;
+    case MVT::v4i32: return WebAssembly::V128_0;
+    case MVT::v4f32: return WebAssembly::V128_0;
+    default: return MVT::INVALID_SIMPLE_VALUE_TYPE;
+  }
+}
+
 /// WebAssemblyOperand - Instances of this class represent the operands in a
 /// parsed WASM machine instruction.
 struct WebAssemblyOperand : public MCParsedAsmOperand {
-  enum KindTy { Token, Integer, Float, Symbol } Kind;
+  enum KindTy { Token, Local, Stack, Integer, Float, Symbol } Kind;
 
   SMLoc StartLoc, EndLoc;
 
   struct TokOp {
     StringRef Tok;
   };
 
+  struct RegOp {
+    // This is a (virtual) local or stack register represented as 0..
+    unsigned RegNo;
+    // In most targets, the register number also encodes the type, but for
+    // wasm we have to track that seperately since we have an unbounded
+    // number of registers.
+    // This has the unfortunate side effect that we supply a different value
+    // to the table-gen matcher at different times in the process (when it
+    // calls getReg() or addRegOperands().
+    // TODO: While this works, it feels brittle. and would be nice to clean up.
+    MVT::SimpleValueType Type;
+  };
+
   struct IntOp {
     int64_t Val;
   };
@@ -59,13 +89,16 @@ struct WebAssemblyOperand : public MCParsedAsmOperand {
 
   union {
     struct TokOp Tok;
+    struct RegOp Reg;
     struct IntOp Int;
     struct FltOp Flt;
     struct SymOp Sym;
   };
 
   WebAssemblyOperand(KindTy K, SMLoc Start, SMLoc End, TokOp T)
     : Kind(K), StartLoc(Start), EndLoc(End), Tok(T) {}
+  WebAssemblyOperand(KindTy K, SMLoc Start, SMLoc End, RegOp R)
+    : Kind(K), StartLoc(Start), EndLoc(End), Reg(R) {}
   WebAssemblyOperand(KindTy K, SMLoc Start, SMLoc End, IntOp I)
     : Kind(K), StartLoc(Start), EndLoc(End), Int(I) {}
   WebAssemblyOperand(KindTy K, SMLoc Start, SMLoc End, FltOp F)
@@ -77,12 +110,14 @@ struct WebAssemblyOperand : public MCParsedAsmOperand {
   bool isImm() const override { return Kind == Integer ||
                                        Kind == Float ||
                                        Kind == Symbol; }
+  bool isReg() const override { return Kind == Local || Kind == Stack; }
   bool isMem() const override { return false; }
-  bool isReg() const override { return false; }
 
   unsigned getReg() const override {
-    llvm_unreachable("Assembly inspects a register operand");
-    return 0;
+    assert(isReg());
+    // This is called from the tablegen matcher (MatchInstructionImpl)
+    // where it expects to match the type of register, see RegOp above.
+    return MVTToWasmReg(Reg.Type);
   }
 
   StringRef getToken() const {
@@ -93,9 +128,19 @@ struct WebAssemblyOperand : public MCParsedAsmOperand {
   SMLoc getStartLoc() const override { return StartLoc; }
   SMLoc getEndLoc() const override { return EndLoc; }
 
-  void addRegOperands(MCInst &, unsigned) const {
-    // Required by the assembly matcher.
-    llvm_unreachable("Assembly matcher creates register operands");
+  void addRegOperands(MCInst &Inst, unsigned N) const {
+    assert(N == 1 && "Invalid number of operands!");
+    assert(isReg() && "Not a register operand!");
+    // This is called from the tablegen matcher (MatchInstructionImpl)
+    // where it expects to output the actual register index, see RegOp above.
+    unsigned R = Reg.RegNo;
+    if (Kind == Stack) {
+      // A stack register is represented as a large negative number.
+      // See WebAssemblyRegNumbering::runOnMachineFunction and
+      // getWARegStackId for why this | is needed.
+      R |= INT32_MIN;
+    }
+    Inst.addOperand(MCOperand::createReg(R));
   }
 
   void addImmOperands(MCInst &Inst, unsigned N) const {
@@ -115,6 +160,12 @@ struct WebAssemblyOperand : public MCParsedAsmOperand {
     case Token:
       OS << "Tok:" << Tok.Tok;
       break;
+    case Local:
+      OS << "Loc:" << Reg.RegNo << ":" << static_cast<int>(Reg.Type);
+      break;
+    case Stack:
+      OS << "Stk:" << Reg.RegNo << ":" << static_cast<int>(Reg.Type);
+      break;
     case Integer:
       OS << "Int:" << Int.Val;
       break;
@@ -131,6 +182,11 @@ struct WebAssemblyOperand : public MCParsedAsmOperand {
 class WebAssemblyAsmParser final : public MCTargetAsmParser {
   MCAsmParser &Parser;
   MCAsmLexer &Lexer;
+  // These are for the current function being parsed:
+  // These are vectors since register assignments are so far non-sparse.
+  // Replace by map if necessary.
+  std::vector<MVT::SimpleValueType> LocalTypes;
+  std::vector<MVT::SimpleValueType> StackTypes;
   MCSymbol *LastLabel;
 
 public:
@@ -180,6 +236,68 @@ class WebAssemblyAsmParser final : public MCTargetAsmParser {
         .Default(MVT::INVALID_SIMPLE_VALUE_TYPE);
   }
 
+  MVT::SimpleValueType &GetType(
+      std::vector<MVT::SimpleValueType> &Types, size_t i) {
+    Types.resize(std::max(i + 1, Types.size()), MVT::INVALID_SIMPLE_VALUE_TYPE);
+    return Types[i];
+  }
+
+  bool ParseReg(OperandVector &Operands, StringRef TypePrefix) {
+    if (Lexer.is(AsmToken::Integer)) {
+      auto &Local = Lexer.getTok();
+      // This is a reference to a local, turn it into a virtual register.
+      auto LocalNo = static_cast<unsigned>(Local.getIntVal());
+      Operands.push_back(make_unique<WebAssemblyOperand>(
+                           WebAssemblyOperand::Local, Local.getLoc(),
+                           Local.getEndLoc(),
+                           WebAssemblyOperand::RegOp{LocalNo,
+                               GetType(LocalTypes, LocalNo)}));
+      Parser.Lex();
+    } else if (Lexer.is(AsmToken::Identifier)) {
+      auto &StackRegTok = Lexer.getTok();
+      // These are push/pop/drop pseudo stack registers, which we turn
+      // into virtual registers also. The stackify pass will later turn them
+      // back into implicit stack references if possible.
+      auto StackReg = StackRegTok.getString();
+      auto StackOp = StackReg.take_while([](char c) { return isalpha(c); });
+      auto Reg = StackReg.drop_front(StackOp.size());
+      unsigned long long ParsedRegNo = 0;
+      if (!Reg.empty() && getAsUnsignedInteger(Reg, 10, ParsedRegNo))
+        return Error("Cannot parse stack register index: ", StackRegTok);
+      unsigned RegNo = static_cast<unsigned>(ParsedRegNo);
+      if (StackOp == "push") {
+        // This defines a result, record register type.
+        auto RegType = ParseRegType(TypePrefix);
+        GetType(StackTypes, RegNo) = RegType;
+        Operands.push_back(make_unique<WebAssemblyOperand>(
+                             WebAssemblyOperand::Stack,
+                             StackRegTok.getLoc(),
+                             StackRegTok.getEndLoc(),
+                             WebAssemblyOperand::RegOp{RegNo, RegType}));
+      } else if (StackOp == "pop") {
+        // This uses a previously defined stack value.
+        auto RegType = GetType(StackTypes, RegNo);
+        Operands.push_back(make_unique<WebAssemblyOperand>(
+                             WebAssemblyOperand::Stack,
+                             StackRegTok.getLoc(),
+                             StackRegTok.getEndLoc(),
+                             WebAssemblyOperand::RegOp{RegNo, RegType}));
+      } else if (StackOp == "drop") {
+        // This operand will be dropped, since it is part of an instruction
+        // whose result is void.
+      } else {
+        return Error("Unknown stack register prefix: ", StackRegTok);
+      }
+      Parser.Lex();
+    } else {
+      return Error(
+            "Expected identifier/integer following $, instead got: ",
+            Lexer.getTok());
+    }
+    IsNext(AsmToken::Equal);
+    return false;
+  }
+
   void ParseSingleInteger(bool IsNegative, OperandVector &Operands) {
     auto &Int = Lexer.getTok();
     int64_t Val = Int.getIntVal();
@@ -192,26 +310,36 @@ class WebAssemblyAsmParser final : public MCTargetAsmParser {
 
   bool ParseOperandStartingWithInteger(bool IsNegative,
                                        OperandVector &Operands,
-                                       StringRef InstName) {
+                                       StringRef InstType) {
     ParseSingleInteger(IsNegative, Operands);
-    // FIXME: there is probably a cleaner way to do this.
-    auto IsLoadStore = InstName.startswith("load") ||
-                       InstName.startswith("store") ||
-                       InstName.startswith("atomic_load") ||
-                       InstName.startswith("atomic_store");
-    if (IsLoadStore) {
-      // Parse load/store operands of the form: offset align
-      auto &Offset = Lexer.getTok();
-      if (Offset.is(AsmToken::Integer)) {
+    if (Lexer.is(AsmToken::LParen)) {
+      // Parse load/store operands of the form: offset($reg)align
+      auto &LParen = Lexer.getTok();
+      Operands.push_back(
+            make_unique<WebAssemblyOperand>(WebAssemblyOperand::Token,
+                                            LParen.getLoc(),
+                                            LParen.getEndLoc(),
+                                            WebAssemblyOperand::TokOp{
+                                              LParen.getString()}));
+      Parser.Lex();
+      if (Expect(AsmToken::Dollar, "register")) return true;
+      if (ParseReg(Operands, InstType)) return true;
+      auto &RParen = Lexer.getTok();
+      Operands.push_back(
+            make_unique<WebAssemblyOperand>(WebAssemblyOperand::Token,
+                                            RParen.getLoc(),
+                                            RParen.getEndLoc(),
+                                            WebAssemblyOperand::TokOp{
+                                              RParen.getString()}));
+      if (Expect(AsmToken::RParen, ")")) return true;
+      if (Lexer.is(AsmToken::Integer)) {
         ParseSingleInteger(false, Operands);
       } else {
         // Alignment not specified.
         // FIXME: correctly derive a default from the instruction.
-        // We can't just call WebAssembly::GetDefaultP2Align since we don't have
-        // an opcode until after the assembly matcher.
         Operands.push_back(make_unique<WebAssemblyOperand>(
-                             WebAssemblyOperand::Integer, Offset.getLoc(),
-                             Offset.getEndLoc(), WebAssemblyOperand::IntOp{0}));
+                             WebAssemblyOperand::Integer, RParen.getLoc(),
+                             RParen.getEndLoc(), WebAssemblyOperand::IntOp{0}));
       }
     }
     return false;
@@ -232,6 +360,11 @@ class WebAssemblyAsmParser final : public MCTargetAsmParser {
     while (Lexer.isNot(AsmToken::EndOfStatement)) {
       auto &Tok = Lexer.getTok();
       switch (Tok.getKind()) {
+      case AsmToken::Dollar: {
+        Parser.Lex();
+        if (ParseReg(Operands, NamePair.first)) return true;
+        break;
+      }
       case AsmToken::Identifier: {
         auto &Id = Lexer.getTok();
         const MCExpr *Val;
@@ -247,11 +380,11 @@ class WebAssemblyAsmParser final : public MCTargetAsmParser {
         Parser.Lex();
         if (Lexer.isNot(AsmToken::Integer))
           return Error("Expected integer instead got: ", Lexer.getTok());
-        if (ParseOperandStartingWithInteger(true, Operands, NamePair.second))
+        if (ParseOperandStartingWithInteger(true, Operands, NamePair.first))
           return true;
         break;
       case AsmToken::Integer:
-        if (ParseOperandStartingWithInteger(false, Operands, NamePair.second))
+        if (ParseOperandStartingWithInteger(false, Operands, NamePair.first))
           return true;
         break;
       case AsmToken::Real: {
@@ -272,6 +405,35 @@ class WebAssemblyAsmParser final : public MCTargetAsmParser {
       }
     }
     Parser.Lex();
+    // Call instructions are vararg, but the tablegen matcher doesn't seem to
+    // support that, so for now we strip these extra operands.
+    // This is problematic if these arguments are not simple $pop stack
+    // registers, since e.g. a local register would get lost, so we check for
+    // this. This can be the case when using -disable-wasm-explicit-locals
+    // which currently s2wasm requires.
+    // TODO: Instead, we can move this code to MatchAndEmitInstruction below and
+    // actually generate get_local instructions on the fly.
+    // Or even better, improve the matcher to support vararg?
+    auto IsIndirect = NamePair.second == "call_indirect";
+    if (IsIndirect || NamePair.second == "call") {
+      // Figure out number of fixed operands from the instruction.
+      size_t CallOperands = 1;  // The name token.
+      if (!IsIndirect) CallOperands++;  // The function index.
+      if (!NamePair.first.empty()) CallOperands++;  // The result register.
+      if (Operands.size() > CallOperands) {
+        // Ensure operands we drop are all $pop.
+        for (size_t I = CallOperands; I < Operands.size(); I++) {
+          auto Operand =
+              reinterpret_cast<WebAssemblyOperand *>(Operands[I].get());
+          if (Operand->Kind != WebAssemblyOperand::Stack)
+            Parser.Error(NameLoc,
+              "Call instruction has non-stack arguments, if this code was "
+              "generated with -disable-wasm-explicit-locals please remove it");
+        }
+        // Drop unneeded operands.
+        Operands.resize(CallOperands);
+      }
+    }
     // Block instructions require a signature index, but these are missing in
     // assembly, so we add a dummy one explicitly (since we have no control
     // over signature tables here, we assume these will be regenerated when
@@ -281,6 +443,17 @@ class WebAssemblyAsmParser final : public MCTargetAsmParser {
                            WebAssemblyOperand::Integer, NameLoc,
                            NameLoc, WebAssemblyOperand::IntOp{-1}));
     }
+    // These don't specify the type, which has to derived from the local index.
+    if (NamePair.second == "get_local" || NamePair.second == "tee_local") {
+      if (Operands.size() >= 3 && Operands[1]->isReg() &&
+          Operands[2]->isImm()) {
+        auto Op1 = reinterpret_cast<WebAssemblyOperand *>(Operands[1].get());
+        auto Op2 = reinterpret_cast<WebAssemblyOperand *>(Operands[2].get());
+        auto Type = GetType(LocalTypes, static_cast<size_t>(Op2->Int.Val));
+        Op1->Reg.Type = Type;
+        GetType(StackTypes, Op1->Reg.RegNo) = Type;
+      }
+    }
     return false;
   }
 
@@ -304,6 +477,11 @@ class WebAssemblyAsmParser final : public MCTargetAsmParser {
             IsNext(AsmToken::At) &&
             Lexer.is(AsmToken::Identifier)))
         return Error("Expected label,@type declaration, got: ", Lexer.getTok());
+      if (Lexer.getTok().getString() == "function") {
+        // Track locals from start of function.
+        LocalTypes.clear();
+        StackTypes.clear();
+      }
       Parser.Lex();
       //Out.EmitSymbolAttribute(??, MCSA_ELF_TypeFunction);
     } else if (DirectiveID.getString() == ".param" ||
@@ -316,6 +494,7 @@ class WebAssemblyAsmParser final : public MCTargetAsmParser {
       while (Lexer.is(AsmToken::Identifier)) {
         auto RegType = ParseRegType(Lexer.getTok().getString());
         if (RegType == MVT::INVALID_SIMPLE_VALUE_TYPE) return true;
+        LocalTypes.push_back(RegType);
         if (DirectiveID.getString() == ".param") {
           Params.push_back(RegType);
         } else {