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//==- WebAssemblyAsmParser.cpp - Assembler for WebAssembly -*- C++ -*-==//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
///
/// \file
/// This file is part of the WebAssembly Assembler.
///
/// It contains code to translate a parsed .s file into MCInsts.
///
//===----------------------------------------------------------------------===//
#include "MCTargetDesc/WebAssemblyMCTargetDesc.h"
#include "MCTargetDesc/WebAssemblyTargetStreamer.h"
#include "WebAssembly.h"
#include "llvm/MC/MCContext.h"
#include "llvm/MC/MCInst.h"
#include "llvm/MC/MCInstrInfo.h"
#include "llvm/MC/MCParser/MCParsedAsmOperand.h"
#include "llvm/MC/MCParser/MCTargetAsmParser.h"
#include "llvm/MC/MCStreamer.h"
#include "llvm/MC/MCSubtargetInfo.h"
#include "llvm/MC/MCSymbol.h"
#include "llvm/MC/MCSymbolWasm.h"
#include "llvm/Support/Endian.h"
#include "llvm/Support/TargetRegistry.h"
using namespace llvm;
#define DEBUG_TYPE "wasm-asm-parser"
namespace {
/// WebAssemblyOperand - Instances of this class represent the operands in a
/// parsed WASM machine instruction.
struct WebAssemblyOperand : public MCParsedAsmOperand {
enum KindTy { Token, Integer, Float, Symbol, BrList } Kind;
SMLoc StartLoc, EndLoc;
struct TokOp {
StringRef Tok;
};
struct IntOp {
int64_t Val;
};
struct FltOp {
double Val;
};
struct SymOp {
const MCExpr *Exp;
};
struct BrLOp {
std::vector<unsigned> List;
};
union {
struct TokOp Tok;
struct IntOp Int;
struct FltOp Flt;
struct SymOp Sym;
struct BrLOp BrL;
};
WebAssemblyOperand(KindTy K, SMLoc Start, SMLoc End, TokOp T)
: Kind(K), StartLoc(Start), EndLoc(End), Tok(T) {}
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)
: Kind(K), StartLoc(Start), EndLoc(End), Flt(F) {}
WebAssemblyOperand(KindTy K, SMLoc Start, SMLoc End, SymOp S)
: Kind(K), StartLoc(Start), EndLoc(End), Sym(S) {}
WebAssemblyOperand(KindTy K, SMLoc Start, SMLoc End)
: Kind(K), StartLoc(Start), EndLoc(End), BrL() {}
~WebAssemblyOperand() {
if (isBrList())
BrL.~BrLOp();
}
bool isToken() const override { return Kind == Token; }
bool isImm() const override {
return Kind == Integer || Kind == Float || Kind == Symbol;
}
bool isMem() const override { return false; }
bool isReg() const override { return false; }
bool isBrList() const { return Kind == BrList; }
unsigned getReg() const override {
llvm_unreachable("Assembly inspects a register operand");
return 0;
}
StringRef getToken() const {
assert(isToken());
return Tok.Tok;
}
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 addImmOperands(MCInst &Inst, unsigned N) const {
assert(N == 1 && "Invalid number of operands!");
if (Kind == Integer)
Inst.addOperand(MCOperand::createImm(Int.Val));
else if (Kind == Float)
Inst.addOperand(MCOperand::createFPImm(Flt.Val));
else if (Kind == Symbol)
Inst.addOperand(MCOperand::createExpr(Sym.Exp));
else
llvm_unreachable("Should be immediate or symbol!");
}
void addBrListOperands(MCInst &Inst, unsigned N) const {
assert(N == 1 && isBrList() && "Invalid BrList!");
for (auto Br : BrL.List)
Inst.addOperand(MCOperand::createImm(Br));
}
void print(raw_ostream &OS) const override {
switch (Kind) {
case Token:
OS << "Tok:" << Tok.Tok;
break;
case Integer:
OS << "Int:" << Int.Val;
break;
case Float:
OS << "Flt:" << Flt.Val;
break;
case Symbol:
OS << "Sym:" << Sym.Exp;
break;
case BrList:
OS << "BrList:" << BrL.List.size();
break;
}
}
};
class WebAssemblyAsmParser final : public MCTargetAsmParser {
MCAsmParser &Parser;
MCAsmLexer &Lexer;
// Much like WebAssemblyAsmPrinter in the backend, we have to own these.
std::vector<std::unique_ptr<wasm::WasmSignature>> Signatures;
// Order of labels, directives and instructions in a .s file have no
// syntactical enforcement. This class is a callback from the actual parser,
// and yet we have to be feeding data to the streamer in a very particular
// order to ensure a correct binary encoding that matches the regular backend
// (the streamer does not enforce this). This "state machine" enum helps
// guarantee that correct order.
enum ParserState {
FileStart,
Label,
FunctionStart,
FunctionLocals,
Instructions,
} CurrentState = FileStart;
// For ensuring blocks are properly nested.
enum NestingType {
Function,
Block,
Loop,
Try,
If,
Else,
Undefined,
};
std::vector<NestingType> NestingStack;
// We track this to see if a .functype following a label is the same,
// as this is how we recognize the start of a function.
MCSymbol *LastLabel = nullptr;
public:
WebAssemblyAsmParser(const MCSubtargetInfo &STI, MCAsmParser &Parser,
const MCInstrInfo &MII, const MCTargetOptions &Options)
: MCTargetAsmParser(Options, STI, MII), Parser(Parser),
Lexer(Parser.getLexer()) {
setAvailableFeatures(ComputeAvailableFeatures(STI.getFeatureBits()));
}
#define GET_ASSEMBLER_HEADER
#include "WebAssemblyGenAsmMatcher.inc"
// TODO: This is required to be implemented, but appears unused.
bool ParseRegister(unsigned & /*RegNo*/, SMLoc & /*StartLoc*/,
SMLoc & /*EndLoc*/) override {
llvm_unreachable("ParseRegister is not implemented.");
}
bool error(const Twine &Msg, const AsmToken &Tok) {
return Parser.Error(Tok.getLoc(), Msg + Tok.getString());
}
bool error(const Twine &Msg) {
return Parser.Error(Lexer.getTok().getLoc(), Msg);
}
void addSignature(std::unique_ptr<wasm::WasmSignature> &&Sig) {
Signatures.push_back(std::move(Sig));
}
std::pair<StringRef, StringRef> nestingString(NestingType NT) {
switch (NT) {
case Function:
return {"function", "end_function"};
case Block:
return {"block", "end_block"};
case Loop:
return {"loop", "end_loop"};
case Try:
return {"try", "end_try"};
case If:
return {"if", "end_if"};
case Else:
return {"else", "end_if"};
default:
llvm_unreachable("unknown NestingType");
}
}
void push(NestingType NT) { NestingStack.push_back(NT); }
bool pop(StringRef Ins, NestingType NT1, NestingType NT2 = Undefined) {
if (NestingStack.empty())
return error(Twine("End of block construct with no start: ") + Ins);
auto Top = NestingStack.back();
if (Top != NT1 && Top != NT2)
return error(Twine("Block construct type mismatch, expected: ") +
nestingString(Top).second + ", instead got: " + Ins);
NestingStack.pop_back();
return false;
}
bool ensureEmptyNestingStack() {
auto err = !NestingStack.empty();
while (!NestingStack.empty()) {
error(Twine("Unmatched block construct(s) at function end: ") +
nestingString(NestingStack.back()).first);
NestingStack.pop_back();
}
return err;
}
bool isNext(AsmToken::TokenKind Kind) {
auto Ok = Lexer.is(Kind);
if (Ok)
Parser.Lex();
return Ok;
}
bool expect(AsmToken::TokenKind Kind, const char *KindName) {
if (!isNext(Kind))
return error(std::string("Expected ") + KindName + ", instead got: ",
Lexer.getTok());
return false;
}
StringRef expectIdent() {
if (!Lexer.is(AsmToken::Identifier)) {
error("Expected identifier, got: ", Lexer.getTok());
return StringRef();
}
auto Name = Lexer.getTok().getString();
Parser.Lex();
return Name;
}
Optional<wasm::ValType> parseType(const StringRef &Type) {
// FIXME: can't use StringSwitch because wasm::ValType doesn't have a
// "invalid" value.
if (Type == "i32")
return wasm::ValType::I32;
if (Type == "i64")
return wasm::ValType::I64;
if (Type == "f32")
return wasm::ValType::F32;
if (Type == "f64")
return wasm::ValType::F64;
if (Type == "v128" || Type == "i8x16" || Type == "i16x8" ||
Type == "i32x4" || Type == "i64x2" || Type == "f32x4" ||
Type == "f64x2")
return wasm::ValType::V128;
if (Type == "except_ref")
return wasm::ValType::EXCEPT_REF;
return Optional<wasm::ValType>();
}
WebAssembly::ExprType parseBlockType(StringRef ID) {
return StringSwitch<WebAssembly::ExprType>(ID)
.Case("i32", WebAssembly::ExprType::I32)
.Case("i64", WebAssembly::ExprType::I64)
.Case("f32", WebAssembly::ExprType::F32)
.Case("f64", WebAssembly::ExprType::F64)
.Case("v128", WebAssembly::ExprType::V128)
.Case("except_ref", WebAssembly::ExprType::ExceptRef)
.Case("void", WebAssembly::ExprType::Void)
.Default(WebAssembly::ExprType::Invalid);
}
bool parseRegTypeList(SmallVectorImpl<wasm::ValType> &Types) {
while (Lexer.is(AsmToken::Identifier)) {
auto Type = parseType(Lexer.getTok().getString());
if (!Type)
return error("unknown type: ", Lexer.getTok());
Types.push_back(Type.getValue());
Parser.Lex();
if (!isNext(AsmToken::Comma))
break;
}
return false;
}
void parseSingleInteger(bool IsNegative, OperandVector &Operands) {
auto &Int = Lexer.getTok();
int64_t Val = Int.getIntVal();
if (IsNegative)
Val = -Val;
Operands.push_back(make_unique<WebAssemblyOperand>(
WebAssemblyOperand::Integer, Int.getLoc(), Int.getEndLoc(),
WebAssemblyOperand::IntOp{Val}));
Parser.Lex();
}
bool parseOperandStartingWithInteger(bool IsNegative, OperandVector &Operands,
StringRef InstName) {
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)) {
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}));
}
}
return false;
}
void addBlockTypeOperand(OperandVector &Operands, SMLoc NameLoc,
WebAssembly::ExprType BT) {
Operands.push_back(make_unique<WebAssemblyOperand>(
WebAssemblyOperand::Integer, NameLoc, NameLoc,
WebAssemblyOperand::IntOp{static_cast<int64_t>(BT)}));
}
bool ParseInstruction(ParseInstructionInfo & /*Info*/, StringRef Name,
SMLoc NameLoc, OperandVector &Operands) override {
// Note: Name does NOT point into the sourcecode, but to a local, so
// use NameLoc instead.
Name = StringRef(NameLoc.getPointer(), Name.size());
// WebAssembly has instructions with / in them, which AsmLexer parses
// as seperate tokens, so if we find such tokens immediately adjacent (no
// whitespace), expand the name to include them:
for (;;) {
auto &Sep = Lexer.getTok();
if (Sep.getLoc().getPointer() != Name.end() ||
Sep.getKind() != AsmToken::Slash)
break;
// Extend name with /
Name = StringRef(Name.begin(), Name.size() + Sep.getString().size());
Parser.Lex();
// We must now find another identifier, or error.
auto &Id = Lexer.getTok();
if (Id.getKind() != AsmToken::Identifier ||
Id.getLoc().getPointer() != Name.end())
return error("Incomplete instruction name: ", Id);
Name = StringRef(Name.begin(), Name.size() + Id.getString().size());
Parser.Lex();
}
// Now construct the name as first operand.
Operands.push_back(make_unique<WebAssemblyOperand>(
WebAssemblyOperand::Token, NameLoc, SMLoc::getFromPointer(Name.end()),
WebAssemblyOperand::TokOp{Name}));
auto NamePair = Name.split('.');
// If no '.', there is no type prefix.
auto BaseName = NamePair.second.empty() ? NamePair.first : NamePair.second;
// If this instruction is part of a control flow structure, ensure
// proper nesting.
bool ExpectBlockType = false;
if (BaseName == "block") {
push(Block);
ExpectBlockType = true;
} else if (BaseName == "loop") {
push(Loop);
ExpectBlockType = true;
} else if (BaseName == "try") {
push(Try);
ExpectBlockType = true;
} else if (BaseName == "if") {
push(If);
ExpectBlockType = true;
} else if (BaseName == "else") {
if (pop(BaseName, If))
return true;
push(Else);
} else if (BaseName == "catch") {
if (pop(BaseName, Try))
return true;
push(Try);
} else if (BaseName == "catch_all") {
if (pop(BaseName, Try))
return true;
push(Try);
} else if (BaseName == "end_if") {
if (pop(BaseName, If, Else))
return true;
} else if (BaseName == "end_try") {
if (pop(BaseName, Try))
return true;
} else if (BaseName == "end_loop") {
if (pop(BaseName, Loop))
return true;
} else if (BaseName == "end_block") {
if (pop(BaseName, Block))
return true;
} else if (BaseName == "end_function") {
if (pop(BaseName, Function) || ensureEmptyNestingStack())
return true;
}
while (Lexer.isNot(AsmToken::EndOfStatement)) {
auto &Tok = Lexer.getTok();
switch (Tok.getKind()) {
case AsmToken::Identifier: {
auto &Id = Lexer.getTok();
if (ExpectBlockType) {
// Assume this identifier is a block_type.
auto BT = parseBlockType(Id.getString());
if (BT == WebAssembly::ExprType::Invalid)
return error("Unknown block type: ", Id);
addBlockTypeOperand(Operands, NameLoc, BT);
Parser.Lex();
} else {
// Assume this identifier is a label.
const MCExpr *Val;
SMLoc End;
if (Parser.parsePrimaryExpr(Val, End))
return error("Cannot parse symbol: ", Lexer.getTok());
Operands.push_back(make_unique<WebAssemblyOperand>(
WebAssemblyOperand::Symbol, Id.getLoc(), Id.getEndLoc(),
WebAssemblyOperand::SymOp{Val}));
}
break;
}
case AsmToken::Minus:
Parser.Lex();
if (Lexer.isNot(AsmToken::Integer))
return error("Expected integer instead got: ", Lexer.getTok());
if (parseOperandStartingWithInteger(true, Operands, BaseName))
return true;
break;
case AsmToken::Integer:
if (parseOperandStartingWithInteger(false, Operands, BaseName))
return true;
break;
case AsmToken::Real: {
double Val;
if (Tok.getString().getAsDouble(Val, false))
return error("Cannot parse real: ", Tok);
Operands.push_back(make_unique<WebAssemblyOperand>(
WebAssemblyOperand::Float, Tok.getLoc(), Tok.getEndLoc(),
WebAssemblyOperand::FltOp{Val}));
Parser.Lex();
break;
}
case AsmToken::LCurly: {
Parser.Lex();
auto Op = make_unique<WebAssemblyOperand>(
WebAssemblyOperand::BrList, Tok.getLoc(), Tok.getEndLoc());
if (!Lexer.is(AsmToken::RCurly))
for (;;) {
Op->BrL.List.push_back(Lexer.getTok().getIntVal());
expect(AsmToken::Integer, "integer");
if (!isNext(AsmToken::Comma))
break;
}
expect(AsmToken::RCurly, "}");
Operands.push_back(std::move(Op));
break;
}
default:
return error("Unexpected token in operand: ", Tok);
}
if (Lexer.isNot(AsmToken::EndOfStatement)) {
if (expect(AsmToken::Comma, ","))
return true;
}
}
if (ExpectBlockType && Operands.size() == 1) {
// Support blocks with no operands as default to void.
addBlockTypeOperand(Operands, NameLoc, WebAssembly::ExprType::Void);
}
Parser.Lex();
return false;
}
void onLabelParsed(MCSymbol *Symbol) override {
LastLabel = Symbol;
CurrentState = Label;
}
bool parseSignature(wasm::WasmSignature *Signature) {
if (expect(AsmToken::LParen, "("))
return true;
if (parseRegTypeList(Signature->Params))
return true;
if (expect(AsmToken::RParen, ")"))
return true;
if (expect(AsmToken::MinusGreater, "->"))
return true;
if (expect(AsmToken::LParen, "("))
return true;
if (parseRegTypeList(Signature->Returns))
return true;
if (expect(AsmToken::RParen, ")"))
return true;
return false;
}
// 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:
// - return true && no tokens consumed -> don't know this directive / let
// the generic parser handle it.
// - return true && tokens consumed -> a parsing error occurred.
// - return false -> processed this directive successfully.
assert(DirectiveID.getKind() == AsmToken::Identifier);
auto &Out = getStreamer();
auto &TOut =
reinterpret_cast<WebAssemblyTargetStreamer &>(*Out.getTargetStreamer());
auto &Ctx = Out.getContext();
// 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() == ".globaltype") {
auto SymName = expectIdent();
if (SymName.empty())
return true;
if (expect(AsmToken::Comma, ","))
return true;
auto TypeTok = Lexer.getTok();
auto TypeName = expectIdent();
if (TypeName.empty())
return true;
auto Type = parseType(TypeName);
if (!Type)
return error("Unknown type in .globaltype directive: ", TypeTok);
// Now set this symbol with the correct type.
auto WasmSym = cast<MCSymbolWasm>(Ctx.getOrCreateSymbol(SymName));
WasmSym->setType(wasm::WASM_SYMBOL_TYPE_GLOBAL);
WasmSym->setGlobalType(
wasm::WasmGlobalType{uint8_t(Type.getValue()), true});
// And emit the directive again.
TOut.emitGlobalType(WasmSym);
return expect(AsmToken::EndOfStatement, "EOL");
}
if (DirectiveID.getString() == ".functype") {
// This code has to send things to the streamer similar to
// WebAssemblyAsmPrinter::EmitFunctionBodyStart.
// TODO: would be good to factor this into a common function, but the
// assembler and backend really don't share any common code, and this code
// parses the locals seperately.
auto SymName = expectIdent();
if (SymName.empty())
return true;
auto WasmSym = cast<MCSymbolWasm>(Ctx.getOrCreateSymbol(SymName));
if (CurrentState == Label && WasmSym == LastLabel) {
// This .functype indicates a start of a function.
if (ensureEmptyNestingStack())
return true;
CurrentState = FunctionStart;
push(Function);
}
auto Signature = make_unique<wasm::WasmSignature>();
if (parseSignature(Signature.get()))
return true;
WasmSym->setSignature(Signature.get());
addSignature(std::move(Signature));
WasmSym->setType(wasm::WASM_SYMBOL_TYPE_FUNCTION);
TOut.emitFunctionType(WasmSym);
// TODO: backend also calls TOut.emitIndIdx, but that is not implemented.
return expect(AsmToken::EndOfStatement, "EOL");
}
if (DirectiveID.getString() == ".eventtype") {
auto SymName = expectIdent();
if (SymName.empty())
return true;
auto WasmSym = cast<MCSymbolWasm>(Ctx.getOrCreateSymbol(SymName));
auto Signature = make_unique<wasm::WasmSignature>();
if (parseRegTypeList(Signature->Params))
return true;
WasmSym->setSignature(Signature.get());
addSignature(std::move(Signature));
WasmSym->setType(wasm::WASM_SYMBOL_TYPE_EVENT);
TOut.emitEventType(WasmSym);
// TODO: backend also calls TOut.emitIndIdx, but that is not implemented.
return expect(AsmToken::EndOfStatement, "EOL");
}
if (DirectiveID.getString() == ".local") {
if (CurrentState != FunctionStart)
return error(".local directive should follow the start of a function",
Lexer.getTok());
SmallVector<wasm::ValType, 4> Locals;
if (parseRegTypeList(Locals))
return true;
TOut.emitLocal(Locals);
CurrentState = FunctionLocals;
return expect(AsmToken::EndOfStatement, "EOL");
}
return true; // We didn't process this directive.
}
bool MatchAndEmitInstruction(SMLoc IDLoc, unsigned & /*Opcode*/,
OperandVector &Operands, MCStreamer &Out,
uint64_t &ErrorInfo,
bool MatchingInlineAsm) override {
MCInst Inst;
unsigned MatchResult =
MatchInstructionImpl(Operands, Inst, ErrorInfo, MatchingInlineAsm);
switch (MatchResult) {
case Match_Success: {
if (CurrentState == FunctionStart) {
// This is the first instruction in a function, but we haven't seen
// a .local directive yet. The streamer requires locals to be encoded
// as a prelude to the instructions, so emit an empty list of locals
// here.
auto &TOut = reinterpret_cast<WebAssemblyTargetStreamer &>(
*Out.getTargetStreamer());
TOut.emitLocal(SmallVector<wasm::ValType, 0>());
}
CurrentState = Instructions;
Out.EmitInstruction(Inst, getSTI());
return false;
}
case Match_MissingFeature:
return Parser.Error(
IDLoc, "instruction requires a WASM feature not currently enabled");
case Match_MnemonicFail:
return Parser.Error(IDLoc, "invalid instruction");
case Match_NearMisses:
return Parser.Error(IDLoc, "ambiguous instruction");
case Match_InvalidTiedOperand:
case Match_InvalidOperand: {
SMLoc ErrorLoc = IDLoc;
if (ErrorInfo != ~0ULL) {
if (ErrorInfo >= Operands.size())
return Parser.Error(IDLoc, "too few operands for instruction");
ErrorLoc = Operands[ErrorInfo]->getStartLoc();
if (ErrorLoc == SMLoc())
ErrorLoc = IDLoc;
}
return Parser.Error(ErrorLoc, "invalid operand for instruction");
}
}
llvm_unreachable("Implement any new match types added!");
}
void onEndOfFile() override { ensureEmptyNestingStack(); }
};
} // end anonymous namespace
// Force static initialization.
extern "C" void LLVMInitializeWebAssemblyAsmParser() {
RegisterMCAsmParser<WebAssemblyAsmParser> X(getTheWebAssemblyTarget32());
RegisterMCAsmParser<WebAssemblyAsmParser> Y(getTheWebAssemblyTarget64());
}
#define GET_REGISTER_MATCHER
#define GET_MATCHER_IMPLEMENTATION
#include "WebAssemblyGenAsmMatcher.inc"