src/wasm.h

/*
 * Copyright 2015 WebAssembly Community Group participants
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

//
// wasm.h: WebAssembly representation and processing library, in one
//         header file.
//
// This represents WebAssembly in an AST format, with a focus on making
// it easy to not just inspect but also to process. For example, some
// things that this enables are:
//
//  * Interpreting: See wasm-interpreter.h.
//  * Optimizing: See asm2wasm.h, which performs some optimizations
//                after code generation.
//  * Validation: See wasm-validator.h.
//  * Pretty-printing: See Print.cpp.
//

//
// wasm.js internal WebAssembly representation design:
//
//  * Unify where possible. Where size isn't a concern, combine
//    classes, so binary ops and relational ops are joined. This
//    simplifies that AST and makes traversals easier.
//  * Optimize for size? This might justify separating if and if_else
//    (so that if doesn't have an always-empty else; also it avoids
//    a branch).
//

#ifndef wasm_wasm_h
#define wasm_wasm_h

#include <cassert>
#include <cmath>
#include <cstddef>
#include <cstdint>
#include <cstring>
#include <fstream>
#include <map>
#include <string>
#include <vector>

#include "compiler-support.h"
#include "emscripten-optimizer/simple_ast.h"
#include "mixed_arena.h"
#include "pretty_printing.h"
#include "support/bits.h"
#include "support/utilities.h"

namespace wasm {

// We use a Name for all of the identifiers. These are IStrings, so they are
// all interned - comparisons etc are just pointer comparisons, so there is no
// perf loss. Having names everywhere makes using the AST much nicer (for
// example, block names are strings and not offsets, which makes composition
// - adding blocks, removing blocks - easy). One exception is local variables,
// where we do use indices, as they are a large proportion of the AST,
// perf matters a lot there, and compositionality is not a problem.
// TODO: as an optimization, IString values < some threshold could be considered
//       numerical indices directly.

struct Name : public cashew::IString {
  Name() : cashew::IString() {}
  Name(const char *str) : cashew::IString(str, false) {}
  Name(cashew::IString str) : cashew::IString(str) {}
  Name(const std::string &str) : cashew::IString(str.c_str(), false) {}

  friend std::ostream& operator<<(std::ostream &o, Name name) {
    assert(name.str);
    return o << '$' << name.str; // reference interpreter requires we prefix all names
  }

  static Name fromInt(size_t i) {
    return cashew::IString(std::to_string(i).c_str(), false);
  }
};

// An index in a wasm module

typedef uint32_t Index;

// Types

enum WasmType {
  none,
  i32,
  i64,
  f32,
  f64,
  unreachable // none means no type, e.g. a block can have no return type. but
              // unreachable is different, as it can be "ignored" when doing
              // type checking across branches
};

inline const char* printWasmType(WasmType type) {
  switch (type) {
    case WasmType::none: return "none";
    case WasmType::i32: return "i32";
    case WasmType::i64: return "i64";
    case WasmType::f32: return "f32";
    case WasmType::f64: return "f64";
    case WasmType::unreachable: return "unreachable";
    default: WASM_UNREACHABLE();
  }
}

inline unsigned getWasmTypeSize(WasmType type) {
  switch (type) {
    case WasmType::none: abort();
    case WasmType::i32: return 4;
    case WasmType::i64: return 8;
    case WasmType::f32: return 4;
    case WasmType::f64: return 8;
    default: WASM_UNREACHABLE();
  }
}

inline bool isWasmTypeFloat(WasmType type) {
  switch (type) {
    case f32:
    case f64: return true;
    default: return false;
  }
}

inline WasmType getWasmType(unsigned size, bool float_) {
  if (size < 4) return WasmType::i32;
  if (size == 4) return float_ ? WasmType::f32 : WasmType::i32;
  if (size == 8) return float_ ? WasmType::f64 : WasmType::i64;
  abort();
}

inline WasmType getReachableWasmType(WasmType a, WasmType b) {
  return a != unreachable ? a : b;
}

inline bool isConcreteWasmType(WasmType type) {
  return type != none && type != unreachable;
}

// Literals

class Literal {
public:
  WasmType type;

private:
  // store only integers, whose bits are deterministic. floats
  // can have their signalling bit set, for example.
  union {
    int32_t i32;
    int64_t i64;
  };

public:
  Literal() : type(WasmType::none), i64(0) {}
  explicit Literal(WasmType type) : type(type), i64(0) {}
  explicit Literal(int32_t  init) : type(WasmType::i32), i32(init) {}
  explicit Literal(uint32_t init) : type(WasmType::i32), i32(init) {}
  explicit Literal(int64_t  init) : type(WasmType::i64), i64(init) {}
  explicit Literal(uint64_t init) : type(WasmType::i64), i64(init) {}
  explicit Literal(float    init) : type(WasmType::f32), i32(bit_cast<int32_t>(init)) {}
  explicit Literal(double   init) : type(WasmType::f64), i64(bit_cast<int64_t>(init)) {}

  Literal castToF32() {
    assert(type == WasmType::i32);
    Literal ret(i32);
    ret.type = WasmType::f32;
    return ret;
  }
  Literal castToF64() {
    assert(type == WasmType::i64);
    Literal ret(i64);
    ret.type = WasmType::f64;
    return ret;
  }
  Literal castToI32() {
    assert(type == WasmType::f32);
    Literal ret(i32);
    ret.type = WasmType::i32;
    return ret;
  }
  Literal castToI64() {
    assert(type == WasmType::f64);
    Literal ret(i64);
    ret.type = WasmType::i64;
    return ret;
  }

  int32_t geti32() const { assert(type == WasmType::i32); return i32; }
  int64_t geti64() const { assert(type == WasmType::i64); return i64; }
  float   getf32() const { assert(type == WasmType::f32); return bit_cast<float>(i32); }
  double  getf64() const { assert(type == WasmType::f64); return bit_cast<double>(i64); }

  int32_t* geti32Ptr() { assert(type == WasmType::i32); return &i32; } // careful!

  int32_t reinterpreti32() const { assert(type == WasmType::f32); return i32; }
  int64_t reinterpreti64() const { assert(type == WasmType::f64); return i64; }
  float   reinterpretf32() const { assert(type == WasmType::i32); return bit_cast<float>(i32); }
  double  reinterpretf64() const { assert(type == WasmType::i64); return bit_cast<double>(i64); }

  int64_t getInteger() {
    switch (type) {
      case WasmType::i32: return i32;
      case WasmType::i64: return i64;
      default: abort();
    }
  }

  double getFloat() {
    switch (type) {
      case WasmType::f32: return getf32();
      case WasmType::f64: return getf64();
      default: abort();
    }
  }

  bool operator==(const Literal& other) const {
    if (type != other.type) return false;
    switch (type) {
      case WasmType::none: return true;
      case WasmType::i32: return i32 == other.i32;
      case WasmType::f32: return getf32() == other.getf32();
      case WasmType::i64: return i64 == other.i64;
      case WasmType::f64: return getf64() == other.getf64();
      default: abort();
    }
  }

  static void printFloat(std::ostream &o, float f) {
    if (std::isnan(f)) {
      const char *sign = std::signbit(f) ? "-" : "";
      o << sign << "nan";
      if (uint32_t payload = ~0xff800000u & bit_cast<uint32_t>(f)) {
        o << ":0x" << std::hex << payload << std::dec;
      }
      return;
    }
    printDouble(o, f);
  }

  static void printDouble(std::ostream &o, double d) {
    if (d == 0 && std::signbit(d)) {
      o << "-0";
      return;
    }
    if (std::isnan(d)) {
      const char *sign = std::signbit(d) ? "-" : "";
      o << sign << "nan";
      if (uint64_t payload = ~0xfff0000000000000ull & bit_cast<uint64_t>(d)) {
        o << ":0x" << std::hex << payload << std::dec;
      }
      return;
    }
    if (!std::isfinite(d)) {
      o << (std::signbit(d) ? "-infinity" : "infinity");
      return;
    }
    const char *text = cashew::JSPrinter::numToString(d);
    // spec interpreter hates floats starting with '.'
    if (text[0] == '.') {
      o << '0';
    } else if (text[0] == '-' && text[1] == '.') {
      o << "-0";
      text++;
    }
    o << text;
  }

  friend std::ostream& operator<<(std::ostream &o, Literal literal) {
    o << '(';
    prepareMinorColor(o) << printWasmType(literal.type) << ".const ";
    switch (literal.type) {
      case none: o << "?"; break;
      case WasmType::i32: o << literal.i32; break;
      case WasmType::i64: o << literal.i64; break;
      case WasmType::f32: literal.printFloat(o, literal.getf32()); break;
      case WasmType::f64: literal.printDouble(o, literal.getf64()); break;
      default: WASM_UNREACHABLE();
    }
    restoreNormalColor(o);
    return o << ')';
  }

  Literal countLeadingZeroes() const {
    if (type == WasmType::i32) return Literal((int32_t)CountLeadingZeroes(i32));
    if (type == WasmType::i64) return Literal((int64_t)CountLeadingZeroes(i64));
    WASM_UNREACHABLE();
  }
  Literal countTrailingZeroes() const {
    if (type == WasmType::i32) return Literal((int32_t)CountTrailingZeroes(i32));
    if (type == WasmType::i64) return Literal((int64_t)CountTrailingZeroes(i64));
    WASM_UNREACHABLE();
  }
  Literal popCount() const {
    if (type == WasmType::i32) return Literal((int32_t)PopCount(i32));
    if (type == WasmType::i64) return Literal((int64_t)PopCount(i64));
    WASM_UNREACHABLE();
  }

  Literal extendToSI64() const {
    assert(type == WasmType::i32);
    return Literal((int64_t)i32);
  }
  Literal extendToUI64() const {
    assert(type == WasmType::i32);
    return Literal((uint64_t)(uint32_t)i32);
  }
  Literal extendToF64() const {
    assert(type == WasmType::f32);
    return Literal(double(getf32()));
  }
  Literal truncateToI32() const {
    assert(type == WasmType::i64);
    return Literal((int32_t)i64);
  }
  Literal truncateToF32() const {
    assert(type == WasmType::f64);
    return Literal(float(getf64()));
  }

  Literal convertSToF32() const {
    if (type == WasmType::i32) return Literal(float(i32));
    if (type == WasmType::i64) return Literal(float(i64));
    WASM_UNREACHABLE();
  }
  Literal convertUToF32() const {
    if (type == WasmType::i32) return Literal(float(uint32_t(i32)));
    if (type == WasmType::i64) return Literal(float(uint64_t(i64)));
    WASM_UNREACHABLE();
  }
  Literal convertSToF64() const {
    if (type == WasmType::i32) return Literal(double(i32));
    if (type == WasmType::i64) return Literal(double(i64));
    WASM_UNREACHABLE();
  }
  Literal convertUToF64() const {
    if (type == WasmType::i32) return Literal(double(uint32_t(i32)));
    if (type == WasmType::i64) return Literal(double(uint64_t(i64)));
    WASM_UNREACHABLE();
  }

  Literal neg() const {
    switch (type) {
      case WasmType::i32: return Literal(i32 ^ 0x80000000);
      case WasmType::i64: return Literal(int64_t(i64 ^ 0x8000000000000000ULL));
      case WasmType::f32: return Literal(i32 ^ 0x80000000).castToF32();
      case WasmType::f64: return Literal(int64_t(i64 ^ 0x8000000000000000ULL)).castToF64();
      default: WASM_UNREACHABLE();
    }
  }
  Literal abs() const {
    switch (type) {
      case WasmType::i32: return Literal(i32 & 0x7fffffff);
      case WasmType::i64: return Literal(int64_t(i64 & 0x7fffffffffffffffULL));
      case WasmType::f32: return Literal(i32 & 0x7fffffff).castToF32();
      case WasmType::f64: return Literal(int64_t(i64 & 0x7fffffffffffffffULL)).castToF64();
      default: WASM_UNREACHABLE();
    }
  }
  Literal ceil() const {
    switch (type) {
      case WasmType::f32: return Literal(std::ceil(getf32()));
      case WasmType::f64: return Literal(std::ceil(getf64()));
      default: WASM_UNREACHABLE();
    }
  }
  Literal floor() const {
    switch (type) {
      case WasmType::f32: return Literal(std::floor(getf32()));
      case WasmType::f64: return Literal(std::floor(getf64()));
      default: WASM_UNREACHABLE();
    }
  }
  Literal trunc() const {
    switch (type) {
      case WasmType::f32: return Literal(std::trunc(getf32()));
      case WasmType::f64: return Literal(std::trunc(getf64()));
      default: WASM_UNREACHABLE();
    }
  }
  Literal nearbyint() const {
    switch (type) {
      case WasmType::f32: return Literal(std::nearbyint(getf32()));
      case WasmType::f64: return Literal(std::nearbyint(getf64()));
      default: WASM_UNREACHABLE();
    }
  }
  Literal sqrt() const {
    switch (type) {
      case WasmType::f32: return Literal(std::sqrt(getf32()));
      case WasmType::f64: return Literal(std::sqrt(getf64()));
      default: WASM_UNREACHABLE();
    }
  }

  Literal add(const Literal& other) const {
    switch (type) {
      case WasmType::i32: return Literal(i32 + other.i32);
      case WasmType::i64: return Literal(i64 + other.i64);
      case WasmType::f32: return Literal(getf32() + other.getf32());
      case WasmType::f64: return Literal(getf64() + other.getf64());
      default: WASM_UNREACHABLE();
    }
  }
  Literal sub(const Literal& other) const {
    switch (type) {
      case WasmType::i32: return Literal(i32 - other.i32);
      case WasmType::i64: return Literal(i64 - other.i64);
      case WasmType::f32: return Literal(getf32() - other.getf32());
      case WasmType::f64: return Literal(getf64() - other.getf64());
      default: WASM_UNREACHABLE();
    }
  }
  Literal mul(const Literal& other) const {
    switch (type) {
      case WasmType::i32: return Literal(i32 * other.i32);
      case WasmType::i64: return Literal(i64 * other.i64);
      case WasmType::f32: return Literal(getf32() * other.getf32());
      case WasmType::f64: return Literal(getf64() * other.getf64());
      default: WASM_UNREACHABLE();
    }
  }
  Literal div(const Literal& other) const {
    switch (type) {
      case WasmType::f32: return Literal(getf32() / other.getf32());
      case WasmType::f64: return Literal(getf64() / other.getf64());
      default: WASM_UNREACHABLE();
    }
  }
  Literal divS(const Literal& other) const {
    switch (type) {
      case WasmType::i32: return Literal(i32 / other.i32);
      case WasmType::i64: return Literal(i64 / other.i64);
      default: WASM_UNREACHABLE();
    }
  }
  Literal divU(const Literal& other) const {
    switch (type) {
      case WasmType::i32: return Literal(uint32_t(i32) / uint32_t(other.i32));
      case WasmType::i64: return Literal(uint64_t(i64) / uint64_t(other.i64));
      default: WASM_UNREACHABLE();
    }
  }
  Literal remS(const Literal& other) const {
    switch (type) {
      case WasmType::i32: return Literal(i32 % other.i32);
      case WasmType::i64: return Literal(i64 % other.i64);
      default: WASM_UNREACHABLE();
    }
  }
  Literal remU(const Literal& other) const {
    switch (type) {
      case WasmType::i32: return Literal(uint32_t(i32) % uint32_t(other.i32));
      case WasmType::i64: return Literal(uint64_t(i64) % uint64_t(other.i64));
      default: WASM_UNREACHABLE();
    }
  }
  Literal and_(const Literal& other) const {
    switch (type) {
      case WasmType::i32: return Literal(i32 & other.i32);
      case WasmType::i64: return Literal(i64 & other.i64);
      default: WASM_UNREACHABLE();
    }
  }
  Literal or_(const Literal& other) const {
    switch (type) {
      case WasmType::i32: return Literal(i32 | other.i32);
      case WasmType::i64: return Literal(i64 | other.i64);
      default: WASM_UNREACHABLE();
    }
  }
  Literal xor_(const Literal& other) const {
    switch (type) {
      case WasmType::i32: return Literal(i32 ^ other.i32);
      case WasmType::i64: return Literal(i64 ^ other.i64);
      default: WASM_UNREACHABLE();
    }
  }
  Literal shl(const Literal& other) const {
    switch (type) {
      case WasmType::i32: return Literal(i32 << other.i32);
      case WasmType::i64: return Literal(i64 << other.i64);
      default: WASM_UNREACHABLE();
    }
  }
  Literal shrS(const Literal& other) const {
    switch (type) {
      case WasmType::i32: return Literal(i32 >> other.i32);
      case WasmType::i64: return Literal(i64 >> other.i64);
      default: WASM_UNREACHABLE();
    }
  }
  Literal shrU(const Literal& other) const {
    switch (type) {
      case WasmType::i32: return Literal(uint32_t(i32) >> uint32_t(other.i32));
      case WasmType::i64: return Literal(uint64_t(i64) >> uint64_t(other.i64));
      default: WASM_UNREACHABLE();
    }
  }
  Literal rotL(const Literal& other) const {
    switch (type) {
      case WasmType::i32: return Literal(RotateLeft(uint32_t(i32), uint32_t(other.i32)));
      case WasmType::i64: return Literal(RotateLeft(uint64_t(i64), uint64_t(other.i64)));
      default: WASM_UNREACHABLE();
    }
  }
  Literal rotR(const Literal& other) const {
    switch (type) {
      case WasmType::i32: return Literal(RotateRight(uint32_t(i32), uint32_t(other.i32)));
      case WasmType::i64: return Literal(RotateRight(uint64_t(i64), uint64_t(other.i64)));
      default: WASM_UNREACHABLE();
    }
  }

  Literal eq(const Literal& other) const {
    switch (type) {
      case WasmType::i32: return Literal(i32 == other.i32);
      case WasmType::i64: return Literal(i64 == other.i64);
      case WasmType::f32: return Literal(getf32() == other.getf32());
      case WasmType::f64: return Literal(getf64() == other.getf64());
      default: WASM_UNREACHABLE();
    }
  }
  Literal ne(const Literal& other) const {
    switch (type) {
      case WasmType::i32: return Literal(i32 != other.i32);
      case WasmType::i64: return Literal(i64 != other.i64);
      case WasmType::f32: return Literal(getf32() != other.getf32());
      case WasmType::f64: return Literal(getf64() != other.getf64());
      default: WASM_UNREACHABLE();
    }
  }
  Literal ltS(const Literal& other) const {
    switch (type) {
      case WasmType::i32: return Literal(i32 < other.i32);
      case WasmType::i64: return Literal(i64 < other.i64);
      default: WASM_UNREACHABLE();
    }
  }
  Literal ltU(const Literal& other) const {
    switch (type) {
      case WasmType::i32: return Literal(uint32_t(i32) < uint32_t(other.i32));
      case WasmType::i64: return Literal(uint64_t(i64) < uint64_t(other.i64));
      default: WASM_UNREACHABLE();
    }
  }
  Literal lt(const Literal& other) const {
    switch (type) {
      case WasmType::f32: return Literal(getf32() < other.getf32());
      case WasmType::f64: return Literal(getf64() < other.getf64());
      default: WASM_UNREACHABLE();
    }
  }
  Literal leS(const Literal& other) const {
    switch (type) {
      case WasmType::i32: return Literal(i32 <= other.i32);
      case WasmType::i64: return Literal(i64 <= other.i64);
      default: WASM_UNREACHABLE();
    }
  }
  Literal leU(const Literal& other) const {
    switch (type) {
      case WasmType::i32: return Literal(uint32_t(i32) <= uint32_t(other.i32));
      case WasmType::i64: return Literal(uint64_t(i64) <= uint64_t(other.i64));
      default: WASM_UNREACHABLE();
    }
  }
  Literal le(const Literal& other) const {
    switch (type) {
      case WasmType::f32: return Literal(getf32() <= other.getf32());
      case WasmType::f64: return Literal(getf64() <= other.getf64());
      default: WASM_UNREACHABLE();
    }
  }

  Literal gtS(const Literal& other) const {
    switch (type) {
      case WasmType::i32: return Literal(i32 > other.i32);
      case WasmType::i64: return Literal(i64 > other.i64);
      default: WASM_UNREACHABLE();
    }
  }
  Literal gtU(const Literal& other) const {
    switch (type) {
      case WasmType::i32: return Literal(uint32_t(i32) > uint32_t(other.i32));
      case WasmType::i64: return Literal(uint64_t(i64) > uint64_t(other.i64));
      default: WASM_UNREACHABLE();
    }
  }
  Literal gt(const Literal& other) const {
    switch (type) {
      case WasmType::f32: return Literal(getf32() > other.getf32());
      case WasmType::f64: return Literal(getf64() > other.getf64());
      default: WASM_UNREACHABLE();
    }
  }
  Literal geS(const Literal& other) const {
    switch (type) {
      case WasmType::i32: return Literal(i32 >= other.i32);
      case WasmType::i64: return Literal(i64 >= other.i64);
      default: WASM_UNREACHABLE();
    }
  }
  Literal geU(const Literal& other) const {
    switch (type) {
      case WasmType::i32: return Literal(uint32_t(i32) >= uint32_t(other.i32));
      case WasmType::i64: return Literal(uint64_t(i64) >= uint64_t(other.i64));
      default: WASM_UNREACHABLE();
    }
  }
  Literal ge(const Literal& other) const {
    switch (type) {
      case WasmType::f32: return Literal(getf32() >= other.getf32());
      case WasmType::f64: return Literal(getf64() >= other.getf64());
      default: WASM_UNREACHABLE();
    }
  }

  Literal min(const Literal& other) const {
    switch (type) {
      case WasmType::f32: {
        auto l = getf32(), r = other.getf32();
        if (l == r && l == 0) return Literal(std::signbit(l) ? l : r);
        auto result = std::min(l, r);
        bool lnan = std::isnan(l), rnan = std::isnan(r);
        if (!std::isnan(result) && !lnan && !rnan) return Literal(result);
        if (!lnan && !rnan) return Literal((int32_t)0x7fc00000).castToF32();
        return Literal(lnan ? l : r).castToI32().or_(Literal(0xc00000)).castToF32();
      }
      case WasmType::f64: {
        auto l = getf64(), r = other.getf64();
        if (l == r && l == 0) return Literal(std::signbit(l) ? l : r);
        auto result = std::min(l, r);
        bool lnan = std::isnan(l), rnan = std::isnan(r);
        if (!std::isnan(result) && !lnan && !rnan) return Literal(result);
        if (!lnan && !rnan) return Literal((int64_t)0x7ff8000000000000LL).castToF64();
        return Literal(lnan ? l : r).castToI64().or_(Literal(int64_t(0x8000000000000LL))).castToF64();
      }
      default: WASM_UNREACHABLE();
    }
  }
  Literal max(const Literal& other) const {
    switch (type) {
      case WasmType::f32: {
        auto l = getf32(), r = other.getf32();
        if (l == r && l == 0) return Literal(std::signbit(l) ? r : l);
        auto result = std::max(l, r);
        bool lnan = std::isnan(l), rnan = std::isnan(r);
        if (!std::isnan(result) && !lnan && !rnan) return Literal(result);
        if (!lnan && !rnan) return Literal((int32_t)0x7fc00000).castToF32();
        return Literal(lnan ? l : r).castToI32().or_(Literal(0xc00000)).castToF32();
      }
      case WasmType::f64: {
        auto l = getf64(), r = other.getf64();
        if (l == r && l == 0) return Literal(std::signbit(l) ? r : l);
        auto result = std::max(l, r);
        bool lnan = std::isnan(l), rnan = std::isnan(r);
        if (!std::isnan(result) && !lnan && !rnan) return Literal(result);
        if (!lnan && !rnan) return Literal((int64_t)0x7ff8000000000000LL).castToF64();
        return Literal(lnan ? l : r).castToI64().or_(Literal(int64_t(0x8000000000000LL))).castToF64();
      }
      default: WASM_UNREACHABLE();
    }
  }
  Literal copysign(const Literal& other) const {
    // operate on bits directly, to avoid signalling bit being set on a float
    switch (type) {
      case WasmType::f32: return Literal((i32 & 0x7fffffff) | (other.i32 & 0x80000000)).castToF32(); break;
      case WasmType::f64: return Literal((i64 & 0x7fffffffffffffffUL) | (other.i64 & 0x8000000000000000UL)).castToF64(); break;
      default: WASM_UNREACHABLE();
    }
  }
};

// Operators

enum UnaryOp {
  Clz, Ctz, Popcnt, // int
  Neg, Abs, Ceil, Floor, Trunc, Nearest, Sqrt, // float
  // relational
  EqZ,
  // conversions
  ExtendSInt32, ExtendUInt32, WrapInt64, TruncSFloat32, TruncUFloat32, TruncSFloat64, TruncUFloat64, ReinterpretFloat, // int
  ConvertSInt32, ConvertUInt32, ConvertSInt64, ConvertUInt64, PromoteFloat32, DemoteFloat64, ReinterpretInt // float
};

enum BinaryOp {
  Add, Sub, Mul, // int or float
  DivS, DivU, RemS, RemU, And, Or, Xor, Shl, ShrU, ShrS, RotL, RotR, // int
  Div, CopySign, Min, Max, // float
  // relational ops
  Eq, Ne, // int or float
  LtS, LtU, LeS, LeU, GtS, GtU, GeS, GeU, // int
  Lt, Le, Gt, Ge // float
};

enum HostOp {
  PageSize, CurrentMemory, GrowMemory, HasFeature
};

//
// Expressions
//
// Note that little is provided in terms of constructors for these. The rationale
// is that writing  new Something(a, b, c, d, e)  is not the clearest, and it would
// be better to write   new Something(name=a, leftOperand=b...  etc., but C++
// lacks named operands, so in asm2wasm etc. you will see things like
//   auto x = new Something();
//   x->name = a;
//   x->leftOperand = b;
//   ..
// which is less compact but less ambiguous. See wasm-builder.h for a more
// friendly API for building nodes.
//
// Most nodes have no need of internal allocation, and when arena-allocated
// they drop the provided arena on the floor. You can create random instances
// of those that are not in an arena without issue. However, the nodes that
// have internal allocation will need an allocator provided to them in order
// to be constructed.

class Expression {
public:
  enum Id {
    InvalidId = 0,
    BlockId,
    IfId,
    LoopId,
    BreakId,
    SwitchId,
    CallId,
    CallImportId,
    CallIndirectId,
    GetLocalId,
    SetLocalId,
    LoadId,
    StoreId,
    ConstId,
    UnaryId,
    BinaryId,
    SelectId,
    ReturnId,
    HostId,
    NopId,
    UnreachableId,
    NumExpressionIds
  };
  Id _id;

  WasmType type; // the type of the expression: its *output*, not necessarily its input(s)

  Expression(Id id) : _id(id), type(none) {}

  void finalize() {}

  template<class T>
  bool is() {
    return int(_id) == int(T::SpecificId);
  }

  template<class T>
  T* dynCast() {
    return int(_id) == int(T::SpecificId) ? (T*)this : nullptr;
  }

  template<class T>
  T* cast() {
    assert(int(_id) == int(T::SpecificId));
    return (T*)this;
  }
};

inline const char *getExpressionName(Expression *curr) {
  switch (curr->_id) {
    case Expression::Id::InvalidId: abort();
    case Expression::Id::BlockId: return "block";
    case Expression::Id::IfId: return "if";
    case Expression::Id::LoopId: return "loop";
    case Expression::Id::BreakId: return "break";
    case Expression::Id::SwitchId: return "switch";
    case Expression::Id::CallId: return "call";
    case Expression::Id::CallImportId: return "call_import";
    case Expression::Id::CallIndirectId: return "call_indirect";
    case Expression::Id::GetLocalId: return "get_local";
    case Expression::Id::SetLocalId: return "set_local";
    case Expression::Id::LoadId: return "load";
    case Expression::Id::StoreId: return "store";
    case Expression::Id::ConstId: return "const";
    case Expression::Id::UnaryId: return "unary";
    case Expression::Id::BinaryId: return "binary";
    case Expression::Id::SelectId: return "select";
    case Expression::Id::ReturnId: return "return";
    case Expression::Id::HostId: return "host";
    case Expression::Id::NopId: return "nop";
    case Expression::Id::UnreachableId: return "unreachable";
    default: WASM_UNREACHABLE();
  }
}

typedef ArenaVector<Expression*> ExpressionList;

template<Expression::Id SID>
class SpecificExpression : public Expression {
public:
  enum {
    SpecificId = SID // compile-time access to the type for the class
  };

  SpecificExpression() : Expression(SID) {}
};

class Nop : public SpecificExpression<Expression::NopId> {
public:
  Nop() {}
  Nop(MixedArena& allocator) {}
};

class Block : public SpecificExpression<Expression::BlockId> {
public:
  Block(MixedArena& allocator) : list(allocator) {}

  Name name;
  ExpressionList list;

  // set the type of a block if you already know it
  void finalize(WasmType type_) {
    type = type;
  }

  // set the type of a block based on its contents. this scans the block, so it is not fast
  void finalize();
};

class If : public SpecificExpression<Expression::IfId> {
public:
  If() : ifFalse(nullptr) {}
  If(MixedArena& allocator) : If() {}

  Expression *condition, *ifTrue, *ifFalse;

  void finalize() {
    if (ifFalse) {
      type = getReachableWasmType(ifTrue->type, ifFalse->type);
    }
  }
};

class Loop : public SpecificExpression<Expression::LoopId> {
public:
  Loop() {}
  Loop(MixedArena& allocator) {}

  Name out, in;
  Expression *body;

  void finalize() {
    type = body->type; // loop might have a type, if the body ends in something that does not break
  }
};

class Break : public SpecificExpression<Expression::BreakId> {
public:
  Break() : value(nullptr), condition(nullptr) {}
  Break(MixedArena& allocator) : Break() {
    type = unreachable;
  }

  Name name;
  Expression *value;
  Expression *condition;

  void finalize() {
    if (condition) {
      type = none;
    }
  }
};

class Switch : public SpecificExpression<Expression::SwitchId> {
public:
  Switch(MixedArena& allocator) : targets(allocator), condition(nullptr), value(nullptr) {
    type = unreachable;
  }

  ArenaVector<Name> targets;
  Name default_;
  Expression *condition;
  Expression *value;
};

class Call : public SpecificExpression<Expression::CallId> {
public:
  Call(MixedArena& allocator) : operands(allocator) {}

  ExpressionList operands;
  Name target;
};

class CallImport : public SpecificExpression<Expression::CallImportId> {
public:
  CallImport(MixedArena& allocator) : operands(allocator) {}

  ExpressionList operands;
  Name target;
};

class FunctionType {
public:
  Name name;
  WasmType result;
  std::vector<WasmType> params;

  FunctionType() : result(none) {}

  bool operator==(FunctionType& b) {
    if (name != b.name) return false; // XXX
    if (result != b.result) return false;
    if (params.size() != b.params.size()) return false;
    for (size_t i = 0; i < params.size(); i++) {
      if (params[i] != b.params[i]) return false;
    }
    return true;
  }
  bool operator!=(FunctionType& b) {
    return !(*this == b);
  }
};

class CallIndirect : public SpecificExpression<Expression::CallIndirectId> {
public:
  CallIndirect(MixedArena& allocator) : operands(allocator) {}

  ExpressionList operands;
  FunctionType *fullType;
  Expression *target;
};

class GetLocal : public SpecificExpression<Expression::GetLocalId> {
public:
  GetLocal() {}
  GetLocal(MixedArena& allocator) {}

  Index index;
};

class SetLocal : public SpecificExpression<Expression::SetLocalId> {
public:
  SetLocal() {}
  SetLocal(MixedArena& allocator) {}

  Index index;
  Expression *value;
};

class Load : public SpecificExpression<Expression::LoadId> {
public:
  Load() {}
  Load(MixedArena& allocator) {}

  uint32_t bytes;
  bool signed_;
  uint32_t offset;
  uint32_t align;
  Expression *ptr;

  // type must be set during creation, cannot be inferred
};

class Store : public SpecificExpression<Expression::StoreId> {
public:
  Store() {}
  Store(MixedArena& allocator) {}

  unsigned bytes;
  uint32_t offset;
  unsigned align;
  Expression *ptr, *value;

  void finalize() {
    type = value->type;
  }
};

class Const : public SpecificExpression<Expression::ConstId> {
public:
  Const() {}
  Const(MixedArena& allocator) {}

  Literal value;

  Const* set(Literal value_) {
    value = value_;
    type = value.type;
    return this;
  }
};

class Unary : public SpecificExpression<Expression::UnaryId> {
public:
  Unary() {}
  Unary(MixedArena& allocator) {}

  UnaryOp op;
  Expression *value;

  bool isRelational() { return op == EqZ; }

  // no finalize since some opcodes have more than one type, so user must set it anyhow
};

class Binary : public SpecificExpression<Expression::BinaryId> {
public:
  Binary() {}
  Binary(MixedArena& allocator) {}

  BinaryOp op;
  Expression *left, *right;

  // the type is always the type of the operands,
  // except for relationals

  bool isRelational() { return op >= Eq; }

  void finalize() {
    if (isRelational()) {
      type = i32;
    } else {
      type = getReachableWasmType(left->type, right->type);
    }
  }
};

class Select : public SpecificExpression<Expression::SelectId> {
public:
  Select() {}
  Select(MixedArena& allocator) {}

  Expression *ifTrue, *ifFalse, *condition;

  void finalize() {
    type = getReachableWasmType(ifTrue->type, ifFalse->type);
  }
};

class Return : public SpecificExpression<Expression::ReturnId> {
public:
  Return() : value(nullptr) {
    type = unreachable;
  }
  Return(MixedArena& allocator) : Return() {}

  Expression *value;
};

class Host : public SpecificExpression<Expression::HostId> {
public:
  Host(MixedArena& allocator) : operands(allocator) {}

  HostOp op;
  Name nameOperand;
  ExpressionList operands;

  void finalize() {
    switch (op) {
      case PageSize: case CurrentMemory: case HasFeature: {
        type = i32;
        break;
      }
      case GrowMemory: {
        type = i32;
        break;
      }
      default: abort();
    }
  }
};

class Unreachable : public SpecificExpression<Expression::UnreachableId> {
public:
  Unreachable() {}
  Unreachable(MixedArena& allocator) {
    type = unreachable;
  }
};

// Globals

class Function {
public:
  Name name;
  WasmType result;
  std::vector<WasmType> params; // function locals are
  std::vector<WasmType> vars;   // params plus vars
  Name type; // if null, it is implicit in params and result
  Expression *body;

  // local names. these are optional.
  std::vector<Name> localNames;
  std::map<Name, Index> localIndices;

  Function() : result(none) {}

  size_t getNumParams() {
    return params.size();
  }
  size_t getNumVars() {
    return vars.size();
  }
  size_t getNumLocals() {
    return params.size() + vars.size();
  }

  bool isParam(Index index) {
    return index < params.size();
  }
  bool isVar(Index index) {
    return index >= params.size();
  }

  Name getLocalName(Index index) {
    assert(index < localNames.size() && localNames[index].is());
    return localNames[index];
  }
  Name tryLocalName(Index index) {
    if (index < localNames.size() && localNames[index].is()) {
      return localNames[index];
    }
    // this is an unnamed local
    return Name();
  }
  Index getLocalIndex(Name name) {
    assert(localIndices.count(name) > 0);
    return localIndices[name];
  }
  Index getVarIndexBase() {
    return params.size();
  }
  WasmType getLocalType(Index index) {
    if (isParam(index)) {
      return params[index];
    } else if (isVar(index)) {
      return vars[index - getVarIndexBase()];
    } else {
      WASM_UNREACHABLE();
    }
  }
};

class Import {
public:
  Import() : type(nullptr) {}

  Name name, module, base; // name = module.base
  FunctionType* type;
};

class Export {
public:
  Name name;  // exported name
  Name value; // internal name
};

class Table {
public:
  std::vector<Name> names;
};

class Memory {
public:
  static const size_t kPageSize = 64 * 1024;
  static const size_t kPageMask = ~(kPageSize - 1);
  struct Segment {
    size_t offset;
    std::vector<char> data; // TODO: optimize
    Segment() {}
    Segment(size_t offset, const char *init, size_t size) : offset(offset) {
      data.resize(size);
      memcpy(&data[0], init, size);
    }
    Segment(size_t offset, std::vector<char>& init) : offset(offset) {
      data.swap(init);
    }
  };

  size_t initial, max; // sizes are in pages
  std::vector<Segment> segments;
  Name exportName;

  Memory() : initial(0), max((uint32_t)-1) {}
};

class Module {
public:
  // wasm contents (generally you shouldn't access these from outside, except maybe for iterating; use add*() and the get() functions)
  std::vector<std::unique_ptr<FunctionType>> functionTypes;
  std::vector<std::unique_ptr<Import>> imports;
  std::vector<std::unique_ptr<Export>> exports;
  std::vector<std::unique_ptr<Function>> functions;

  Table table;
  Memory memory;
  Name start;

  MixedArena allocator;

private:
  // TODO: add a build option where Names are just indices, and then these methods are not needed
  std::map<Name, FunctionType*> functionTypesMap;
  std::map<Name, Import*> importsMap;
  std::map<Name, Export*> exportsMap;
  std::map<Name, Function*> functionsMap;

public:
  Module() : functionTypeIndex(0), importIndex(0), exportIndex(0), functionIndex(0) {}

  FunctionType* getFunctionType(size_t i) { assert(i < functionTypes.size()); return functionTypes[i].get(); }
  Import* getImport(size_t i) { assert(i < imports.size()); return imports[i].get(); }
  Export* getExport(size_t i) { assert(i < exports.size()); return exports[i].get(); }
  Function* getFunction(size_t i) { assert(i < functions.size()); return functions[i].get(); }

  FunctionType* getFunctionType(Name name) { assert(functionTypesMap[name]); return functionTypesMap[name]; }
  Import* getImport(Name name) { assert(importsMap[name]); return importsMap[name]; }
  Export* getExport(Name name) { assert(exportsMap[name]); return exportsMap[name]; }
  Function* getFunction(Name name) { assert(functionsMap[name]); return functionsMap[name]; }

  FunctionType* checkFunctionType(Name name) { if (functionTypesMap.find(name) == functionTypesMap.end()) return nullptr; return functionTypesMap[name]; }
  Import* checkImport(Name name) { if (importsMap.find(name) == importsMap.end()) return nullptr; return importsMap[name]; }
  Export* checkExport(Name name) { if (exportsMap.find(name) == exportsMap.end()) return nullptr; return exportsMap[name]; }
  Function* checkFunction(Name name) { if (functionsMap.find(name) == functionsMap.end()) return nullptr; return functionsMap[name]; }

  void addFunctionType(FunctionType* curr) {
    Name numericName = Name::fromInt(functionTypeIndex); // TODO: remove all these, assert on names already existing, do numeric stuff in wasm-s-parser etc.
    if (curr->name.isNull()) {
      curr->name = numericName;
    }
    functionTypes.push_back(std::unique_ptr<FunctionType>(curr));
    functionTypesMap[curr->name] = curr;
    functionTypesMap[numericName] = curr;
    functionTypeIndex++;
  }
  void addImport(Import* curr) {
    Name numericName = Name::fromInt(importIndex);
    if (curr->name.isNull()) {
      curr->name = numericName;
    }
    imports.push_back(std::unique_ptr<Import>(curr));
    importsMap[curr->name] = curr;
    importsMap[numericName] = curr;
    importIndex++;
  }
  void addExport(Export* curr) {
    Name numericName = Name::fromInt(exportIndex);
    if (curr->name.isNull()) {
      curr->name = numericName;
    }
    exports.push_back(std::unique_ptr<Export>(curr));
    exportsMap[curr->name] = curr;
    exportsMap[numericName] = curr;
    exportIndex++;
  }
  void addFunction(Function* curr) {
    Name numericName = Name::fromInt(functionIndex);
    if (curr->name.isNull()) {
      curr->name = numericName;
    }
    functions.push_back(std::unique_ptr<Function>(curr));
    functionsMap[curr->name] = curr;
    functionsMap[numericName] = curr;
    functionIndex++;
  }
  void addStart(const Name &s) {
    start = s;
  }

  void removeImport(Name name) {
    for (size_t i = 0; i < imports.size(); i++) {
      if (imports[i]->name == name) {
        imports.erase(imports.begin() + i);
        break;
      }
    }
    importsMap.erase(name);
  }

private:
  size_t functionTypeIndex, importIndex, exportIndex, functionIndex;
};

} // namespace wasm

#endif // wasm_wasm_h