// Copyright 2015 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef V8_WASM_AST_DECODER_H_
#define V8_WASM_AST_DECODER_H_

#include "src/signature.h"
#include "src/wasm/wasm-opcodes.h"
#include "src/wasm/wasm-result.h"

namespace v8 {
namespace internal {

namespace compiler {  // external declarations from compiler.
class WasmGraphBuilder;
}

namespace wasm {

typedef compiler::WasmGraphBuilder TFBuilder;
struct ModuleEnv;  // forward declaration of module interface.

// Interface the function environment during decoding, include the signature
// and number of locals.
struct FunctionEnv {
  ModuleEnv* module;             // module environment
  FunctionSig* sig;              // signature of this function
  uint32_t local_int32_count;    // number of int32 locals
  uint32_t local_int64_count;    // number of int64 locals
  uint32_t local_float32_count;  // number of float32 locals
  uint32_t local_float64_count;  // number of float64 locals
  uint32_t total_locals;         // sum of parameters and all locals

  bool IsValidLocal(uint32_t index) { return index < total_locals; }
  uint32_t GetLocalCount() { return total_locals; }
  LocalType GetLocalType(uint32_t index) {
    if (index < static_cast<uint32_t>(sig->parameter_count())) {
      return sig->GetParam(index);
    }
    index -= static_cast<uint32_t>(sig->parameter_count());
    if (index < local_int32_count) return kAstI32;
    index -= local_int32_count;
    if (index < local_int64_count) return kAstI64;
    index -= local_int64_count;
    if (index < local_float32_count) return kAstF32;
    index -= local_float32_count;
    if (index < local_float64_count) return kAstF64;
    return kAstStmt;
  }

  void AddLocals(LocalType type, uint32_t count) {
    switch (type) {
      case kAstI32:
        local_int32_count += count;
        break;
      case kAstI64:
        local_int64_count += count;
        break;
      case kAstF32:
        local_float32_count += count;
        break;
      case kAstF64:
        local_float64_count += count;
        break;
      default:
        UNREACHABLE();
    }
    total_locals += count;
    DCHECK(total_locals ==
           (sig->parameter_count() + local_int32_count + local_int64_count +
            local_float32_count + local_float64_count));
  }

  void SumLocals() {
    total_locals = static_cast<uint32_t>(sig->parameter_count()) +
                   local_int32_count + local_int64_count + local_float32_count +
                   local_float64_count;
  }
};

struct Tree;
typedef Result<Tree*> TreeResult;

std::ostream& operator<<(std::ostream& os, const Tree& tree);

TreeResult VerifyWasmCode(FunctionEnv* env, const byte* base, const byte* start,
                          const byte* end);
TreeResult BuildTFGraph(TFBuilder* builder, FunctionEnv* env, const byte* base,
                        const byte* start, const byte* end);

inline TreeResult VerifyWasmCode(FunctionEnv* env, const byte* start,
                                 const byte* end) {
  return VerifyWasmCode(env, nullptr, start, end);
}

inline TreeResult BuildTFGraph(TFBuilder* builder, FunctionEnv* env,
                               const byte* start, const byte* end) {
  return BuildTFGraph(builder, env, nullptr, start, end);
}

enum ReadUnsignedLEB128ErrorCode { kNoError, kInvalidLEB128, kMissingLEB128 };

ReadUnsignedLEB128ErrorCode ReadUnsignedLEB128Operand(const byte*, const byte*,
                                                      int*, uint32_t*);

// Computes the length of the opcode at the given address.
int OpcodeLength(const byte* pc);

// Computes the arity (number of sub-nodes) of the opcode at the given address.
int OpcodeArity(FunctionEnv* env, const byte* pc);
}  // namespace wasm
}  // namespace internal
}  // namespace v8

#endif  // V8_WASM_AST_DECODER_H_