[wasm] Refactoring: move bytecode operands into wasm-decoder-impl.h

src/wasm/function-body-decoder.h

Index: src/wasm/function-body-decoder.h
diff --git a/src/wasm/function-body-decoder.h b/src/wasm/function-body-decoder.h
index 1115b1a450354cf9567669456c883dc7f31c0ecf..6e6b824727e9f2905dea40df7f70d08f015b55b0 100644
--- a/src/wasm/function-body-decoder.h
+++ b/src/wasm/function-body-decoder.h
@@ -26,295 +26,10 @@ class WasmGraphBuilder;
 
 namespace wasm {
 
-const uint32_t kMaxNumWasmLocals = 8000000;
-struct WasmGlobal;
-
-// Helpers for decoding different kinds of operands which follow bytecodes.
-struct LocalIndexOperand {
-  uint32_t index;
-  ValueType type;
-  unsigned length;
-
-  inline LocalIndexOperand(Decoder* decoder, const byte* pc) {
-    index = decoder->checked_read_u32v(pc, 1, &length, "local index");
-    type = kWasmStmt;
-  }
-};
-
-struct ImmI8Operand {
-  int8_t value;
-  unsigned length;
-  inline ImmI8Operand(Decoder* decoder, const byte* pc) {
-    value = bit_cast<int8_t>(decoder->checked_read_u8(pc, 1, "immi8"));
-    length = 1;
-  }
-};
-
-struct ImmI32Operand {
-  int32_t value;
-  unsigned length;
-  inline ImmI32Operand(Decoder* decoder, const byte* pc) {
-    value = decoder->checked_read_i32v(pc, 1, &length, "immi32");
-  }
-};
-
-struct ImmI64Operand {
-  int64_t value;
-  unsigned length;
-  inline ImmI64Operand(Decoder* decoder, const byte* pc) {
-    value = decoder->checked_read_i64v(pc, 1, &length, "immi64");
-  }
-};
-
-struct ImmF32Operand {
-  float value;
-  unsigned length;
-  inline ImmF32Operand(Decoder* decoder, const byte* pc) {
-    // Avoid bit_cast because it might not preserve the signalling bit of a NaN.
-    uint32_t tmp = decoder->checked_read_u32(pc, 1, "immf32");
-    memcpy(&value, &tmp, sizeof(value));
-    length = 4;
-  }
-};
-
-struct ImmF64Operand {
-  double value;
-  unsigned length;
-  inline ImmF64Operand(Decoder* decoder, const byte* pc) {
-    // Avoid bit_cast because it might not preserve the signalling bit of a NaN.
-    uint64_t tmp = decoder->checked_read_u64(pc, 1, "immf64");
-    memcpy(&value, &tmp, sizeof(value));
-    length = 8;
-  }
-};
-
-struct GlobalIndexOperand {
-  uint32_t index;
-  ValueType type;
-  const WasmGlobal* global;
-  unsigned length;
-
-  inline GlobalIndexOperand(Decoder* decoder, const byte* pc) {
-    index = decoder->checked_read_u32v(pc, 1, &length, "global index");
-    global = nullptr;
-    type = kWasmStmt;
-  }
-};
-
-struct BlockTypeOperand {
-  uint32_t arity;
-  const byte* types;  // pointer to encoded types for the block.
-  unsigned length;
-
-  inline BlockTypeOperand(Decoder* decoder, const byte* pc) {
-    uint8_t val = decoder->checked_read_u8(pc, 1, "block type");
-    ValueType type = kWasmStmt;
-    length = 1;
-    arity = 0;
-    types = nullptr;
-    if (decode_local_type(val, &type)) {
-      arity = type == kWasmStmt ? 0 : 1;
-      types = pc + 1;
-    } else {
-      // Handle multi-value blocks.
-      if (!FLAG_wasm_mv_prototype) {
-        decoder->error(pc, pc + 1, "invalid block arity > 1");
-        return;
-      }
-      if (val != kMultivalBlock) {
-        decoder->error(pc, pc + 1, "invalid block type");
-        return;
-      }
-      // Decode and check the types vector of the block.
-      unsigned len = 0;
-      uint32_t count = decoder->checked_read_u32v(pc, 2, &len, "block arity");
-      // {count} is encoded as {arity-2}, so that a {0} count here corresponds
-      // to a block with 2 values. This makes invalid/redundant encodings
-      // impossible.
-      arity = count + 2;
-      length = 1 + len + arity;
-      types = pc + 1 + 1 + len;
-
-      for (uint32_t i = 0; i < arity; i++) {
-        uint32_t offset = 1 + 1 + len + i;
-        val = decoder->checked_read_u8(pc, offset, "block type");
-        decode_local_type(val, &type);
-        if (type == kWasmStmt) {
-          decoder->error(pc, pc + offset, "invalid block type");
-          return;
-        }
-      }
-    }
-  }
-  // Decode a byte representing a local type. Return {false} if the encoded
-  // byte was invalid or {kMultivalBlock}.
-  bool decode_local_type(uint8_t val, ValueType* result) {
-    switch (static_cast<ValueTypeCode>(val)) {
-      case kLocalVoid:
-        *result = kWasmStmt;
-        return true;
-      case kLocalI32:
-        *result = kWasmI32;
-        return true;
-      case kLocalI64:
-        *result = kWasmI64;
-        return true;
-      case kLocalF32:
-        *result = kWasmF32;
-        return true;
-      case kLocalF64:
-        *result = kWasmF64;
-        return true;
-      case kLocalS128:
-        *result = kWasmS128;
-        return true;
-      default:
-        *result = kWasmStmt;
-        return false;
-    }
-  }
-  ValueType read_entry(unsigned index) {
-    DCHECK_LT(index, arity);
-    ValueType result;
-    CHECK(decode_local_type(types[index], &result));
-    return result;
-  }
-};
-
-struct Control;
-struct BreakDepthOperand {
-  uint32_t depth;
-  Control* target;
-  unsigned length;
-  inline BreakDepthOperand(Decoder* decoder, const byte* pc) {
-    depth = decoder->checked_read_u32v(pc, 1, &length, "break depth");
-    target = nullptr;
-  }
-};
-
-struct CallIndirectOperand {
-  uint32_t table_index;
-  uint32_t index;
-  FunctionSig* sig;
-  unsigned length;
-  inline CallIndirectOperand(Decoder* decoder, const byte* pc) {
-    unsigned len = 0;
-    index = decoder->checked_read_u32v(pc, 1, &len, "signature index");
-    table_index = decoder->checked_read_u8(pc, 1 + len, "table index");
-    if (table_index != 0) {
-      decoder->error(pc, pc + 1 + len, "expected table index 0, found %u",
-                     table_index);
-    }
-    length = 1 + len;
-    sig = nullptr;
-  }
-};
-
-struct CallFunctionOperand {
-  uint32_t index;
-  FunctionSig* sig;
-  unsigned length;
-  inline CallFunctionOperand(Decoder* decoder, const byte* pc) {
-    unsigned len1 = 0;
-    unsigned len2 = 0;
-    index = decoder->checked_read_u32v(pc, 1 + len1, &len2, "function index");
-    length = len1 + len2;
-    sig = nullptr;
-  }
-};
-
-struct MemoryIndexOperand {
-  uint32_t index;
-  unsigned length;
-  inline MemoryIndexOperand(Decoder* decoder, const byte* pc) {
-    index = decoder->checked_read_u8(pc, 1, "memory index");
-    if (index != 0) {
-      decoder->error(pc, pc + 1, "expected memory index 0, found %u", index);
-    }
-    length = 1;
-  }
-};
-
-struct BranchTableOperand {
-  uint32_t table_count;
-  const byte* start;
-  const byte* table;
-  inline BranchTableOperand(Decoder* decoder, const byte* pc) {
-    DCHECK_EQ(kExprBrTable, decoder->checked_read_u8(pc, 0, "opcode"));
-    start = pc + 1;
-    unsigned len1 = 0;
-    table_count = decoder->checked_read_u32v(pc, 1, &len1, "table count");
-    if (table_count > (UINT_MAX / sizeof(uint32_t)) - 1 ||
-        len1 > UINT_MAX - (table_count + 1) * sizeof(uint32_t)) {
-      decoder->error(pc, "branch table size overflow");
-    }
-    table = pc + 1 + len1;
-  }
-};
-
-// A helper to iterate over a branch table.
-class BranchTableIterator {
- public:
-  unsigned cur_index() { return index_; }
-  bool has_next() { return decoder_->ok() && index_ <= table_count_; }
-  uint32_t next() {
-    DCHECK(has_next());
-    index_++;
-    unsigned length = 0;
-    uint32_t result =
-        decoder_->checked_read_u32v(pc_, 0, &length, "branch table entry");
-    pc_ += length;
-    return result;
-  }
-  // length, including the length of the {BranchTableOperand}, but not the
-  // opcode.
-  unsigned length() {
-    while (has_next()) next();
-    return static_cast<unsigned>(pc_ - start_);
-  }
-  const byte* pc() { return pc_; }
-
-  BranchTableIterator(Decoder* decoder, BranchTableOperand& operand)
-      : decoder_(decoder),
-        start_(operand.start),
-        pc_(operand.table),
-        index_(0),
-        table_count_(operand.table_count) {}
-
- private:
-  Decoder* decoder_;
-  const byte* start_;
-  const byte* pc_;
-  uint32_t index_;        // the current index.
-  uint32_t table_count_;  // the count of entries, not including default.
-};
-
-struct MemoryAccessOperand {
-  uint32_t alignment;
-  uint32_t offset;
-  unsigned length;
-  inline MemoryAccessOperand(Decoder* decoder, const byte* pc,
-                             uint32_t max_alignment) {
-    unsigned alignment_length;
-    alignment =
-        decoder->checked_read_u32v(pc, 1, &alignment_length, "alignment");
-    if (max_alignment < alignment) {
-      decoder->error(pc, pc + 1,
-                     "invalid alignment; expected maximum alignment is %u, "
-                     "actual alignment is %u",
-                     max_alignment, alignment);
-    }
-    unsigned offset_length;
-    offset = decoder->checked_read_u32v(pc, 1 + alignment_length,
-                                        &offset_length, "offset");
-    length = alignment_length + offset_length;
-  }
-};
-
 typedef compiler::WasmGraphBuilder TFBuilder;
 struct WasmModule;  // forward declaration of module interface.
 
-// All of the various data structures necessary to decode a function body.
+// A wrapper around the signature and bytes of a function.
 struct FunctionBody {
   FunctionSig* sig;   // function signature
   const byte* base;   // base of the module bytes, for error reporting