[wasm] Introduce the TrapIf and TrapUnless operators to generate trap code.

src/compiler/instruction-codes.h

 // Copyright 2014 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_COMPILER_INSTRUCTION_CODES_H_
 #define V8_COMPILER_INSTRUCTION_CODES_H_
 
 #include <iosfwd>
 
 #if V8_TARGET_ARCH_ARM
@@ skipping 134 matching lines @@
 };
 
 V8_EXPORT_PRIVATE std::ostream& operator<<(std::ostream& os,
                                            const AddressingMode& am);
 
 // The mode of the flags continuation (see below).
 enum FlagsMode {
   kFlags_none = 0,
   kFlags_branch = 1,
   kFlags_deoptimize = 2,
-  kFlags_set = 3
+  kFlags_set = 3,
+  kFlags_trap = 4
 };
 
 V8_EXPORT_PRIVATE std::ostream& operator<<(std::ostream& os,
                                            const FlagsMode& fm);
 
 // The condition of flags continuation (see below).
 enum FlagsCondition {
   kEqual,
   kNotEqual,
   kSignedLessThan,
@@ skipping 34 matching lines @@
 // interesting to the register allocator, as the inputs and flags on the
 // instructions specify everything of interest.
 typedef int32_t InstructionCode;
 
 // Helpers for encoding / decoding InstructionCode into the fields needed
 // for code generation. We encode the instruction, addressing mode, and flags
 // continuation into a single InstructionCode which is stored as part of
 // the instruction.
 typedef BitField<ArchOpcode, 0, 8> ArchOpcodeField;
 typedef BitField<AddressingMode, 8, 5> AddressingModeField;
-typedef BitField<FlagsMode, 13, 2> FlagsModeField;
-typedef BitField<FlagsCondition, 15, 5> FlagsConditionField;
-typedef BitField<int, 20, 12> MiscField;
+typedef BitField<FlagsMode, 13, 3> FlagsModeField;
+typedef BitField<FlagsCondition, 16, 5> FlagsConditionField;
+typedef BitField<int, 21, 11> MiscField;
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_COMPILER_INSTRUCTION_CODES_H_