[ignition] Use absolute values for jump offsets

src/interpreter/interpreter-assembler.h

 // 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_INTERPRETER_INTERPRETER_ASSEMBLER_H_
 #define V8_INTERPRETER_INTERPRETER_ASSEMBLER_H_
 
 #include "src/allocation.h"
 #include "src/builtins/builtins.h"
 #include "src/code-stub-assembler.h"
@@ skipping 21 matching lines @@
   compiler::Node* BytecodeOperandFlag(int operand_index);
   // Returns the 32-bit zero-extended index immediate for bytecode operand
   // |operand_index| in the current bytecode.
   compiler::Node* BytecodeOperandIdx(int operand_index);
   // Returns the smi index immediate for bytecode operand |operand_index|
   // in the current bytecode.
   compiler::Node* BytecodeOperandIdxSmi(int operand_index);
   // Returns the 32-bit unsigned immediate for bytecode operand |operand_index|
   // in the current bytecode.
   compiler::Node* BytecodeOperandUImm(int operand_index);
+  // Returns the word-size unsigned immediate for bytecode operand
+  // |operand_index| in the current bytecode.
+  compiler::Node* BytecodeOperandUImmWord(int operand_index);
   // Returns the 32-bit signed immediate for bytecode operand |operand_index|
   // in the current bytecode.
   compiler::Node* BytecodeOperandImm(int operand_index);
   // Returns the word-size signed immediate for bytecode operand |operand_index|
   // in the current bytecode.
   compiler::Node* BytecodeOperandImmIntPtr(int operand_index);
   // Returns the smi immediate for bytecode operand |operand_index| in the
   // current bytecode.
   compiler::Node* BytecodeOperandImmSmi(int operand_index);
   // Returns the word-size sign-extended register index for bytecode operand
@@ skipping 90 matching lines @@
                                 compiler::Node* slot_id,
                                 compiler::Node* type_feedback_vector);
 
   // Call runtime function with |arg_count| arguments and the first argument
   // located at |first_arg|.
   compiler::Node* CallRuntimeN(compiler::Node* function_id,
                                compiler::Node* context,
                                compiler::Node* first_arg,
                                compiler::Node* arg_count, int return_size = 1);
 
-  // Jump relative to the current bytecode by |jump_offset|.
-  compiler::Node* Jump(compiler::Node* jump_offset);
+  // Jump relative to the current bytecode by the unsigned |jump_offset|. If
+  // |backwards|, then jump backwards, otherwise jump forwards.
+  compiler::Node* Jump(compiler::Node* jump_offset, bool backwards = false);

[rmcilroy, 2017/01/19 09:22:38]

Nit, could you just make this a seperate JumpBackwards bytecode.

[Leszek Swirski, 2017/01/19 10:52:59]

Done, though this function still exists (private) as a helper to remove
duplicate code.

Also, named it JumpBackward instead of JumpBackwards since we optimize rather
than optimising.

 
-  // Jump relative to the current bytecode by |jump_offset| if the
+  // Jump forward relative to the current bytecode by |jump_offset| if the
   // word values |lhs| and |rhs| are equal.
   void JumpIfWordEqual(compiler::Node* lhs, compiler::Node* rhs,
                        compiler::Node* jump_offset);
 
-  // Jump relative to the current bytecode by |jump_offset| if the
+  // Jump forward relative to the current bytecode by |jump_offset| if the
   // word values |lhs| and |rhs| are not equal.
   void JumpIfWordNotEqual(compiler::Node* lhs, compiler::Node* rhs,
                           compiler::Node* jump_offset);
 
   // Returns true if the stack guard check triggers an interrupt.
   compiler::Node* StackCheckTriggeredInterrupt();
 
   // Updates the profiler interrupt budget for a return.
   void UpdateInterruptBudgetOnReturn();
 
@@ skipping 49 matching lines @@
   // frame when performing a call.
   void CallPrologue();
   void CallEpilogue();
 
   // Increment the dispatch counter for the (current, next) bytecode pair.
   void TraceBytecodeDispatch(compiler::Node* target_index);
 
   // Traces the current bytecode by calling |function_id|.
   void TraceBytecode(Runtime::FunctionId function_id);
 
-  // Updates the bytecode array's interrupt budget by a 32-bit signed |weight|
-  // and calls Runtime::kInterrupt if counter reaches zero.
-  void UpdateInterruptBudget(compiler::Node* weight);
+  // Updates the bytecode array's interrupt budget by a 32-bit unsigned |weight|
+  // and calls Runtime::kInterrupt if counter reaches zero. If |backwards|, then
+  // the interrupt budget is decremented, otherwise it is incremented.
+  void UpdateInterruptBudget(compiler::Node* weight, bool backwards);
 
   // Returns the offset of register |index| relative to RegisterFilePointer().
   compiler::Node* RegisterFrameOffset(compiler::Node* index);
 
   // Returns the offset of an operand relative to the current bytecode offset.
   compiler::Node* OperandOffset(int operand_index);
 
   // Returns a value built from an sequence of bytes in the bytecode
   // array starting at |relative_offset| from the current bytecode.
   // The |result_type| determines the size and signedness.  of the
@@ skipping 10 matching lines @@
   compiler::Node* BytecodeOperandUnsignedQuad(int operand_index);
   compiler::Node* BytecodeOperandSignedQuad(int operand_index);
 
   // Returns zero- or sign-extended to word32 value of the operand of
   // given size.
   compiler::Node* BytecodeSignedOperand(int operand_index,
                                         OperandSize operand_size);
   compiler::Node* BytecodeUnsignedOperand(int operand_index,
                                           OperandSize operand_size);
 
-  // Jump relative to the current bytecode by |jump_offset| if the
+  // Jump forward relative to the current bytecode by |jump_offset| if the
   // |condition| is true. Helper function for JumpIfWordEqual and
   // JumpIfWordNotEqual.
   void JumpConditional(compiler::Node* condition, compiler::Node* jump_offset);
 
   // Updates and returns BytecodeOffset() advanced by the current bytecode's
   // size. Traces the exit of the current bytecode.
   compiler::Node* Advance();
 
   // Updates and returns BytecodeOffset() advanced by delta bytecodes.
   // Traces the exit of the current bytecode.
   compiler::Node* Advance(int delta);
-  compiler::Node* Advance(compiler::Node* delta);
+  compiler::Node* Advance(compiler::Node* delta, bool backwards = false);
 
   // Load the bytecode at |bytecode_offset|.
   compiler::Node* LoadBytecode(compiler::Node* bytecode_offset);
 
   // Look ahead for Star and inline it in a branch. Returns a new target
   // bytecode node for dispatch.
   compiler::Node* StarDispatchLookahead(compiler::Node* target_bytecode);
 
   // Build code for Star at the current BytecodeOffset() and Advance() to the
   // next dispatch offset.
@@ skipping 26 matching lines @@
   compiler::Node* stack_pointer_before_call_;
 
   DISALLOW_COPY_AND_ASSIGN(InterpreterAssembler);
 };
 
 }  // namespace interpreter
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_INTERPRETER_INTERPRETER_ASSEMBLER_H_