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// Copyright (c) 2018, the Dart project authors. Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.
#ifndef RUNTIME_VM_STACK_FRAME_KBC_H_
#define RUNTIME_VM_STACK_FRAME_KBC_H_
namespace dart {
/* Kernel Bytecode Frame Layout
IMPORTANT: KBC stack is growing upwards which is different from all other
architectures. This enables efficient addressing for locals via unsigned index.
| | <- TOS
Callee frame | ... |
| saved FP | (FP of current frame)
| saved PC | (PC of current frame)
| code object |
| function object |
+--------------------+
Current frame | ... T| <- SP of current frame
| ... T|
| first local T| <- FP of current frame
| caller's FP *|
| caller's PC *|
| code object T| (current frame's code object)
| function object T| (current frame's function object)
+--------------------+
Caller frame | last parameter | <- SP of caller frame
| ... |
T against a slot indicates it needs to be traversed during GC.
* against a slot indicates that it can be traversed during GC
because it will look like a smi to the visitor.
*/
static const int kKBCDartFrameFixedSize = 4; // Function, Code, PC, FP
static const int kKBCSavedPcSlotFromSp = 3;
static const int kKBCFirstObjectSlotFromFp = -4; // Used by GC.
static const int kKBCLastFixedObjectSlotFromFp = -3;
static const int kKBCSavedCallerFpSlotFromFp = -1;
static const int kKBCSavedCallerPcSlotFromFp = -2;
static const int kKBCCallerSpSlotFromFp = -kKBCDartFrameFixedSize - 1;
static const int kKBCPcMarkerSlotFromFp = -3;
static const int kKBCFunctionSlotFromFp = -4;
static const int kKBCParamEndSlotFromFp = 4;
// Entry and exit frame layout.
static const int kKBCEntrySavedSlots = 3;
static const int kKBCExitLinkSlotFromEntryFp = 0;
static const int kKBCSavedArgDescSlotFromEntryFp = 1;
static const int kKBCSavedPpSlotFromEntryFp = 2;
// Value for stack limit that is used to cause an interrupt.
// Note that on KBC stack is growing upwards so interrupt limit is 0 unlike
// on all other architectures.
static const uword kKBCInterruptStackLimit = 0;
} // namespace dart
#endif // RUNTIME_VM_STACK_FRAME_KBC_H_