stack_frame_kbc.h source code [engine/third_party/dart/runtime/vm/stack_frame_kbc.h]

1	// Copyright (c) 2018, the Dart project authors. Please see the AUTHORS file
2	// for details. All rights reserved. Use of this source code is governed by a
3	// BSD-style license that can be found in the LICENSE file.
4
5	#ifndef RUNTIME_VM_STACK_FRAME_KBC_H_
6	#define RUNTIME_VM_STACK_FRAME_KBC_H_
7
8	#include "platform/globals.h"
9
10	namespace dart {
11
12	/ Kernel Bytecode Frame Layout*
13
14	IMPORTANT: KBC stack is growing upwards which is different from all other
15	architectures. This enables efficient addressing for locals via unsigned index.
16
17	\| \| <- TOS
18	Callee frame \| ... \|
19	\| saved FP \| (FP of current frame)
20	\| saved PC \| (PC of current frame)
21	\| code object \|
22	\| function object \|
23	+--------------------+
24	Current frame \| ... T\| <- SP of current frame
25	\| ... T\|
26	\| first local T\| <- FP of current frame
27	\| caller's FP \|
28	\| caller's PC \|
29	\| code object T\| (current frame's code object)
30	\| function object T\| (current frame's function object)
31	+--------------------+
32	Caller frame \| last parameter \| <- SP of caller frame
33	\| ... \|
34
35	T against a slot indicates it needs to be traversed during GC.
36	*/
37
38	static const int kKBCDartFrameFixedSize = `4`; // Function, Code, PC, FP
39	static const int kKBCSavedPcSlotFromSp = `3`;
40
41	static const int kKBCFirstObjectSlotFromFp = -`4`; // Used by GC.
42	static const int kKBCLastFixedObjectSlotFromFp = -`3`;
43
44	static const int kKBCSavedCallerFpSlotFromFp = -`1`;
45	static const int kKBCSavedCallerPcSlotFromFp = -`2`;
46	static const int kKBCCallerSpSlotFromFp = -kKBCDartFrameFixedSize - `1`;
47	static const int kKBCPcMarkerSlotFromFp = -`3`;
48	static const int kKBCFunctionSlotFromFp = -`4`;
49	static const int kKBCParamEndSlotFromFp = `4`;
50
51	// Entry and exit frame layout.
52	static const int kKBCEntrySavedSlots = `3`;
53	static const int kKBCExitLinkSlotFromEntryFp = `0`;
54	static const int kKBCSavedArgDescSlotFromEntryFp = `1`;
55	static const int kKBCSavedPpSlotFromEntryFp = `2`;
56
57	// Value for stack limit that is used to cause an interrupt.
58	// Note that on KBC stack is growing upwards so interrupt limit is 0 unlike
59	// on all other architectures.
60	static const uword kKBCInterruptStackLimit = `0`;
61
62	} // namespace dart
63
64	#endif // RUNTIME_VM_STACK_FRAME_KBC_H_
65

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