1/*
2 * Copyright (C) 2013 Apple Inc. All rights reserved.
3 *
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions
6 * are met:
7 * 1. Redistributions of source code must retain the above copyright
8 * notice, this list of conditions and the following disclaimer.
9 * 2. Redistributions in binary form must reproduce the above copyright
10 * notice, this list of conditions and the following disclaimer in the
11 * documentation and/or other materials provided with the distribution.
12 *
13 * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
14 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
15 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
16 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR
17 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
18 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
19 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
20 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
21 * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
22 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
23 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
24 */
25
26#ifndef StackAlignment_h
27#define StackAlignment_h
28
29#include "JSCJSValue.h"
30#include "JSStack.h"
31#include <wtf/MathExtras.h>
32
33namespace JSC {
34
35// NB. Different platforms may have different requirements here. But 16 bytes is very common.
36inline unsigned stackAlignmentBytes() { return 16; }
37
38inline unsigned stackAlignmentRegisters()
39{
40 return stackAlignmentBytes() / sizeof(EncodedJSValue);
41}
42
43// Align argument count taking into account the CallFrameHeaderSize may be
44// an "unaligned" count of registers.
45inline unsigned roundArgumentCountToAlignFrame(unsigned argumentCount)
46{
47 return WTF::roundUpToMultipleOf(stackAlignmentRegisters(), argumentCount + JSStack::CallFrameHeaderSize) - JSStack::CallFrameHeaderSize;
48}
49
50// Align local register count to make the last local end on a stack aligned address given the
51// CallFrame is at an address that is stack aligned minus JSStack::CallerFrameAndPCSize
52inline unsigned roundLocalRegisterCountForFramePointerOffset(unsigned localRegisterCount)
53{
54 return WTF::roundUpToMultipleOf(stackAlignmentRegisters(), localRegisterCount + JSStack::CallerFrameAndPCSize) - JSStack::CallerFrameAndPCSize;
55}
56
57inline unsigned logStackAlignmentRegisters()
58{
59 return WTF::fastLog2(stackAlignmentRegisters());
60}
61
62} // namespace JSC
63
64#endif // StackAlignment_h
65
66