1  /*
 2   * Copyright (C) 2013, 2016 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  #pragma once
27  
28  #include "Register.h"
29  #include "StackAlignment.h"
30  #include <wtf/Assertions.h>
31  
32  namespace JSC {
33  
34  // The maxFrameExtentForSlowPathCall is the max amount of stack space (in bytes)
35  // that can be used for outgoing args when calling a slow path C function
36  // from JS code.
37  
38  #if !ENABLE(ASSEMBLER)
39  static constexpr size_t maxFrameExtentForSlowPathCall = 0;
40  
41  #elif CPU(X86_64) && OS(WINDOWS)
42  // 4 args in registers, but stack space needs to be allocated for all args.
43  static constexpr size_t maxFrameExtentForSlowPathCall = 64;
44  
45  #elif CPU(X86_64)
46  // All args in registers.
47  static constexpr size_t maxFrameExtentForSlowPathCall = 0;
48  
49  #elif CPU(X86)
50  // 7 args on stack (28 bytes).
51  static constexpr size_t maxFrameExtentForSlowPathCall = 40;
52  
53  #elif CPU(ARM64) || CPU(ARM64E)
54  // All args in registers.
55  static constexpr size_t maxFrameExtentForSlowPathCall = 0;
56  
57  #elif CPU(ARM)
58  // First four args in registers, remaining 4 args on stack.
59  static constexpr size_t maxFrameExtentForSlowPathCall = 24;
60  
61  #elif CPU(MIPS)
62  // Though args are in registers, there need to be space on the stack for all args.
63  static constexpr size_t maxFrameExtentForSlowPathCall = 40;
64  
65  #else
66  #error "Unsupported CPU: need value for maxFrameExtentForSlowPathCall"
67  
68  #endif
69  
70  static_assert(!(maxFrameExtentForSlowPathCall % sizeof(Register)), "Extent must be in multiples of registers");
71  
72  #if ENABLE(ASSEMBLER)
73  // Make sure that cfr - maxFrameExtentForSlowPathCall bytes will make the stack pointer aligned
74  static_assert((maxFrameExtentForSlowPathCall % 16) == 16 - sizeof(CallerFrameAndPC), "Extent must align stack from callframe pointer");
75  #endif
76  
77  static constexpr size_t maxFrameExtentForSlowPathCallInRegisters = maxFrameExtentForSlowPathCall / sizeof(Register);
78  
79  } // namespace JSC