1 | /* |
2 | * Copyright (C) 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 "CPU.h" |
29 | #include <wtf/StdLibExtras.h> |
30 | |
31 | namespace JSC { |
32 | |
33 | #if USE(JSVALUE64) |
34 | // According to C++ rules, a type used for the return signature of function with C linkage (i.e. |
35 | // 'extern "C"') needs to be POD; hence putting any constructors into it could cause either compiler |
36 | // warnings, or worse, a change in the ABI used to return these types. |
37 | struct SlowPathReturnType { |
38 | CPURegister a; |
39 | CPURegister b; |
40 | }; |
41 | static_assert(sizeof(SlowPathReturnType) >= sizeof(void*) * 2, "SlowPathReturnType should fit in two machine registers" ); |
42 | |
43 | inline SlowPathReturnType encodeResult(const void* a, const void* b) |
44 | { |
45 | SlowPathReturnType result; |
46 | result.a = reinterpret_cast<CPURegister>(a); |
47 | result.b = reinterpret_cast<CPURegister>(b); |
48 | return result; |
49 | } |
50 | |
51 | inline void decodeResult(SlowPathReturnType result, const void*& a, const void*& b) |
52 | { |
53 | a = reinterpret_cast<void*>(result.a); |
54 | b = reinterpret_cast<void*>(result.b); |
55 | } |
56 | |
57 | #else // USE(JSVALUE32_64) |
58 | typedef int64_t SlowPathReturnType; |
59 | |
60 | typedef union { |
61 | struct { |
62 | const void* a; |
63 | const void* b; |
64 | } pair; |
65 | int64_t i; |
66 | } SlowPathReturnTypeEncoding; |
67 | |
68 | inline SlowPathReturnType encodeResult(const void* a, const void* b) |
69 | { |
70 | SlowPathReturnTypeEncoding u; |
71 | u.pair.a = a; |
72 | u.pair.b = b; |
73 | return u.i; |
74 | } |
75 | |
76 | inline void decodeResult(SlowPathReturnType result, const void*& a, const void*& b) |
77 | { |
78 | SlowPathReturnTypeEncoding u; |
79 | u.i = result; |
80 | a = u.pair.a; |
81 | b = u.pair.b; |
82 | } |
83 | #endif // USE(JSVALUE32_64) |
84 | |
85 | } // namespace JSC |
86 | |