1/*
2 * Copyright (C) 2015-2016 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#if ENABLE(B3_JIT)
29
30namespace JSC { namespace B3 { namespace Air {
31
32enum class StackSlotKind : uint8_t {
33 // A locked stack slot is an area of stack requested by the client. It cannot be killed. The
34 // client can get its FP offset and write to it from stack walking code, so we must assume
35 // that reads and writes to a locked stack slot can be clobbered the same way as reads and
36 // writes to any memory location.
37 Locked,
38
39 // A spill slot. These have fundamentally different behavior than a typical memory location.
40 // They are lowered to from temporaries. This means for example that a 32-bit ZDef store to a
41 // 8 byte stack slot will zero the top 4 bytes, even though a 32-bit ZDef store to any other
42 // kind of memory location would do no such thing. UseAddr on a spill slot is not allowed, so
43 // they never escape.
44 Spill
45
46 // FIXME: We should add a third mode, which means that the stack slot will be read asynchronously
47 // as with Locked, but never written to asynchronously. Then, Air could optimize spilling and
48 // filling by tracking whether the value had been stored to a read-only locked slot. If it had,
49 // then we can refill from that slot.
50 // https://bugs.webkit.org/show_bug.cgi?id=150587
51};
52
53} } } // namespace JSC::B3::Air
54
55namespace WTF {
56
57class PrintStream;
58
59void printInternal(PrintStream&, JSC::B3::Air::StackSlotKind);
60
61} // namespace WTF
62
63#endif // ENABLE(B3_JIT)
64