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AirStackSlotKind.h
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63 lines (51 loc) · 2.74 KB
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/*
* Copyright (C) 2015-2016 Apple Inc. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR
* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
* OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#pragma once
#if ENABLE(B3_JIT)
namespace JSC { namespace B3 { namespace Air {
enum class StackSlotKind : uint8_t {
// A locked stack slot is an area of stack requested by the client. It cannot be killed. The
// client can get its FP offset and write to it from stack walking code, so we must assume
// that reads and writes to a locked stack slot can be clobbered the same way as reads and
// writes to any memory location.
Locked,
// A spill slot. These have fundamentally different behavior than a typical memory location.
// They are lowered to from temporaries. This means for example that a 32-bit ZDef store to a
// 8 byte stack slot will zero the top 4 bytes, even though a 32-bit ZDef store to any other
// kind of memory location would do no such thing. UseAddr on a spill slot is not allowed, so
// they never escape.
Spill
// FIXME: We should add a third mode, which means that the stack slot will be read asynchronously
// as with Locked, but never written to asynchronously. Then, Air could optimize spilling and
// filling by tracking whether the value had been stored to a read-only locked slot. If it had,
// then we can refill from that slot.
// https://bugs.webkit.org/show_bug.cgi?id=150587
};
} } } // namespace JSC::B3::Air
namespace WTF {
class PrintStream;
void printInternal(PrintStream&, JSC::B3::Air::StackSlotKind);
} // namespace WTF
#endif // ENABLE(B3_JIT)