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/*
* Copyright (C) 2020 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
#include <cstdint>
#include <wtf/Assertions.h>
namespace JSC {
class VM;
namespace DFG {
struct DoesGCCheck {
enum class Special {
Uninitialized,
DFGOSRExit,
FTLOSRExit,
NumberOfSpecials
};
DoesGCCheck()
{
u.encoded = encode(true, Special::Uninitialized);
}
static uint64_t encode(bool expectDoesGC, unsigned nodeIndex, unsigned nodeOp)
{
Union un;
un.nodeIndex = nodeIndex;
un.other = (nodeOp << nodeOpShift) | bits(expectDoesGC);
return un.encoded;
}
static uint64_t encode(bool expectDoesGC, Special special)
{
Union un;
un.nodeIndex = 0;
un.other = bits(special) << specialShift | isSpecialBit | bits(expectDoesGC);
return un.encoded;
}
void set(bool expectDoesGC, unsigned nodeIndex, unsigned nodeOp)
{
u.encoded = encode(expectDoesGC, nodeIndex, nodeOp);
}
void set(bool expectDoesGC, Special special)
{
u.encoded = encode(expectDoesGC, special);
}
bool expectDoesGC() const { return u.other & expectDoesGCBit; }
bool isSpecial() const { return u.other & isSpecialBit; }
Special special() { return static_cast<Special>(u.other >> specialShift); }
unsigned nodeOp() { return (u.other >> nodeOpShift) & nodeOpMask; }
unsigned nodeIndex() { return u.nodeIndex; }
#if ENABLE(DFG_DOES_GC_VALIDATION)
JS_EXPORT_PRIVATE void verifyCanGC(VM&);
#endif
private:
template<typename T> static uint32_t bits(T value) { return static_cast<uint32_t>(value); }
// The value cannot be both a Special and contain node information at the
// time. Hence, the 2 can have separate encodings. The isSpecial bit
// determines which encoding is in use.
static constexpr unsigned expectDoesGCBit = 1 << 0;
static constexpr unsigned isSpecialBit = 1 << 1;
static constexpr unsigned commonBits = 2;
static_assert((expectDoesGCBit | isSpecialBit) == (1 << commonBits) - 1);
static constexpr unsigned specialShift = commonBits;
static constexpr unsigned nodeOpBits = 9;
static constexpr unsigned nodeOpMask = (1 << nodeOpBits) - 1;
static constexpr unsigned nodeOpShift = commonBits;
public:
union Union {
struct {
uint32_t other;
uint32_t nodeIndex;
};
uint64_t encoded;
} u;
};
} // namespace DFG
using DFG::DoesGCCheck;
} // namespace JSC
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