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/*
* Copyright (C) 2012-2021 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
namespace JSC {
ALWAYS_INLINE constexpr bool isDarwin()
{
#if OS(DARWIN)
return true;
#else
return false;
#endif
}
ALWAYS_INLINE constexpr bool isIOS()
{
#if PLATFORM(IOS_FAMILY)
return true;
#else
return false;
#endif
}
ALWAYS_INLINE bool isInt9(int32_t value)
{
return value == ((value << 23) >> 23);
}
template<typename Type>
ALWAYS_INLINE bool isUInt12(Type value)
{
return !(value & ~static_cast<Type>(0xfff));
}
template<int datasize>
ALWAYS_INLINE bool isValidScaledUImm12(int32_t offset)
{
int32_t maxPImm = 4095 * (datasize / 8);
if (offset < 0)
return false;
if (offset > maxPImm)
return false;
if (offset & ((datasize / 8) - 1))
return false;
return true;
}
ALWAYS_INLINE bool isValidSignedImm9(int32_t value)
{
return isInt9(value);
}
ALWAYS_INLINE bool isValidSignedImm7(int32_t value, int alignmentShiftAmount)
{
constexpr int32_t disallowedHighBits = 32 - 7;
int32_t shiftedValue = value >> alignmentShiftAmount;
bool fitsIn7Bits = shiftedValue == ((shiftedValue << disallowedHighBits) >> disallowedHighBits);
bool hasCorrectAlignment = value == (shiftedValue << alignmentShiftAmount);
return fitsIn7Bits && hasCorrectAlignment;
}
class ARM64LogicalImmediate {
public:
static ARM64LogicalImmediate create32(uint32_t value)
{
// Check for 0, -1 - these cannot be encoded.
if (!value || !~value)
return InvalidLogicalImmediate;
// First look for a 32-bit pattern, then for repeating 16-bit
// patterns, 8-bit, 4-bit, and finally 2-bit.
unsigned hsb, lsb;
bool inverted;
if (findBitRange<32>(value, hsb, lsb, inverted))
return encodeLogicalImmediate<32>(hsb, lsb, inverted);
if ((value & 0xffff) != (value >> 16))
return InvalidLogicalImmediate;
value &= 0xffff;
if (findBitRange<16>(value, hsb, lsb, inverted))
return encodeLogicalImmediate<16>(hsb, lsb, inverted);
if ((value & 0xff) != (value >> 8))
return InvalidLogicalImmediate;
value &= 0xff;
if (findBitRange<8>(value, hsb, lsb, inverted))
return encodeLogicalImmediate<8>(hsb, lsb, inverted);
if ((value & 0xf) != (value >> 4))
return InvalidLogicalImmediate;
value &= 0xf;
if (findBitRange<4>(value, hsb, lsb, inverted))
return encodeLogicalImmediate<4>(hsb, lsb, inverted);
if ((value & 0x3) != (value >> 2))
return InvalidLogicalImmediate;
value &= 0x3;
if (findBitRange<2>(value, hsb, lsb, inverted))
return encodeLogicalImmediate<2>(hsb, lsb, inverted);
return InvalidLogicalImmediate;
}
static ARM64LogicalImmediate create64(uint64_t value)
{
// Check for 0, -1 - these cannot be encoded.
if (!value || !~value)
return InvalidLogicalImmediate;
// Look for a contiguous bit range.
unsigned hsb, lsb;
bool inverted;
if (findBitRange<64>(value, hsb, lsb, inverted))
return encodeLogicalImmediate<64>(hsb, lsb, inverted);
// If the high & low 32 bits are equal, we can try for a 32-bit (or narrower) pattern.
if (static_cast<uint32_t>(value) == static_cast<uint32_t>(value >> 32))
return create32(static_cast<uint32_t>(value));
return InvalidLogicalImmediate;
}
int value() const
{
ASSERT(isValid());
return m_value;
}
bool isValid() const
{
return m_value != InvalidLogicalImmediate;
}
bool is64bit() const
{
return m_value & (1 << 12);
}
private:
ARM64LogicalImmediate(int value)
: m_value(value)
{
}
// Generate a mask with bits in the range hsb..0 set, for example:
// hsb:63 = 0xffffffffffffffff
// hsb:42 = 0x000007ffffffffff
// hsb: 0 = 0x0000000000000001
static uint64_t mask(unsigned hsb)
{
ASSERT(hsb < 64);
return 0xffffffffffffffffull >> (63 - hsb);
}
template<unsigned N>
static void partialHSB(uint64_t& value, unsigned&result)
{
if (value & (0xffffffffffffffffull << N)) {
result += N;
value >>= N;
}
}
// Find the bit number of the highest bit set in a non-zero value, for example:
// 0x8080808080808080 = hsb:63
// 0x0000000000000001 = hsb: 0
// 0x000007ffffe00000 = hsb:42
static unsigned highestSetBit(uint64_t value)
{
ASSERT(value);
unsigned hsb = 0;
partialHSB<32>(value, hsb);
partialHSB<16>(value, hsb);
partialHSB<8>(value, hsb);
partialHSB<4>(value, hsb);
partialHSB<2>(value, hsb);
partialHSB<1>(value, hsb);
return hsb;
}
// This function takes a value and a bit width, where value obeys the following constraints:
// * bits outside of the width of the value must be zero.
// * bits within the width of value must neither be all clear or all set.
// The input is inspected to detect values that consist of either two or three contiguous
// ranges of bits. The output range hsb..lsb will describe the second range of the value.
// if the range is set, inverted will be false, and if the range is clear, inverted will
// be true. For example (with width 8):
// 00001111 = hsb:3, lsb:0, inverted:false
// 11110000 = hsb:3, lsb:0, inverted:true
// 00111100 = hsb:5, lsb:2, inverted:false
// 11000011 = hsb:5, lsb:2, inverted:true
template<unsigned width>
static bool findBitRange(uint64_t value, unsigned& hsb, unsigned& lsb, bool& inverted)
{
ASSERT(value & mask(width - 1));
ASSERT(value != mask(width - 1));
ASSERT(!(value & ~mask(width - 1)));
// Detect cases where the top bit is set; if so, flip all the bits & set invert.
// This halves the number of patterns we need to look for.
const uint64_t msb = 1ull << (width - 1);
if ((inverted = (value & msb)))
value ^= mask(width - 1);
// Find the highest set bit in value, generate a corresponding mask & flip all
// bits under it.
hsb = highestSetBit(value);
value ^= mask(hsb);
if (!value) {
// If this cleared the value, then the range hsb..0 was all set.
lsb = 0;
return true;
}
// Try making one more mask, and flipping the bits!
lsb = highestSetBit(value);
value ^= mask(lsb);
if (!value) {
// Success - but lsb actually points to the hsb of a third range - add one
// to get to the lsb of the mid range.
++lsb;
return true;
}
return false;
}
// Encodes the set of immN:immr:imms fields found in a logical immediate.
template<unsigned width>
static int encodeLogicalImmediate(unsigned hsb, unsigned lsb, bool inverted)
{
// Check width is a power of 2!
ASSERT(!(width & (width -1)));
ASSERT(width <= 64 && width >= 2);
ASSERT(hsb >= lsb);
ASSERT(hsb < width);
int immN = 0;
int imms = 0;
int immr = 0;
// For 64-bit values this is easy - just set immN to true, and imms just
// contains the bit number of the highest set bit of the set range. For
// values with narrower widths, these are encoded by a leading set of
// one bits, followed by a zero bit, followed by the remaining set of bits
// being the high bit of the range. For a 32-bit immediate there are no
// leading one bits, just a zero followed by a five bit number. For a
// 16-bit immediate there is one one bit, a zero bit, and then a four bit
// bit-position, etc.
if (width == 64)
immN = 1;
else
imms = 63 & ~(width + width - 1);
if (inverted) {
// if width is 64 & hsb is 62, then we have a value something like:
// 0x80000000ffffffff (in this case with lsb 32).
// The ror should be by 1, imms (effectively set width minus 1) is
// 32. Set width is full width minus cleared width.
immr = (width - 1) - hsb;
imms |= (width - ((hsb - lsb) + 1)) - 1;
} else {
// if width is 64 & hsb is 62, then we have a value something like:
// 0x7fffffff00000000 (in this case with lsb 32).
// The value is effectively rol'ed by lsb, which is equivalent to
// a ror by width - lsb (or 0, in the case where lsb is 0). imms
// is hsb - lsb.
immr = (width - lsb) & (width - 1);
imms |= hsb - lsb;
}
return immN << 12 | immr << 6 | imms;
}
static constexpr int InvalidLogicalImmediate = -1;
int m_value;
};
} // namespace JSC.