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/*
* Copyright (C) 2015-2019 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.
*/
#include "config.h"
#include "JITDivGenerator.h"
#if ENABLE(JIT)
#include "ArithProfile.h"
#include "JSCJSValueInlines.h"
#include "MathCommon.h"
namespace JSC {
void JITDivGenerator::loadOperand(CCallHelpers& jit, SnippetOperand& opr, JSValueRegs oprRegs, FPRReg destFPR)
{
if (opr.isConstInt32()) {
// FIXME: this does not looks right.
// -On x86_64, CVTSI2SD has partial register stall on its FPR.
// A move or load might be a tiny bit larger but safer.
// -On ARM64 we also have FMOV that can load small immediates.
jit.move(CCallHelpers::Imm32(opr.asConstInt32()), m_scratchGPR);
jit.convertInt32ToDouble(m_scratchGPR, destFPR);
#if USE(JSVALUE64)
} else if (opr.isConstDouble()) {
jit.move(CCallHelpers::Imm64(opr.asRawBits()), m_scratchGPR);
jit.move64ToDouble(m_scratchGPR, destFPR);
#endif
} else {
if (!opr.definitelyIsNumber())
m_slowPathJumpList.append(jit.branchIfNotNumber(oprRegs, m_scratchGPR));
CCallHelpers::Jump notInt32 = jit.branchIfNotInt32(oprRegs);
jit.convertInt32ToDouble(oprRegs.payloadGPR(), destFPR);
CCallHelpers::Jump oprIsLoaded = jit.jump();
notInt32.link(&jit);
jit.unboxDoubleNonDestructive(oprRegs, destFPR, m_scratchGPR);
oprIsLoaded.link(&jit);
}
}
void JITDivGenerator::generateFastPath(CCallHelpers& jit)
{
ASSERT(m_scratchGPR != InvalidGPRReg);
ASSERT(m_scratchGPR != m_left.payloadGPR());
ASSERT(m_scratchGPR != m_right.payloadGPR());
#if USE(JSVALUE32_64)
ASSERT(m_scratchGPR != m_left.tagGPR());
ASSERT(m_scratchGPR != m_right.tagGPR());
ASSERT(m_scratchFPR != InvalidFPRReg);
#endif
ASSERT(!m_didEmitFastPath);
if (!jit.supportsFloatingPoint())
return;
if (!m_leftOperand.mightBeNumber() || !m_rightOperand.mightBeNumber())
return;
ASSERT(!m_leftOperand.isConstInt32() || !m_rightOperand.isConstInt32());
m_didEmitFastPath = true;
loadOperand(jit, m_leftOperand, m_left, m_leftFPR);
#if USE(JSVALUE64)
std::optional<double> safeReciprocal;
if (m_rightOperand.isConst()) {
double constant = m_rightOperand.asConstNumber();
safeReciprocal = safeReciprocalForDivByConst(constant);
}
if (safeReciprocal) {
jit.move(CCallHelpers::Imm64(std::bit_cast<int64_t>(*safeReciprocal)), m_scratchGPR);
jit.move64ToDouble(m_scratchGPR, m_rightFPR);
jit.mulDouble(m_rightFPR, m_leftFPR);
} else
#endif
{
loadOperand(jit, m_rightOperand, m_right, m_rightFPR);
jit.divDouble(m_rightFPR, m_leftFPR);
}
// Is the result actually an integer? The DFG JIT would really like to know. If it's
// not an integer, we set a bit. If this together with the slow case counter are below
// threshold then the DFG JIT will compile this division with a speculation that the
// remainder is zero.
// As well, there are cases where a double result here would cause an important field
// in the heap to sometimes have doubles in it, resulting in double predictions getting
// propagated to a use site where it might cause damage (such as the index to an array
// access). So if we are DFG compiling anything in the program, we want this code to
// ensure that it produces integers whenever possible.
CCallHelpers::JumpList notInt32;
jit.branchConvertDoubleToInt32(m_leftFPR, m_scratchGPR, notInt32, m_scratchFPR);
// If we've got an integer, we might as well make that the result of the division.
jit.boxInt32(m_scratchGPR, m_result);
m_endJumpList.append(jit.jump());
notInt32.link(&jit);
#if USE(JSVALUE64)
jit.moveDoubleTo64(m_leftFPR, m_scratchGPR);
CCallHelpers::Jump notDoubleZero = jit.branchTest64(CCallHelpers::NonZero, m_scratchGPR);
jit.move(GPRInfo::numberTagRegister, m_result.payloadGPR());
m_endJumpList.append(jit.jump());
notDoubleZero.link(&jit);
#endif
if (m_arithProfile)
m_arithProfile->emitUnconditionalSet(jit, BinaryArithProfile::specialFastPathBit);
jit.boxDouble(m_leftFPR, m_result);
}
} // namespace JSC
#endif // ENABLE(JIT)
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