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Optimized prolog/epilog for private linkage on X86 #2460

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Jul 26, 2018
Merged

Optimized prolog/epilog for private linkage on X86 #2460

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78 changes: 12 additions & 66 deletions runtime/compiler/x/codegen/X86PrivateLinkage.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -673,17 +673,13 @@ void TR::X86PrivateLinkage::createPrologue(TR::Instruction *cursor)
// Compute frame size
//
// allocSize: bytes to be subtracted from the stack pointer when allocating the frame
// frameSize: total bytes of stack the prologue consumes
// peakSize: maximum bytes of stack this method might consume before encountering another stack check
//
const int32_t localSize = _properties.getOffsetToFirstLocal() - bodySymbol->getLocalMappingCursor();
TR_ASSERT(localSize >= 0, "assertion failure");

// Note that the return address doesn't appear here because it is allocated by the call instruction
//
int32_t allocSize = localSize + preservedRegsSize
+ ( _properties.getReservesOutgoingArgsInPrologue()? outgoingArgSize : 0 );

{
int32_t frameSize = localSize + preservedRegsSize + ( _properties.getReservesOutgoingArgsInPrologue()? outgoingArgSize : 0 );
uint32_t stackSize = frameSize + _properties.getRetAddressWidth();
Expand All @@ -698,7 +694,7 @@ void TR::X86PrivateLinkage::createPrologue(TR::Instruction *cursor)
_properties.getOutgoingArgAlignment(),
_properties.getRetAddressWidth());
}

auto allocSize = cg()->getFrameSizeInBytes();

// Here we conservatively assume there is a call in this method that will require space for its return address
const int32_t peakSize = allocSize + _properties.getPointerSize();
Expand Down Expand Up @@ -1001,19 +997,6 @@ void TR::X86PrivateLinkage::createPrologue(TR::Instruction *cursor)
}
}

int32_t allocateSize = 0;
// Add paddings
if (cg()->getStackFramePaddingSizeInBytes())
{
allocateSize += cg()->getStackFramePaddingSizeInBytes();
}

if (allocateSize)
{
const TR_X86OpCodes subOp = (allocateSize <= 127)? SUBRegImms() : SUBRegImm4();
cursor = new (trHeapMemory()) TR::X86RegImmInstruction(cursor, subOp, espReal, allocateSize, cg());
}

#if defined(DEBUG)
debugFrameSlotInfo = new (trHeapMemory()) TR_DebugFrameSegmentInfo(comp(),
-localSize - preservedRegsSize - outgoingArgSize,
Expand Down Expand Up @@ -1049,19 +1032,9 @@ void TR::X86PrivateLinkage::createPrologue(TR::Instruction *cursor)
// for shrinkwrapping
bool TR::X86PrivateLinkage::needsFrameDeallocation()
{
// frame needs a deallocation if allocSize == 0
// frame needs a deallocation if FrameSize == 0
//
TR::ResolvedMethodSymbol *bodySymbol = comp()->getJittedMethodSymbol();
int32_t localSize = _properties.getOffsetToFirstLocal() - bodySymbol->getLocalMappingCursor();
int32_t allocSize = cg()->getFrameSizeInBytes();

if (!_properties.getAlwaysDedicateFramePointerRegister() &&
allocSize == 0)
{
return true;
}

return false;
return !_properties.getAlwaysDedicateFramePointerRegister() && cg()->getFrameSizeInBytes() == 0;
}

TR::Instruction *TR::X86PrivateLinkage::deallocateFrameIfNeeded(TR::Instruction *cursor, int32_t size)
Expand All @@ -1072,62 +1045,35 @@ TR::Instruction *TR::X86PrivateLinkage::deallocateFrameIfNeeded(TR::Instruction

void TR::X86PrivateLinkage::createEpilogue(TR::Instruction *cursor)
{
TR::RealRegister *espReal = machine()->getX86RealRegister(TR::RealRegister::esp);
TR::RealRegister *framePointer = machine()->getX86RealRegister(TR::RealRegister::vfp);
const TR::RealRegister::RegNum noReg = TR::RealRegister::NoReg;
TR::ResolvedMethodSymbol *bodySymbol = comp()->getJittedMethodSymbol();

const int32_t localSize = _properties.getOffsetToFirstLocal() - bodySymbol->getLocalMappingCursor();
int32_t allocSize = cg()->getFrameSizeInBytes() - cg()->getStackFramePaddingSizeInBytes();
TR::RealRegister* espReal = machine()->getX86RealRegister(TR::RealRegister::esp);

cursor = cg()->generateDebugCounter(cursor, "cg.epilogues", 1, TR::DebugCounter::Expensive);

int32_t deallocateSize = 0;
// Deallocate padding
if (cg()->getStackFramePaddingSizeInBytes())
{
deallocateSize += cg()->getStackFramePaddingSizeInBytes();
if (comp()->getOption(TR_TraceCG))
{
traceMsg(comp(), "Bytes of stack frame padding to be deallocated %d\n", cg()->getStackFramePaddingSizeInBytes());
}
}

if (deallocateSize)
{
TR_X86OpCodes op = (deallocateSize <= 127) ? ADDRegImms() : ADDRegImm4();
cursor = new (trHeapMemory()) TR::X86RegImmInstruction(cursor, op, espReal, deallocateSize, cg());
}

// Restore preserved regs
//
cursor = restorePreservedRegisters(cursor);

// Deallocate the stack frame
//
bool needsDeallocationForShrinkWrapping = false;
if (_properties.getAlwaysDedicateFramePointerRegister())
{
// Restore stack pointer from frame pointer
//
cursor = new (trHeapMemory()) TR::X86RegRegInstruction(cursor, MOVRegReg(), espReal, machine()->getX86RealRegister(_properties.getFramePointerRegister()), cg());
cursor = new (trHeapMemory()) TR::X86RegInstruction(cursor, POPReg, machine()->getX86RealRegister(_properties.getFramePointerRegister()), cg());
}
else if (allocSize == 0)
{
// No need to do anything
if (cg()->getShrinkWrappingDone())
needsDeallocationForShrinkWrapping = true;
cursor = generateRegRegInstruction(cursor, MOVRegReg(), espReal, machine()->getX86RealRegister(_properties.getFramePointerRegister()), cg());
cursor = generateRegInstruction(cursor, POPReg, machine()->getX86RealRegister(_properties.getFramePointerRegister()), cg());
}
else
{
TR_X86OpCodes op = (allocSize <= 127) ? ADDRegImms() : ADDRegImm4();
cursor = new (trHeapMemory()) TR::X86RegImmInstruction(cursor, op, espReal, allocSize, cg());
auto frameSize = cg()->getFrameSizeInBytes();
if (frameSize != 0)
{
cursor = generateRegImmInstruction(cursor, (frameSize <= 127) ? ADDRegImms() : ADDRegImm4(), espReal, frameSize, cg());
}
}

if (cursor->getNext()->getOpCodeValue() == RETImm2)
{
toIA32ImmInstruction(cursor->getNext())->setSourceImmediate(bodySymbol->getNumParameterSlots() << getProperties().getParmSlotShift());
toIA32ImmInstruction(cursor->getNext())->setSourceImmediate(comp()->getJittedMethodSymbol()->getNumParameterSlots() << getProperties().getParmSlotShift());
}
}

Expand Down