/// calculateFrameObjectOffsets - Calculate actual frame offsets for all of the
/// abstract stack objects.
///
void LocalStackSlotPass::calculateFrameObjectOffsets(MachineFunction &Fn) {
// Loop over all of the stack objects, assigning sequential addresses...
MachineFrameInfo *MFI = Fn.getFrameInfo();
const TargetFrameInfo &TFI = *Fn.getTarget().getFrameInfo();
bool StackGrowsDown =
TFI.getStackGrowthDirection() == TargetFrameInfo::StackGrowsDown;
int64_t Offset = 0;
unsigned MaxAlign = 0;
// Make sure that the stack protector comes before the local variables on the
// stack.
SmallSet<int, 16> LargeStackObjs;
if (MFI->getStackProtectorIndex() >= 0) {
AdjustStackOffset(MFI, MFI->getStackProtectorIndex(), Offset,
StackGrowsDown, MaxAlign);
// Assign large stack objects first.
for (unsigned i = 0, e = MFI->getObjectIndexEnd(); i != e; ++i) {
if (MFI->isDeadObjectIndex(i))
continue;
if (MFI->getStackProtectorIndex() == (int)i)
continue;
if (!MFI->MayNeedStackProtector(i))
continue;
AdjustStackOffset(MFI, i, Offset, StackGrowsDown, MaxAlign);
LargeStackObjs.insert(i);
}
}
// Then assign frame offsets to stack objects that are not used to spill
// callee saved registers.
for (unsigned i = 0, e = MFI->getObjectIndexEnd(); i != e; ++i) {
if (MFI->isDeadObjectIndex(i))
continue;
if (MFI->getStackProtectorIndex() == (int)i)
continue;
if (LargeStackObjs.count(i))
continue;
AdjustStackOffset(MFI, i, Offset, StackGrowsDown, MaxAlign);
}
// Remember how big this blob of stack space is
MFI->setLocalFrameSize(Offset);
MFI->setLocalFrameMaxAlign(MaxAlign);
}
/// calculateFrameObjectOffsets - Calculate actual frame offsets for all of the
/// abstract stack objects.
///
void PEI::calculateFrameObjectOffsets(MachineFunction &Fn) {
const TargetFrameLowering &TFI = *Fn.getTarget().getFrameLowering();
bool StackGrowsDown =
TFI.getStackGrowthDirection() == TargetFrameLowering::StackGrowsDown;
// Loop over all of the stack objects, assigning sequential addresses...
MachineFrameInfo *MFI = Fn.getFrameInfo();
// Start at the beginning of the local area.
// The Offset is the distance from the stack top in the direction
// of stack growth -- so it's always nonnegative.
int LocalAreaOffset = TFI.getOffsetOfLocalArea();
if (StackGrowsDown)
LocalAreaOffset = -LocalAreaOffset;
assert(LocalAreaOffset >= 0
&& "Local area offset should be in direction of stack growth");
int64_t Offset = LocalAreaOffset;
// If there are fixed sized objects that are preallocated in the local area,
// non-fixed objects can't be allocated right at the start of local area.
// We currently don't support filling in holes in between fixed sized
// objects, so we adjust 'Offset' to point to the end of last fixed sized
// preallocated object.
for (int i = MFI->getObjectIndexBegin(); i != 0; ++i) {
int64_t FixedOff;
if (StackGrowsDown) {
// The maximum distance from the stack pointer is at lower address of
// the object -- which is given by offset. For down growing stack
// the offset is negative, so we negate the offset to get the distance.
FixedOff = -MFI->getObjectOffset(i);
} else {
// The maximum distance from the start pointer is at the upper
// address of the object.
FixedOff = MFI->getObjectOffset(i) + MFI->getObjectSize(i);
}
if (FixedOff > Offset) Offset = FixedOff;
}
// First assign frame offsets to stack objects that are used to spill
// callee saved registers.
if (StackGrowsDown) {
for (unsigned i = MinCSFrameIndex; i <= MaxCSFrameIndex; ++i) {
// If the stack grows down, we need to add the size to find the lowest
// address of the object.
Offset += MFI->getObjectSize(i);
unsigned Align = MFI->getObjectAlignment(i);
// Adjust to alignment boundary
Offset = (Offset+Align-1)/Align*Align;
MFI->setObjectOffset(i, -Offset); // Set the computed offset
}
} else {
int MaxCSFI = MaxCSFrameIndex, MinCSFI = MinCSFrameIndex;
for (int i = MaxCSFI; i >= MinCSFI ; --i) {
unsigned Align = MFI->getObjectAlignment(i);
// Adjust to alignment boundary
Offset = (Offset+Align-1)/Align*Align;
MFI->setObjectOffset(i, Offset);
Offset += MFI->getObjectSize(i);
}
}
unsigned MaxAlign = MFI->getMaxAlignment();
// Make sure the special register scavenging spill slot is closest to the
// frame pointer if a frame pointer is required.
const TargetRegisterInfo *RegInfo = Fn.getTarget().getRegisterInfo();
if (RS && TFI.hasFP(Fn) && RegInfo->useFPForScavengingIndex(Fn) &&
!RegInfo->needsStackRealignment(Fn)) {
int SFI = RS->getScavengingFrameIndex();
if (SFI >= 0)
AdjustStackOffset(MFI, SFI, StackGrowsDown, Offset, MaxAlign);
}
// FIXME: Once this is working, then enable flag will change to a target
// check for whether the frame is large enough to want to use virtual
// frame index registers. Functions which don't want/need this optimization
// will continue to use the existing code path.
if (MFI->getUseLocalStackAllocationBlock()) {
unsigned Align = MFI->getLocalFrameMaxAlign();
// Adjust to alignment boundary.
Offset = (Offset + Align - 1) / Align * Align;
DEBUG(dbgs() << "Local frame base offset: " << Offset << "\n");
// Resolve offsets for objects in the local block.
for (unsigned i = 0, e = MFI->getLocalFrameObjectCount(); i != e; ++i) {
std::pair<int, int64_t> Entry = MFI->getLocalFrameObjectMap(i);
int64_t FIOffset = (StackGrowsDown ? -Offset : Offset) + Entry.second;
DEBUG(dbgs() << "alloc FI(" << Entry.first << ") at SP[" <<
FIOffset << "]\n");
MFI->setObjectOffset(Entry.first, FIOffset);
}
// Allocate the local block
Offset += MFI->getLocalFrameSize();
MaxAlign = std::max(Align, MaxAlign);
}
// Make sure that the stack protector comes before the local variables on the
// stack.
SmallSet<int, 16> LargeStackObjs;
if (MFI->getStackProtectorIndex() >= 0) {
AdjustStackOffset(MFI, MFI->getStackProtectorIndex(), StackGrowsDown,
Offset, MaxAlign);
// Assign large stack objects first.
for (unsigned i = 0, e = MFI->getObjectIndexEnd(); i != e; ++i) {
if (MFI->isObjectPreAllocated(i) &&
MFI->getUseLocalStackAllocationBlock())
continue;
if (i >= MinCSFrameIndex && i <= MaxCSFrameIndex)
continue;
if (RS && (int)i == RS->getScavengingFrameIndex())
continue;
if (MFI->isDeadObjectIndex(i))
continue;
if (MFI->getStackProtectorIndex() == (int)i)
continue;
if (!MFI->MayNeedStackProtector(i))
continue;
AdjustStackOffset(MFI, i, StackGrowsDown, Offset, MaxAlign);
LargeStackObjs.insert(i);
}
}
// Then assign frame offsets to stack objects that are not used to spill
// callee saved registers.
for (unsigned i = 0, e = MFI->getObjectIndexEnd(); i != e; ++i) {
if (MFI->isObjectPreAllocated(i) &&
MFI->getUseLocalStackAllocationBlock())
continue;
if (i >= MinCSFrameIndex && i <= MaxCSFrameIndex)
continue;
if (RS && (int)i == RS->getScavengingFrameIndex())
continue;
if (MFI->isDeadObjectIndex(i))
continue;
if (MFI->getStackProtectorIndex() == (int)i)
continue;
if (LargeStackObjs.count(i))
continue;
AdjustStackOffset(MFI, i, StackGrowsDown, Offset, MaxAlign);
}
// Make sure the special register scavenging spill slot is closest to the
// stack pointer.
if (RS && (!TFI.hasFP(Fn) || RegInfo->needsStackRealignment(Fn) ||
!RegInfo->useFPForScavengingIndex(Fn))) {
int SFI = RS->getScavengingFrameIndex();
if (SFI >= 0)
AdjustStackOffset(MFI, SFI, StackGrowsDown, Offset, MaxAlign);
}
if (!TFI.targetHandlesStackFrameRounding()) {
// If we have reserved argument space for call sites in the function
// immediately on entry to the current function, count it as part of the
// overall stack size.
if (MFI->adjustsStack() && TFI.hasReservedCallFrame(Fn))
Offset += MFI->getMaxCallFrameSize();
// Round up the size to a multiple of the alignment. If the function has
// any calls or alloca's, align to the target's StackAlignment value to
// ensure that the callee's frame or the alloca data is suitably aligned;
// otherwise, for leaf functions, align to the TransientStackAlignment
// value.
unsigned StackAlign;
if (MFI->adjustsStack() || MFI->hasVarSizedObjects() ||
(RegInfo->needsStackRealignment(Fn) && MFI->getObjectIndexEnd() != 0))
StackAlign = TFI.getStackAlignment();
else
StackAlign = TFI.getTransientStackAlignment();
// If the frame pointer is eliminated, all frame offsets will be relative to
// SP not FP. Align to MaxAlign so this works.
StackAlign = std::max(StackAlign, MaxAlign);
unsigned AlignMask = StackAlign - 1;
Offset = (Offset + AlignMask) & ~uint64_t(AlignMask);
}
// Update frame info to pretend that this is part of the stack...
int64_t StackSize = Offset - LocalAreaOffset;
MFI->setStackSize(StackSize);
NumBytesStackSpace += StackSize;
}
