/// calculateFrameObjectOffsets - Calculate actual frame offsets for all of the
/// abstract stack objects.
void PEI::calculateFrameObjectOffsets(MachineFunction &MF) {
const TargetFrameLowering &TFI = *MF.getSubtarget().getFrameLowering();
bool StackGrowsDown =
TFI.getStackGrowthDirection() == TargetFrameLowering::StackGrowsDown;
// Loop over all of the stack objects, assigning sequential addresses...
MachineFrameInfo &MFI = MF.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;
// Skew to be applied to alignment.
unsigned Skew = TFI.getStackAlignmentSkew(MF);
// 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.
// 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 = alignTo(Offset, Align, Skew);
LLVM_DEBUG(dbgs() << "alloc FI(" << i << ") at SP[" << -Offset << "]\n");
MFI.setObjectOffset(i, -Offset); // Set the computed offset
}
} else if (MaxCSFrameIndex >= MinCSFrameIndex) {
// Be careful about underflow in comparisons agains MinCSFrameIndex.
for (unsigned i = MaxCSFrameIndex; i != MinCSFrameIndex - 1; --i) {
if (MFI.isDeadObjectIndex(i))
continue;
unsigned Align = MFI.getObjectAlignment(i);
// Adjust to alignment boundary
Offset = alignTo(Offset, Align, Skew);
LLVM_DEBUG(dbgs() << "alloc FI(" << i << ") at SP[" << Offset << "]\n");
MFI.setObjectOffset(i, Offset);
Offset += MFI.getObjectSize(i);
}
}
// FixedCSEnd is the stack offset to the end of the fixed and callee-save
// stack area.
int64_t FixedCSEnd = Offset;
unsigned MaxAlign = MFI.getMaxAlignment();
// Make sure the special register scavenging spill slot is closest to the
// incoming stack pointer if a frame pointer is required and is closer
// to the incoming rather than the final stack pointer.
const TargetRegisterInfo *RegInfo = MF.getSubtarget().getRegisterInfo();
bool EarlyScavengingSlots = (TFI.hasFP(MF) &&
TFI.isFPCloseToIncomingSP() &&
RegInfo->useFPForScavengingIndex(MF) &&
!RegInfo->needsStackRealignment(MF));
if (RS && EarlyScavengingSlots) {
SmallVector<int, 2> SFIs;
RS->getScavengingFrameIndices(SFIs);
for (SmallVectorImpl<int>::iterator I = SFIs.begin(),
IE = SFIs.end(); I != IE; ++I)
AdjustStackOffset(MFI, *I, StackGrowsDown, Offset, MaxAlign, Skew);
}
// 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 = alignTo(Offset, Align, Skew);
LLVM_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;
LLVM_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);
}
// Retrieve the Exception Handler registration node.
int EHRegNodeFrameIndex = std::numeric_limits<int>::max();
if (const WinEHFuncInfo *FuncInfo = MF.getWinEHFuncInfo())
EHRegNodeFrameIndex = FuncInfo->EHRegNodeFrameIndex;
// Make sure that the stack protector comes before the local variables on the
// stack.
SmallSet<int, 16> ProtectedObjs;
if (MFI.getStackProtectorIndex() >= 0) {
StackObjSet LargeArrayObjs;
StackObjSet SmallArrayObjs;
StackObjSet AddrOfObjs;
AdjustStackOffset(MFI, MFI.getStackProtectorIndex(), StackGrowsDown,
Offset, MaxAlign, Skew);
// 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 && RS->isScavengingFrameIndex((int)i))
continue;
if (MFI.isDeadObjectIndex(i))
continue;
if (MFI.getStackProtectorIndex() == (int)i ||
EHRegNodeFrameIndex == (int)i)
continue;
switch (MFI.getObjectSSPLayout(i)) {
case MachineFrameInfo::SSPLK_None:
continue;
case MachineFrameInfo::SSPLK_SmallArray:
SmallArrayObjs.insert(i);
continue;
case MachineFrameInfo::SSPLK_AddrOf:
AddrOfObjs.insert(i);
continue;
case MachineFrameInfo::SSPLK_LargeArray:
LargeArrayObjs.insert(i);
continue;
}
llvm_unreachable("Unexpected SSPLayoutKind.");
}
AssignProtectedObjSet(LargeArrayObjs, ProtectedObjs, MFI, StackGrowsDown,
Offset, MaxAlign, Skew);
AssignProtectedObjSet(SmallArrayObjs, ProtectedObjs, MFI, StackGrowsDown,
Offset, MaxAlign, Skew);
AssignProtectedObjSet(AddrOfObjs, ProtectedObjs, MFI, StackGrowsDown,
Offset, MaxAlign, Skew);
}
SmallVector<int, 8> ObjectsToAllocate;
// Then prepare to 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 && RS->isScavengingFrameIndex((int)i))
continue;
if (MFI.isDeadObjectIndex(i))
continue;
if (MFI.getStackProtectorIndex() == (int)i ||
EHRegNodeFrameIndex == (int)i)
continue;
if (ProtectedObjs.count(i))
continue;
// Add the objects that we need to allocate to our working set.
ObjectsToAllocate.push_back(i);
}
// Allocate the EH registration node first if one is present.
if (EHRegNodeFrameIndex != std::numeric_limits<int>::max())
AdjustStackOffset(MFI, EHRegNodeFrameIndex, StackGrowsDown, Offset,
MaxAlign, Skew);
// Give the targets a chance to order the objects the way they like it.
if (MF.getTarget().getOptLevel() != CodeGenOpt::None &&
MF.getTarget().Options.StackSymbolOrdering)
TFI.orderFrameObjects(MF, ObjectsToAllocate);
// Keep track of which bytes in the fixed and callee-save range are used so we
// can use the holes when allocating later stack objects. Only do this if
// stack protector isn't being used and the target requests it and we're
// optimizing.
BitVector StackBytesFree;
if (!ObjectsToAllocate.empty() &&
MF.getTarget().getOptLevel() != CodeGenOpt::None &&
MFI.getStackProtectorIndex() < 0 && TFI.enableStackSlotScavenging(MF))
computeFreeStackSlots(MFI, StackGrowsDown, MinCSFrameIndex, MaxCSFrameIndex,
FixedCSEnd, StackBytesFree);
// Now walk the objects and actually assign base offsets to them.
for (auto &Object : ObjectsToAllocate)
if (!scavengeStackSlot(MFI, Object, StackGrowsDown, MaxAlign,
StackBytesFree))
AdjustStackOffset(MFI, Object, StackGrowsDown, Offset, MaxAlign, Skew);
// Make sure the special register scavenging spill slot is closest to the
// stack pointer.
if (RS && !EarlyScavengingSlots) {
SmallVector<int, 2> SFIs;
RS->getScavengingFrameIndices(SFIs);
for (SmallVectorImpl<int>::iterator I = SFIs.begin(),
IE = SFIs.end(); I != IE; ++I)
AdjustStackOffset(MFI, *I, StackGrowsDown, Offset, MaxAlign, Skew);
}
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(MF))
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(MF) && 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);
Offset = alignTo(Offset, StackAlign, Skew);
}
// Update frame info to pretend that this is part of the stack...
int64_t StackSize = Offset - LocalAreaOffset;
MFI.setStackSize(StackSize);
NumBytesStackSpace += StackSize;
}
bool GcInfoRecorder::runOnMachineFunction(MachineFunction &MF) {
const Function *F = MF.getFunction();
if (!GcInfo::isGcFunction(F)) {
return false;
}
LLILCJitContext *Context = LLILCJit::TheJit->getLLILCJitContext();
GcFuncInfo *GcFuncInfo = Context->GcInfo->getGcInfo(F);
ValueMap<const AllocaInst *, AllocaInfo> &AllocaMap = GcFuncInfo->AllocaMap;
#if !defined(NDEBUG)
bool EmitLogs = Context->Options->LogGcInfo;
if (EmitLogs) {
dbgs() << "GcInfoRecorder: " << MF.getFunction()->getName() << "\n";
}
#endif // !NDEBUG
const MachineFrameInfo *FrameInfo = MF.getFrameInfo();
int ObjectIndexBegin = FrameInfo->getObjectIndexBegin();
int ObjectIndexEnd = FrameInfo->getObjectIndexEnd();
// FrameInfo reports the allocation offsets in terms of the
// incoming (caller's) StackPointer. Convert these in terms of the
// current (callee's) StackPointer.
uint64_t StackPointerSize = MF.getDataLayout().getPointerSize();
uint64_t SpOffset = FrameInfo->getStackSize() + StackPointerSize;
for (int Idx = ObjectIndexBegin; Idx < ObjectIndexEnd; Idx++) {
const AllocaInst *Alloca = FrameInfo->getObjectAllocation(Idx);
if (Alloca == nullptr) {
continue;
}
if (GcFuncInfo->hasRecord(Alloca)) {
int32_t SlotOffset = SpOffset + FrameInfo->getObjectOffset(Idx);
AllocaInfo &AllocaInfo = AllocaMap[Alloca];
assert(SlotOffset >= 0);
assert(AllocaInfo.Offset == GcInfo::InvalidPointerOffset &&
"Two slots for the same alloca!");
AllocaInfo.Offset = SlotOffset;
#if !defined(NDEBUG)
if (AllocaInfo.isGcAggregate()) {
assert(isa<StructType>(Alloca->getAllocatedType()) &&
"Unhandled Type of GcAggregate");
} else if (AllocaInfo.isGcPointer()) {
assert(GcInfo::isGcPointer(Alloca->getAllocatedType()));
} else {
assert(!GcInfo::isGcAllocation(Alloca));
}
if (EmitLogs) {
dbgs() << AllocaInfo.getAllocTypeString() << " @ sp+" << SlotOffset
<< " [";
Alloca->printAsOperand(dbgs(), false);
dbgs() << "]\n";
}
#endif // !NDEBUG
} else {
// All GC-aggregate Allocas must be registered before this phase.
// This ensures that the allocations are properly initialized,
// and marked as frame-escaped if necessary.
//
// TODO: The following check should be:
// assert(!GcInfo::isGcAllocation(Alloca) &&
// "Gc Allocation Record missing");
#if !defined(NDEBUG)
if (GcInfo::isGcAllocation(Alloca)) {
// However, some Gc-pointer slots created by WinEHPrepare phase
// go unrecorded currently because the AllocaInfos are recorded
// by the Reader post-pass.
// TODO: Report the Spill slots created by WinEHPrepare
// https://github.com/dotnet/llilc/issues/901
assert(Alloca->hasName());
assert(Alloca->getName().find(".wineh.spillslot") != StringRef::npos);
// WinEH shouldn't spill GC-aggregates
assert(!GcInfo::isGcAggregate(Alloca->getAllocatedType()));
// The unreported slots are live across safepoints in the
// EH path, so the execution is correct unless we take the
// exception path.
assert(!(Context->Options->ExecuteHandlers &&
Context->Options->DoInsertStatepoints) &&
"Untested: Use at your own risk");
}
#endif // !NDEBUG
}
}
// Unlike the other offsets reported to the GC, the PSPSym offset is relative
// to Initial-SP (i.e. the value of the stack pointer just after this
// method's prolog), NOT Caller-SP.
if (WinEHFuncInfo *EHInfo = MF.getWinEHFuncInfo()) {
int PSPSymIndex = EHInfo->PSPSymFrameIdx;
if (PSPSymIndex != INT_MAX) {
GcFuncInfo->HasFunclets = true;
const TargetFrameLowering *TFL = MF.getSubtarget().getFrameLowering();
// SPReg is an out parameter that we're not using here.
unsigned SPReg;
int PSPOffset = TFL->getFrameIndexReferenceFromSP(MF, PSPSymIndex, SPReg);
assert(PSPOffset >= 0);
GcFuncInfo->PSPSymOffset = static_cast<uint32_t>(PSPOffset);
}
}
return false; // success
}
