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Better handling of local offsets for downwards growing stacks. This corrects
relative offsets when there are offsets encoded in the instructions and simplifies final allocation in PEI. rdar://8277890 llvm-svn: 111836
This commit is contained in:
Jim Grosbach
parent
6bd4b1cc6c
commit
2bce13a3a4
@ -46,7 +46,7 @@ namespace {
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SmallVector<int64_t,16> LocalOffsets;
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void AdjustStackOffset(MachineFrameInfo *MFI, int FrameIdx, int64_t &Offset,
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unsigned &MaxAlign);
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bool StackGrowsDown, unsigned &MaxAlign);
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void calculateFrameObjectOffsets(MachineFunction &Fn);
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bool insertFrameReferenceRegisters(MachineFunction &Fn);
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public:
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@ -102,7 +102,12 @@ bool LocalStackSlotPass::runOnMachineFunction(MachineFunction &MF) {
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/// AdjustStackOffset - Helper function used to adjust the stack frame offset.
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void LocalStackSlotPass::AdjustStackOffset(MachineFrameInfo *MFI,
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int FrameIdx, int64_t &Offset,
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bool StackGrowsDown,
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unsigned &MaxAlign) {
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// If the stack grows down, add the object size to find the lowest address.
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if (StackGrowsDown)
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Offset += MFI->getObjectSize(FrameIdx);
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unsigned Align = MFI->getObjectAlignment(FrameIdx);
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// If the alignment of this object is greater than that of the stack, then
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@ -112,13 +117,16 @@ void LocalStackSlotPass::AdjustStackOffset(MachineFrameInfo *MFI,
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// Adjust to alignment boundary.
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Offset = (Offset + Align - 1) / Align * Align;
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int64_t LocalOffset = StackGrowsDown ? -Offset : Offset;
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DEBUG(dbgs() << "Allocate FI(" << FrameIdx << ") to local offset "
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<< Offset << "\n");
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<< LocalOffset << "\n");
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// Keep the offset available for base register allocation
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LocalOffsets[FrameIdx] = Offset;
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LocalOffsets[FrameIdx] = LocalOffset;
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// And tell MFI about it for PEI to use later
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MFI->mapLocalFrameObject(FrameIdx, Offset);
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Offset += MFI->getObjectSize(FrameIdx);
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MFI->mapLocalFrameObject(FrameIdx, LocalOffset);
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if (!StackGrowsDown)
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Offset += MFI->getObjectSize(FrameIdx);
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++NumAllocations;
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}
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@ -129,6 +137,9 @@ void LocalStackSlotPass::AdjustStackOffset(MachineFrameInfo *MFI,
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void LocalStackSlotPass::calculateFrameObjectOffsets(MachineFunction &Fn) {
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// Loop over all of the stack objects, assigning sequential addresses...
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MachineFrameInfo *MFI = Fn.getFrameInfo();
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const TargetFrameInfo &TFI = *Fn.getTarget().getFrameInfo();
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bool StackGrowsDown =
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TFI.getStackGrowthDirection() == TargetFrameInfo::StackGrowsDown;
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int64_t Offset = 0;
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unsigned MaxAlign = 0;
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@ -136,7 +147,8 @@ void LocalStackSlotPass::calculateFrameObjectOffsets(MachineFunction &Fn) {
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// stack.
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SmallSet<int, 16> LargeStackObjs;
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if (MFI->getStackProtectorIndex() >= 0) {
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AdjustStackOffset(MFI, MFI->getStackProtectorIndex(), Offset, MaxAlign);
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AdjustStackOffset(MFI, MFI->getStackProtectorIndex(), Offset,
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StackGrowsDown, MaxAlign);
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// Assign large stack objects first.
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for (unsigned i = 0, e = MFI->getObjectIndexEnd(); i != e; ++i) {
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@ -147,7 +159,7 @@ void LocalStackSlotPass::calculateFrameObjectOffsets(MachineFunction &Fn) {
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if (!MFI->MayNeedStackProtector(i))
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continue;
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AdjustStackOffset(MFI, i, Offset, MaxAlign);
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AdjustStackOffset(MFI, i, Offset, StackGrowsDown, MaxAlign);
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LargeStackObjs.insert(i);
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}
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}
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@ -162,7 +174,7 @@ void LocalStackSlotPass::calculateFrameObjectOffsets(MachineFunction &Fn) {
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if (LargeStackObjs.count(i))
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continue;
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AdjustStackOffset(MFI, i, Offset, MaxAlign);
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AdjustStackOffset(MFI, i, Offset, StackGrowsDown, MaxAlign);
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}
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// Remember how big this blob of stack space is
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@ -173,8 +185,8 @@ void LocalStackSlotPass::calculateFrameObjectOffsets(MachineFunction &Fn) {
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static inline bool
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lookupCandidateBaseReg(const SmallVector<std::pair<unsigned, int64_t>, 8> &Regs,
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std::pair<unsigned, int64_t> &RegOffset,
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int64_t FrameSizeAdjust,
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int64_t LocalFrameOffset,
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bool StackGrowsDown,
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const MachineInstr *MI,
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const TargetRegisterInfo *TRI) {
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unsigned e = Regs.size();
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@ -182,9 +194,7 @@ lookupCandidateBaseReg(const SmallVector<std::pair<unsigned, int64_t>, 8> &Regs,
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RegOffset = Regs[i];
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// Check if the relative offset from the where the base register references
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// to the target address is in range for the instruction.
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int64_t Offset = LocalFrameOffset - RegOffset.second;
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if (StackGrowsDown)
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Offset = -Offset;
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int64_t Offset = FrameSizeAdjust + LocalFrameOffset - RegOffset.second;
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if (TRI->isFrameOffsetLegal(MI, Offset))
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return true;
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}
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@ -241,6 +251,8 @@ bool LocalStackSlotPass::insertFrameReferenceRegisters(MachineFunction &Fn) {
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if (TRI->needsFrameBaseReg(MI, i)) {
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unsigned BaseReg = 0;
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int64_t Offset = 0;
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int64_t FrameSizeAdjust = StackGrowsDown ? MFI->getLocalFrameSize()
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: 0;
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DEBUG(dbgs() << " Replacing FI in: " << *MI);
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@ -251,15 +263,15 @@ bool LocalStackSlotPass::insertFrameReferenceRegisters(MachineFunction &Fn) {
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// register.
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std::pair<unsigned, int64_t> RegOffset;
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if (lookupCandidateBaseReg(BaseRegisters, RegOffset,
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FrameSizeAdjust,
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LocalOffsets[FrameIdx],
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StackGrowsDown, MI, TRI)) {
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MI, TRI)) {
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DEBUG(dbgs() << " Reusing base register " <<
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RegOffset.first << "\n");
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// We found a register to reuse.
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BaseReg = RegOffset.first;
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Offset = LocalOffsets[FrameIdx] - RegOffset.second;
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if (StackGrowsDown)
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Offset = -Offset;
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Offset = FrameSizeAdjust + LocalOffsets[FrameIdx] -
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RegOffset.second;
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} else {
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// No previously defined register was in range, so create a
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// new one.
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@ -280,9 +292,10 @@ bool LocalStackSlotPass::insertFrameReferenceRegisters(MachineFunction &Fn) {
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// applied twice.
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Offset = -InstrOffset;
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int64_t BaseOffset = FrameSizeAdjust + LocalOffsets[FrameIdx] +
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InstrOffset;
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BaseRegisters.push_back(
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std::pair<unsigned, int64_t>(BaseReg,
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LocalOffsets[FrameIdx] + InstrOffset));
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std::pair<unsigned, int64_t>(BaseReg, BaseOffset));
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++NumBaseRegisters;
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UsedBaseReg = true;
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}
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@ -295,7 +308,6 @@ bool LocalStackSlotPass::insertFrameReferenceRegisters(MachineFunction &Fn) {
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++NumReplacements;
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}
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}
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}
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}
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@ -572,16 +572,18 @@ void PEI::calculateFrameObjectOffsets(MachineFunction &Fn) {
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DEBUG(dbgs() << "Local frame base offset: " << Offset << "\n");
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// Allocate the local block
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Offset += MFI->getLocalFrameSize();
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// Resolve offsets for objects in the local block.
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for (unsigned i = 0, e = MFI->getLocalFrameObjectCount(); i != e; ++i) {
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std::pair<int, int64_t> Entry = MFI->getLocalFrameObjectMap(i);
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int64_t FIOffset = MFI->getLocalFrameBaseOffset() + Entry.second;
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AdjustStackOffset(MFI, Entry.first, StackGrowsDown, FIOffset, MaxAlign);
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int64_t FIOffset = (StackGrowsDown ? -Offset : Offset) + Entry.second;
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DEBUG(dbgs() << "alloc FI(" << Entry.first << ") at SP[" <<
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FIOffset << "]\n");
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MFI->setObjectOffset(Entry.first, FIOffset);
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}
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// Allocate the local block
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Offset += MFI->getLocalFrameSize();
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MaxAlign = std::max(Align, MaxAlign);
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}
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// Make sure that the stack protector comes before the local variables on the
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