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Better handling of offsets on frame index references. rdar://8277890

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llvm-svn: 111585
This commit is contained in:
Jim Grosbach
2010-08-19 23:52:25 +00:00
parent b3774b5c1e
commit 56e56323c8
4 changed files with 99 additions and 23 deletions
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28
llvm/lib/CodeGen/LocalStackSlotAllocation.cpp
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@@ -182,7 +182,7 @@ lookupCandidateBaseReg(const SmallVector<std::pair<unsigned, int64_t>, 8> &Regs,
// Check if the relative offset from the where the base register references
// to the target address is in range for the instruction.
int64_t Offset = LocalFrameOffset - RegOffset.second;
if (TRI->isBaseRegInRange(MI, RegOffset.first, Offset))
if (TRI->isFrameOffsetLegal(MI, Offset))
return true;
}
return false;
@@ -225,6 +225,7 @@ void LocalStackSlotPass::insertFrameReferenceRegisters(MachineFunction &Fn) {
// an object allocated in the local block.
if (MI->getOperand(i).isFI()) {
int FrameIdx = MI->getOperand(i).getIndex();
// Don't try this with values not in the local block.
if (!MFI->isObjectPreAllocated(FrameIdx))
continue;
@@ -232,13 +233,15 @@ void LocalStackSlotPass::insertFrameReferenceRegisters(MachineFunction &Fn) {
DEBUG(dbgs() << "Considering: " << *MI);
if (TRI->needsFrameBaseReg(MI, i)) {
unsigned BaseReg = 0;
unsigned Offset = 0;
int64_t Offset = 0;
DEBUG(dbgs() << " Replacing FI in: " << *MI);
// If we have a suitable base register available, use it; otherwise
// create a new one.
// create a new one. Note that any offset encoded in the
// instruction itself will be taken into account by the target,
// so we don't have to adjust for it here when reusing a base
// register.
std::pair<unsigned, int64_t> RegOffset;
if (lookupCandidateBaseReg(BaseRegisters, RegOffset,
LocalOffsets[FrameIdx], MI, TRI)) {
@@ -250,15 +253,26 @@ void LocalStackSlotPass::insertFrameReferenceRegisters(MachineFunction &Fn) {
} else {
// No previously defined register was in range, so create a
// new one.
int64_t InstrOffset = TRI->getFrameIndexInstrOffset(MI, i);
const TargetRegisterClass *RC = TRI->getPointerRegClass();
BaseReg = Fn.getRegInfo().createVirtualRegister(RC);
DEBUG(dbgs() << " Materializing base register " << BaseReg <<
" at frame local offset " <<
LocalOffsets[FrameIdx] + InstrOffset << "\n");
// Tell the target to insert the instruction to initialize
// the base register.
TRI->materializeFrameBaseRegister(I, BaseReg, FrameIdx);
TRI->materializeFrameBaseRegister(I, BaseReg, FrameIdx,
InstrOffset);
BaseRegisters.push_back(std::pair<unsigned, int64_t>(BaseReg,
Offset));
// The base register already includes any offset specified
// by the instruction, so account for that so it doesn't get
// applied twice.
Offset = -InstrOffset;
BaseRegisters.push_back(
std::pair<unsigned, int64_t>(BaseReg,
LocalOffsets[FrameIdx] + InstrOffset));
++NumBaseRegisters;
}
assert(BaseReg != 0 && "Unable to allocate virtual base register!");