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If we see a load from a stack slot into a physreg, consider it as providing

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the stack slot.  This fixes PR943.

llvm-svn: 30898
This commit is contained in:
Chris Lattner 2006-10-12 02:34:07 +00:00
parent 65264c811f
commit d781da5f26
1 changed files with 32 additions and 17 deletions
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19
lib/CodeGen/VirtRegMap.cpp
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@ -706,10 +706,10 @@ void LocalSpiller::RewriteMBB(MachineBasicBlock &MBB, VirtRegMap &VRM) {
if ((MR & VirtRegMap::isRef) && !(MR & VirtRegMap::isMod)) {
int FrameIdx;
if (unsigned DestReg = TII->isLoadFromStackSlot(&MI, FrameIdx)) {
if (FrameIdx == SS) {
// If this spill slot is available, turn it into a copy (or nothing)
// instead of leaving it as a load!
unsigned InReg;
if (FrameIdx == SS && (InReg = Spills.getSpillSlotPhysReg(SS))) {
if (unsigned InReg = Spills.getSpillSlotPhysReg(SS)) {
DEBUG(std::cerr << "Promoted Load To Copy: " << MI);
MachineFunction &MF = *MBB.getParent();
if (DestReg != InReg) {
@ -727,6 +727,7 @@ void LocalSpiller::RewriteMBB(MachineBasicBlock &MBB, VirtRegMap &VRM) {
}
}
}
}
// If this reference is not a use, any previous store is now dead.
// Otherwise, the store to this stack slot is not dead anymore.
@ -791,7 +792,21 @@ void LocalSpiller::RewriteMBB(MachineBasicBlock &MBB, VirtRegMap &VRM) {
VRM.RemoveFromFoldedVirtMap(&MI);
goto ProcessNextInst;
}
// If it's not a no-op copy, it clobbers the value in the destreg.
Spills.ClobberPhysReg(VirtReg);
// Check to see if this instruction is a load from a stack slot into
// a register. If so, this provides the stack slot value in the reg.
int FrameIdx;
if (unsigned DestReg = TII->isLoadFromStackSlot(&MI, FrameIdx)) {
assert(DestReg == VirtReg && "Unknown load situation!");
// Otherwise, if it wasn't available, remember that it is now!
Spills.addAvailable(FrameIdx, DestReg);
goto ProcessNextInst;
}
continue;
}