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Be more accurate about the slot index reading a register when dealing with defs 

and early clobbers.

Assert when trying to find an undefined value.

llvm-svn: 127856
This commit is contained in:
Jakob Stoklund Olesen 2011-03-18 03:06:02 +00:00
parent fca6fd4aed
commit c099dde918
1 changed files with 20 additions and 4 deletions
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24
llvm/lib/CodeGen/SplitKit.cpp
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@ -348,6 +348,7 @@ void SplitEditor::extendRange(unsigned RegIdx, SlotIndex Idx) {
// Using LiveOutCache as a visited set, perform a BFS for all reaching defs. // Using LiveOutCache as a visited set, perform a BFS for all reaching defs.
for (unsigned i = 0; i != LiveIn.size(); ++i) { for (unsigned i = 0; i != LiveIn.size(); ++i) {
MachineBasicBlock *MBB = LiveIn[i]->getBlock(); MachineBasicBlock *MBB = LiveIn[i]->getBlock();
assert(!MBB->pred_empty() && "Value live-in to entry block?");
for (MachineBasicBlock::pred_iterator PI = MBB->pred_begin(), for (MachineBasicBlock::pred_iterator PI = MBB->pred_begin(),
PE = MBB->pred_end(); PI != PE; ++PI) { PE = MBB->pred_end(); PI != PE; ++PI) {
MachineBasicBlock *Pred = *PI; MachineBasicBlock *Pred = *PI;
@ -757,7 +758,8 @@ void SplitEditor::rewriteAssigned(bool ExtendRanges) {
} }
SlotIndex Idx = LIS.getInstructionIndex(MI); SlotIndex Idx = LIS.getInstructionIndex(MI);
Idx = MO.isUse() ? Idx.getUseIndex() : Idx.getDefIndex(); if (MO.isDef())
Idx = MO.isEarlyClobber() ? Idx.getUseIndex() : Idx.getDefIndex();
// Rewrite to the mapped register at Idx. // Rewrite to the mapped register at Idx.
unsigned RegIdx = RegAssign.lookup(Idx); unsigned RegIdx = RegAssign.lookup(Idx);
@ -765,9 +767,23 @@ void SplitEditor::rewriteAssigned(bool ExtendRanges) {
DEBUG(dbgs() << " rewr BB#" << MI->getParent()->getNumber() << '\t' DEBUG(dbgs() << " rewr BB#" << MI->getParent()->getNumber() << '\t'
<< Idx << ':' << RegIdx << '\t' << *MI); << Idx << ':' << RegIdx << '\t' << *MI);
// Extend liveness to Idx. // Extend liveness to Idx if the instruction reads reg.
if (ExtendRanges) if (!ExtendRanges)
extendRange(RegIdx, Idx); continue;
// Skip instructions that don't read Reg.
if (MO.isDef()) {
if (!MO.getSubReg() && !MO.isEarlyClobber())
continue;
// We may wan't to extend a live range for a partial redef, or for a use
// tied to an early clobber.
Idx = Idx.getPrevSlot();
if (!Edit->getParent().liveAt(Idx))
continue;
} else
Idx = Idx.getUseIndex();
extendRange(RegIdx, Idx);
} }
} }