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When we find a reaching definition, make sure it is visited from all paths by 

erasing it from the visited set. That ensures we create the right phi defs.

llvm-svn: 115666
This commit is contained in:
Jakob Stoklund Olesen 2010-10-05 20:36:28 +00:00
parent b0cedd5f96
commit 671bab1c7d
1 changed files with 11 additions and 4 deletions
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15
llvm/lib/CodeGen/SplitKit.cpp
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@ -424,10 +424,14 @@ VNInfo *LiveIntervalMap::mapValue(const VNInfo *ParentVNI, SlotIndex Idx,
// This may change during the DFS as we create new phi-defs.
typedef DenseMap<MachineBasicBlock*, VNInfo*> MBBValueMap;
MBBValueMap DomValue;
typedef SplitAnalysis::BlockPtrSet BlockPtrSet;
BlockPtrSet Visited;
for (idf_iterator<MachineBasicBlock*>
IDFI = idf_begin(IdxMBB),
IDFE = idf_end(IdxMBB); IDFI != IDFE;) {
// Iterate over IdxMBB predecessors in a depth-first order.
// Skip begin() since that is always IdxMBB.
for (idf_ext_iterator<MachineBasicBlock*, BlockPtrSet>
IDFI = llvm::next(idf_ext_begin(IdxMBB, Visited)),
IDFE = idf_ext_end(IdxMBB, Visited); IDFI != IDFE;) {
MachineBasicBlock *MBB = *IDFI;
SlotIndex End = lis_.getMBBEndIdx(MBB).getPrevSlot();
@ -444,7 +448,10 @@ VNInfo *LiveIntervalMap::mapValue(const VNInfo *ParentVNI, SlotIndex Idx,
continue;
}
// Yes, VNI dominates MBB. Track the path back to IdxMBB, creating phi-defs
// Yes, VNI dominates MBB. Make sure we visit MBB again from other paths.
Visited.erase(MBB);
// Track the path back to IdxMBB, creating phi-defs
// as needed along the way.
for (unsigned PI = IDFI.getPathLength()-1; PI != 0; --PI) {
// Start from MBB's immediate successor. End at IdxMBB.