Account for undef values from predecessors in extendSegmentsToUses
It is legal for a PHI node not to have a live value in a predecessor
as long as the end of the predecessor is jointly dominated by an undef
value.
llvm-svn: 335607
diff --git a/llvm/lib/CodeGen/LiveRangeCalc.cpp b/llvm/lib/CodeGen/LiveRangeCalc.cpp
index 66c23b7..0432494 100644
--- a/llvm/lib/CodeGen/LiveRangeCalc.cpp
+++ b/llvm/lib/CodeGen/LiveRangeCalc.cpp
@@ -584,3 +584,24 @@
}
} while (Changed);
}
+
+bool LiveRangeCalc::isJointlyDominated(const MachineBasicBlock *MBB,
+ ArrayRef<SlotIndex> Defs,
+ const SlotIndexes &Indexes) {
+ const MachineFunction &MF = *MBB->getParent();
+ BitVector DefBlocks(MF.getNumBlockIDs());
+ for (SlotIndex I : Defs)
+ DefBlocks.set(Indexes.getMBBFromIndex(I)->getNumber());
+
+ SetVector<unsigned> PredQueue;
+ PredQueue.insert(MBB->getNumber());
+ for (unsigned i = 0; i != PredQueue.size(); ++i) {
+ unsigned BN = PredQueue[i];
+ if (DefBlocks[BN])
+ return true;
+ const MachineBasicBlock *B = MF.getBlockNumbered(BN);
+ for (const MachineBasicBlock *P : B->predecessors())
+ PredQueue.insert(P->getNumber());
+ }
+ return false;
+}
