[LiveRangeCalc] Fix isJointlyDominated (#116020)
Check that every path from the entry block to the use block passes
through at least one def block. Previously we only checked that at least
one path passed through a def block.
diff --git a/llvm/lib/CodeGen/LiveRangeCalc.cpp b/llvm/lib/CodeGen/LiveRangeCalc.cpp
index dfd4d29..1a9bc69 100644
--- a/llvm/lib/CodeGen/LiveRangeCalc.cpp
+++ b/llvm/lib/CodeGen/LiveRangeCalc.cpp
@@ -441,15 +441,21 @@
for (SlotIndex I : Defs)
DefBlocks.set(Indexes.getMBBFromIndex(I)->getNumber());
+ unsigned EntryNum = MF.front().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;
+ continue;
+ if (BN == EntryNum) {
+ // We found a path from MBB back to the entry block without hitting any of
+ // the def blocks.
+ return false;
+ }
const MachineBasicBlock *B = MF.getBlockNumbered(BN);
for (const MachineBasicBlock *P : B->predecessors())
PredQueue.insert(P->getNumber());
}
- return false;
+ return true;
}
