From c79532d1010617d9428c934d4c2c8724cef8fa97 Mon Sep 17 00:00:00 2001 From: Rafael Espindola Date: Wed, 14 Nov 2012 05:08:56 +0000 Subject: Handle DAG CSE adding new uses during ReplaceAllUsesWith. Fixes PR14333. llvm-svn: 167912 --- llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp | 13 ++++++++++++- 1 file changed, 12 insertions(+), 1 deletion(-) (limited to 'llvm/lib/CodeGen') diff --git a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp index 5416a5c1d7a..37d7731aa15 100644 --- a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp +++ b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp @@ -7728,7 +7728,18 @@ bool DAGCombiner::MergeConsecutiveStores(StoreSDNode* St) { if (StoreNodes[i].MemNode == EarliestOp) continue; StoreSDNode *St = cast(StoreNodes[i].MemNode); - DAG.ReplaceAllUsesOfValueWith(SDValue(St, 0), St->getChain()); + // ReplaceAllUsesWith will replace all uses that existed when it was + // called, but graph optimizations may cause new ones to appear. For + // example, the case in pr14333 looks like + // + // St's chain -> St -> another store -> X + // + // And the only difference from St to the other store is the chain. + // When we change it's chain to be St's chain they become identical, + // get CSEed and the net result is that X is now a use of St. + // Since we know that St is redundant, just iterate. + while (!St->use_empty()) + DAG.ReplaceAllUsesWith(SDValue(St, 0), St->getChain()); removeFromWorkList(St); DAG.DeleteNode(St); } -- cgit v1.2.3