From db4201235b515c6ebeb0afb031b0cacfcae656e2 Mon Sep 17 00:00:00 2001 From: Owen Anderson Date: Thu, 19 Mar 2015 22:48:57 +0000 Subject: Fix a nasty bug in DAGCombine of STORE nodes. This is very related to the bug fixed in r174431. The problem is that SelectionDAG does not include alignment in the uniquing of loads and stores. When an otherwise no-op DAGCombine would increase the alignment of a load or store, the original node would be returned (with the alignment increased), which would cause the node not to be processed by any further DAGCombines. I don't have a direct testcase for this that manifests on an in-tree target, but I did see some noise in the tests for other targets and have updated them for it. llvm-svn: 232780 --- llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp | 11 ++++++++--- 1 file changed, 8 insertions(+), 3 deletions(-) (limited to 'llvm/lib/CodeGen') diff --git a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp index 8ea1d41b245..702147155ba 100644 --- a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp +++ b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp @@ -9072,7 +9072,8 @@ SDValue DAGCombiner::visitLOAD(SDNode *N) { LD->getMemoryVT(), LD->isVolatile(), LD->isNonTemporal(), LD->isInvariant(), Align, LD->getAAInfo()); - return CombineTo(N, NewLoad, SDValue(NewLoad.getNode(), 1), true); + if (NewLoad.getNode() != N) + return CombineTo(N, NewLoad, SDValue(NewLoad.getNode(), 1), true); } } } @@ -10703,11 +10704,15 @@ SDValue DAGCombiner::visitSTORE(SDNode *N) { // Try to infer better alignment information than the store already has. if (OptLevel != CodeGenOpt::None && ST->isUnindexed()) { if (unsigned Align = DAG.InferPtrAlignment(Ptr)) { - if (Align > ST->getAlignment()) - return DAG.getTruncStore(Chain, SDLoc(N), Value, + if (Align > ST->getAlignment()) { + SDValue NewStore = + DAG.getTruncStore(Chain, SDLoc(N), Value, Ptr, ST->getPointerInfo(), ST->getMemoryVT(), ST->isVolatile(), ST->isNonTemporal(), Align, ST->getAAInfo()); + if (NewStore.getNode() != N) + return CombineTo(ST, NewStore, true); + } } } -- cgit v1.2.3