From d101a72d79d910abf781e6573be0edac99061acc Mon Sep 17 00:00:00 2001 From: Evan Cheng Date: Tue, 21 Jul 2009 05:40:15 +0000 Subject: Fix a dagga combiner bug: avoid creating illegal constant. Is this really a winning transformation? fold (shl (srl x, c1), c2) -> (shl (and x, (shl -1, c1)), (sub c2, c1)) or (srl (and x, (shl -1, c1)), (sub c1, c2)) git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@76535 91177308-0d34-0410-b5e6-96231b3b80d8 --- lib/CodeGen/SelectionDAG/DAGCombiner.cpp | 21 ++++++++++++--------- 1 file changed, 12 insertions(+), 9 deletions(-) (limited to 'lib/CodeGen') diff --git a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp index 4ff2a3aded..370054d296 100644 --- a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp +++ b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp @@ -2475,15 +2475,18 @@ SDValue DAGCombiner::visitSHL(SDNode *N) { if (N1C && N0.getOpcode() == ISD::SRL && N0.getOperand(1).getOpcode() == ISD::Constant) { uint64_t c1 = cast(N0.getOperand(1))->getZExtValue(); - uint64_t c2 = N1C->getZExtValue(); - SDValue Mask = DAG.getNode(ISD::AND, N0.getDebugLoc(), VT, N0.getOperand(0), - DAG.getConstant(~0ULL << c1, VT)); - if (c2 > c1) - return DAG.getNode(ISD::SHL, N->getDebugLoc(), VT, Mask, - DAG.getConstant(c2-c1, N1.getValueType())); - else - return DAG.getNode(ISD::SRL, N->getDebugLoc(), VT, Mask, - DAG.getConstant(c1-c2, N1.getValueType())); + if (c1 < VT.getSizeInBits()) { + uint64_t c2 = N1C->getZExtValue(); + SDValue Mask = DAG.getNode(ISD::AND, N0.getDebugLoc(), VT, + N0.getOperand(0), + DAG.getConstant(~0ULL << c1, VT)); + if (c2 > c1) + return DAG.getNode(ISD::SHL, N->getDebugLoc(), VT, Mask, + DAG.getConstant(c2-c1, N1.getValueType())); + else + return DAG.getNode(ISD::SRL, N->getDebugLoc(), VT, Mask, + DAG.getConstant(c1-c2, N1.getValueType())); + } } // fold (shl (sra x, c1), c1) -> (and x, (shl -1, c1)) if (N1C && N0.getOpcode() == ISD::SRA && N1 == N0.getOperand(1)) -- cgit v1.2.3-70-g09d2