diff options
Diffstat (limited to 'llvm/lib')
| -rw-r--r-- | llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp | 19 |
1 files changed, 18 insertions, 1 deletions
diff --git a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp index eb98f75b9fa..ffe38e3fb06 100644 --- a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp +++ b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp @@ -3074,12 +3074,15 @@ static SDValue simplifyDivRem(SDNode *N, SelectionDAG &DAG) { EVT VT = N->getValueType(0); SDLoc DL(N); + unsigned Opc = N->getOpcode(); + bool IsDiv = (ISD::SDIV == Opc) || (ISD::UDIV == Opc); + // X / undef -> undef // X % undef -> undef // X / 0 -> undef // X % 0 -> undef // NOTE: This includes vectors where any divisor element is zero/undef. - if (DAG.isUndef(N->getOpcode(), {N0, N1})) + if (DAG.isUndef(Opc, {N0, N1})) return DAG.getUNDEF(VT); // undef / X -> 0 @@ -3087,6 +3090,20 @@ static SDValue simplifyDivRem(SDNode *N, SelectionDAG &DAG) { if (N0.isUndef()) return DAG.getConstant(0, DL, VT); + // TODO: 0 / X -> 0 + // TODO: 0 % X -> 0 + + // X / X -> 1 + // X % X -> 0 + if (N0 == N1) + return DAG.getConstant(IsDiv ? 1 : 0, DL, VT); + + // TODO: X / 1 -> X + // TODO: X % 1 -> 0 + // If this is a boolean op (single-bit element type), we can't have + // division-by-zero or remainder-by-zero, so assume the divisor is 1. + // Similarly, if we're zero-extending a boolean divisor, then assume it's a 1. + return SDValue(); } |
