diff options
Diffstat (limited to 'llvm/lib/CodeGen')
| -rw-r--r-- | llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp | 20 |
1 files changed, 19 insertions, 1 deletions
diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp index 7a123aa9aa0..c3d1bb398e4 100644 --- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp +++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp @@ -843,6 +843,7 @@ SDOperand SelectionDAG::SimplifySelectCC(SDOperand N1, SDOperand N2, SDOperand N3, SDOperand N4, ISD::CondCode CC) { MVT::ValueType VT = N3.getValueType(); + ConstantSDNode *N1C = dyn_cast<ConstantSDNode>(N1.Val); ConstantSDNode *N2C = dyn_cast<ConstantSDNode>(N2.Val); ConstantSDNode *N3C = dyn_cast<ConstantSDNode>(N3.Val); ConstantSDNode *N4C = dyn_cast<ConstantSDNode>(N4.Val); @@ -865,6 +866,23 @@ SDOperand SelectionDAG::SimplifySelectCC(SDOperand N1, SDOperand N2, } } + // check to see if we're select_cc'ing a select_cc. + // this allows us to turn: + // select_cc set[eq,ne] (select_cc cc, lhs, rhs, 1, 0), 0, true, false -> + // select_cc cc, lhs, rhs, true, false + if ((N1C && N1C->isNullValue() && N2.getOpcode() == ISD::SELECT_CC) || + (N2C && N2C->isNullValue() && N1.getOpcode() == ISD::SELECT_CC) && + (CC == ISD::SETEQ || CC == ISD::SETNE)) { + SDOperand SCC = N1C ? N2 : N1; + ConstantSDNode *SCCT = dyn_cast<ConstantSDNode>(SCC.getOperand(2)); + ConstantSDNode *SCCF = dyn_cast<ConstantSDNode>(SCC.getOperand(3)); + if (SCCT && SCCF && SCCF->isNullValue() && SCCT->getValue() == 1ULL) { + if (CC == ISD::SETEQ) std::swap(N3, N4); + return getNode(ISD::SELECT_CC, N3.getValueType(), SCC.getOperand(0), + SCC.getOperand(1), N3, N4, SCC.getOperand(4)); + } + } + // Check to see if we can perform the "gzip trick", transforming // select_cc setlt X, 0, A, 0 -> and (sra X, size(X)-1), A if (N2C && N2C->isNullValue() && N4C && N4C->isNullValue() && @@ -894,7 +912,7 @@ SDOperand SelectionDAG::SimplifySelectCC(SDOperand N1, SDOperand N2, } } - // Check to see if this is the equivalent of setcc X, 0 + // Check to see if this is the equivalent of setcc if (N4C && N4C->isNullValue() && N3C && (N3C->getValue() == 1ULL)) { MVT::ValueType XType = N1.getValueType(); if (TLI.isOperationLegal(ISD::SETCC, TLI.getSetCCResultTy())) |
