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canonicalize constants to the RHS of addc/adde. If nothing uses the carry out of
addc, turn it into add. This allows us to compile: long long test(long long A, unsigned B) { return (A + ((long long)B << 32)) & 123; } into: _test: movl $123, %eax andl 4(%esp), %eax xorl %edx, %edx ret instead of: _test: xorl %edx, %edx movl %edx, %eax addl 4(%esp), %eax ;; add of zero andl $123, %eax ret git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@34909 91177308-0d34-0410-b5e6-96231b3b80d8
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@ -205,6 +205,8 @@ namespace {
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SDOperand visitTokenFactor(SDNode *N);
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SDOperand visitADD(SDNode *N);
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SDOperand visitSUB(SDNode *N);
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SDOperand visitADDC(SDNode *N);
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SDOperand visitADDE(SDNode *N);
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SDOperand visitMUL(SDNode *N);
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SDOperand visitSDIV(SDNode *N);
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SDOperand visitUDIV(SDNode *N);
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@ -502,6 +504,8 @@ SDOperand DAGCombiner::visit(SDNode *N) {
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case ISD::TokenFactor: return visitTokenFactor(N);
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case ISD::ADD: return visitADD(N);
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case ISD::SUB: return visitSUB(N);
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case ISD::ADDC: return visitADDC(N);
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case ISD::ADDE: return visitADDE(N);
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case ISD::MUL: return visitMUL(N);
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case ISD::SDIV: return visitSDIV(N);
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case ISD::UDIV: return visitUDIV(N);
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@ -740,6 +744,49 @@ SDOperand DAGCombiner::visitADD(SDNode *N) {
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return SDOperand();
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}
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SDOperand DAGCombiner::visitADDC(SDNode *N) {
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SDOperand N0 = N->getOperand(0);
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SDOperand N1 = N->getOperand(1);
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ConstantSDNode *N0C = dyn_cast<ConstantSDNode>(N0);
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ConstantSDNode *N1C = dyn_cast<ConstantSDNode>(N1);
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MVT::ValueType VT = N0.getValueType();
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// If the flag result is dead, turn this into an ADD.
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if (N->hasNUsesOfValue(0, 1))
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return CombineTo(N, DAG.getNode(ISD::ADD, VT, N1, N0),
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SDOperand(N, 1));
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// canonicalize constant to RHS.
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if (N0C && !N1C)
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return DAG.getNode(ISD::ADDC, VT, N1, N0);
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// fold (add x, 0) -> x + no carry out
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//if (N1C && N1C->isNullValue())
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// return N0;
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return SDOperand();
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}
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SDOperand DAGCombiner::visitADDE(SDNode *N) {
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SDOperand N0 = N->getOperand(0);
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SDOperand N1 = N->getOperand(1);
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ConstantSDNode *N0C = dyn_cast<ConstantSDNode>(N0);
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ConstantSDNode *N1C = dyn_cast<ConstantSDNode>(N1);
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MVT::ValueType VT = N0.getValueType();
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// canonicalize constant to RHS
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if (N0C && !N1C)
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return DAG.getNode(ISD::ADDE, VT, N1, N0, N->getOperand(2));
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// fold (add x, 0) -> x
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//if (N1C && N1C->isNullValue())
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// return N0;
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return SDOperand();
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}
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SDOperand DAGCombiner::visitSUB(SDNode *N) {
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SDOperand N0 = N->getOperand(0);
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SDOperand N1 = N->getOperand(1);
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