From e2e13caeb2fa68330258e71594d3efddb5f49fc7 Mon Sep 17 00:00:00 2001 From: Chris Lattner Date: Sun, 4 Mar 2007 20:03:15 +0000 Subject: [PATCH] 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 llvm-svn: 34909 --- llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp | 47 +++++++++++++++++++ 1 file changed, 47 insertions(+) diff --git a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp index 79d9e79d2b30..d48f4190340b 100644 --- a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp +++ b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp @@ -205,6 +205,8 @@ namespace { SDOperand visitTokenFactor(SDNode *N); SDOperand visitADD(SDNode *N); SDOperand visitSUB(SDNode *N); + SDOperand visitADDC(SDNode *N); + SDOperand visitADDE(SDNode *N); SDOperand visitMUL(SDNode *N); SDOperand visitSDIV(SDNode *N); SDOperand visitUDIV(SDNode *N); @@ -502,6 +504,8 @@ SDOperand DAGCombiner::visit(SDNode *N) { case ISD::TokenFactor: return visitTokenFactor(N); case ISD::ADD: return visitADD(N); case ISD::SUB: return visitSUB(N); + case ISD::ADDC: return visitADDC(N); + case ISD::ADDE: return visitADDE(N); case ISD::MUL: return visitMUL(N); case ISD::SDIV: return visitSDIV(N); case ISD::UDIV: return visitUDIV(N); @@ -740,6 +744,49 @@ SDOperand DAGCombiner::visitADD(SDNode *N) { return SDOperand(); } +SDOperand DAGCombiner::visitADDC(SDNode *N) { + SDOperand N0 = N->getOperand(0); + SDOperand N1 = N->getOperand(1); + ConstantSDNode *N0C = dyn_cast(N0); + ConstantSDNode *N1C = dyn_cast(N1); + MVT::ValueType VT = N0.getValueType(); + + // If the flag result is dead, turn this into an ADD. + if (N->hasNUsesOfValue(0, 1)) + return CombineTo(N, DAG.getNode(ISD::ADD, VT, N1, N0), + SDOperand(N, 1)); + + // canonicalize constant to RHS. + if (N0C && !N1C) + return DAG.getNode(ISD::ADDC, VT, N1, N0); + + // fold (add x, 0) -> x + no carry out + //if (N1C && N1C->isNullValue()) + // return N0; + + return SDOperand(); +} + +SDOperand DAGCombiner::visitADDE(SDNode *N) { + SDOperand N0 = N->getOperand(0); + SDOperand N1 = N->getOperand(1); + ConstantSDNode *N0C = dyn_cast(N0); + ConstantSDNode *N1C = dyn_cast(N1); + MVT::ValueType VT = N0.getValueType(); + + // canonicalize constant to RHS + if (N0C && !N1C) + return DAG.getNode(ISD::ADDE, VT, N1, N0, N->getOperand(2)); + + // fold (add x, 0) -> x + //if (N1C && N1C->isNullValue()) + // return N0; + + return SDOperand(); +} + + + SDOperand DAGCombiner::visitSUB(SDNode *N) { SDOperand N0 = N->getOperand(0); SDOperand N1 = N->getOperand(1);