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Add common code for reassociating ops in the dag combiner 

llvm-svn: 25934
This commit is contained in:
Nate Begeman 2006-02-03 06:46:56 +00:00
parent d65461c232
commit 22e251abf1
1 changed files with 55 additions and 50 deletions
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105
llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
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@ -33,7 +33,6 @@
// FIXME: divide by zero is currently left unfolded. do we want to turn this
// into an undef?
// FIXME: select ne (select cc, 1, 0), 0, true, false -> select cc, true, false
// FIXME: reassociate (X+C)+Y into (X+Y)+C if the inner expression has one use
//
//===----------------------------------------------------------------------===//
@ -179,6 +178,8 @@ namespace {
SDOperand visitLOCATION(SDNode *N);
SDOperand visitDEBUGLOC(SDNode *N);
SDOperand ReassociateOps(unsigned Opc, SDOperand LHS, SDOperand RHS);
bool SimplifySelectOps(SDNode *SELECT, SDOperand LHS, SDOperand RHS);
SDOperand SimplifySelect(SDOperand N0, SDOperand N1, SDOperand N2);
SDOperand SimplifySelectCC(SDOperand N0, SDOperand N1, SDOperand N2,
@ -418,6 +419,37 @@ static bool isCommutativeBinOp(unsigned Opcode) {
}
}
SDOperand DAGCombiner::ReassociateOps(unsigned Opc, SDOperand N0, SDOperand N1){
MVT::ValueType VT = N0.getValueType();
// reassoc. (op (op x, c1), y) -> (op (op x, y), c1) iff x+c1 has one use
// reassoc. (op (op x, c1), c2) -> (op x, (op c1, c2))
if (N0.getOpcode() == Opc && isa<ConstantSDNode>(N0.getOperand(1))) {
if (isa<ConstantSDNode>(N1)) {
SDOperand OpNode = DAG.getNode(Opc, VT, N0.getOperand(1), N1);
WorkList.push_back(OpNode.Val);
return DAG.getNode(Opc, VT, OpNode, N0.getOperand(0));
} else if (N0.hasOneUse()) {
SDOperand OpNode = DAG.getNode(Opc, VT, N0.getOperand(0), N1);
WorkList.push_back(OpNode.Val);
return DAG.getNode(Opc, VT, OpNode, N0.getOperand(1));
}
}
// reassoc. (op y, (op x, c1)) -> (op (op x, y), c1) iff x+c1 has one use
// reassoc. (op c2, (op x, c1)) -> (op x, (op c1, c2))
if (N1.getOpcode() == Opc && isa<ConstantSDNode>(N1.getOperand(1))) {
if (isa<ConstantSDNode>(N0)) {
SDOperand OpNode = DAG.getNode(Opc, VT, N1.getOperand(1), N0);
WorkList.push_back(OpNode.Val);
return DAG.getNode(Opc, VT, OpNode, N1.getOperand(0));
} else if (N1.hasOneUse()) {
SDOperand OpNode = DAG.getNode(Opc, VT, N1.getOperand(0), N0);
WorkList.push_back(OpNode.Val);
return DAG.getNode(Opc, VT, OpNode, N1.getOperand(1));
}
}
return SDOperand();
}
void DAGCombiner::Run(bool RunningAfterLegalize) {
// set the instance variable, so that the various visit routines may use it.
AfterLegalize = RunningAfterLegalize;
@ -587,25 +619,16 @@ SDOperand DAGCombiner::visitADD(SDNode *N) {
// fold (add x, 0) -> x
if (N1C && N1C->isNullValue())
return N0;
// fold (add (add x, c1), c2) -> (add x, c1+c2)
if (N1C && N0.getOpcode() == ISD::ADD) {
ConstantSDNode *N00C = dyn_cast<ConstantSDNode>(N0.getOperand(0));
ConstantSDNode *N01C = dyn_cast<ConstantSDNode>(N0.getOperand(1));
if (N00C)
return DAG.getNode(ISD::ADD, VT, N0.getOperand(1),
DAG.getConstant(N1C->getValue()+N00C->getValue(), VT));
if (N01C)
return DAG.getNode(ISD::ADD, VT, N0.getOperand(0),
DAG.getConstant(N1C->getValue()+N01C->getValue(), VT));
}
// fold ((c1-A)+c2) -> (c1+c2)-A
if (N1C && N0.getOpcode() == ISD::SUB)
if (ConstantSDNode *N0C = dyn_cast<ConstantSDNode>(N0.getOperand(0)))
return DAG.getNode(ISD::SUB, VT,
DAG.getConstant(N1C->getValue()+N0C->getValue(), VT),
N0.getOperand(1));
// reassociate add
SDOperand RADD = ReassociateOps(ISD::ADD, N0, N1);
if (RADD.Val != 0)
return RADD;
// fold ((0-A) + B) -> B-A
if (N0.getOpcode() == ISD::SUB && isa<ConstantSDNode>(N0.getOperand(0)) &&
cast<ConstantSDNode>(N0.getOperand(0))->isNullValue())
@ -678,19 +701,10 @@ SDOperand DAGCombiner::visitMUL(SDNode *N) {
DAG.getConstant(Log2_64(-N1C->getSignExtended()),
TLI.getShiftAmountTy())));
}
// fold (mul (mul x, c1), c2) -> (mul x, c1*c2)
if (N1C && N0.getOpcode() == ISD::MUL) {
ConstantSDNode *N00C = dyn_cast<ConstantSDNode>(N0.getOperand(0));
ConstantSDNode *N01C = dyn_cast<ConstantSDNode>(N0.getOperand(1));
if (N00C)
return DAG.getNode(ISD::MUL, VT, N0.getOperand(1),
DAG.getConstant(N1C->getValue()*N00C->getValue(), VT));
if (N01C)
return DAG.getNode(ISD::MUL, VT, N0.getOperand(0),
DAG.getConstant(N1C->getValue()*N01C->getValue(), VT));
}
// reassociate mul
SDOperand RMUL = ReassociateOps(ISD::MUL, N0, N1);
if (RMUL.Val != 0)
return RMUL;
return SDOperand();
}
@ -866,17 +880,10 @@ SDOperand DAGCombiner::visitAND(SDNode *N) {
if (N1C &&
TLI.MaskedValueIsZero(N0, ~N1C->getValue() & (~0ULL>>(64-OpSizeInBits))))
return N0;
// fold (and (and x, c1), c2) -> (and x, c1^c2)
if (N1C && N0.getOpcode() == ISD::AND) {
ConstantSDNode *N00C = dyn_cast<ConstantSDNode>(N0.getOperand(0));
ConstantSDNode *N01C = dyn_cast<ConstantSDNode>(N0.getOperand(1));
if (N00C)
return DAG.getNode(ISD::AND, VT, N0.getOperand(1),
DAG.getConstant(N1C->getValue()&N00C->getValue(), VT));
if (N01C)
return DAG.getNode(ISD::AND, VT, N0.getOperand(0),
DAG.getConstant(N1C->getValue()&N01C->getValue(), VT));
}
// reassociate and
SDOperand RAND = ReassociateOps(ISD::AND, N0, N1);
if (RAND.Val != 0)
return RAND;
// fold (and (sign_extend_inreg x, i16 to i32), 1) -> (and x, 1)
if (N1C && N0.getOpcode() == ISD::SIGN_EXTEND_INREG) {
unsigned ExtendBits =
@ -1031,19 +1038,13 @@ SDOperand DAGCombiner::visitOR(SDNode *N) {
if (N1C &&
TLI.MaskedValueIsZero(N0,~N1C->getValue() & (~0ULL>>(64-OpSizeInBits))))
return N1;
// fold (or (or x, c1), c2) -> (or x, c1|c2)
if (N1C && N0.getOpcode() == ISD::OR) {
ConstantSDNode *N00C = dyn_cast<ConstantSDNode>(N0.getOperand(0));
ConstantSDNode *N01C = dyn_cast<ConstantSDNode>(N0.getOperand(1));
if (N00C)
return DAG.getNode(ISD::OR, VT, N0.getOperand(1),
DAG.getConstant(N1C->getValue()|N00C->getValue(), VT));
if (N01C)
return DAG.getNode(ISD::OR, VT, N0.getOperand(0),
DAG.getConstant(N1C->getValue()|N01C->getValue(), VT));
} else if (N1C && N0.getOpcode() == ISD::AND && N0.Val->hasOneUse() &&
// reassociate or
SDOperand ROR = ReassociateOps(ISD::OR, N0, N1);
if (ROR.Val != 0)
return ROR;
// Canonicalize (or (and X, c1), c2) -> (and (or X, c2), c1|c2)
if (N1C && N0.getOpcode() == ISD::AND && N0.Val->hasOneUse() &&
isa<ConstantSDNode>(N0.getOperand(1))) {
// Canonicalize (or (and X, c1), c2) -> (and (or X, c2), c1|c2)
ConstantSDNode *C1 = cast<ConstantSDNode>(N0.getOperand(1));
return DAG.getNode(ISD::AND, VT, DAG.getNode(ISD::OR, VT, N0.getOperand(0),
N1),
@ -1160,6 +1161,10 @@ SDOperand DAGCombiner::visitXOR(SDNode *N) {
// fold (xor x, 0) -> x
if (N1C && N1C->isNullValue())
return N0;
// reassociate xor
SDOperand RXOR = ReassociateOps(ISD::XOR, N0, N1);
if (RXOR.Val != 0)
return RXOR;
// fold !(x cc y) -> (x !cc y)
if (N1C && N1C->getValue() == 1 && isSetCCEquivalent(N0, LHS, RHS, CC)) {
bool isInt = MVT::isInteger(LHS.getValueType());