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DAG combiner fix for rotates. Previously the outer-most condition checks 

for ROTL availability. This prevents it from forming ROTR for targets that
has ROTR only.

llvm-svn: 29997
This commit is contained in:
Evan Cheng 2006-08-31 07:41:12 +00:00
parent a700a19d04
commit 31305c45da
1 changed files with 44 additions and 27 deletions
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71
llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
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@ -1160,35 +1160,52 @@ SDOperand DAGCombiner::visitOR(SDNode *N) {
// check for rotl, rotr
if (N0.getOpcode() == ISD::SHL && N1.getOpcode() == ISD::SRL &&
N0.getOperand(0) == N1.getOperand(0) &&
TLI.isOperationLegal(ISD::ROTL, VT) && TLI.isTypeLegal(VT)) {
// fold (or (shl x, C1), (srl x, C2)) -> (rotl x, C1)
if (N0.getOperand(1).getOpcode() == ISD::Constant &&
N1.getOperand(1).getOpcode() == ISD::Constant) {
uint64_t c1val = cast<ConstantSDNode>(N0.getOperand(1))->getValue();
uint64_t c2val = cast<ConstantSDNode>(N1.getOperand(1))->getValue();
if ((c1val + c2val) == OpSizeInBits)
return DAG.getNode(ISD::ROTL, VT, N0.getOperand(0), N0.getOperand(1));
}
// fold (or (shl x, y), (srl x, (sub 32, y))) -> (rotl x, y)
if (N1.getOperand(1).getOpcode() == ISD::SUB &&
N0.getOperand(1) == N1.getOperand(1).getOperand(1))
if (ConstantSDNode *SUBC =
dyn_cast<ConstantSDNode>(N1.getOperand(1).getOperand(0)))
if (SUBC->getValue() == OpSizeInBits)
return DAG.getNode(ISD::ROTL, VT, N0.getOperand(0), N0.getOperand(1));
// fold (or (shl x, (sub 32, y)), (srl x, r)) -> (rotr x, y)
if (N0.getOperand(1).getOpcode() == ISD::SUB &&
N1.getOperand(1) == N0.getOperand(1).getOperand(1))
if (ConstantSDNode *SUBC =
dyn_cast<ConstantSDNode>(N0.getOperand(1).getOperand(0)))
if (SUBC->getValue() == OpSizeInBits) {
if (TLI.isOperationLegal(ISD::ROTR, VT) && TLI.isTypeLegal(VT))
return DAG.getNode(ISD::ROTR, VT, N0.getOperand(0),
N1.getOperand(1));
else
TLI.isTypeLegal(VT)) {
bool HasROTL = TLI.isOperationLegal(ISD::ROTL, VT);
bool HasROTR = TLI.isOperationLegal(ISD::ROTR, VT);
if (HasROTL || HasROTR) {
// fold (or (shl x, C1), (srl x, C2)) -> (rotl x, C1)
// fold (or (shl x, C1), (srl x, C2)) -> (rotr x, C2)
if (N0.getOperand(1).getOpcode() == ISD::Constant &&
N1.getOperand(1).getOpcode() == ISD::Constant) {
uint64_t c1val = cast<ConstantSDNode>(N0.getOperand(1))->getValue();
uint64_t c2val = cast<ConstantSDNode>(N1.getOperand(1))->getValue();
if ((c1val + c2val) == OpSizeInBits)
if (HasROTL)
return DAG.getNode(ISD::ROTL, VT, N0.getOperand(0),
N0.getOperand(1));
}
else
return DAG.getNode(ISD::ROTR, VT, N0.getOperand(0),
N1.getOperand(1));
}
// fold (or (shl x, y), (srl x, (sub 32, y))) -> (rotl x, y)
// fold (or (shl x, y), (srl x, (sub 32, y))) -> (rotr x, (sub 32, y))
if (N1.getOperand(1).getOpcode() == ISD::SUB &&
N0.getOperand(1) == N1.getOperand(1).getOperand(1))
if (ConstantSDNode *SUBC =
dyn_cast<ConstantSDNode>(N1.getOperand(1).getOperand(0)))
if (SUBC->getValue() == OpSizeInBits)
if (HasROTL)
return DAG.getNode(ISD::ROTL, VT, N0.getOperand(0),
N0.getOperand(1));
else
return DAG.getNode(ISD::ROTR, VT, N0.getOperand(0),
N1.getOperand(1));
// fold (or (shl x, (sub 32, y)), (srl x, r)) -> (rotr x, y)
// fold (or (shl x, (sub 32, y)), (srl x, r)) -> (rotl x, (sub 32, y))
if (N0.getOperand(1).getOpcode() == ISD::SUB &&
N1.getOperand(1) == N0.getOperand(1).getOperand(1))
if (ConstantSDNode *SUBC =
dyn_cast<ConstantSDNode>(N0.getOperand(1).getOperand(0)))
if (SUBC->getValue() == OpSizeInBits)
if (HasROTR)
return DAG.getNode(ISD::ROTR, VT, N0.getOperand(0),
N1.getOperand(1));
else
return DAG.getNode(ISD::ROTL, VT, N0.getOperand(0),
N0.getOperand(1));
}
}
return SDOperand();
}