Changes in directory llvm/lib/CodeGen/SelectionDAG:
DAGCombiner.cpp updated: 1.186 -> 1.187
---
Log message:
Fold (X & C1) | (Y & C2) -> (X|Y) & C3 when possible.
This implements CodeGen/X86/and-or-fold.ll
---
Diffs of the changes: (+20 -0)
DAGCombiner.cpp | 20 ++++++++++++++++++++
1 files changed, 20 insertions(+)
Index: llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
diff -u llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp:1.186
llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp:1.187
--- llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp:1.186 Thu Sep 14 15:50:57 2006
+++ llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp Thu Sep 14 16:11:37 2006
@@ -1155,6 +1155,26 @@
if (Tmp.Val) return Tmp;
}
+ // (X & C1) | (Y & C2) -> (X|Y) & C3 if possible.
+ if (N0.getOpcode() == ISD::AND &&
+ N1.getOpcode() == ISD::AND &&
+ N0.getOperand(1).getOpcode() == ISD::Constant &&
+ N1.getOperand(1).getOpcode() == ISD::Constant &&
+ // Don't increase # computations.
+ (N0.Val->hasOneUse() || N1.Val->hasOneUse())) {
+ // We can only do this xform if we know that bits from X that are set in C2
+ // but not in C1 are already zero. Likewise for Y.
+ uint64_t LHSMask = cast<ConstantSDNode>(N0.getOperand(1))->getValue();
+ uint64_t RHSMask = cast<ConstantSDNode>(N1.getOperand(1))->getValue();
+
+ if (TLI.MaskedValueIsZero(N0.getOperand(0), RHSMask&~LHSMask) &&
+ TLI.MaskedValueIsZero(N1.getOperand(0), LHSMask&~RHSMask)) {
+ SDOperand X =DAG.getNode(ISD::OR, VT, N0.getOperand(0),
N1.getOperand(0));
+ return DAG.getNode(ISD::AND, VT, X, DAG.getConstant(LHSMask|RHSMask,
VT));
+ }
+ }
+
+
// See if this is some rotate idiom.
if (SDNode *Rot = MatchRotate(N0, N1))
return SDOperand(Rot, 0);
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