canonicalize a bunch of operations involving fneg
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@21160 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/SelectionDAG/SelectionDAG.cpp b/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
index 04ccc77..93ef372 100644
--- a/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
+++ b/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
@@ -565,6 +565,8 @@
if (ConstantFPSDNode *C = dyn_cast<ConstantFPSDNode>(Operand.Val))
switch (Opcode) {
+ case ISD::FNEG:
+ return getConstantFP(-C->getValue(), VT);
case ISD::FP_ROUND:
case ISD::FP_EXTEND:
return getConstantFP(C->getValue(), VT);
@@ -602,6 +604,17 @@
return Operand.Val->getOperand(0);
}
break;
+ case ISD::FNEG:
+ if (OpOpcode == ISD::SUB) // -(X-Y) -> (Y-X)
+ return getNode(ISD::SUB, VT, Operand.Val->getOperand(1),
+ Operand.Val->getOperand(0));
+ if (OpOpcode == ISD::FNEG) // --X -> X
+ return Operand.Val->getOperand(0);
+ break;
+ case ISD::FABS:
+ if (OpOpcode == ISD::FNEG) // abs(-X) -> abs(X)
+ return getNode(ISD::FABS, VT, Operand.Val->getOperand(0));
+ break;
}
SDNode *&N = UnaryOps[std::make_pair(Opcode, std::make_pair(Operand, VT))];
@@ -859,6 +872,12 @@
case ISD::XOR:
if (N1 == N2) return getConstant(0, VT); // xor X, Y -> 0
break;
+ case ISD::ADD:
+ if (N2.getOpcode() == ISD::FNEG) // (A+ (-B) -> A-B
+ return getNode(ISD::SUB, VT, N1, N2.getOperand(0));
+ if (N1.getOpcode() == ISD::FNEG) // ((-A)+B) -> B-A
+ return getNode(ISD::SUB, VT, N2, N1.getOperand(0));
+ break;
case ISD::SUB:
if (N1.getOpcode() == ISD::ADD) {
if (N1.Val->getOperand(0) == N2)
@@ -866,6 +885,8 @@
if (N1.Val->getOperand(1) == N2)
return N1.Val->getOperand(0); // (A+B)-B == A
}
+ if (N2.getOpcode() == ISD::FNEG) // (A- (-B) -> A+B
+ return getNode(ISD::ADD, VT, N1, N2.getOperand(0));
break;
}