Make it possible for a target to mark FSUB as Expand. This requires providing a default expansion (FADD+FNEG), and teaching DAGCombine not to form FSUBs post-legalize if they are not legal.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@152079 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp b/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
index 31df458..c6167aa 100644
--- a/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
+++ b/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
@@ -3032,6 +3032,16 @@
Results.push_back(Results[0].getValue(1));
break;
}
+ case ISD::FSUB: {
+ EVT VT = Node->getValueType(0);
+ assert(TLI.isOperationLegalOrCustom(ISD::FADD, VT) &&
+ TLI.isOperationLegalOrCustom(ISD::FNEG, VT) &&
+ "Don't know how to expand this FP subtraction!");
+ Tmp1 = DAG.getNode(ISD::FNEG, dl, VT, Node->getOperand(1));
+ Tmp1 = DAG.getNode(ISD::FADD, dl, VT, Node->getOperand(0), Tmp1);
+ Results.push_back(Tmp1);
+ break;
+ }
case ISD::SUB: {
EVT VT = Node->getValueType(0);
assert(TLI.isOperationLegalOrCustom(ISD::ADD, VT) &&