2 files changed, 19 insertions, 9 deletions
diff --git a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index 7e8e46fba5..e4b24f1aaf 100644
--- a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -3853,6 +3853,9 @@ SDValue DAGCombiner::visitFSUB(SDNode *N) {
   // fold (fsub c1, c2) -> c1-c2
   if (N0CFP && N1CFP && VT != MVT::ppcf128)
     return DAG.getNode(ISD::FSUB, VT, N0, N1);
+  // fold (A-0) -> A
+  if (UnsafeFPMath && N1CFP && N1CFP->getValueAPF().isZero())
+    return N0;
   // fold (0-B) -> -B
   if (UnsafeFPMath && N0CFP && N0CFP->getValueAPF().isZero()) {
     if (isNegatibleForFree(N1, LegalOperations))
diff --git a/lib/CodeGen/SelectionDAG/SelectionDAG.cpp b/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
index 2974486208..6d1fdd2340 100644
--- a/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
+++ b/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
@@ -2402,15 +2402,22 @@ SDValue SelectionDAG::getNode(unsigned Opcode, MVT VT,
   case ISD::FMUL:
   case ISD::FDIV:
   case ISD::FREM:
-    if (UnsafeFPMath && Opcode == ISD::FADD) {
-      // 0+x --> x
-      if (ConstantFPSDNode *CFP = dyn_cast<ConstantFPSDNode>(N1))
-        if (CFP->getValueAPF().isZero())
-          return N2;
-      // x+0 --> x
-      if (ConstantFPSDNode *CFP = dyn_cast<ConstantFPSDNode>(N2))
-        if (CFP->getValueAPF().isZero())
-          return N1;
+    if (UnsafeFPMath) {
+      if (Opcode == ISD::FADD) {
+        // 0+x --> x
+        if (ConstantFPSDNode *CFP = dyn_cast<ConstantFPSDNode>(N1))
+          if (CFP->getValueAPF().isZero())
+            return N2;
+        // x+0 --> x
+        if (ConstantFPSDNode *CFP = dyn_cast<ConstantFPSDNode>(N2))
+          if (CFP->getValueAPF().isZero())
+            return N1;
+      } else if (Opcode == ISD::FSUB) {
+        // x-0 --> x
+        if (ConstantFPSDNode *CFP = dyn_cast<ConstantFPSDNode>(N2))
+          if (CFP->getValueAPF().isZero())
+            return N1;
+      }
     }
     assert(N1.getValueType() == N2.getValueType() &&
            N1.getValueType() == VT && "Binary operator types must match!");