Fold adds and subtracts of zero immediately, instead of waiting

for dagcombine to do this.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@51886 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/CodeGen/SelectionDAG/SelectionDAG.cpp b/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
index c8f5d534e488b312e66399daa8f50dca345a5ad2..a9b7381a096c75d32c88211bf5c8c4ed2911c5a3 100644 (file)
--- a/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
+++ b/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
@@ -2115,10 +2115,12 @@ SDOperand SelectionDAG::getNode(unsigned Opcode, MVT::ValueType VT,
     break;
   case ISD::OR:
   case ISD::XOR:
+  case ISD::ADD:
+  case ISD::SUB:
     assert(MVT::isInteger(VT) && N1.getValueType() == N2.getValueType() &&
            N1.getValueType() == VT && "Binary operator types must match!");
-    // (X ^| 0) -> X.  This commonly occurs when legalizing i64 values, so it's
-    // worth handling here.
+    // (X ^|+- 0) -> X.  This commonly occurs when legalizing i64 values, so
+    // it's worth handling here.
     if (N2C && N2C->isNullValue())
       return N1;
     break;
@@ -2128,8 +2130,6 @@ SDOperand SelectionDAG::getNode(unsigned Opcode, MVT::ValueType VT,
   case ISD::MULHS:
     assert(MVT::isInteger(VT) && "This operator does not apply to FP types!");
     // fall through
-  case ISD::ADD:
-  case ISD::SUB:
   case ISD::MUL:
   case ISD::SDIV:
   case ISD::SREM: