Optimization for "~x + 1" to "-x" (dotnet#69003)

SkiFoD · May 20, 2022 · c40ab69 · c40ab69
1 parent 3914bcc
commit c40ab69
Showing 1 changed file with 9 additions and 0 deletions.
diff --git a/src/coreclr/jit/morph.cpp b/src/coreclr/jit/morph.cpp
@@ -12874,6 +12874,15 @@ GenTree* Compiler::fgOptimizeAddition(GenTreeOp* add)
         return op1;
     }
 
+    // Fold (~x + 1) to -x.
+    if (op1->OperIs(GT_NOT) && op2->IsIntegralConst(1))
+    {
+        op1->SetOper(GT_NEG);
+        DEBUG_DESTROY_NODE(op2);
+        DEBUG_DESTROY_NODE(add);
+        return op1;
+    }
+
     // Note that these transformations are legal for floating-point ADDs as well.
     if (opts.OptimizationEnabled())
     {