[turbofan] Introduce integer multiplication with overflow.

src/compiler/machine-operator-reducer.cc

Index: src/compiler/machine-operator-reducer.cc
diff --git a/src/compiler/machine-operator-reducer.cc b/src/compiler/machine-operator-reducer.cc
index a93713824dc2bf387aefc22f1eaaebffeff1b080..71b7d981a405932f6dbb3b86dd226809f57414e9 100644
--- a/src/compiler/machine-operator-reducer.cc
+++ b/src/compiler/machine-operator-reducer.cc
@@ -815,6 +815,7 @@ Reduction MachineOperatorReducer::ReduceStore(Node* node) {
       }
       break;
     }
+    // TODO(mvstanton): put kInt32MulWithOverflow here too, eh?

[Benedikt Meurer, 2016/07/12 04:09:28]

Nope, that doesn't make sense. The rules for the shift/and above are unnecessary
extensions/truncations.

[mvstanton, 2016/07/12 08:52:49]

Done.

     default:
       break;
   }