[compiler] [wasm] Introduce Word32/64ReverseBytes as TF Optional Opcode

src/compiler/int64-lowering.cc

Index: src/compiler/int64-lowering.cc
diff --git a/src/compiler/int64-lowering.cc b/src/compiler/int64-lowering.cc
index 68d37723ef7ee1bd5722d866ce0adca0a64e19cb..fe9ba7e3fb8acad04b34ca9183bebde5580aba8b 100644
--- a/src/compiler/int64-lowering.cc
+++ b/src/compiler/int64-lowering.cc
@@ -749,6 +749,16 @@ void Int64Lowering::LowerNode(Node* node) {
       }
       break;
     }
+    case IrOpcode::kWord64ReverseBytes: {
+      DCHECK(machine()->Word64ReverseBytes().IsSupported());

[ahaas, 2016/07/28 14:12:59]

If the machine already supports Word64ReverseBytes, why do you want to lower? If
the machine does not actually support Word64ReverseBytes, then
machine()->Word64ReverseBytes().IsSupported() should be false.

[john.yan, 2016/07/28 18:03:50]

Check is now removed.

+      DCHECK(machine()->Word32ReverseBytes().IsSupported());
+      Node* input = node->InputAt(0);
+      ReplaceNode(node, graph()->NewNode(machine()->Word32ReverseBytes().op(),
+                                         GetReplacementHigh(input)),
+                  graph()->NewNode(machine()->Word32ReverseBytes().op(),
+                                   GetReplacementLow(input)));
+      break;
+    }
 
     default: { DefaultLowering(node); }
   }