[wasm] Remove x / -1 = -x constant folding for wasm

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 b3dcd2f507123e5392c67079d6276a5059e1528e..3eb8a7bd49b49a14060d519bfd400f3c76492744 100644
--- a/src/compiler/machine-operator-reducer.cc
+++ b/src/compiler/machine-operator-reducer.cc
@@ -437,7 +437,7 @@ Reduction MachineOperatorReducer::Reduce(Node* node) {
       if (m.IsFoldable()) {  // K / K => K
         return ReplaceFloat64(m.left().Value() / m.right().Value());
       }
-      if (m.right().Is(-1)) {  // x / -1.0 => -x
+      if (!wasm_origin_ && m.right().Is(-1)) {  // x / -1.0 => -x

[titzer, 2017/01/31 17:24:49]

Can we rename this option to something closer to what it means, e.g.
"preserve_nan_bits" or something similar?

[ahaas, 2017/01/31 19:43:37]

Done with the rebasing.

         node->RemoveInput(1);
         NodeProperties::ChangeOp(node, machine()->Float64Neg());
         return Changed(node);