[turbofan] Fix bogus covering of Word64Equal w/ zero.

src/compiler/x64/instruction-selector-x64.cc

Index: src/compiler/x64/instruction-selector-x64.cc
diff --git a/src/compiler/x64/instruction-selector-x64.cc b/src/compiler/x64/instruction-selector-x64.cc
index f10ad06cb07708dfdb2f33b672e340fff80c569b..10637430fdfc35053f72e81a463f0235ce25fbf0 100644
--- a/src/compiler/x64/instruction-selector-x64.cc
+++ b/src/compiler/x64/instruction-selector-x64.cc
@@ -1068,25 +1068,12 @@ void InstructionSelector::VisitBranch(Node* branch, BasicBlock* tbranch,
   FlagsContinuation cont(kNotEqual, tbranch, fbranch);
 
   // Try to combine with comparisons against 0 by simply inverting the branch.
-  while (CanCover(user, value)) {
-    if (value->opcode() == IrOpcode::kWord32Equal) {
-      Int32BinopMatcher m(value);
-      if (m.right().Is(0)) {
-        user = value;
-        value = m.left().node();
-        cont.Negate();
-      } else {
-        break;
-      }
-    } else if (value->opcode() == IrOpcode::kWord64Equal) {
-      Int64BinopMatcher m(value);
-      if (m.right().Is(0)) {
-        user = value;
-        value = m.left().node();
-        cont.Negate();
-      } else {
-        break;
-      }
+  while (CanCover(user, value) && value->opcode() == IrOpcode::kWord32Equal) {
+    Int32BinopMatcher m(value);
+    if (m.right().Is(0)) {
+      user = value;
+      value = m.left().node();
+      cont.Negate();
     } else {
       break;
     }