[turbofan] Fix NumberIsHoleNaN to check the upper word.

The NumberIsHoleNaN operator used to test the lower word of the double
input which is obviously wrong.

R=jarin@chromium.org

Review-Url: https://codereview.chromium.org/2022753002
Cr-Commit-Position: refs/heads/master@{#36584}

src/compiler/simplified-lowering.cc

@@ -1091,14 +1091,14 @@ class RepresentationSelector {
         VisitUnop(node, UseInfo::TruncatingFloat64(),
                   MachineRepresentation::kBit);
         if (lower()) {
-          // NumberIsHoleNaN(x) => Word32Equal(Float64ExtractLowWord32(x),
-          //                                   #HoleNaNLower32)
-          node->ReplaceInput(0,
-                             jsgraph_->graph()->NewNode(
-                                 lowering->machine()->Float64ExtractLowWord32(),
-                                 node->InputAt(0)));
+          // NumberIsHoleNaN(x) => Word32Equal(Float64ExtractHighWord32(x),
+          //                                   #HoleNanUpper32)
+          node->ReplaceInput(
+              0, jsgraph_->graph()->NewNode(
+                     lowering->machine()->Float64ExtractHighWord32(),
+                     node->InputAt(0)));
           node->AppendInput(jsgraph_->zone(),
-                            jsgraph_->Int32Constant(kHoleNanLower32));
+                            jsgraph_->Int32Constant(kHoleNanUpper32));
           NodeProperties::ChangeOp(node, jsgraph_->machine()->Word32Equal());
         }
         break;

test/mjsunit/compiler/regress-number-is-hole-nan.js

+// Copyright 2016 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// Flags: --allow-natives-syntax
+
+var a = [, 2.121736758e-314];
+
+function foo() { return a[1]; }
+
+assertEquals(2.121736758e-314, foo());
+assertEquals(2.121736758e-314, foo());
+%OptimizeFunctionOnNextCall(foo);
+assertEquals(2.121736758e-314, foo());