[turbofan] Optimize Uint32LessThan with Word32Sar.

test/unittests/compiler/machine-operator-reducer-unittest.cc

 // Copyright 2014 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.
 
 #include "src/base/bits.h"
 #include "src/compiler/js-graph.h"
 #include "src/compiler/machine-operator-reducer.h"
 #include "src/compiler/typer.h"
 #include "test/unittests/compiler/graph-unittest.h"
 
@@ skipping 638 matching lines @@
 
       r = Reduce(graph()->NewNode(common()->Projection(0), add));
       ASSERT_TRUE(r.Changed());
       EXPECT_THAT(r.replacement(), IsInt32Constant(z));
     }
   }
 }
 
 
 // -----------------------------------------------------------------------------
+// Uint32LessThan
+
+
+TEST_F(MachineOperatorReducerTest, Uint32LessThanWithWord32Sar) {
+  Node* const p0 = Parameter(0);
+  TRACED_FORRANGE(uint32_t, shift, 1, 3) {
+    const uint32_t limit = (kMaxInt >> shift) - 1;
+    Node* const node = graph()->NewNode(
+        machine()->Uint32LessThan(),
+        graph()->NewNode(machine()->Word32Sar(), p0, Uint32Constant(shift)),
+        Uint32Constant(limit));
+
+    Reduction r = Reduce(node);
+    ASSERT_TRUE(r.Changed());
+    EXPECT_THAT(
+        r.replacement(),
+        IsUint32LessThan(p0, IsInt32Constant(bit_cast<int32_t>(
+                                 (limit << shift) | ((1u << shift) - 1)))));
+  }
+}
+
+
+// -----------------------------------------------------------------------------
 // Store
 
 
 TEST_F(MachineOperatorReducerTest, StoreRepWord8WithWord32And) {
   const StoreRepresentation rep(kRepWord8, kNoWriteBarrier);
   Node* const base = Parameter(0);
   Node* const index = Parameter(1);
   Node* const value = Parameter(2);
   Node* const effect = graph()->start();
   Node* const control = graph()->start();
@@ skipping 29 matching lines @@
     Reduction r = Reduce(node);
     ASSERT_TRUE(r.Changed());
     EXPECT_THAT(r.replacement(),
                 IsStore(rep, base, index, value, effect, control));
   }
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8