[turbofan] remove redundant '& 0x1F' for shifts.

test/cctest/compiler/test-machine-operator-reducer.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 "test/cctest/cctest.h"
 
 #include "src/base/utils/random-number-generator.h"
 #include "src/codegen.h"
 #include "src/compiler/graph-inl.h"
 #include "src/compiler/js-graph.h"
@@ skipping 34 matching lines @@
 
 template <>
 double ValueOfOperator<double>(const Operator* op) {
   CHECK_EQ(IrOpcode::kFloat64Constant, op->opcode());
   return OpParameter<double>(op);
 }
 
 
 class ReducerTester : public HandleAndZoneScope {
  public:
-  explicit ReducerTester(int num_parameters = 0)
+  explicit ReducerTester(
+      int num_parameters = 0,
+      MachineOperatorBuilder::Flags flags = MachineOperatorBuilder::kNoFlags)
       : isolate(main_isolate()),
         binop(NULL),
         unop(NULL),
-        machine(main_zone()),
+        machine(main_zone(), kMachPtr, flags),
         common(main_zone()),
         graph(main_zone()),
         javascript(main_zone()),
         typer(&graph, MaybeHandle<Context>()),
         jsgraph(&graph, &common, &javascript, &machine),
         maxuint32(Constant<int32_t>(kMaxUInt32)) {
     Node* s = graph.NewNode(common.Start(num_parameters));
     graph.SetStart(s);
   }
 
@@ skipping 281 matching lines @@
 
   R.CheckDontPutConstantOnRight(44);
 
   Node* x = R.Parameter();
   Node* zero = R.Constant<int32_t>(0);
 
   R.CheckBinop(x, x, zero);  // x >> 0  => x
 }
 
 
-TEST(ReduceWord32Equal) {
+static void CheckJsShift(ReducerTester* R) {
+  DCHECK(R->machine.Word32ShiftIsSafe());
+
+  Node* x = R->Parameter(0);
+  Node* y = R->Parameter(1);
+  Node* thirty_one = R->Constant<int32_t>(0x1f);
+  Node* y_and_thirty_one =
+      R->graph.NewNode(R->machine.Word32And(), y, thirty_one);
+
+  // If the underlying machine shift instructions 'and' their right operand
+  // with 0x1f then:  x << (y & 0x1f) => x << y
+  R->CheckFoldBinop(x, y, x, y_and_thirty_one);
+}
+
+
+TEST(ReduceJsShifts) {
+  ReducerTester R(0, MachineOperatorBuilder::kWord32ShiftIsSafe);
+
+  R.binop = R.machine.Word32Shl();
+  CheckJsShift(&R);
+
+  R.binop = R.machine.Word32Shr();
+  CheckJsShift(&R);
+
+  R.binop = R.machine.Word32Sar();
+  CheckJsShift(&R);
+}
+
+
+TEST(Word32Equal) {
   ReducerTester R;
   R.binop = R.machine.Word32Equal();
 
   FOR_INT32_INPUTS(pl) {
     FOR_INT32_INPUTS(pr) {
       int32_t x = *pl, y = *pr;
       R.CheckFoldBinop<int32_t>(x == y ? 1 : 0, x, y);
     }
   }
 
@@ skipping 461 matching lines @@
 // TODO(titzer): test MachineOperatorReducer for Int64Mul
 // TODO(titzer): test MachineOperatorReducer for Int64UMul
 // TODO(titzer): test MachineOperatorReducer for Int64Div
 // TODO(titzer): test MachineOperatorReducer for Uint64Div
 // TODO(titzer): test MachineOperatorReducer for Int64Mod
 // TODO(titzer): test MachineOperatorReducer for Uint64Mod
 // TODO(titzer): test MachineOperatorReducer for Int64Neg
 // TODO(titzer): test MachineOperatorReducer for ChangeInt32ToFloat64
 // TODO(titzer): test MachineOperatorReducer for ChangeFloat64ToInt32
 // TODO(titzer): test MachineOperatorReducer for Float64Compare