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

src/compiler/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 "src/compiler/machine-operator-reducer.h"
 
 #include "src/base/bits.h"
 #include "src/base/division-by-constant.h"
 #include "src/codegen.h"
 #include "src/compiler/diamond.h"
@@ skipping 133 matching lines @@
       if (m.right().Is(0)) return Replace(m.left().node());    // x | 0  => x
       if (m.right().Is(-1)) return Replace(m.right().node());  // x | -1 => -1
       if (m.IsFoldable()) {                                    // K | K  => K
         return ReplaceInt32(m.left().Value() | m.right().Value());
       }
       if (m.LeftEqualsRight()) return Replace(m.left().node());  // x | x => x
       if (m.left().IsWord32Shl() && m.right().IsWord32Shr()) {
         Int32BinopMatcher mleft(m.left().node());
         Int32BinopMatcher mright(m.right().node());
         if (mleft.left().node() == mright.left().node()) {
-          // (x << y) | (x >> (32 - y)) => x ror y
+          // TODO(turbofan): here we are matching rotate left, shall we add
+          // support for rotate right?
+          // (x << y) | (x >>> (32 - y)) => x ror (32 - y)
           if (mright.right().IsInt32Sub()) {
             Int32BinopMatcher mrightright(mright.right().node());
             if (mrightright.left().Is(32) &&
                 mrightright.right().node() == mleft.right().node()) {
               node->set_op(machine()->Word32Ror());
               node->ReplaceInput(0, mleft.left().node());
-              node->ReplaceInput(1, mleft.right().node());
+              node->ReplaceInput(1, mright.right().node());
               return Changed(node);
             }
           }
-          // (x << K) | (x >> (32 - K)) => x ror K
+          // (x << K) | (x >>> (32 - K)) => x ror (32 - K)
           if (mleft.right().IsInRange(0, 31) &&
               mright.right().Is(32 - mleft.right().Value())) {
             node->set_op(machine()->Word32Ror());
             node->ReplaceInput(0, mleft.left().node());
-            node->ReplaceInput(1, mleft.right().node());
+            node->ReplaceInput(1, mright.right().node());
             return Changed(node);
           }
         }
       }
       if (m.left().IsWord32Shr() && m.right().IsWord32Shl()) {
-        // (x >> (32 - y)) | (x << y)  => x ror y
+        // (x >>> (32 - y)) | (x << y)  => x ror (32 -y)
         Int32BinopMatcher mleft(m.left().node());
         Int32BinopMatcher mright(m.right().node());
         if (mleft.left().node() == mright.left().node()) {
           if (mleft.right().IsInt32Sub()) {
             Int32BinopMatcher mleftright(mleft.right().node());
             if (mleftright.left().Is(32) &&
                 mleftright.right().node() == mright.right().node()) {
               node->set_op(machine()->Word32Ror());
               node->ReplaceInput(0, mright.left().node());
-              node->ReplaceInput(1, mright.right().node());
+              node->ReplaceInput(1, mleft.right().node());
               return Changed(node);
             }
           }
-          // (x >> (32 - K)) | (x << K) => x ror K
+          // (x >>> (32 - K)) | (x << K) => x ror (32 - K)
           if (mright.right().IsInRange(0, 31) &&
               mleft.right().Is(32 - mright.right().Value())) {
             node->set_op(machine()->Word32Ror());
             node->ReplaceInput(0, mright.left().node());
-            node->ReplaceInput(1, mright.right().node());
+            node->ReplaceInput(1, mleft.right().node());
             return Changed(node);
           }
         }
       }
       break;
     }
     case IrOpcode::kWord32Xor: {
       Int32BinopMatcher m(node);
       if (m.right().Is(0)) return Replace(m.left().node());  // x ^ 0 => x
       if (m.IsFoldable()) {                                  // K ^ K => K
@@ skipping 21 matching lines @@
           Int32BinopMatcher mleft(m.left().node());
           if (mleft.right().Is(m.right().Value())) {
             node->set_op(machine()->Word32And());
             node->ReplaceInput(0, mleft.left().node());
             node->ReplaceInput(
                 1, Uint32Constant(~((1U << m.right().Value()) - 1U)));
             return Changed(node);
           }
         }
       }
-      break;
+      return ReduceWord32Shifts(node);
     }
     case IrOpcode::kWord32Shr: {
       Uint32BinopMatcher m(node);
       if (m.right().Is(0)) return Replace(m.left().node());  // x >>> 0 => x
       if (m.IsFoldable()) {                                  // K >>> K => K
         return ReplaceInt32(m.left().Value() >> m.right().Value());
       }
-      break;
+      return ReduceWord32Shifts(node);
     }
     case IrOpcode::kWord32Sar: {
       Int32BinopMatcher m(node);
       if (m.right().Is(0)) return Replace(m.left().node());  // x >> 0 => x
       if (m.IsFoldable()) {                                  // K >> K => K
         return ReplaceInt32(m.left().Value() >> m.right().Value());
       }
       if (m.left().IsWord32Shl()) {
         Int32BinopMatcher mleft(m.left().node());
         if (mleft.left().IsLoad()) {
           LoadRepresentation const rep =
               OpParameter<LoadRepresentation>(mleft.left().node());
           if (m.right().Is(24) && mleft.right().Is(24) && rep == kMachInt8) {
             // Load[kMachInt8] << 24 >> 24 => Load[kMachInt8]
             return Replace(mleft.left().node());
           }
           if (m.right().Is(16) && mleft.right().Is(16) && rep == kMachInt16) {
             // Load[kMachInt16] << 16 >> 16 => Load[kMachInt8]
             return Replace(mleft.left().node());
           }
         }
       }
-      break;
+      return ReduceWord32Shifts(node);
     }
     case IrOpcode::kWord32Ror: {
       Int32BinopMatcher m(node);
       if (m.right().Is(0)) return Replace(m.left().node());  // x ror 0 => x
       if (m.IsFoldable()) {                                  // K ror K => K
         return ReplaceInt32(
             base::bits::RotateRight32(m.left().Value(), m.right().Value()));
       }
       break;
     }
@@ skipping 519 matching lines @@
       }
       break;
     }
     default:
       break;
   }
   return NoChange();
 }
 
 
+Reduction MachineOperatorReducer::ReduceWord32Shifts(Node* node) {
+  DCHECK((node->opcode() == IrOpcode::kWord32Shl) ||
+         (node->opcode() == IrOpcode::kWord32Shr) ||
+         (node->opcode() == IrOpcode::kWord32Sar));
+
+  if (machine()->Word32ShiftIsSafe()) {
+    // Remove the explicit 'and' with 0x1f if the shift provided by the machine
+    // instruction matches that required by JavaScript.
+    Int32BinopMatcher m(node);
+    if (m.right().IsWord32And()) {
+      Int32BinopMatcher mright(m.right().node());
+      if (mright.right().Is(0x1f)) {
+        node->ReplaceInput(1, mright.left().node());
+        return Changed(node);
+      }
+    }
+  }
+  return NoChange();
+}
+
+
 CommonOperatorBuilder* MachineOperatorReducer::common() const {
   return jsgraph()->common();
 }
 
 
 MachineOperatorBuilder* MachineOperatorReducer::machine() const {
   return jsgraph()->machine();
 }
 
 
 Graph* MachineOperatorReducer::graph() const { return jsgraph()->graph(); }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8