Implement optional turbofan UnalignedLoad and UnalignedStore operators

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 421 matching lines @@
       if (m.HasValue()) return ReplaceFloat32(DoubleToFloat32(m.Value()));
       if (m.IsChangeFloat32ToFloat64()) return Replace(m.node()->InputAt(0));
       break;
     }
     case IrOpcode::kFloat64InsertLowWord32:
       return ReduceFloat64InsertLowWord32(node);
     case IrOpcode::kFloat64InsertHighWord32:
       return ReduceFloat64InsertHighWord32(node);
     case IrOpcode::kStore:
       return ReduceStore(node);
+    case IrOpcode::kUnalignedStore:
+      return ReduceUnalignedStore(node);
     case IrOpcode::kFloat64Equal:
     case IrOpcode::kFloat64LessThan:
     case IrOpcode::kFloat64LessThanOrEqual:
       return ReduceFloat64Compare(node);
     default:
       break;
   }
   return NoChange();
 }
 
@@ skipping 253 matching lines @@
         }
       }
       break;
     }
     default:
       break;
   }
   return NoChange();
 }
 
+Reduction MachineOperatorReducer::ReduceUnalignedStore(Node* node) {

[titzer, 2016/03/22 15:00:20]

This looks like an exact duplicate of the above method. Can you factor this out
to be a common routine?

[titzer, 2016/03/29 08:42:48]

New patchset got lost here?

+  MachineRepresentation const rep = UnalignedStoreRepresentationOf(node->op());
+  Node* const value = node->InputAt(2);
+  switch (value->opcode()) {
+    case IrOpcode::kWord32And: {
+      Uint32BinopMatcher m(value);
+      if (m.right().HasValue() && ((rep == MachineRepresentation::kWord8 &&
+                                    (m.right().Value() & 0xff) == 0xff) ||
+                                   (rep == MachineRepresentation::kWord16 &&
+                                    (m.right().Value() & 0xffff) == 0xffff))) {
+        node->ReplaceInput(2, m.left().node());
+        return Changed(node);
+      }
+      break;
+    }
+    case IrOpcode::kWord32Sar: {
+      Int32BinopMatcher m(value);
+      if (m.left().IsWord32Shl() && ((rep == MachineRepresentation::kWord8 &&
+                                      m.right().IsInRange(1, 24)) ||
+                                     (rep == MachineRepresentation::kWord16 &&
+                                      m.right().IsInRange(1, 16)))) {
+        Int32BinopMatcher mleft(m.left().node());
+        if (mleft.right().Is(m.right().Value())) {
+          node->ReplaceInput(2, mleft.left().node());
+          return Changed(node);
+        }
+      }
+      break;
+    }
+    default:
+      break;
+  }
+  return NoChange();
+}
+
 
 Reduction MachineOperatorReducer::ReduceProjection(size_t index, Node* node) {
   switch (node->opcode()) {
     case IrOpcode::kInt32AddWithOverflow: {
       DCHECK(index == 0 || index == 1);
       Int32BinopMatcher m(node);
       if (m.IsFoldable()) {
         int32_t val;
         bool ovf = base::bits::SignedAddOverflow32(m.left().Value(),
                                                    m.right().Value(), &val);
@@ skipping 357 matching lines @@
 MachineOperatorBuilder* MachineOperatorReducer::machine() const {
   return jsgraph()->machine();
 }
 
 
 Graph* MachineOperatorReducer::graph() const { return jsgraph()->graph(); }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8