VM: Optimized code for all of [External]{One|Two}ByteString::codeUnitAt.

runtime/vm/flow_graph_inliner.cc

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/flow_graph_inliner.h"
 
 #include "vm/aot_optimizer.h"
 #include "vm/block_scheduler.h"
 #include "vm/branch_optimizer.h"
 #include "vm/compiler.h"
@@ skipping 2785 matching lines @@
   cursor = flow_graph->AppendTo(cursor, length, NULL, FlowGraph::kValue);
   // Bounds check.
   cursor = flow_graph->AppendTo(cursor,
                                 new(Z) CheckArrayBoundInstr(
                                     new(Z) Value(length),
                                     new(Z) Value(index),
                                     call->deopt_id()),
                                 call->env(),
                                 FlowGraph::kEffect);
 
+  // For external strings: Load backing store.
+  if (cid == kExternalOneByteStringCid) {
+    str = new LoadUntaggedInstr(new Value(str),
+                                ExternalOneByteString::external_data_offset());
+    cursor = flow_graph->AppendTo(cursor, str, NULL, FlowGraph::kValue);
+    str = new LoadUntaggedInstr(
+        new Value(str),
+        RawExternalOneByteString::ExternalData::data_offset());
+    cursor = flow_graph->AppendTo(cursor, str, NULL, FlowGraph::kValue);
+  } else if (cid == kExternalTwoByteStringCid) {
+    str = new LoadUntaggedInstr(new Value(str),
+                                ExternalTwoByteString::external_data_offset());
+    cursor = flow_graph->AppendTo(cursor, str, NULL, FlowGraph::kValue);
+    str = new LoadUntaggedInstr(
+        new Value(str),
+        RawExternalTwoByteString::ExternalData::data_offset());
+    cursor = flow_graph->AppendTo(cursor, str, NULL, FlowGraph::kValue);
+  }
+
   LoadIndexedInstr* load_indexed = new(Z) LoadIndexedInstr(
       new(Z) Value(str),
       new(Z) Value(index),
       Instance::ElementSizeFor(cid),
       cid,
       Thread::kNoDeoptId,
       call->token_pos());
 
   cursor = flow_graph->AppendTo(cursor, load_indexed, NULL, FlowGraph::kValue);
   ASSERT(cursor == load_indexed);
   return load_indexed;
 }
 
 
 static bool InlineStringBaseCharAt(
     FlowGraph* flow_graph,
     Instruction* call,
     intptr_t cid,
     TargetEntryInstr** entry,
     Definition** last) {
-  // TODO(johnmccutchan): Handle external strings in PrepareInlineStringIndexOp.
-  if (RawObject::IsExternalStringClassId(cid) || cid != kOneByteStringCid) {
+  if ((cid != kOneByteStringCid) && (cid != kExternalOneByteStringCid)) {
     return false;
   }
   Definition* str = call->ArgumentAt(0);
   Definition* index = call->ArgumentAt(1);
 
   *entry = new(Z) TargetEntryInstr(flow_graph->allocate_block_id(),
                                    call->GetBlock()->try_index());
   (*entry)->InheritDeoptTarget(Z, call);
 
   *last = PrepareInlineStringIndexOp(flow_graph, call, cid, str, index, *entry);
 
-  StringFromCharCodeInstr* char_at = new(Z) StringFromCharCodeInstr(
-      new(Z) Value(*last), cid);
+  OneByteStringFromCharCodeInstr* char_at =
+      new(Z) OneByteStringFromCharCodeInstr(new(Z) Value(*last));
 
   flow_graph->AppendTo(*last, char_at, NULL, FlowGraph::kValue);
   *last = char_at;
 
   return true;
 }
 
 
 static bool InlineStringCodeUnitAt(
     FlowGraph* flow_graph,
     Instruction* call,
     intptr_t cid,
     TargetEntryInstr** entry,
     Definition** last) {
-  // TODO(johnmccutchan): Handle external strings in PrepareInlineStringIndexOp.
-  if (RawObject::IsExternalStringClassId(cid)) {
-    return false;
-  }
-
   Definition* str = call->ArgumentAt(0);
   Definition* index = call->ArgumentAt(1);
 
   *entry = new(Z) TargetEntryInstr(flow_graph->allocate_block_id(),
                                    call->GetBlock()->try_index());
   (*entry)->InheritDeoptTarget(Z, call);
 
   *last = PrepareInlineStringIndexOp(flow_graph, call, cid, str, index, *entry);
 
   return true;
@@ skipping 220 matching lines @@
                                       kTypedDataFloat32x4ArrayCid,
                                       entry, last);
     case MethodRecognizer::kByteArrayBaseSetInt32x4:
       if (!ShouldInlineSimd()) {
         return false;
       }
       return InlineByteArrayBaseStore(flow_graph, target, call, receiver,
                                       receiver_cid,
                                       kTypedDataInt32x4ArrayCid,
                                       entry, last);
-    case MethodRecognizer::kStringBaseCodeUnitAt:
+    case MethodRecognizer::kOneByteStringCodeUnitAt:
+    case MethodRecognizer::kTwoByteStringCodeUnitAt:
+    case MethodRecognizer::kExternalOneByteStringCodeUnitAt:
+    case MethodRecognizer::kExternalTwoByteStringCodeUnitAt:
       return InlineStringCodeUnitAt(
           flow_graph, call, receiver_cid, entry, last);
     case MethodRecognizer::kStringBaseCharAt:
       return InlineStringBaseCharAt(
           flow_graph, call, receiver_cid, entry, last);
     case MethodRecognizer::kDoubleAdd:
       return InlineDoubleOp(flow_graph, Token::kADD, call, entry, last);
     case MethodRecognizer::kDoubleSub:
       return InlineDoubleOp(flow_graph, Token::kSUB, call, entry, last);
     case MethodRecognizer::kDoubleMul:
       return InlineDoubleOp(flow_graph, Token::kMUL, call, entry, last);
     case MethodRecognizer::kDoubleDiv:
       return InlineDoubleOp(flow_graph, Token::kDIV, call, entry, last);
     default:
       return false;
   }
 }
 
 
 }  // namespace dart