Reland 21774: Generate KeyedLoadGeneric with Hydrogen

src/hydrogen-dehoist.cc

 // Copyright 2013 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 35 matching lines @@
     constant = HConstant::cast(binary_operation->right());
   } else {
     return;
   }
 
   if (!constant->HasInteger32Value()) return;
   int32_t sign = binary_operation->IsSub() ? -1 : 1;
   int32_t value = constant->Integer32Value() * sign;
   // We limit offset values to 30 bits because we want to avoid the risk of
   // overflows when the offset is added to the object header size.
-  if (value >= 1 << array_operation->MaxIndexOffsetBits() || value < 0) return;
+  if (value >= 1 << array_operation->MaxBaseOffsetBits() || value < 0) return;

[Toon Verwaest, 2013/12/04 17:29:26]

"value >= 1 << ..." is quite hard to understand. Could we extract this to
temporary variables that declare their meaning?

[danno, 2014/06/06 15:43:50]

Done.

   array_operation->SetKey(subexpression);
   if (binary_operation->HasNoUses()) {
     binary_operation->DeleteAndReplaceWith(NULL);
   }
-  array_operation->SetIndexOffset(static_cast<uint32_t>(value));
+  value <<= ElementsKindToShiftSize(array_operation->elements_kind());
+  array_operation->IncreaseBaseOffset(static_cast<uint32_t>(value));
   array_operation->SetDehoisted(true);
 }
 
 
 void HDehoistIndexComputationsPhase::Run() {
   const ZoneList<HBasicBlock*>* blocks(graph()->blocks());
   for (int i = 0; i < blocks->length(); ++i) {
     for (HInstructionIterator it(blocks->at(i)); !it.Done(); it.Advance()) {
       HInstruction* instr = it.Current();
       if (instr->IsLoadKeyed()) {
         DehoistArrayIndex(HLoadKeyed::cast(instr));
       } else if (instr->IsStoreKeyed()) {
         DehoistArrayIndex(HStoreKeyed::cast(instr));
       }
     }
   }
 }
 
 } }  // namespace v8::internal