Fix improved LoadICs for dictionaries with callbacks.

src/arm/stub-cache-arm.cc

 // Copyright 2012 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 1220 matching lines @@
 
 
 void StubCompiler::GenerateDictionaryLoadCallback(Register receiver,
                                                   Register name_reg,
                                                   Register scratch1,
                                                   Register scratch2,
                                                   Register scratch3,
                                                   Handle<AccessorInfo> callback,
                                                   Handle<String> name,
                                                   Label* miss) {
+  ASSERT(!receiver.is(scratch2));
+  ASSERT(!receiver.is(scratch3));
   Register dictionary = scratch1;
-  Register index = scratch2;
+  bool must_preserve_dictionary_reg = receiver.is(dictionary);
+
+  // Load the properties dictionary.
+  if (must_preserve_dictionary_reg) {
+    __ push(dictionary);

[Erik Corry, 2012/08/14 11:03:33]

This is slow on ARM and unnecessary when there are 16 registers.

[Michael Starzinger, 2012/08/14 11:44:05]

Done.

+  }
   __ ldr(dictionary, FieldMemOperand(receiver, JSObject::kPropertiesOffset));
 
   // Probe the dictionary.
-  Label probe_done;
+  Label probe_done, pop_and_miss;
   StringDictionaryLookupStub::GeneratePositiveLookup(masm(),
-                                                     miss,
+                                                     &pop_and_miss,
                                                      &probe_done,
                                                      dictionary,
                                                      name_reg,
-                                                     index,  // Set if we hit.
+                                                     scratch2,
                                                      scratch3);
+  __ bind(&pop_and_miss);
+  if (must_preserve_dictionary_reg) {
+    __ pop(dictionary);
+  }
+  __ jmp(miss);
   __ bind(&probe_done);
+  if (must_preserve_dictionary_reg) {
+    __ pop(dictionary);
+  }
 
-  // If probing finds an entry in the dictionary, check that the value is the
-  // callback.
-  const int kElementsStartOffset =
-      StringDictionary::kHeaderSize +
+  // If probing finds an entry in the dictionary, scratch3 contains the
+  // pointer into the dictionary. Check that the value is the callback.
+  Register pointer = scratch3;
+  const int kElementsStartOffset = StringDictionary::kHeaderSize +
       StringDictionary::kElementsStartIndex * kPointerSize;
   const int kValueOffset = kElementsStartOffset + kPointerSize;
-  __ add(scratch1, dictionary, Operand(kValueOffset - kHeapObjectTag));
-  __ ldr(scratch3, MemOperand(scratch1, index, LSL, kPointerSizeLog2));
-  __ cmp(scratch3, Operand(callback));
+  __ ldr(scratch2, FieldMemOperand(pointer, kValueOffset));
+  __ cmp(scratch2, Operand(callback));
   __ b(ne, miss);
 }
 
 
 void StubCompiler::GenerateLoadCallback(Handle<JSObject> object,
                                         Handle<JSObject> holder,
                                         Register receiver,
                                         Register name_reg,
                                         Register scratch1,
                                         Register scratch2,
                                         Register scratch3,
                                         Handle<AccessorInfo> callback,
                                         Handle<String> name,
                                         Label* miss) {
   // Check that the receiver isn't a smi.
   __ JumpIfSmi(receiver, miss);
 
   // Check that the maps haven't changed.
   Register reg = CheckPrototypes(object, receiver, holder, scratch1,
                                  scratch2, scratch3, name, miss);
 
   if (!holder->HasFastProperties() && !holder->IsJSGlobalObject()) {
     GenerateDictionaryLoadCallback(
-        receiver, name_reg, scratch1, scratch2, scratch3, callback, name, miss);
+        reg, name_reg, scratch1, scratch2, scratch3, callback, name, miss);
   }
 
   // Build AccessorInfo::args_ list on the stack and push property name below
   // the exit frame to make GC aware of them and store pointers to them.
   __ push(receiver);
   __ mov(scratch2, sp);  // scratch2 = AccessorInfo::args_
   if (heap()->InNewSpace(callback->data())) {
     __ Move(scratch3, callback);
     __ ldr(scratch3, FieldMemOperand(scratch3, AccessorInfo::kDataOffset));
   } else {
@@ skipping 3422 matching lines @@
     __ Jump(ic_slow, RelocInfo::CODE_TARGET);
   }
 }
 
 
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_ARM