Porting r9392 to x64 (smi-only arrays).

src/x64/ic-x64.cc

 // Copyright 2011 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 674 matching lines @@
   // Check the key against the length in the array, compute the
   // address to store into and fall through to fast case.
   __ SmiCompareInteger32(FieldOperand(rdx, JSArray::kLengthOffset), rcx);
   __ j(below_equal, &extra);
 
   // Fast case: Do the store.
   __ bind(&fast);
   // rax: value
   // rbx: receiver's elements array (a FixedArray)
   // rcx: index
+
+  if (FLAG_smi_only_arrays) {

[William Hesse, 2011/09/23 13:25:22]

The JumpIfNotSmi can be moved above the guard, together with the movq and ret
for the two smi cases (now made one case).  I think this speeds and simplifies
the code.

[Yang, 2011/09/23 14:19:12]

Done.

+    Label not_smi_only;
+    // Make sure the elements are smi-only.
+    __ movq(rdi, FieldOperand(rdx, HeapObject::kMapOffset));
+    __ CheckFastSmiOnlyElements(rdi, &not_smi_only, Label::kNear);
+    // Non-smis need to call into the runtime if the array is smi only.
+    __ JumpIfNotSmi(rax, &slow);
+    __ movq(FieldOperand(rbx, rcx, times_pointer_size, FixedArray::kHeaderSize),
+            rax);
+    __ ret(0);
+    __ bind(&not_smi_only);
+  }
+
   Label non_smi_value;
   __ movq(FieldOperand(rbx, rcx, times_pointer_size, FixedArray::kHeaderSize),
           rax);
   __ JumpIfNotSmi(rax, &non_smi_value, Label::kNear);
   __ ret(0);
   __ bind(&non_smi_value);
   // Slow case that needs to retain rcx for use by RecordWrite.
   // Update write barrier for the elements array address.
   __ movq(rdx, rax);
   __ lea(rcx,
@@ skipping 967 matching lines @@
   Condition cc = *jmp_address == Assembler::kJncShortOpcode
       ? not_zero
       : zero;
   *jmp_address = static_cast<byte>(Assembler::kJccShortPrefix | cc);
 }
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_X64