Adapt Danno's Track Allocation Info idea to fast literals. When allocating a literal array,

src/arm/macro-assembler-arm.cc

Index: src/arm/macro-assembler-arm.cc
diff --git a/src/arm/macro-assembler-arm.cc b/src/arm/macro-assembler-arm.cc
index 0764e090dde3fd9631421f9badbdfe0ba6573790..5368e519ffdf5cba24c2f93949106c211cd3a345 100644
--- a/src/arm/macro-assembler-arm.cc
+++ b/src/arm/macro-assembler-arm.cc
@@ -3883,6 +3883,39 @@ void MacroAssembler::CheckEnumCache(Register null_value, Label* call_runtime) {
 }
 
 
+void MacroAssembler::PerformAllocationSiteInfoCheck(
+    Label* allocation_info_present) {
+  Label no_info_available;
+  // ----------- S t a t e -------------
+  //  -- r2    : receiver

[danno, 2013/01/04 08:50:55]

Pass in receiver_reg and scratch_reg.

[mvstanton, 2013/01/04 12:07:52]

Done.

+  //  r4 is clobbered.
+  // -----------------------------------
+  ExternalReference new_space_start =
+      ExternalReference::new_space_start(isolate());
+  ExternalReference new_space_allocation_top =
+      ExternalReference::new_space_allocation_top_address(isolate());
+
+  ldr(r4, FieldMemOperand(r2, JSArray::kSize + AllocationSiteInfo::kSize));
+  cmp(r4, Operand(new_space_start));
+  b(lt, &no_info_available);
+  cmp(r4, Operand(new_space_allocation_top));
+  b(hs, &no_info_available);
+  ldr(r4, MemOperand(r4, 0));
+  cmp(r4,
+      Operand(Handle<Map>(isolate()->heap()->
+                               allocation_site_info_map())));

[danno, 2013/01/04 08:50:55]

nit: formatting above, Operand can be on same line as r4 and
allocation_site_info_map should be indented 4 spaces.

[mvstanton, 2013/01/04 12:07:52]

Done.

+
+  // Use the j/jmp sequence below for debugging, but the j(equal) sequence

[danno, 2013/01/04 08:50:55]

Keep the sequence below uncommented on this and other platforms, just wrap it in
a if (FLAG_debug_code) {}

[mvstanton, 2013/01/04 12:07:52]

I decided to remove it because debug_code should be for additional checks,
whereas my int3() was just so a developer can stop in a debugger to examine the
generated code. I will think about doing some debug_code work in the next
checkin, which does more extensive things with the AllocationSiteInfo payload.
(I can check if the payload is a smi or object, for example).

+  // for production.
+  // b(not_equal, &no_info_available);
+  // int3();
+  // jmp(allocation_info_present);
+  // or
+  b(eq, allocation_info_present);
+  bind(&no_info_available);
+}
+
+
 #ifdef DEBUG
 bool AreAliased(Register reg1,
                 Register reg2,