[aarch64-port-dev ] Weird thing in c1 compiler code

[Edward Nevill]

On Mon, 2014-08-18 at 14:49 +0100, Andrew Dinn wrote:
> On 08/08/14 10:08, Andrew Haley wrote:
> > On 07/08/14 21:59, Andrew Haley wrote:
> >>> Specifically, why is the else if branch testing for T_DOUBLE?
> >> It shouldn't be: AFAICS that case is unreachable.
> > 
> > Ah, but it might not be: it is possible to stash a double in an
> > integer register.  That might be why it's there.
> 
> Ok, that does indeed make sense -- although the same case is not present
> in the x86 code yet the same possibility is there with x86, no? (also,
> mutatis mutandis, with a float value and an integer register).
> 
> I was just wondering if whoever added this case had a good reason why.
> Ed, maybe?

Beats me.

The change was added by Andrew on May 22 last year.

# HG changeset patch
# User aph
# Date 1369218144 -3600
#      Wed May 22 11:22:24 2013 +0100
# Branch aarch64_c1
# Node ID 31a822a80cae49157ef2c02baabfd5018822b171
# Parent  9baee4e65ac5665fa3d8c6ba75d6b58018c317f4
More minor C1 bug fixes.

...
@@ -688,7 +703,7 @@
     if (type == T_ARRAY || type == T_OBJECT) {
       __ str(src->as_register(), frame_map()->address_for_slot(dest->single_stack_ix()));
       __ verify_oop(src->as_register());
-    } else if (type == T_METADATA) {
+    } else if (type == T_METADATA || type == T_DOUBLE) {
       __ str(src->as_register(), frame_map()->address_for_slot(dest->single_stack_ix()));
     } else {
       __ strw(src->as_register(), frame_map()->address_for_slot(dest->single_stack_ix()));
...

The change seems to have been added as a specific change. IE It does not seem to be the result of an accidental merge.

I guess the reasons are just lost in history.

Regards,
Ed.