[Bug middle-end/28283] SuperH: Very unoptimal code generated for 64-bit ints

["amylaar at gcc dot gnu dot org" <gcc-bugzilla at gcc dot gnu dot org>]

------- Comment #7 from amylaar at gcc dot gnu dot org  2006-07-07 13:50 -------
(In reply to comment #3)
> When I disable the offending code (by altering add_cost[DImode] at the right
> moment), I get the right result for little endian.  However, compiling for
> big endian gives wrong code:
> 
> _expand64:
>         mov     #0,r5
>         mov     r4,r0
>         rts     
>         mov     r5,r1
>         .size   _expand64, .-_expand64
>         .ident  "GCC: (GNU) 4.2.0 20060620 (experimental)"
> 
> 3.4.0 was sane:
> _expand64:
>         mov     r4,r5
>         mov     #0,r4
>         mov     r4,r0
>         rts
>         mov     r5,r1
>         .size   _expand64, .-_expand64
>         .ident  "GCC: (GNU) 3.4.0 20040113 (experimental)"
> 
Oops, I got mixed up here - I somehow thought the argument was long long,
i.e. the lowpart in r5.  Since the argument is actually unsigned int, it is
passed in r4.

And the 3.4.0 code for big endian is actually:
_expand64:
        mov     #0,r5
        mov     r4,r0
        rts
        mov     r5,r1
        .size   _expand64, .-_expand64
        .ident  "GCC: (GNU) 3.4.0 20040113 (experimental)"


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=28283