Re: Patch: PR40900, extending call patterns

[Eric Botcazou <ebotcazou@adacore.com>]

> Seems to be because it's a signed operation, and arm has
>
> #define PROMOTE_MODE(MODE, UNSIGNEDP, TYPE)     \
>   if (GET_MODE_CLASS (MODE) == MODE_INT         \
>       && GET_MODE_SIZE (MODE) < 4)              \
>     {                                           \
>       if (MODE == QImode)                       \
>         UNSIGNEDP = 1;                          \
>       else if (MODE == HImode)                  \
>         UNSIGNEDP = 1;                          \
>       (MODE) = SImode;                          \
>     }
>
> while ppc doesn't modify UNSIGNEDP.

Can't we be clever during RTL expansion and avoid blindly zero-extending the 
value when we known that

  D.2014_1 = shortv2 ();

and promote_function_mode sign-extends?  The kind of extension for a specific 
variable can be changed since the SUBREG_PROMOTED_* machinery records it.  In 
other words, can't we just override promote_decl_mode in the SSA_NAME case of 
expand_expr_real_1?

-- 
Eric Botcazou