re: toolchain/58411: GCC/x86_64 10.5 and 12.4 miscompile GCC/sh3 12.4

[matthew green <mrg%eterna23.net@localhost>]

looking at config/i386/x86-tune-costs.h nocona, i see that between
gcc10 and gcc12 this gained some additional things:

struct processor_costs nocona_cost = {     
[ ... ]
  20, 12,                               /* mask->integer and integer->mask moves */
  {4, 4, 4},                            /* cost of loading mask register
                                           in QImode, HImode, SImode.  */
  {4, 4, 4},                            /* cost if storing mask register
                                           in QImode, HImode, SImode.  */
  2,                                    /* cost of moving mask register.  */

which might be related (the mask/int parts?)

for generic_cost, the change is:

  6, 6,                                /* mask->integer and integer->mask moves */
  {6, 6, 6},                           /* cost of loading mask register
                                          in QImode, HImode, SImode.  */
  {6, 6, 6},                   /* cost if storing mask register
                                          in QImode, HImode, SImode.  */
  2,                                   /* cost of moving mask register.  */


.mrg.