[Bug target/56010] Powerpc, -mcpu=native and -mtune=native use the wrong name for target 7450

[bergner at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=56010

Peter Bergner <bergner at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |ASSIGNED
   Last reconfirmed|                            |2018-01-10
           Assignee|unassigned at gcc dot gnu.org      |bergner at gcc dot gnu.org
     Ever confirmed|0                           |1

--- Comment #5 from Peter Bergner <bergner at gcc dot gnu.org> ---
Going through the kernel cputable.c file and comparing it to rs6000-cpus.def, I
think the name translation should like:

These kernel AT_PLATFORM names can be used as is:
  .platform = "powerpc",
  .platform = "power3",
  .platform = "power4",
  .platform = "power5",
  .platform = "power5+",
  .platform = "power6",
  .platform = "power6x",
  .platform = "power7",
  .platform = "power8",
  .platform = "power9",

This kernel AT_PLATFORM name should strip the '+' off:
  .platform = "power7+", -> "power7"

These kernel AT_PLATFORM names should strip the 'ppc' prefix off:
  .platform = "ppc970", -> "970"
  .platform = "ppc601", -> "601"
  .platform = "ppc603", -> "603"
  .platform = "ppc604", -> "604"
  .platform = "ppc750", -> "750"
  .platform = "ppc7400", -> "7400"
  .platform = "ppc7450", -> "7450"
  .platform = "ppc823", -> "823"
  .platform = "ppc403", -> "403"
  .platform = "ppc8540", -> "8540"
  .platform = "ppc8548", -> "8548"
  .platform = "ppce5500", -> "e5500"
  .platform = "ppce6500", -> "e6500"

These kernel AT_PLATFORM names should strip their prefix and suffix off:
  .platform = "ppc440gp", -> "440"
  .platform = "ppc-cell-be", -> "cell"

These kernel AT_PLATFORM names should strip the 'ppc' prefix off, as
well as test the AT_HWCAP for PPC_FEATURE_HAS_FPU:
  .platform = "ppc405", -> "405" | "405fp"
  .platform = "ppc440", -> "440" | "440fp"

This kernel AT_PLATFORM name should strip the 'ppc' prefix off, change
470 to 476 as well as test the AT_HWCAP for PPC_FEATURE_HAS_FPU:
  .platform = "ppc470", -> "476" | "476fp"

This kernel AT_PLATFORM name should strip the 'ppc' prefix off, as
well as test the AT_HWCAP for PPC_FEATURE_64::
  .platform = "ppce500mc", -> "e500mc" | "e500mc64"

These kernel AT_PLATFORM names do not seem to have an equivalent
rs6000-cpus.def entry, so we probably should just treat them as
unknown/non-existent names:
  .platform = "pa6t",
  .platform = "ppc5554",

I will take a stab at adding this name translation, which should also fix
PR83743.

I do question though, whether we should test the AT_HWCAP bits or not.  Just
because we're on, say a 476fp system, doesn't mean the toolchain and libraries
are compiled with FP support.  Thoughts anyone?