[Bug target/88346] New: [9 Regression] Inconsistent list of CPUs supported by the rs6000 backend after r266502

[asolokha at gmx dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88346

            Bug ID: 88346
           Summary: [9 Regression] Inconsistent list of CPUs supported by
                    the rs6000 backend after r266502
           Product: gcc
           Version: 9.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: target
          Assignee: unassigned at gcc dot gnu.org
          Reporter: asolokha at gmx dot com
                CC: amodra at gcc dot gnu.org
  Target Milestone: ---
            Target: powerpc-*-linux-gnu

After r266502 gcc still lists powerpc64, rs64, and titan as valid arguments to
-mcpu when emitting diagnostic for invalid -mcpu= argument:

% powerpc-e300c3-linux-gnu-gcc-9.0.0-alpha20181202 -mcpu=list
powerpc-e300c3-linux-gnu-gcc-9.0.0-alpha20181202: error: unrecognized argument
in option '-mcpu=list'
powerpc-e300c3-linux-gnu-gcc-9.0.0-alpha20181202: note: valid arguments to
'-mcpu=' are: 401 403 405 405fp 440 440fp 464 464fp 476 476fp 505 601 602 603
603e 604 604e 620 630 740 7400 7450 750 801 821 823 8540 8548 860 970 G3 G4 G5
a2 cell e300c2 e300c3 e500mc e500mc64 e5500 e6500 ec603e native power3 power4
power5 power5+ power6 power6x power7 power8 power9 powerpc powerpc64
powerpc64le rs64 titan
powerpc-e300c3-linux-gnu-gcc-9.0.0-alpha20181202: fatal error: no input files
compilation terminated.

However, when provided w/ -mcpu=powerpc64, =rs64, or =titan, it now fails w/
the following:

% powerpc-e300c3-linux-gnu-gcc-9.0.0-alpha20181202 -mcpu=powerpc64 -w -c test.c
-o /dev/null
powerpc-e300c3-linux-gnu-gcc-9.0.0-alpha20181202: error: Missing -mcpu option
in ASM_SPEC_CPU?

which actually agrees w/ what is defined for ASM_CPU_SPEC in
config/rs6000/rs6000.h.

I also believe that ASM_SPEC_CPU in :%eMissing -mcpu option in ASM_SPEC_CPU?\n
defined in config/rs6000/aix72.h, config/rs6000/aix71.h, and
config/rs6000/rs6000.h should actually read ASM_CPU_SPEC.