[Bug target/34422] Bootstrap error with --enable-fixed-point

[Bug target/34422] Bootstrap error with --enable-fixed-point

[egall at gwmail dot gwu.edu]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=34422

Eric Gallager <egall at gwmail dot gwu.edu> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |egall at gwmail dot gwu.edu

--- Comment #6 from Eric Gallager <egall at gwmail dot gwu.edu> ---
(In reply to Andrew Pinski from comment #5)
> fixed point support is only currently supported for the MIPS target.

So could the configure script error out earlier, then, if it is passed
--enable-fixed-point for a target other than MIPS?

[Bug target/34422] Bootstrap error with --enable-fixed-point

[egallager at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=34422

Eric Gallager <egallager at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |sbenzel at acm dot org

--- Comment #7 from Eric Gallager <egallager at gcc dot gnu.org> ---
*** Bug 97916 has been marked as a duplicate of this bug. ***

[Bug target/34422] Bootstrap error with --enable-fixed-point (configure should reject --enable-fixed-point on platforms that don't support it)

[egallager at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=34422

Eric Gallager <egallager at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
            Summary|Bootstrap error with        |Bootstrap error with
                   |--enable-fixed-point        |--enable-fixed-point
                   |                            |(configure should reject
                   |                            |--enable-fixed-point on
                   |                            |platforms that don't
                   |                            |support it)
           Assignee|unassigned at gcc dot gnu.org      |egallager at gcc dot gnu.org

--- Comment #8 from Eric Gallager <egallager at gcc dot gnu.org> ---
(In reply to Eric Gallager from comment #6)
> (In reply to Andrew Pinski from comment #5)
> > fixed point support is only currently supported for the MIPS target.
> 
> So could the configure script error out earlier, then, if it is passed
> --enable-fixed-point for a target other than MIPS?

I'm going to re-title and self-assign on that basis.

[Bug target/34422] Bootstrap error with --enable-fixed-point (configure should reject --enable-fixed-point on platforms that don't support it)

[egallager at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=34422

Eric Gallager <egallager at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |ASSIGNED

[Bug target/34422] Bootstrap error with --enable-fixed-point (configure should reject --enable-fixed-point on platforms that don't support it)

[egallager at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=34422

Eric Gallager <egallager at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Last reconfirmed|2008-01-22 00:58:46         |2022-5-24
                 CC|                            |Chao-Ying.Fu at imgtec dot com,
                   |                            |schwab at gcc dot gnu.org

--- Comment #9 from Eric Gallager <egallager at gcc dot gnu.org> ---
(In reply to Eric Gallager from comment #8)
> (In reply to Eric Gallager from comment #6)
> > So could the configure script error out earlier, then, if it is passed
> > --enable-fixed-point for a target other than MIPS?
> 
> I'm going to re-title and self-assign on that basis.

...ok, so wait, looking at gcc/configure.ac, it looks like there's already code
to ignore --enable-fixed-point for unsupported targets? (current list of
supported targets is arm, mips, and loongarch, for reference)
Furthermore, it looks like that code has been there since Chao-ying Fu first
added the flag in r0-82714-gab22c1fa94acc0... so why didn't it work and result
in the flag being properly ignored? I just checked again and the error still
occurs; now it reads:

/Users/ericgallager/gcc_newgit/abcdefghijklmnopqrstuvwxyz_01234567890.build/./gcc/xgcc
-B/Users/ericgallager/gcc_newgit/abcdefghijklmnopqrstuvwxyz_01234567890.build/./gcc/
-B/usr/local/x86_64-apple-darwin20/bin/ -B/usr/local/x86_64-apple-darwin20/lib/
-isystem /usr/local/x86_64-apple-darwin20/include -isystem
/usr/local/x86_64-apple-darwin20/sys-include    -g -O2 -g -Os -O2  -g -O2 -g
-Os -DIN_GCC -fPIC   -W -Wall -Wno-narrowing -Wwrite-strings -Wcast-qual
-Wstrict-prototypes -Wmissing-prototypes -Wold-style-definition  -isystem
./include   -mmacosx-version-min=10.4 -fno-common -g -DIN_LIBGCC2
-fbuilding-libgcc -fno-stack-protector   -mmacosx-version-min=10.4 -fno-common
-I. -I. -I../.././gcc -I../../../libgcc -I../../../libgcc/.
-I../../../libgcc/../gcc -I../../../libgcc/../include  -DHAVE_CC_TLS
-DUSE_EMUTLS  -o _addQQ_s.o -MT _addQQ_s.o -MD -MP -MF _addQQ_s.dep -DSHARED
-DL_add -DQQ_MODE -c ../../../libgcc/fixed-bit.c
In file included from ../../../libgcc/fixed-bit.c:55:
../../../libgcc/fixed-bit.h:64:1: error: unable to emulate 'QQ'
   64 | typedef          _Fract QQtype  __attribute__ ((mode (QQ)));
      | ^~~~~~~
../../../libgcc/fixed-bit.h:65:1: error: unable to emulate 'UQQ'
   65 | typedef unsigned _Fract UQQtype __attribute__ ((mode (UQQ)));
      | ^~~~~~~
../../../libgcc/fixed-bit.h:66:1: error: unable to emulate 'HQ'
   66 | typedef          _Fract HQtype  __attribute__ ((mode (HQ)));
      | ^~~~~~~
../../../libgcc/fixed-bit.h:67:1: error: unable to emulate 'UHQ'
   67 | typedef unsigned _Fract UHQtype __attribute__ ((mode (UHQ)));
      | ^~~~~~~
../../../libgcc/fixed-bit.h:68:1: error: unable to emulate 'HA'
   68 | typedef          _Fract HAtype  __attribute__ ((mode (HA)));
      | ^~~~~~~
../../../libgcc/fixed-bit.h:69:1: error: unable to emulate 'UHA'
   69 | typedef unsigned _Fract UHAtype __attribute__ ((mode (UHA)));
      | ^~~~~~~
../../../libgcc/fixed-bit.h:84:1: error: unable to emulate 'SQ'
   84 | typedef          _Fract SQtype  __attribute__ ((mode (SQ)));
      | ^~~~~~~
../../../libgcc/fixed-bit.h:85:1: error: unable to emulate 'USQ'
   85 | typedef unsigned _Fract USQtype __attribute__ ((mode (USQ)));
      | ^~~~~~~
../../../libgcc/fixed-bit.h:86:1: error: unable to emulate 'SA'
   86 | typedef          _Fract SAtype  __attribute__ ((mode (SA)));
      | ^~~~~~~
../../../libgcc/fixed-bit.h:87:1: error: unable to emulate 'USA'
   87 | typedef unsigned _Fract USAtype __attribute__ ((mode (USA)));
      | ^~~~~~~
../../../libgcc/fixed-bit.h:98:1: error: unable to emulate 'DQ'
   98 | typedef          _Fract DQtype  __attribute__ ((mode (DQ)));
      | ^~~~~~~
../../../libgcc/fixed-bit.h:99:1: error: unable to emulate 'UDQ'
   99 | typedef unsigned _Fract UDQtype __attribute__ ((mode (UDQ)));
      | ^~~~~~~
../../../libgcc/fixed-bit.h:100:1: error: unable to emulate 'DA'
  100 | typedef          _Fract DAtype  __attribute__ ((mode (DA)));
      | ^~~~~~~
../../../libgcc/fixed-bit.h:101:1: error: unable to emulate 'UDA'
  101 | typedef unsigned _Fract UDAtype __attribute__ ((mode (UDA)));
      | ^~~~~~~
../../../libgcc/fixed-bit.h:112:1: error: unable to emulate 'TQ'
  112 | typedef          _Fract TQtype  __attribute__ ((mode (TQ)));
      | ^~~~~~~
../../../libgcc/fixed-bit.h:113:1: error: unable to emulate 'UTQ'
  113 | typedef unsigned _Fract UTQtype __attribute__ ((mode (UTQ)));
      | ^~~~~~~
../../../libgcc/fixed-bit.h:114:1: error: unable to emulate 'TA'
  114 | typedef          _Fract TAtype  __attribute__ ((mode (TA)));
      | ^~~~~~~
../../../libgcc/fixed-bit.h:115:1: error: unable to emulate 'UTA'
  115 | typedef unsigned _Fract UTAtype __attribute__ ((mode (UTA)));
      | ^~~~~~~
../../../libgcc/fixed-bit.c: In function '__addqq3':
../../../libgcc/fixed-bit.c:60:1: internal compiler error: in
classify_argument, at config/i386/i386.cc:2494
   60 | {
      | ^
Please submit a full bug report, with preprocessed source (by using
-freport-bug).
See <https://gcc.gnu.org/bugs/> for instructions.
make[1]: *** [_addQQ_s.o] Error 1
make: *** [all-target-libgcc] Error 2

cc-ing people who touched the code in gcc/configure.ac that ought to cause the
flag to be ignored most recently, according to git blame.

[Bug target/34422] Bootstrap error with --enable-fixed-point (configure should reject --enable-fixed-point on platforms that don't support it)

[egallager at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=34422

--- Comment #10 from Eric Gallager <egallager at gcc dot gnu.org> ---
Current code is like this:

# Enable C extension for fixed-point arithmetic.
AC_ARG_ENABLE(fixed-point,
[AS_HELP_STRING([--enable-fixed-point],
                [enable fixed-point arithmetic extension to C])],
[],
[
  case $target in
    arm*)
      enable_fixed_point=yes
      ;;

    mips*-*-*)
      enable_fixed_point=yes
      ;;
    loongarch*-*-*)
      enable_fixed_point=yes
      ;;
    *)
      AC_MSG_WARN([fixed-point is not supported for this target, ignored])
      enable_fixed_point=no
      ;;
  esac
])
AC_SUBST(enable_fixed_point)

Let's check the documentation for AC_ARG_ENABLE:
https://www.gnu.org/savannah-checkouts/gnu/autoconf/manual/autoconf-2.71/html_node/Package-Options.html

So, argument 3 is used if the flag is given, and argument 4 is used when the
flag is *not* given... so when it says "ignored" in the warning, there's
nothing being ignored, because the flag wasn't actually given... perhaps the
3rd and 4th arguments just need to be swapped?

[Bug target/34422] Bootstrap error with --enable-fixed-point (configure should reject --enable-fixed-point on platforms that don't support it)

[egallager at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=34422

Eric Gallager <egallager at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |patch
                URL|                            |https://gcc.gnu.org/piperma
                   |                            |il/gcc-patches/2022-June/59
                   |                            |6654.html

--- Comment #11 from Eric Gallager <egallager at gcc dot gnu.org> ---
Patch posted to gcc-patches:
https://gcc.gnu.org/pipermail/gcc-patches/2022-June/596654.html

[Bug target/34422] Bootstrap error with --enable-fixed-point (configure should reject --enable-fixed-point on platforms that don't support it)

[egallager at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=34422

Eric Gallager <egallager at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |aoliva at gcc dot gnu.org

--- Comment #12 from Eric Gallager <egallager at gcc dot gnu.org> ---
(In reply to Eric Gallager from comment #11)
> Patch posted to gcc-patches:
> https://gcc.gnu.org/pipermail/gcc-patches/2022-June/596654.html

So this patch needs some more work; it might take awhile before I get to fixing
it though... should I unassign? I still intend to get back to this later, but I
just want to make sure that people are clear that they can give it a try
themselves in the meantime...

[Bug target/34422] Bootstrap error with --enable-fixed-point (configure should reject --enable-fixed-point on platforms that don't support it)

[egallager at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=34422

Eric Gallager <egallager at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|ASSIGNED                    |NEW
           Assignee|egallager at gcc dot gnu.org       |unassigned at gcc dot gnu.org

--- Comment #13 from Eric Gallager <egallager at gcc dot gnu.org> ---
(In reply to Eric Gallager from comment #12)
> (In reply to Eric Gallager from comment #11)
> > Patch posted to gcc-patches:
> > https://gcc.gnu.org/pipermail/gcc-patches/2022-June/596654.html
> 
> So this patch needs some more work; it might take awhile before I get to
> fixing it though... should I unassign? I still intend to get back to this
> later, but I just want to make sure that people are clear that they can give
> it a try themselves in the meantime...

...ok yeah I think I'm going to unassign; if anyone thinks they can address the
feedback from here, feel free to take it:
https://gcc.gnu.org/pipermail/gcc-patches/2022-June/597046.html