[Bug bootstrap/55175] New: i386/sfp-exceptions.c:52:7: error: impossible constraint in 'asm'

[Bug bootstrap/55175] New: i386/sfp-exceptions.c:52:7: error: impossible constraint in 'asm'

[corsepiu at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55175

             Bug #: 55175
           Summary: i386/sfp-exceptions.c:52:7: error: impossible
                    constraint in 'asm'
    Classification: Unclassified
           Product: gcc
           Version: 4.8.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: bootstrap
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: corsepiu@gcc.gnu.org


Created attachment 28594
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=28594
*.i of the file raising the breakdown

Bootstrapping gcc-trunk (xgcc (GCC) 4.8.0 20120927 (experimental)) fails with
this error for --target=i386-rtems4.11:

...
/users/rtems/src/rtems.org/rtems-gcc/BUILD-i386/./gcc/xgcc
-B/users/rtems/src/rtems.org/rtems-gcc/BUILD-i386/./gcc/ -nostdinc
-B/users/rtems/src/rtems.org/rtems-gcc/BUILD-i386/i386-rtems4.11/soft-float/newlib/
-isystem
/users/rtems/src/rtems.org/rtems-gcc/BUILD-i386/i386-rtems4.11/soft-float/newlib/targ-include
-isystem /users/rtems/src/rtems.org/rtems-gcc/newlib/libc/include
-B/opt/rtems-4.11/i386-rtems4.11/bin/ -B/opt/rtems-4.11/i386-rtems4.11/lib/
-isystem /opt/rtems-4.11/i386-rtems4.11/include -isystem
/opt/rtems-4.11/i386-rtems4.11/sys-include  -msoft-float -g -O2 -Wall -O2
-I../../../../libgcc/../newlib/libc/sys/rtems/include -g -O2 -Wall -DIN_GCC
-DCROSS_DIRECTORY_STRUCTURE  -W -Wall -Wno-narrowing -Wwrite-strings
-Wcast-qual -Wstrict-prototypes -Wmissing-prototypes -Wold-style-definition 
-isystem ./include   -g -DIN_LIBGCC2 -fbuilding-libgcc -fno-stack-protector
-Dinhibit_libc  -I. -I. -I../../.././gcc -I../../../../libgcc
-I../../../../libgcc/. -I../../../../libgcc/../gcc
-I../../../../libgcc/../include  -DHAVE_CC_TLS  -o sfp-exceptions.o -MT
sfp-exceptions.o -MD -MP -MF sfp-exceptions.dep  -c
../../../../libgcc/config/i386/sfp-exceptions.c -fvisibility=hidden
-DHIDE_EXPORTS
../../../../libgcc/config/i386/sfp-exceptions.c: In function
'__sfp_handle_exceptions':
../../../../libgcc/config/i386/sfp-exceptions.c:52:7: error: impossible
constraint in 'asm'
       asm volatile ("fdiv\t{%y0, %0|%0, %y0}" : "+t" (f));
       ^
../../../../libgcc/config/i386/sfp-exceptions.c:62:7: error: impossible
constraint in 'asm'
       asm volatile ("fdivs\t%1" : "+t" (f) : "m" (g));
       ^
make: *** [sfp-exceptions.o] Error 1

[Bug bootstrap/55175] i386/sfp-exceptions.c:52:7: error: impossible constraint in 'asm'

[ubizjak at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55175

--- Comment #1 from Uros Bizjak <ubizjak at gmail dot com> 2012-11-02 10:01:44 UTC ---
Created attachment 28596
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=28596
Proposed patch

Patch that disables relevant parts of soft-fp library

[Bug bootstrap/55175] i386/sfp-exceptions.c:52:7: error: impossible constraint in 'asm'

[ubizjak at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55175

--- Comment #2 from Uros Bizjak <ubizjak at gmail dot com> 2012-11-02 10:05:24 UTC ---
Can you please try to build with attached (untested) patch?

The patch disables the part that handles exceptions and where rounding mode is
set. We need either x87 or SSE control register for this functionality.

[Bug bootstrap/55175] i386/sfp-exceptions.c:52:7: error: impossible constraint in 'asm'

[joel at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55175

Joel Sherrill <joel at gcc dot gnu.org> changed:

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

--- Comment #3 from Joel Sherrill <joel at gcc dot gnu.org> 2012-11-02 13:29:45 UTC ---
(In reply to comment #2)
> Can you please try to build with attached (untested) patch?
> 
> The patch disables the part that handles exceptions and where rounding mode is
> set. We need either x87 or SSE control register for this functionality.

The patch lets the tool build. I successfully built i386-rtems4.11 using
binutils and newlib cvs heads.

Please commit and close this.

Thanks for fixing this. i386 soft float doesn't attract much attention but some
people still care. :)

[Bug bootstrap/55175] i386/sfp-exceptions.c:52:7: error: impossible constraint in 'asm'

[uros at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55175

--- Comment #4 from uros at gcc dot gnu.org 2012-11-02 14:09:09 UTC ---
Author: uros
Date: Fri Nov  2 14:09:02 2012
New Revision: 193095

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=193095
Log:
    PR target/55175
    * config/i386/sfp-exceptions.c: Guard with _SOFT_FLOAT.
    * config/i386/sfp-machine.h: Guard exception handling
    code with _SOFT_FLOAT.
    * config/i386/32/sfp-machine.h: Guard rounding handling
    code with _SOFT_FLOAT.
    * config/i386/64/sfp-machine.h: Ditto.


Modified:
    trunk/libgcc/ChangeLog
    trunk/libgcc/config/i386/32/sfp-machine.h
    trunk/libgcc/config/i386/64/sfp-machine.h
    trunk/libgcc/config/i386/sfp-exceptions.c
    trunk/libgcc/config/i386/sfp-machine.h

[Bug target/55175] i386/sfp-exceptions.c:52:7: error: impossible constraint in 'asm'

[ubizjak at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55175

Uros Bizjak <ubizjak at gmail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Target|                            |x86
             Status|UNCONFIRMED                 |RESOLVED
                URL|                            |http://gcc.gnu.org/ml/gcc-p
                   |                            |atches/2012-11/msg00190.htm
                   |                            |l
          Component|bootstrap                   |target
         Resolution|                            |FIXED
         AssignedTo|unassigned at gcc dot       |ubizjak at gmail dot com
                   |gnu.org                     |
   Target Milestone|---                         |4.8.0

--- Comment #5 from Uros Bizjak <ubizjak at gmail dot com> 2012-11-02 14:26:09 UTC ---
Fixed.

[Bug target/55175] i386/sfp-exceptions.c:52:7: error: impossible constraint in 'asm'

[corsepiu at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55175

--- Comment #6 from Ralf Corsepius <corsepiu at gcc dot gnu.org> 2012-11-03 06:25:33 UTC ---
I can confirm i386-rtems4.11-gcc now builds.

@Uros: I am inclined to believe this patch probably should be backported to
4.7.x.

At least, RTEMS is facing bizarre compilation issues, which I would not want to
be related to similar issues as this.

[Bug target/55175] i386/sfp-exceptions.c:52:7: error: impossible constraint in 'asm'

[uros at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55175

--- Comment #7 from uros at gcc dot gnu.org 2012-11-04 18:58:32 UTC ---
Author: uros
Date: Sun Nov  4 18:58:29 2012
New Revision: 193140

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=193140
Log:
    PR target/55175
    * config/i386/32/sfp-machine.h: Guard exception handling and
    rounding handling code with _SOFT_FLOAT.
    * config/i386/64/sfp-machine.h: Ditto.


Modified:
    branches/gcc-4_7-branch/libgcc/ChangeLog
    branches/gcc-4_7-branch/libgcc/config/i386/32/sfp-machine.h
    branches/gcc-4_7-branch/libgcc/config/i386/64/sfp-machine.h

[Bug target/55175] i386/sfp-exceptions.c:52:7: error: impossible constraint in 'asm'

[ubizjak at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55175

--- Comment #8 from Uros Bizjak <ubizjak at gmail dot com> 2012-11-04 18:59:53 UTC ---
(In reply to comment #6)
> I can confirm i386-rtems4.11-gcc now builds.
> 
> @Uros: I am inclined to believe this patch probably should be backported to
> 4.7.x.

H have backported similar change to 4.7 branch. Please reopen the PR if there
are still problems.

[Bug target/55175] i386/sfp-exceptions.c:52:7: error: impossible constraint in 'asm'

[ubizjak at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55175

Uros Bizjak <ubizjak at gmail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|4.8.0                       |4.7.3

[Bug target/55175] i386/sfp-exceptions.c:52:7: error: impossible constraint in 'asm'

[corsepiu at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55175

--- Comment #9 from Ralf Corsepius <corsepiu at gcc dot gnu.org> 2012-11-05 11:44:22 UTC ---
(In reply to comment #8)
> H have backported similar change to 4.7 branch.
Thanks for the backport.

> Please reopen the PR if there are still problems.
Unfortunately, your patch doesn't seem to help much:

GCC-4.7's soft-float still seems to be pulling in fp routine from inside of
newlib:
...
/opt/rtems-4.11/lib/gcc/i386-rtems4.11/4.7.2/../../../../i386-rtems4.11/lib/soft-float/libc.a(lib_a-svfprintf.o):
In function `_svfprintf_r':
/builddir/build/BUILD/rtems-4.11-i386-rtems4.11-gcc-4.7.2/build/i386-rtems4.11/soft-float/newlib/libc/stdio/../../../../../../gcc-4.7.2/newlib/libc/stdio/vfprintf.c:1072:
undefined reference to `__truncxfdf2'
/builddir/build/BUILD/rtems-4.11-i386-rtems4.11-gcc-4.7.2/build/i386-rtems4.11/soft-float/newlib/libc/stdio/../../../../../../gcc-4.7.2/newlib/libc/stdio/vfprintf.c:1084:
undefined reference to `__ltdf2'
/builddir/build/BUILD/rtems-4.11-i386-rtems4.11-gcc-4.7.2/build/i386-rtems4.11/soft-float/newlib/libc/stdio/../../../../../../gcc-4.7.2/newlib/libc/stdio/vfprintf.c:1556:
undefined reference to `__eqdf2'
/builddir/build/BUILD/rtems-4.11-i386-rtems4.11-gcc-4.7.2/build/i386-rtems4.11/soft-float/newlib/libc/stdio/../../../../../../gcc-4.7.2/newlib/libc/stdio/vfprintf.c:1603:
undefined reference to `__nedf2'

[Bug target/55175] i386/sfp-exceptions.c:52:7: error: impossible constraint in 'asm'

[ubizjak at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55175

--- Comment #10 from Uros Bizjak <ubizjak at gmail dot com> 2012-11-05 12:11:53 UTC ---
(In reply to comment #9)
> (In reply to comment #8)
> > H have backported similar change to 4.7 branch.
> Thanks for the backport.
> 
> > Please reopen the PR if there are still problems.
> Unfortunately, your patch doesn't seem to help much:
> 
> GCC-4.7's soft-float still seems to be pulling in fp routine from inside of
> newlib:

This is the other way around: newlib doesn't find libgcc.

This is newlib's problem.

[Bug target/55175] i386/sfp-exceptions.c:52:7: error: impossible constraint in 'asm'

[ubizjak at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55175

--- Comment #11 from Uros Bizjak <ubizjak at gmail dot com> 2012-11-05 12:28:53 UTC ---
(In reply to comment #9)
> (In reply to comment #8)
> > H have backported similar change to 4.7 branch.
> Thanks for the backport.
> 
> > Please reopen the PR if there are still problems.
> Unfortunately, your patch doesn't seem to help much:
> 
> GCC-4.7's soft-float still seems to be pulling in fp routine from inside of
> newlib:

You should use t-softfp instead of 386/t-softfp for i[34567]86-*-rtems* in
libgcc/config.host.

In fact, there should be no i386/t-softfp for any x86 target.

[Bug target/55175] i386/sfp-exceptions.c:52:7: error: impossible constraint in 'asm'

[corsepiu at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55175

--- Comment #12 from Ralf Corsepius <corsepiu at gcc dot gnu.org> 2012-11-05 12:41:56 UTC ---
(In reply to comment #11)

> You should use t-softfp instead of 386/t-softfp for i[34567]86-*-rtems* in
> libgcc/config.host.
> 
> In fact, there should be no i386/t-softfp for any x86 target.

You mean, we should apply a patch similar to this?

--- a/libgcc/config.host
+++ b/libgcc/config.host
@@ -568,7 +568,7 @@ i[34567]86-*-nto-qnx*)
        extra_parts=crtbegin.o
        ;;
 i[34567]86-*-rtems*)
-       tmake_file="$tmake_file i386/t-softfp i386/t-crtstuff"
+       tmake_file="$tmake_file i386/t-crtstuff"
        extra_parts="$extra_parts crti.o crtn.o"
        ;;
 i[34567]86-*-solaris2* | x86_64-*-solaris2.1[0-9]*)
@@ -1165,6 +1165,7 @@ i[34567]86-*-darwin* | x86_64-*-darwin* | \
   i[34567]86-*-kfreebsd*-gnu | x86_64-*-kfreebsd*-gnu | \
   i[34567]86-*-linux* | x86_64-*-linux* | \
   i[34567]86-*-gnu* | \
+  i[34567]86-*-rtems* | \
   i[34567]86-*-solaris2* | x86_64-*-solaris2.1[0-9]* | \
   i[34567]86-*-cygwin* | i[34567]86-*-mingw* | x86_64-*-mingw* | \
   i[34567]86-*-freebsd* | x86_64-*-freebsd*)


The breakdown above is with this patch applied.

[Bug target/55175] i386/sfp-exceptions.c:52:7: error: impossible constraint in 'asm'

[ubizjak at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55175

--- Comment #13 from Uros Bizjak <ubizjak at gmail dot com> 2012-11-05 14:15:16 UTC ---
(In reply to comment #12)

> > You should use t-softfp instead of 386/t-softfp for i[34567]86-*-rtems* in
> > libgcc/config.host.
> > 
> > In fact, there should be no i386/t-softfp for any x86 target.
> 
> You mean, we should apply a patch similar to this?

Yes.

> The breakdown above is with this patch applied.

Then the problem is either in newlib or generic libgcc configury.

Anyway, original problem with soft-fp was fixed.

[Bug target/55175] i386/sfp-exceptions.c:52:7: error: impossible constraint in 'asm'

[ubizjak at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55175

--- Comment #14 from Uros Bizjak <ubizjak at gmail dot com> 2012-11-05 14:24:43 UTC ---
(In reply to comment #13)

> Then the problem is either in newlib or generic libgcc configury.

Please note that t-fdpbit is not enabled by default for x86 anymore. I don't
know if this was intentional omission during libgcc conversion, but nobody
missed it until today.

The second part of your patch enables TFmode soft-float, probably not needed
for RTEMS. I think that you need either t-fdpbit or t-softfp-sfdf added to
i[34567]86-*-rtems*)

[Bug target/55175] i386/sfp-exceptions.c:52:7: error: impossible constraint in 'asm'

[corsepiu at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55175

--- Comment #15 from Ralf Corsepius <corsepiu at gcc dot gnu.org> 2012-11-05 14:38:44 UTC ---
(In reply to comment #14)
> (In reply to comment #13)
> 
> > Then the problem is either in newlib or generic libgcc configury.

I meanwhile came to the latter conclusion. 

The math calls are being pulled-in by gcc's code generation from inside of
newlib's libm, but soft-fp emulation is missing in libgcc. As we have both hard
and soft-float multilib variants, I think RTEMS needs a "softfp wrapper".

> Please note that t-fdpbit is not enabled by default for x86 anymore. I don't
> know if this was intentional omission during libgcc conversion, but nobody
> missed it until today.

OK, will check.

> The second part of your patch enables TFmode soft-float, probably not needed
> for RTEMS. I think that you need either t-fdpbit or t-softfp-sfdf added to
> i[34567]86-*-rtems*)

Thanks for these hints - I am currently investigating, but ... things like
these take _a lot of time_.