[Bug c/32843] New: [4.3 Regression] : libffi.call/return_sc.c

[Bug c/32843] New: [4.3 Regression] : libffi.call/return_sc.c

[hjl at lucon dot org]

On Linux/ia32, this patch

http://gcc.gnu.org/ml/gcc-cvs/2007-07/msg00336.html

caused

FAIL: libffi.call/return_sc.c -O0 -W -Wall execution test
FAIL: libffi.call/return_sc.c -O2 execution test
FAIL: libffi.call/return_sc.c -O3 execution test


-- 
           Summary: [4.3 Regression] : libffi.call/return_sc.c
           Product: gcc
           Version: 4.3.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: hjl at lucon dot org
GCC target triplet: i686-pc-linux-gnu


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32843

[Bug c/32843] [4.3 Regression] : libffi.call/return_sc.c

[pinskia at gcc dot gnu dot org]

-- 

pinskia at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |pinskia at gcc dot gnu dot
                   |                            |org
   Target Milestone|---                         |4.3.0


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32843

[Bug c/32843] [4.3 Regression] : libffi.call/return_sc.c

[rguenth at gcc dot gnu dot org]

------- Comment #1 from rguenth at gcc dot gnu dot org  2007-07-24 10:11 -------
The problem seems to be a backend one(?).  What happens is that for

signed char return_sc (signed char sc)
{
  return sc;
}

the return value is now zero-extended instead of sign-extended (the sign
extension was done in the C frontend code).  The C standard in 6.8.6.4
specifies that for the return statement _only_ if the expression has
a different type from the return type of the function then
'the value is converted as if by assignment to an object having the return
type of the function'.  Which reading either way doesn't specify whether
the return value is implicitly sign-extended or not (AFAIK whether in
this case the value is sign or zero extended should be / is specified by the
target ABI).

On x86_64 we get

return_sc:
.LFB12:
        movl    %edi, %eax
        ret

...
        movl    $-127, %edi
        call    return_sc

which is why we may be lucky here(?).  On i686 we pass on the stack like

return_sc:
        pushl   %ebp
        movl    %esp, %ebp
        movzbl  8(%ebp), %eax
        popl    %ebp
        ret

...
        movl    $-127, (%esp)
        call    return_sc

explicitly doing zero-extension.  Now the libffi testcase explicitly checks
for sign-extension(!) of the return value:

  for (sc = (signed char) -127;
       sc < (signed char) 127; sc++)
    {
      ffi_call(&cif, FFI_FN(return_sc), &rint, values);
      CHECK(rint == (ffi_arg) sc);
    }

as rint is of type ffi_arg (unsigned long) and sc is signed char.  I wonder
whether this is desired or not.  Andreas?

Micha, how is promotion of the return value specified in the x86 ABI?


-- 

rguenth at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |matz at suse dot de,
                   |                            |andreast at gcc dot gnu dot
                   |                            |org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32843

[Bug c/32843] [4.3 Regression] : libffi.call/return_sc.c

[rguenth at gcc dot gnu dot org]

------- Comment #2 from rguenth at gcc dot gnu dot org  2007-07-24 10:13 -------
The following is a function that is now differently compiled on both x86_64 and
i686:

signed char return_sc (signed char *sc)
{
  return *sc;
}


-- 

rguenth at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
     Ever Confirmed|0                           |1
   Last reconfirmed|0000-00-00 00:00:00         |2007-07-24 10:13:13
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32843

[Bug testsuite/32843] [4.3 Regression] : libffi.call/return_sc.c

[rguenth at gcc dot gnu dot org]

------- Comment #3 from rguenth at gcc dot gnu dot org  2007-07-24 10:25 -------
So, my final conclusion would be that this is a testsuite bug because whether
we do zero or sign extension for returns in a register does not matter for
valid uses of this return value.


-- 

rguenth at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
          Component|c                           |testsuite


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32843

[Bug testsuite/32843] [4.3 Regression] : libffi.call/return_sc.c

[rguenth at gcc dot gnu dot org]

------- Comment #4 from rguenth at gcc dot gnu dot org  2007-07-24 10:27 -------
Index: return_sc.c
===================================================================
--- return_sc.c (revision 126678)
+++ return_sc.c (working copy)
@@ -30,7 +30,7 @@ int main (void)
        sc < (signed char) 127; sc++)
     {
       ffi_call(&cif, FFI_FN(return_sc), &rint, values);
-      CHECK(rint == (ffi_arg) sc);
+      CHECK((signed char) rint == sc);
     }
   exit(0);
 }

?


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32843

[Bug testsuite/32843] [4.3 Regression] : libffi.call/return_sc.c

[rguenth at gcc dot gnu dot org]

------- Comment #5 from rguenth at gcc dot gnu dot org  2007-07-24 11:47 -------
The 32bit psABI specifies Integral Arguments as 'Functions pass all
integer-valued
arguments as words, expanding or padding signed or unsigned bytes and
halfwords as needed'. For return values the best I can find is 'A function that
returns an integral or pointer value places its result in register %eax.'
Both are not exactly clear whether sign- or zero-extension is required.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32843

[Bug testsuite/32843] [4.3 Regression] : libffi.call/return_sc.c

[andreast at gcc dot gnu dot org]

------- Comment #6 from andreast at gcc dot gnu dot org  2007-07-25 20:11 -------
Fine with me, thanks and sorry for the delay. Pls ci.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32843

[Bug testsuite/32843] [4.3 Regression] : libffi.call/return_sc.c

[rguenth at gcc dot gnu dot org]

------- Comment #7 from rguenth at gcc dot gnu dot org  2007-07-26 09:14 -------
Fixed.


-- 

rguenth at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|                            |FIXED


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32843

[Bug testsuite/32843] [4.3 Regression] : libffi.call/return_sc.c

[rguenth at gcc dot gnu dot org]

------- Comment #8 from rguenth at gcc dot gnu dot org  2007-07-26 09:14 -------
Subject: Bug 32843

Author: rguenth
Date: Thu Jul 26 09:13:58 2007
New Revision: 126950

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=126950
Log:
2007-07-26  Richard Guenther  <rguenther@suse.de>

        PR testsuite/32843
        * testsuite/libffi.call/return_sc.c (main): Verify call
        result as signed char, not ffi_arg.

Modified:
    trunk/libffi/ChangeLog
    trunk/libffi/testsuite/libffi.call/return_sc.c


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32843

[Bug testsuite/32843] [4.3 Regression] : libffi.call/return_sc.c

[jakub at gcc dot gnu dot org]

------- Comment #9 from jakub at gcc dot gnu dot org  2007-07-26 09:25 -------
But the change was in generic code, are you very sure you haven't changed ABI
on any of the targets?


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32843

[Bug testsuite/32843] [4.3 Regression] : libffi.call/return_sc.c

[rguenth at gcc dot gnu dot org]

------- Comment #10 from rguenth at gcc dot gnu dot org  2007-07-26 10:01 -------
Well, honestly not.  Still other frontends do not do return type promotion
themselves, so the backend is responsible for doing this.  Do you have any
suggestion on what target to look at to verify this?


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32843

[Bug testsuite/32843] [4.3 Regression] : libffi.call/return_sc.c

[aph at gcc dot gnu dot org]

------- Comment #11 from aph at gcc dot gnu dot org  2007-07-31 15:06 -------
Subject: Bug 32843

Author: aph
Date: Tue Jul 31 15:05:52 2007
New Revision: 127093

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=127093
Log:
2007-07-30  Andrew Haley  <aph@redhat.com>

        PR testsuite/32843
        * src/x86/ffi.c (ffi_prep_cif_machdep): in x86 case, add code for
        signed/unsigned int8/16.
        * src/x86/sysv.S (ffi_call_SYSV): Rewrite to:
        Use a jump table.
        Remove code to pop args from the stack after call.
        Special-case signed/unsigned int8/16.
        * testsuite/libffi.call/return_sc.c (main): Revert.


Modified:
    trunk/libffi/ChangeLog
    trunk/libffi/src/x86/ffi.c
    trunk/libffi/src/x86/sysv.S
    trunk/libffi/testsuite/libffi.call/return_sc.c


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32843

[Bug testsuite/32843] [4.3 Regression] : libffi.call/return_sc.c

[aph at gcc dot gnu dot org]

------- Comment #12 from aph at gcc dot gnu dot org  2007-08-06 12:48 -------
Subject: Bug 32843

Author: aph
Date: Mon Aug  6 12:48:07 2007
New Revision: 127241

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=127241
Log:
        PR testsuite/32843
        * src/x86/sysv.S (ffi_closure_raw_SYSV): Handle FFI_TYPE_UINT8,
        FFI_TYPE_SINT8, FFI_TYPE_UINT16, FFI_TYPE_SINT16, FFI_TYPE_UINT32,
        FFI_TYPE_SINT32.


Modified:
    trunk/libffi/ChangeLog
    trunk/libffi/src/x86/sysv.S


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32843

[Bug testsuite/32843] [4.3 Regression] : libffi.call/return_sc.c

[aph at gcc dot gnu dot org]

------- Comment #13 from aph at gcc dot gnu dot org  2007-08-06 12:53 -------
> The 32bit psABI specifies Integral Arguments as 'Functions pass all
> integer-valued
> arguments as words, expanding or padding signed or unsigned bytes and
> halfwords as needed'. For return values the best I can find is 'A function that
> returns an integral or pointer value places its result in register %eax.'
> Both are not exactly clear whether sign- or zero-extension is required.

On the contrary, this implies very strongly to me that all integer-valued
arguments are passed as words, fully sign- or zero-extended for their type.
To read this in any other way strikes me as perverse.  If we are not correctly
sign- or zero-extendening return values we have broken the ABI.  To suggest
that this sign- or zero-extension does not apply to return values is also
perverse.


-- 

aph at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |aph at gcc dot gnu dot org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32843

[Bug testsuite/32843] [4.3 Regression] : libffi.call/return_sc.c

[aph at gcc dot gnu dot org]

------- Comment #14 from aph at gcc dot gnu dot org  2007-08-06 13:35 -------
In addition: I suspect that this bug also is manifested on x86 Darwin, but my
patch should not affect that system at all, and therefore I suspect that this
bug is still manifested on that system.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32843

[Bug testsuite/32843] [4.3 Regression] : libffi.call/return_sc.c

[doko at gcc dot gnu dot org]

------- Comment #15 from doko at gcc dot gnu dot org  2007-08-06 20:13 -------
Subject: Bug 32843

Author: doko
Date: Mon Aug  6 20:13:06 2007
New Revision: 127249

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=127249
Log:
- Revert the changes for PR testsuite/32843, not needed on the branch.

Modified:
    branches/ubuntu/gcc-4_2-branch/libffi/ChangeLog
    branches/ubuntu/gcc-4_2-branch/libffi/src/x86/ffi.c
    branches/ubuntu/gcc-4_2-branch/libffi/src/x86/sysv.S
    branches/ubuntu/gcc-4_2-branch/libffi/testsuite/libffi.call/return_sc.c


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32843

[Bug testsuite/32843] [4.3 Regression] : libffi.call/return_sc.c

[andreast at gcc dot gnu dot org]

------- Comment #16 from andreast at gcc dot gnu dot org  2008-01-02 21:48 -------
Regarding comment #14, yep. Patch posted here:
http://gcc.gnu.org/ml/gcc-patches/2008-01/msg00041.html


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32843

[Bug testsuite/32843] [4.3 Regression] : libffi.call/return_sc.c

[andreast at gcc dot gnu dot org]

------- Comment #17 from andreast at gcc dot gnu dot org  2008-01-05 20:50 -------
Subject: Bug 32843

Author: andreast
Date: Sat Jan  5 20:49:41 2008
New Revision: 131343

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=131343
Log:
2008-01-05  Andreas Tobler  <a.tobler@schweiz.org>

        PR testsuite/32843
        * src/x86/ffi.c (ffi_prep_cif_machdep): Add code for
        signed/unsigned int8/16 for X86_DARWIN.
        Updated copyright info.
        Handle one and two byte structs with special cif->flags.
        * src/x86/ffitarget.h: Add special types for one and two byte structs.
        Updated copyright info.
        * src/x86/darwin.S (ffi_call_SYSV): Rewrite to use a jump table like
        sysv.S
        Remove code to pop args from the stack after call.
        Special-case signed/unsigned for int8/16, one and two byte structs.
        (ffi_closure_raw_SYSV): Handle FFI_TYPE_UINT8,
        FFI_TYPE_SINT8, FFI_TYPE_UINT16, FFI_TYPE_SINT16, FFI_TYPE_UINT32,
        FFI_TYPE_SINT32.
        Updated copyright info.

Modified:
    trunk/libffi/ChangeLog
    trunk/libffi/src/x86/darwin.S
    trunk/libffi/src/x86/ffi.c
    trunk/libffi/src/x86/ffitarget.h


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32843

[Bug testsuite/32843] [4.3 Regression] : libffi.call/return_sc.c

[ljrittle at gcc dot gnu dot org]

------- Comment #18 from ljrittle at gcc dot gnu dot org  2009-09-17 20:55 -------
Subject: Bug 32843

Author: ljrittle
Date: Thu Sep 17 20:54:56 2009
New Revision: 151819

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=151819
Log:
2009-09-17  Loren J. Rittle  <ljrittle@acm.org>

        PR testsuite/32843 (strikes again)
        * src/x86/ffi.c (ffi_prep_cif_machdep): Add X86_FREEBSD to
        enable proper extension on char and short.

Modified:
    trunk/libffi/ChangeLog
    trunk/libffi/src/x86/ffi.c


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32843

[Bug testsuite/32843] [4.3 Regression] : libffi.call/return_sc.c

[gerald at gcc dot gnu dot org]

------- Comment #19 from gerald at gcc dot gnu dot org  2010-06-20 17:12 -------
Subject: Bug 32843

Author: gerald
Date: Sun Jun 20 17:12:11 2010
New Revision: 161048

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=161048
Log:
        Backport from mainline:
        2009-09-17  Loren J. Rittle  <ljrittle@acm.org>

        PR testsuite/32843 (strikes again)
        src/x86/ffi.c (ffi_prep_cif_machdep): Add X86_FREEBSD to
        enable proper extension on char and short.

Modified:
    branches/gcc-4_4-branch/libffi/ChangeLog
    branches/gcc-4_4-branch/libffi/src/x86/ffi.c


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32843