Re: target/7493: [SPRAC] Possible instruction jump too large for assembler.

Re: target/7493: [SPRAC] Possible instruction jump too large for assembler.

[ehrhardt]

Old Synopsis: Possible instruction jump too large for assembler.
New Synopsis: [SPRAC] Possible instruction jump too large for assembler.

State-Changed-From-To: open->feedback
State-Changed-By: cae
State-Changed-When: Tue Dec 10 08:52:59 2002
State-Changed-Why:
    The problem in the assembler output is an instructions sequence
    like this on sparc:
    call	f,0
    add	%o7,(.LL100-.-4),%o7
    
    which is compiled by GNU as without a warning even if the result
    of .LL100-.-4 is larger than 4095, SUN as complains about the error though.
    However, I can't get gcc to produce such assemble code. I did a few tests
    with 3.3. and 2.95.3 but gcc always detected that the jump distance is
    more than what can be added to o7 with a single add instruction and
    replaced the add with a ``nop; b,a .LL100'' sequence.
    To debug this further we'll need a self contained testcase, i.e.
    preprocessed source (see -save-temps option, the .i file is what we're
    interested in). Due to the nature of the bug a single function (with
    everything it needs to compile!) will probably suffice as a useful testcase.
    
        regards   Christian Ehrhardt
    

http://gcc.gnu.org/cgi-bin/gnatsweb.pl?cmd=view%20audit-trail&database=gcc&pr=7493

Re: target/7493: [SPRAC] Possible instruction jump too large for assembler.

[Christian Ehrhardt]

The following reply was made to PR target/7493; it has been noted by GNATS.

From: "Christian Ehrhardt" <ehrhardt@mathematik.uni-ulm.de>
To: Marcus MacWilliam <marcusma@lsl.co.uk>
Cc: gcc-bugs@gcc.gnu.org, gcc-prs@gcc.gnu.org, nobody@gcc.gnu.org,
  gcc-gnats@gcc.gnu.org
Subject: Re: target/7493: [SPRAC] Possible instruction jump too large for assembler.
Date: Tue, 10 Dec 2002 18:39:22 +0100

 On Tue, Dec 10, 2002 at 05:28:19PM +0000, Marcus MacWilliam wrote:
 > I was using gcc v3.1, when the error occured.
 > The assembler code produced, was contained in the original defect.
 > The original error message was included in the defect.
 > The error is there.
 > 
 > However, we re-wrote the function to be smaller, to get rid of the
 > problem, so it is not as much of an issue now, as it was then.
 
 I'm still interested in a test case for this but unless you're
 able to provide us with C-Code that triggers the problem noone can
 help you. Maybe you can invest some time and produce a modified/stipped down
 version of the original code that still triggers the bug.
 If you can't provide a test case I'll have to close this report.
 
     regards   Christian
 
 -- 
 THAT'S ALL FOLKS!

Re: target/7493: [SPRAC] Possible instruction jump too large for assembler.

[Marcus MacWilliam]

The following reply was made to PR target/7493; it has been noted by GNATS.

From: Marcus MacWilliam <marcusma@lsl.co.uk>
To: ehrhardt@mathematik.uni-ulm.de, gcc-bugs@gcc.gnu.org,
 	gcc-prs@gcc.gnu.org, marcusma@lsl.co.uk, nobody@gcc.gnu.org,
 	gcc-gnats@gcc.gnu.org
Cc:  
Subject: Re: target/7493: [SPRAC] Possible instruction jump too large for 
 assembler.
Date: Tue, 10 Dec 2002 17:28:19 +0000

 ehrhardt@mathematik.uni-ulm.de wrote:
 
 > Old Synopsis: Possible instruction jump too large for assembler.
 > New Synopsis: [SPRAC] Possible instruction jump too large for assembler.
 >
 > State-Changed-From-To: open->feedback
 > State-Changed-By: cae
 > State-Changed-When: Tue Dec 10 08:52:59 2002
 > State-Changed-Why:
 >     The problem in the assembler output is an instructions sequence
 >     like this on sparc:
 >     call        f,0
 >     add %o7,(.LL100-.-4),%o7
 >
 >     which is compiled by GNU as without a warning even if the result
 >     of .LL100-.-4 is larger than 4095, SUN as complains about the error though.
 >     However, I can't get gcc to produce such assemble code. I did a few tests
 >     with 3.3. and 2.95.3 but gcc always detected that the jump distance is
 >     more than what can be added to o7 with a single add instruction and
 >     replaced the add with a ``nop; b,a .LL100'' sequence.
 >     To debug this further we'll need a self contained testcase, i.e.
 >     preprocessed source (see -save-temps option, the .i file is what we're
 >     interested in). Due to the nature of the bug a single function (with
 >     everything it needs to compile!) will probably suffice as a useful testcase.
 >
 >         regards   Christian Ehrhardt
 >
 >
 > http://gcc.gnu.org/cgi-bin/gnatsweb.pl?cmd=view%20audit-trail&database=gcc&pr=7493
 
 I was using gcc v3.1, when the error occured.
 The assembler code produced, was contained in the original defect.
 The original error message was included in the defect.
 The error is there.
 
 However, we re-wrote the function to be smaller, to get rid of the
 problem, so it is not as much of an issue now, as it was then.
 
 Thanks anyway,
 --
  Marcus A.T MacWilliam, MSc, CEng, MBCS, BSc(Hons).
  Senior Software Engineer, Laser-Scan Ltd, Cambridge, CB4 0FY.
  Tel: +44 (0)1223 420414 x220. Mobile: +44 (0)7803 706597.
  Fax: +44 (0)1223 420044. Web: http://www.laser-scan.co.uk/