bugAVR C Runtime Library - Bugs: bug #12739, Gcc assumes that target libc...


bug #12739: Gcc assumes that target libc provides ffs function

Submitted by:  None
Submitted on:  Tue 19 Apr 2005 07:21:02 PM UTC  
Category:  Library Severity:  3 - Normal
Priority:  5 - Normal Item Group:  None
Status:  Fixed Assigned to:  None
Percent Complete:  0% Originator Email:  -email is unavailable-
Open/Closed:  Closed Release:  None
Fixed Release:  None

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( Jump to the original submission)

Sun 25 Sep 2005 12:04:14 AM UTC, comment #9: 

Patch to 'avr-libc-sources-20050915'.
It is a result of 'cvs rdiff -u' command.
New functions are included with DOXYGEN comments.
Tests are not included.

Tue 13 Sep 2005 09:23:15 PM UTC, comment #8: 

Diff for CVS version. I have not insert documentation comments and have not check documentation building for the present. Tests are not included.

Sun 11 Sep 2005 08:47:00 PM UTC, comment #7: 

Re-opened after recent discussion in avr-libc-dev.

Joerg Wunsch <joerg_wunsch>
Project Administrator
Thu 08 Sep 2005 06:51:58 PM UTC, comment #6: 

Björn rather wants to fix that inside libgcc.

Joerg Wunsch <joerg_wunsch>
Project Administrator
Wed 07 Sep 2005 10:02:11 PM UTC, comment #5: 

Today I have taken a 'ffs-20050423.tar.gz' to check up, what version of functions there is. The file did not manage to be unpacked! I have found at myself an initial variant. It has appeared, that the length of files coincides only, and contents are completely destroyed! I send a file repeatedly, having changed only date in a name of archive.


Wed 07 Sep 2005 07:49:48 PM UTC, comment #4: 

Is there any news from any of those who discussed that item
previously?  Otherwise, I'd go ahead and commit what's there.

Joerg Wunsch <joerg_wunsch>
Project Administrator
Sat 23 Apr 2005 09:13:04 AM UTC, comment #3: 

I've had a look at your functions.

Very good! Most interesting for me has been that there is this __builtin_constant_p () function! Very useful!
Did not know that beforehand.

Suggestion from my side concerning the implementation is:

I'd try to make the function as efficient as a real builtin function of gcc by defining

char ffs inline (int param)
  inline asm stating in which registers to pass parameters
  and which registers are actually clobbered.

Possibly this way one could also remove things like the
"clr r25" for the zero-extension that possibly is not necessary.

I'll think about that and send a more detailed suggestion.



Sat 23 Apr 2005 03:12:36 AM UTC, comment #2: 

AVR-optimized 'ffs' functions family is present. And tests.

Tue 19 Apr 2005 07:26:40 PM UTC, comment #1: 

For reference, the ffs function can be found in newlib.

Eric Weddington <arcanum>
Project Administrator
Tue 19 Apr 2005 07:21:02 PM UTC, original submission:  

GCC assumes that a ffs function is provided by the target's libc. The corresponding gcc bug reference is


This is not at all an urgent issue. Meanwhile I will mark the absence of support for ffs as known bug in the gcc testsuite framework.





(Note: upload size limit is set to 16384 kB, after insertion of the required escape characters.)

Attach Files:

Attached Files
file #2956:  ffs-20051011.diff.gz added by None (3KiB - application/x-gzip - Patch to avr-libc-20050915, Copyright added.)
file #3045:  ffs-20050923.diff.gz added by None (2KiB - application/x-gzip - Patch to avr-libc-20050915)
file #3239:  ffs-20050914.diff.gz added by None (2KiB - application/x-gzip - Diff for CVS. Without documentation now.)
file #3460:  ffs-20050908.tar.gz added by None (4KiB - application/x-tgz - The same, as 'ffs-20050423.tar.gz'. Last is destroyed.)
file #2880:  ffs-20050423.tar.gz added by None (4KiB - application/x-tgz - Tarball with sources and tests.)


Depends on the following items: None found

Items that depend on this one: None found


CC list is empty




Follow 14 latest changes.

Date Changed by Updated Field Previous Value => Replaced by
2005-10-18 aesok StatusNone => Fixed
    Assigned toaesok => None
    Open/ClosedOpen => Closed
2005-10-11 None Attached File- => Added ffs-20051011.diff.gz, #3037
2005-10-09 aesok Assigned toNone => aesok
2005-09-25 None Attached File- => Added ffs-20050923.diff.gz, #2996
2005-09-13 None Attached File- => Added ffs-20050914.diff.gz, #2949
2005-09-11 joerg_wunsch StatusWont Fix => None
    Open/ClosedClosed => Open
2005-09-08 joerg_wunsch StatusNone => Wont Fix
    Open/ClosedOpen => Closed
2005-09-07 None Attached File- => Added ffs-20050908.tar.gz, #2927
2005-04-23 None Attached File- => Added ffs-20050423.tar.gz, #2432
2005-04-19 None Carbon-Copy- => Added bjoern --PUNKT-- m --PUNKT-- haase --AT-- web --PUNKT-- de

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