Re: [avr-gcc-list] What GCC bug currently effect the AVR port of GCC?

[E. Weddington]

Bob Paddock wrote:

> Eric Weddington wrote:
>
> > If you *really* want to know, I can put together a list of the bug  
> > numbers currently affecting >the AVR port later on today.
>
>
> Yes I *REALLY* want to know. :-)  Thank you for doing it.
>
> I switched from a commercial AVR compiler because of spending more 
> time  debugging
> that compiler than my own code.
>
> Such a list will help save all of us users from wondering if the 
> compiler  is doing
> the correct thing, when we come across some questionable output form it.
> Also we can then avoid writing code in the first place that would 
> otherwise
> require debugging time.

Ok, here it is.  I've also taken the liberty to CC a few other 
interested parties. Sorry for any duplicate messages.

A few precautionary notes however:

- The list is long. But that doesn't mean that there are a lot of "real 
bugs". A number of these are "enhancements", not really bugs but listed 
as things to improve about the port. Some bugs are listed as "minor". 
Some of these are just strictly documentation bugs. Some of these have 
to do with the Ada language for the AVR. Some have to do with other 
parts that really don't affect the core C and C++ compilers for the AVR. 
Some of these have the status of UNCONFIRMED, meaning it hasn't been 
double-checked to see if it's truly a bug.

- I wrote a quick note after each one to try to give an idea of either 
the severity of the bug and/or what it's related to. HTH.

- Any time any mention is made in a bug report of "ICE", it means 
Internal Compiler Error.

As always you can go to the GCC bug database 
<http://gcc.gnu.org/bugzilla/buglist.cgi?cmdtype=runnamed&namedcmd=avr> 
and look up each individual bug. If you want to help keep track of it, 
feel free to put your email address in the CC list and you'll get all 
the gory details of the traffic flow about that bug.

ANY help is always appreciated for any of these bugs, even if you don't 
"hack GCC". A lot of times it helps to just test the UNCONFIRMED bugs to 
see if they're truly bugs; then leave a note in the bug report saying 
you were un/able to confirm it. Or testing older bugs to see if they're 
still bugs with the latest sources or if they were bugs in old sources. 
There's a lot of different ways to help.

And of course, this is just a snapshot. Things change over time.

Finally, *this is NOT intended to start a discussion about the internal 
details of every little bug on this list*. Please start different 
threads for the bug in question, or better still, keep the discussion 
limited to being on the bug reports themselves.

AVR specific bugs as of 2005.02.28:
--------------------------------------
1078: Documentation bug. Easy to fix as the description needed is in the 
avr-libc user manual.
3507:  Listed as for i386 target, but comments mention problems on the 
AVR as well.
10733:  Modulus bug. Possibly fixed. Needs more testing and verification.
10768: ICE on building Ada support library for the AVR. Checked recently 
and is still a bug.
11180: missed optimization. Enhancement bug. This could use some help to 
fix.
11259: missed optimization. Enhancement bug. Last comment is old. Needs 
rechecking against current sources.
12017: ICE in building the Objective-C language library. Obscure bug as 
Objective-C is now disabled for the AVR unless somebody wants to try to 
get this language going for the AVR.
14118: Cannot build libmudflap for the AVR. This bug has been SUSPENDED. 
libmudflap may never build for the AVR and is probably unnecessary. 
(libmudflap is a library that comes with gcc.)
16276: Affects C++. Looks like this is fixed in 4.0, and is scheduled to 
be backported to 3.4.4?
16563:  Looks to be a fairly major bug for the AVR. This needs testing 
to see if it still exists in the latest release (3.4.3) and in CVS 4.0 
branch.
17822: Very minor bug concerning hard coded values in the source that 
should be set by configure. Would be easy to fix, though.
17993: Error in dwarf2 debug output of bitfield members. This is listed 
as UNCONFIRMED, even though it was submitted by Torleif Sandness of 
Atmel. This affects AVR Studio support of DWARF2.
17994: No output of a dwarf2 .debug_frame section. This is listed as 
UNCONFIRMED, even though it was submitted by Torleif Sandness of Atmel. 
This affects AVR Studio support of DWARF2.
18065: missed optimization. Enhancement bug. This one is difficult to go 
through the wordy comments to figure out exactly what the issue is.
18145: Enhancement bug.
18251: Major AVR bug (ICE on valid code). Patches are available for 
4.0.0 and recently, 3.4.x. This needs to be finished up and get the 
patches into CVS.
18551: Wrong code bug for C++. This is assigned to Denis Chertykov but 
there has been no work on it.
18553: Minor bug: gcc give annoying warning. This is assigned to Denis 
Chertykov but there has been no work on it.
18887: ICE on valid code bug. Björn Haase posted a patch, but it needs 
to be tested and gone through the process of getting it into CVS.
18989: Comment #1 of this bug narrows what is a bug and what isn't with 
this report. This needs to be tested with a recent HEAD snapshot. Björn 
Haase's fixes for bit shifts may have fixed this, perhaps.
19087: Overflowed address in dwarf debug line information. Listed as 
UNCONFIRMED. Reported by Torleif of Atmel and affects AVR Studio DWARF2. 
Potential fix in comments. Needs more testing.
19154: missed optimization. Comments imply this is due to rtx_cost, 
which IIRC was recently rewritten and comitted. So this needs testing 
with recent HEAD to see if it still exists.
19329: This looks like it's fixed in 4.0 and 3.4.x and all it needs is 
to be is formally closed. Marek, you did the commits, can you close this?
19331: Patch posted by Roger Sayle. I think this bug might be fixed, but 
needs to be verified and closed.
19636: ICE on valid code. Listed as UNCONFIRMED. Somebody with 
sufficient permissions needs to verify that this is a bug.
19676: Minor bug: Loop optimizer fails to reverse simple loop. Andy 
Hutchinson is supposed to be looking into this I think.
19684: Wrong size in asm comment. Listed as UNCONFIRMED. Needs double 
checking that this is a bug.
19686: missed optimization. Minor bug. Loop performance decrease, not 
comparing against 0.
19815: Documentation change. Listed as UNCOFIRMED. Needs double checking 
by someone with sufficient permissions to be confirmed.
19835: missed optimization: Loop variable gets widened to long instead 
of int.
19885: avr dwarf-2 support is broken for head 4.0/4.1. This is a 
regression and needs to get fixed before 4.0 is released or AVR Studio 
can't be used for debugging a GCC project.
19959: Can't compile gnattools for the cross targets. This is a 
regression for the Ada language for the AVR. This is an issue in getting 
AVR-Ada into WinAVR for GCC 4.0.
20016: Enhancement bug. Easy to fix, and needs testing.
20082: ICE: unrecognizable insn. Listed as UNCONFIRMED. Needs verification.
20243: UCONFIRMED. This is difficult to tell what the bug is, or whether 
it's a design issue.

There you have it.

HTH
Eric Weddington