[Bug target/54888] GCC with -Os is faster than -O3 on some AVR code

["gjl at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54888

Georg-Johann Lay <gjl at gcc dot gnu.org> changed:

           What    |Removed                     |Added
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                 CC|                            |gjl at gcc dot gnu.org

--- Comment #5 from Georg-Johann Lay <gjl at gcc dot gnu.org> 2012-10-22 20:10:44 UTC ---
As a start, you could try to enable us to reproduce your problem.

First of all, it is clear that we don't have your hardware (oscilloscope) to
measure things and even if, it is very unlikely someone will start research to
find out exactly were you lost the ticks.

Second, notice that it is ulikely anybody is inclined to pick up buch of code
you dumped above. It's 3800 lines and around 30 functions.  And it fails to
compile.  Maybe you can be more descriptive and point out what /exactly/ goes
wrong and work out a small example and limit to a critical spot or function and
throw away unneeded stuff.

Third, please notice that 4.3 is no more supported since several years now. 
Please supply code that compiles with a supported version of the compiler which
implies at least 4.7 (because you use -mmcu=atxmega128d3).

Fourth, you use inline assembler that is not correct because of missing memory
barrier and might show malfunction in corner cases.

Thus, you may want to fix at least 3. and 4. and rerun your benchmarks to see
if the problem still exists.  Very likely, that is not the case.