On 2014-10-13 03:29:19, peter green wrote: > Found 756777 1.0.2-6 > Thanks > >| Checking encode and decode of colourbars > >| > >| 2: colourbars FAILED > >(colourbars.at:7) > >| > I've just reproduced this locally with both sid's version in sid and > jessie's version in jessie. So this doesn't appear to be related to the > change in the sid package but related to some change in the build > environment. If I had to guess i'd say a computer
I think it's a toolchain bug. I did debug the issue some time after
filing the bug report, but forgot to report my findings to the bug. The
same version built fine in a wheezy chroot on harris, but fails in a
unstable chroot.
Here is the backtrace I got at the time:
#0 dirac::PictureCompressor::SelectQuantisers (this=this@entry=0x207ccc4,
coeff_data=..., bands=..., lambda=lambda@entry=6.25, est_bits=...,
cb_mode=QUANT_SINGLE, pp=..., csort=csort@entry=dirac::Y_COMP) at
picture_compress.cpp:632
#1 0x00036d94 in dirac::PictureCompressor::CodeResidue
(this=this@entry=0x207ccc4, my_buffer=..., pnum=<optimized out>,
p_picture_byteio=p_picture_byteio@entry=0x20e4ae8) at
picture_compress.cpp:449
#2 0x000232ee in dirac::SequenceCompressor::CompressNextPicture
(this=0x207cba8) at seq_compress.cpp:447
#3 0x00018e72 in DiracEncoder::CompressNextPicture (this=this@entry=0x207c400)
at dirac_encoder.cpp:607
#4 0x0001b122 in CompressNextPicture (this=0x207c400) at dirac_encoder.cpp:1141
#5 dirac_encoder_output (encoder=0x207c240) at dirac_encoder.cpp:1106
#6 0x00014b20 in main (argc=<optimized out>, argv=<optimized out>) at
encmain.cpp:1234
The offending line is "est_bits[b] = SelectMultiQuants( coeff_data ,
bands , b, lambda, ...". Printing b (or another index somewhere up the
call trace - I don't remember exactly) immediately before this line,
makes the crash go away. This makes me think gcc fails at optimizing the
code and generates broken output.
I didn't debug it any further.
Cheers
--
Sebastian Ramacher
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