On 2016-02-10 11:23, Magnus Ihse Bursie wrote:
However, I'd like to use the opportunity to talk a bit about the
compare script. :-)
I think it is a very good initiative to fix the compare script so that
two consequitive builds on the same machine should compare equal.
Apparently, that's as close to a reproducible build we'll ever get at
the moment.
This patch does that, and that's good.
However, the "naive" way to get to a clean compare is to stop
comparing anything of value. :-) I'm not suggesting that you are doing
that (or that you should do that), but in a less extreme form, that's
my main worry. Or to phrase it differently, how can we tell that we're
not hiding something important? For instance, all these "accepted size
differences" on solaris. Are they still relevant?
I agree, it would be good to reevaluate a lot of the exceptions. I have
removed some that were obviously just working around differences between
build-infra and old build in JDK 8.
Is there some way to run the compare script without the exceptions
file (apart from hacking it)? If we do that, what would happen? Could
we trim down the exception lists?
No, there isn't. Yes, at least some of those exceptions are needed. I'm
sure we can remove a bunch of them if we assume exact same output dir,
but not all.
The dis filters seems a bit non-optimal too. We have a "global" dis
filter in compare.sh (introduced by me when I didn't know about the
specific dis filters in the exception file), and a specific dis filter
per platform in the exception file. The main task for the dis filters
is to remove differences in hexadecimal numbers, and I think that
could be generalized enough to just be in the global part. Any highly
platform specific filtering, like the "literal pool" stuff for macosx,
could still live in the exception file.
Maybe, not sure. In some cases, the specialized filters also take local
variations on commands like sed into account.
Finally, I still would like to get the string literal comparison into
the configure script, now I run it manually using:
objdump -s -j .rodata $LIBRARY | grep "^ " | xxd -r | strings
(The main hurdle to do this is adding detection for xxd in configure,
I think)
If you have more comparisons, please add them.
/Erik
