Ian Lance Taylor wrote:
Andrew Haley <aph@xxxxxxxxxx> writes:
That's interesting. As far as I'm aware we have never guaranteed that
gcc/binutils will generate binary reproducible output, but there must
be a reason for any differences.
A side comment: we used to guarantee that, and we used it to verify
the whole set of > tools along the lines of gcc's bootstrap compare.
For example, search for "gnu@xxxxxxxxxx" in bfd/coffcode.h.
If I compile with -frandom-seed I seem to get the exact binary every
time. Is there any other ways that the binaries can differ? (Apart from
__DATE__ and other time dependent macros.)
In my current project it currently looks like we, for certification
purposes, need to be able to show that our source code will produce the
exact same binaries that are installed on a system. Yesterday I manged
to get our current code and build scripts generate the binaries with
identical md5sums from two consecutive builds with the use of
-frandom-seed. So it seems that our current version of gcc works fine
for us. I guess my question is this: how likely is this to change in the
future and might there be another scenario where gcc will output
different binaries (with respect to md5sum) today?
Regards,
Mattias
