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Re: is re-running bootstrap after a change safe?
On 4/5/19 4:02 PM, Jeff Law wrote:
On 4/5/19 3:37 PM, Martin Sebor wrote:
On 4/5/19 3:29 PM, Jeff Law wrote:
On 4/5/19 2:50 PM, Eric Botcazou wrote:
Say if the first bootstrap succeeds and I then change a single
GCC .c file and rerun make bootstrap, am I guaranteed to see
the same fallout of the change as I would if I did a pristine
build in a clean directory?
No, this would imply deleting the stage2 and stage3 compilers and
that isn't
what happens. Instead the compiler of each stage is updated in
isolation.
RIght. Thus I always blow away stage2-* stage3-*, and stage1 target
directories along with the "compare" stamp file.
Thanks (all of you). It's amazing that I have been getting away
with it for all these years.
I got away without removing the "compare" stamp file for a long time,
then broke the trunk with a comparison failure :(
Why is this not done automatically? I mean, what is the use case
for make bootstrap without doing these steps first?
During development folks often want to rebuild without going through a
full bootstrap. Obviously for testing the final version of a patch the
"quick" approach of just rebuilding without blowing away the stage
directories isn't sufficient.
I see. So after a bootstrap and a subsequent change to a .c file,
at each stage the next bootstrap recompiles just the changed file
and relinks gcc. It doesn't actually recompile all source files
in stage 2 or 3 with the changed compiler from the last stage.
That's why it's so much faster! Make check then correctly reflects
the change but the compiler doesn't get as fully exercised because
the test suite has low coverage.
This is actually one of the things I'd really like to just automate.
You point to a git commit in a public repo, the tester picks it up and
does a bootstrap & regression test from scratch on whatever targets you
ask for.
That would be great to validate the final patch.
So to be clear: the safe and also most efficient to "rebootstrap"
GCC is to remove what exactly? (I don't see any stage2 or stage3
directories in my build tree.) Is there a make target for this?
Thanks
Martin