Hi!
In <https://gcc.gnu.org/PR77620>, we got a user wonder about released vs.
trunk GCC execution times, not knowing that the latter has more run-time
checking enabled. Once that got clarified, the discussion proceeded:
(In reply to petschy from comment #6)
> Would it be sensible to put an extra line to the output of 'gcc/g++ -v' if
> the slow checks are enabled, which just states this fact / warns about
> (possibly mentioning the use of --enable-checking=release at configure)?
> Future tickets like this might be avoided this way.
(In reply to Andrew Pinski from comment #7)
> We already output one if you use -ftime-report.
(In reply to Jonathan Wakely from comment #8)
> We get reports like this every few months, and nobody ever uses
> -ftime-report before filing a bug. I think something in the -v output would
> be useful.
We kind-of already report that by means of "--enable-checking=[...]" as
part of the "Configured with:" line:
$ gcc-6 -v 2>&1 | sed -n '/^Configured with: /s%.*--enable-checking=\([^
]*\).*%\1%p'
release
$ build-gcc/gcc/xgcc -v 2>&1 | sed -n '/^Configured with:
/s%.*--enable-checking=\([^ ]*\).*%\1%p'
yes,df,fold,extra,rtl
Though, that only gets displayed if "--enable-checking=[...]" has been
specified explicitly, I think?
Is that is generally considered useful, should I look into adding a
separate "Run-time checking: [...]" line? Should that just print the
configured checks, or also some "slow!" notice, as suggested? The latter
only for the really slow checks? Are we able to identify these
generally?
Also, from reading the documentation, I can't tell if (it's the idea
that) running checking-enabled GCC with "-fno-checking" would indeed get
rid of *all* the checking's run-time overhead? (Basically, if all
"ENABLE_*_CHECKING" usage is guarded by "flag_checking", too? Not yet
verified.)
Grüße
Thomas
