On Thu, Nov 28, 2019 at 11:06:12AM +0100, Michal Privoznik wrote:
On 11/27/19 8:38 PM, Ján Tomko wrote:
On Wed, Nov 27, 2019 at 04:22:42PM +0000, Daniel P. Berrangé wrote:
On Fedora 31 with GCC 9.2.1, compiling qemuxml2argvtest takes about 36 seconds since
commit 30c6d99209cd36bba8e14795622f658827698522 Author: Jiri Denemark <jdenemar@redhat.com> Date: Thu Oct 24 17:51:42 2019 +0200
qemuxml2argvtest: Update host arch for DO_TEST*ARCH* tests
The optimizer is hitting some pathelogical performance behaviour due to
*pathological
the high number of branches in the mymain() method.
Missing bugzilla link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=58479
Pushing the branch tests down into the testCompareXMLToArgv method brings the compile time down to 3 seconds.
-fno-var-tracking-assignments brings it down even more for me
Can we turn the flag off for tests?
Don't that hurt us when trying to debug tests?
That seems to be the implication from the info pages on this option Annotate assignments to user variables early in the compilation and attempt to carry the annotations over throughout the compilation all the way to the end, in an attempt to improve debug information while optimizing. Use of '-gdwarf-4' is recommended along with it. Even with this enabled by default it is quite painful debugging due to variables being optimized out, so I'm loathe to make it worse just to shave off a few seconds. Regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|