On 01/08/2023 16.35, Daniel P. Berrangé wrote:
On Tue, Aug 01, 2023 at 03:53:22PM +0200, Markus Armbruster wrote:
Daniel P. Berrangé <berra...@redhat.com> writes:
This is an alternative and/or complementary to Thomas' proposal
to use CLang with msys:
https://lists.gnu.org/archive/html/qemu-devel/2023-07/msg05402.html
First of all, the current msys installer we're using is over 12
months out of date. Thus after running the install, pacman then
replaces most of what we've just installed with new downloaded
content. Using the most update installer cuts 3+1/2 minutes off
the msys install time - 7 minutes becomes 3+1/2.
Secondly, QEMU defaults to compiling with -O2 and this is more
computationally expensive for GCC. Switching to -O0 drops the
build time from 60 minutes down to 45 minutes.
From the fine manual[*]: "The effectiveness of some warnings depends on
optimizations also being enabled. For example '-Wsuggest-final-types'
is more effective with link-time optimization and some instances of
other warnings may not be issued at all unless optimization is enabled.
While optimization in general improves the efficacy of control and data
flow sensitive warnings, in some cases it may also cause false
positives." Do we care?
In general, yes, we do care.
In this specific case though, we're battling to figure out the lesser
of multiple evils.
I agree. Additionally, we also test compiling for Windows with the MinGW
cross compiler suite in a Fedora container, and we still use the default
optimization there, so we should have that covered.
Thomas
