Nick Lewycky <nlewycky <at> google.com> writes: > On 6 May 2015 at 11:58, Carl Eugen Hoyos: > > > Nick Lewycky <nlewycky <at> google.com> writes: > > > > > This occurs when building ffmpeg with clang > > > -fsanitize=address -O1 -fPIE. > > > > What is the usecase for -O1? > > It's very important for asan. ASan instruments > every memory access (outside inline asm, for now) > and if we don't run the optimizer then every local > variable is a stack allocation with loads and > stores, and all those loads and stores get > instrumented leading to both crazy slowdown and > binary size increase.
What I meant was (and I believe I wasn't clear): What is the usecase for -O1 as opposed to default optimization? Or in other words: Is the issue with clang also reproducible with -O2 and -O3? > > Did you check performance with and without > > your patch? > > No. I believe such a performance test is a precondition for an asm patch (but I am not the maintainer). Carl Eugen _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org http://ffmpeg.org/mailman/listinfo/ffmpeg-devel
