On Thu, 26 May 2022 at 11:15, Tom Kacvinsky via Gcc-help <gcc-help@xxxxxxxxxxx> wrote: > A colleague of mine reminded me of this thread: > > slowdown with -std=gnu18 with respect to -std=c99 > > So I checked what the default C standard for GCC 8.3.0 is (gnu11) and 12.1.0 > (gnu17). So I used -std=c99 with the GCC 12.1 build of our code, and things > went back to normal (and sometimes a teensy bit better). N.B. the issue in that thread was the difference between -std=cNN and -std=gnuNN, not the changes in the value of NN. So you should be able to use -std=c17 and get the same performance as -std=c99.
