Removed calls to fminf and fmaxf in the critical sections of the code.

Is there any reason not to do this ? I have replaced calls to fminf and fmaxf by ternary operators. That leads to massive speed-ups.

According to vTune, we were spending large amounts of time inside these functions.

Is there any reason to use them over what I have done ? Any special behaviour of the functions that we would need in some cases ?

Goes from this:

to this:

In both cases we have no vectorization and I used the latest Intel compiler with the default optimizations activated. I was suprised to see this pop us as a function call. Though compilers would optimize that out.

We'll contact Intel about this and get their opinion on this.

In the mean time, I'll merge this in as it is a clear improvement.

Status changed to merged

mentioned in commit 4d45b74f

So according to the gcc documentation:

The ISO C99 functions _Exit, acoshf, acoshl, acosh, [...], fminf, [...], vfscanf, vscanf, vsnprintf and vsscanf are handled as built-in functions except in strict ISO C90 mode (-ansi or -std=c90).

The default language mode is -std=gnu11, so this shouldn't be happening. @pdraper, any insight on whether this could be the cause?

Otherwise, I'm curious to see what Intel have to say about it.

For reference, both cases shown above are compiled as follows on cosma-5:

module load swift swift/c5/intel/intelmpi/5.1.2
./configure --disable-vec --enable-debug