On Fri, Sep 10, 2021 at 02:19:40PM +0200, nsaenzju@xxxxxxxxxx wrote: > > I also don't understand why you explicitly removed the compiler barrier. IIUC > > when without it the compiler could move these instructions to be before/after > > other instructions generated in the c code. That may not really happen in > > practise, but just curious why the explicit removal. > > I removed it too as I see no justification for it. There is nothing, except for > the actual timestamp values (which are safe as they come from an mrs), that > could suffer from the compiler prefetching the value, or reordering accesses. > I'll add a comment on the commit message. Again I have no solid example, but wondering whether when without compiler barrier the compiler would be legal to compile this code clip: t1 = frc(); a = 1; t2 = frc(); into something like: t1 = frc(); t2 = frc(); a = 1; It's just that iiuc compiler barrier has 0 overhead to us. No strong opinion anyways. -- Peter Xu
