On 5/18/22 08:57, Sven Schnelle wrote: > Helge Deller <deller@xxxxxx> writes: > >> On 5/17/22 14:49, Helge Deller wrote: >>> In 2004 Randolph added the shr() assembly macro and noted that the >>> source and target register could not be the same. >>> >>> I did not find any confindence in the docs for this restriction. Maybe >>> it's related that on PA2.0 the upper bits may be clobbered? >> >> Looking at the generated kernel code from C-files, I'll find all over usages of >> extru source, x,y, target >> where source and target are the same register. >> So, at least for 32-bit this restriction can't be true. > > I did a quick objdump on the 64 bit HP-UX kernel and that one also uses > extrd/extrw where target and source are the same register. So i don't > think that restriction is true. Thanks for checking! Maybe it's meant that it clobbers when running *32-bit* code on PA2.0? Just a thought... Helge
