On Fri, 26 May 2023 at 15:34, Stefan Kanthak <stefan.kant...@nexgo.de> wrote: > > "Jonathan Wakely" <jwakely....@gmail.com> wrote: > > > On Fri, 26 May 2023 at 14:55, Stefan Kanthak <stefan.kant...@nexgo.de> > > wrote: > > [...] > > >> NOT obvious is but that -m<feature> -march=<lowerISA> does not clear any > >> <feature> not supported in <lowerISA>, i.e the last one does NOT win here. > > > > The last -march option selects the base set of instructions. The -mISA > > options modify that base. > > You but missed the point, AGAIN: the modifications per -mISA and -mno-ISA > persist, i.e. they are NOT reset by the last -march= option.
Nobody said they are reset, and the docs don't say that, so assume they are not. The last -march option selects a base and the -mISA options modify the base. Note *the* base. The one that was selected. By the last -march option. The base. > Is this SOOOO hard to grok? I understand your question. It's based on failing to read or understand what has been said. There is a base ISA. Then there are additions or subtractions relative to that base. That's it. That actually tells you everything you need to know, if you just apply some thought. Choosing a base does not remove the effects of the additions or subtractions, because they are additions and subtractions relative to whichever base arch is in effect. Where the -misa options appear on the command line relative to -march doesn't matter, which is why it doesn't need to be stated explicitly. The order only matters for -march relative to other -march options, and -misa options relative to other -misa options. > Is this soooo hard to document? I prefer arguing with trolls, it's even easier.
