On Tue, Jan 20, 2015 at 12:41 AM, Alan Modra <amo...@gmail.com> wrote: > On Mon, Jan 19, 2015 at 10:43:29PM -0500, David Edelsohn wrote: >> On Fri, Jan 17, 2014 at 10:58 PM, Alan Modra <amo...@gmail.com> wrote: >> > This patch cures PR59828 by translating all the -mcpu options at once, >> > in order, to their equivalent assembler -m options by using a new spec >> > function. In the process this removes some duplication. >> >> ASM_CPU_SPEC is too fragile a mechanism. I would much prefer to >> expand on the ".machine" directive that I added to >> rs6000_file_start(). The initial implementation explicitly avoids >> .machine when -mcpu= or --with-cpu= is present as a conservative >> start. >> >> It seems much better to select a .machine directive based on the >> actual target ISA flag bits enabled than translating CPU command line >> options to ASM options. Patches to replace ASM_CPU_SPEC with .machine >> and expand functionality for AIX are welcome. > > This might make sense when looking only at gcc, but when considering > the whole toolchain I think you'll run into difficulty. gas and other > powerpc assemblers have always been invoked with -m options to select > the cpu, so if you do away with ASM_CPU_SPEC and rely on .machine then > you will be exercising the assembler in a new way. I am sure that > this will not work for all powerpc assemblers currently in use.
It is stressing .machine more than that feature has been in the past, but it is functionality that is suppose to work. .machine already has been stressed more with IFUNC pushing and popping ISAs. Are you concerned about the fundamental functionality of the pseudo-op or a particular GAS release missing support for a particular ISA? AIX supports .machine, but I think that it expects slightly different processor names. I am not certain about LLVM-AS, but it normally is not fed external assembly language files. Thanks, David
