On Mon, Apr 23, 2012 at 6:59 PM, Sriraman Tallam <tmsri...@google.com> wrote:
>>> i386 maintainers - Is this patch ok? >> >> Has the community reached the consensus on how this kind of >> functionality has to be implemented? I have followed the discussion a >> bit, but IIRC, there was no clear decision. Without this decision, I >> am not able to review the _implementation_ of agreed functionality for >> x86 target. >> >> (I apologize if I have missed the decision, please point me to the >> discussion in this case.) > > The discussions are here: > > http://gcc.gnu.org/ml/gcc-patches/2011-08/msg01446.html > and follow-ups to this. > > I am not sure about consensus, but the important points raised were: > > 1) Constructor ordering: What if some constructors fire before > cpu_indicator_init?, which determines the CPU. I addressed this > problem by making the priority of cpu_indicator_init to be the highest > possible. Still, IFUNC initializers will fire before and they have to > explicitly call __builtin_cpu_init() before checking the CPU type. > 2) Reducing the number of builtins : It is only two now. > * config/i386/i386.c (build_processor_features_struct): New function. > (build_processor_model_struct): New function. > (make_var_decl): New function. > (get_field_from_struct): New function. > (fold_builtin_target): New function. > (ix86_fold_builtin): New function. > (ix86_expand_builtin): Expand new builtins by folding them. > (make_cpu_type_builtin): New functions. > (ix86_init_platform_type_builtins): Make the new builtins. > (ix86_init_builtins): Make new builtins to detect CPU type. > (TARGET_FOLD_BUILTIN): New macro. > (IX86_BUILTIN_CPU_INIT): New enum value. > (IX86_BUILTIN_CPU_IS): New enum value. > (IX86_BUILTIN_CPU_SUPPORTS): New enum value. > * config/i386/i386-builtin-types.def: New function type. > * testsuite/gcc.target/builtin_target.c: New testcase. > * doc/extend.texi: Document builtins. > > * libgcc/config/i386/i386-cpuinfo.c: New file. > * libgcc/config/i386/t-cpuinfo: New file. > * libgcc/config.host: Include t-cpuinfo. > * libgcc/config/i386/libgcc-glibc.ver: Version symbols __cpu_model > and __cpu_features. The patch is OK. I guess that AVX is left as an exercise for a x86 maintainer ;) (I have also CC'd H.J. for his opinion.) Thanks, Uros.
