On Oct 1, 2015 12:18 PM, "Matt Turner" <<a href="mailto:mattst88@gmail.com">mattst88@gmail.com</a>> wrote: > > On Fri, Aug 7, 2015 at 9:31 AM, Neil Roberts <<a href="mailto:neil@linux.intel.com">neil@linux.intel.com</a>> wrote: > > Adds nir_src_is_dynamically_uniform which returns true if the source > > is known to be dynamically uniform. This will be used in a later patch > > to add a workaround for cases that only work with dynamically uniform > > sources. Note that the function is not definitive, it can return false > > negatives (but not false positives). Currently it only detects > > constants and uniform accesses. It could easily be extended to include > > more cases. > > --- > > src/glsl/nir/nir.c | 29 +++++++++++++++++++++++++++++ > > src/glsl/nir/nir.h | 1 + > > 2 files changed, 30 insertions(+) > > > > diff --git a/src/glsl/nir/nir.c b/src/glsl/nir/nir.c > > index 78ff886..242f0b4 100644 > > --- a/src/glsl/nir/nir.c > > +++ b/src/glsl/nir/nir.c > > @@ -1784,6 +1784,35 @@ nir_src_as_const_value(nir_src src) > > return &load->value; > > } > > > > +/** > > + * Returns true if the source is known to be dynamically uniform. Otherwise it > > + * returns false which means it may or may not be dynamically uniform but it > > + * can't be determined. > > + */ > > +bool > > +nir_src_is_dynamically_uniform(nir_src src) > > +{ > > + if (!src.is_ssa) > > + return false; > > + > > + /* Constants are trivially dynamically uniform */ > > + if (src.ssa->parent_instr->type == nir_instr_type_load_const) > > + return true; > > + > > + /* As are uniform variables */ > > + if (src.ssa->parent_instr->type == nir_instr_type_intrinsic) { > > + nir_intrinsic_instr *intr = nir_instr_as_intrinsic(src.ssa->parent_instr); > > + > > + if (intr->intrinsic == nir_intrinsic_load_uniform) > > + return true; > > + } > > + > > + /* XXX: this could have many more tests, such as when a sampler function is > > + * called with dynamically uniform arguments. > > + */ > > + return false; > > +} > > This functions seems correct as-is, so it gets a > > Reviewed-by: Matt Turner <<a href="mailto:mattst88@gmail.com">mattst88@gmail.com</a>> > > On top of being useful for fixing the nonconst/nonuniform piglit > tests, knowing which values are uniform can allow better optimization > and knowing which branches are uniform would allow us to enable Single > Program Flow. > > Cc'ing Jason for a discussion about how we'd like to handle this kind > of information in NIR. Add a bool is_uniform or something to > nir_ssa_def and hook into the metadata system? That was more-or-less my plan. We should probably have a proper pass that handles things like phi nodes and ALU operations. --Jason