[Mesa-dev] [PATCH v3 02/42] intel/compiler: add a NIR pass to lower conversions
Iago Toral
itoral at igalia.com
Mon Jan 21 08:09:22 UTC 2019
On Fri, 2019-01-18 at 06:46 -0600, Jason Ekstrand wrote:
> On January 18, 2019 01:48:25 Iago Toral <itoral at igalia.com> wrote:
>
> > On Thu, 2019-01-17 at 13:42 -0600, Jason Ekstrand wrote:
> > > On Tue, Jan 15, 2019 at 7:54 AM Iago Toral Quiroga <
> > > itoral at igalia.com> wrote
(...)
> > > > + nir_ssa_def *tmp = nir_build_alu(b, op1, src, NULL, NULL,
> > > > NULL);
> > > >
> > > > + nir_ssa_def *res = nir_build_alu(b, op2, tmp, NULL, NULL,
> > > > NULL);
> > > >
> > > > + nir_ssa_def_rewrite_uses(&alu->dest.dest.ssa,
> > > > nir_src_for_ssa(res));
> > > >
> > > > + nir_instr_remove(&alu->instr);
> > > >
> > > > +}
> > > >
> > > > +
> > > >
> > > > +static bool
> > > >
> > > > +lower_instr(nir_builder *b, nir_alu_instr *alu)
> > > >
> > > > +{
> > > >
> > > > + unsigned src_bit_size = nir_src_bit_size(alu->src[0].src);
> > > >
> > > > + nir_alu_type src_type = nir_op_infos[alu-
> > > > >op].input_types[0];
> > > >
> > > > + nir_alu_type src_full_type = (nir_alu_type) (src_type |
> > > > src_bit_size);
> > > >
> > > > +
> > > >
> > > > + unsigned dst_bit_size = nir_dest_bit_size(alu->dest.dest);
> > > >
> > > > + nir_alu_type dst_type = nir_op_infos[alu->op].output_type;
> > > >
> > > > + nir_alu_type dst_full_type = (nir_alu_type) (dst_type |
> > > > dst_bit_size);
> > >
> > > The nir_op_infos[*].output_type will already be a full type.
> > > Maybe just delete the dst_type temporary so that no one gets
> > > confused and thinks it's a base type.
> >
> > Right, will do that.
Actually, we want the base type too, since that is what we pass to the
get_conversion_op() helper, I'll just pick it from the dst_full_type
with the nir_alu_type_get_base_type() helper.
> > > > +
> > > >
> > > > + /* BDW PRM, vol02, Command Reference Instructions, mov -
> > > > MOVE:
> > > >
> > > > + *
> > > >
> > > > + * "There is no direct conversion from HF to DF or DF to
> > > > HF.
> > > >
> > > > + * Use two instructions and F (Float) as an intermediate
> > > > type.
> > > >
> > > > + *
> > > >
> > > > + * There is no direct conversion from HF to Q/UQ or Q/UQ
> > > > to HF.
> > > >
> > > > + * Use two instructions and F (Float) or a word integer
> > > > type
> > > >
> > > > + * or a DWord integer type as an intermediate type."
> > > >
> > > > + */
> > > >
> > > > + if ((src_full_type == nir_type_float16 && dst_bit_size ==
> > > > 64) ||
> > > >
> > > > + (src_bit_size == 64 && dst_full_type ==
> > > > nir_type_float16)) {
> > > >
> > > > + nir_op op1 = get_conversion_op(src_type, src_bit_size,
> > > > src_type, 32,
> > > >
> > > > + nir_rounding_mode_undef);
> > > >
> > > > + nir_op op2 = get_conversion_op(src_type, 32, dst_type,
> > > > dst_bit_size,
> > > >
> > > > +
> > > > get_opcode_rounding_mode(alu->op));
> > > >
> > > > + split_conversion(b, alu, op1, op2);
> > > >
> > > > + return true;
> > > >
> > > > + }
> > > >
> > > > +
> > > >
> > > > + /* SKL PRM, vol 02a, Command Reference: Instructions, Move:
> > > >
> > > > + *
> > > >
> > > > + * "There is no direct conversion from B/UB to DF or DF
> > > > to B/UB. Use
> > > >
> > > > + * two instructions and a word or DWord intermediate
> > > > type."
> > > >
> > > > + *
> > > >
> > > > + * "There is no direct conversion from B/UB to Q/UQ or
> > > > Q/UQ to B/UB.
> > > >
> > > > + * Use two instructions and a word or DWord intermediate
> > > > integer
> > > >
> > > > + * type."
> > > >
> > > > + */
> > > >
> > > > + if ((src_bit_size == 8 && dst_bit_size == 64) ||
> > > >
> > > > + (src_bit_size == 64 && dst_bit_size == 8)) {
> > > >
> > > > + nir_op op1 = get_conversion_op(src_type, src_bit_size,
> > > > src_type, 32,
> > > >
> > > > + nir_rounding_mode_undef);
> > > >
> > > > + nir_op op2 = get_conversion_op(src_type, 32, dst_type,
> > > > dst_bit_size,
> > > >
> > > > + nir_rounding_mode_undef);
> > > >
> > > > + split_conversion(b, alu, op1, op2);
> > > >
> > > > + return true;
> > > >
> > > > + }
> > > >
> > > > +
> > > >
> > > > + return false;
> > > >
> > > > +}
> > > >
> > > > +
> > > >
> > > > +static bool
> > > >
> > > > +lower_impl(nir_function_impl *impl)
> > > >
> > > > +{
> > > >
> > > > + nir_builder b;
> > > >
> > > > + nir_builder_init(&b, impl);
> > > >
> > > > + bool progress = false;
> > > >
> > > > +
> > > >
> > > > + nir_foreach_block(block, impl) {
> > > >
> > > > + nir_foreach_instr_safe(instr, block) {
> > > >
> > > > + if (instr->type != nir_instr_type_alu)
> > > >
> > > > + continue;
> > > >
> > > > +
> > > >
> > > > + nir_alu_instr *alu = nir_instr_as_alu(instr);
> > > >
> > > > + assert(alu->dest.dest.is_ssa);
> > > >
> > > > +
> > > >
> > > > + if (nir_op_infos[alu->op].num_inputs > 1)
> > >
> > > I don't think this is a reliable way to detect conversion
> > > opcodes. There are many unary operations that aren't
> > > conversions. You're only getting lucky because there are non
> > > which do float16 <-> 64=bit or 8-bit <-> 64-bit. I've thought
> > > many times about throwing a boolean in nir_op_infos for
> > > is_conversion. Maybe now is a good time to do it?
> >
> > Yes, I knew that this was not going to only let conversions through
> > and was relying on what you say above. Adding an is_conversion
> > field souns good to me, alternatively I guess we could add a
> > is_conversion() helper, but I guess having the field in
> > nir_op_infos maye be a bit easier to maintain if we want to add
> > more opcodes in the future.
Thinking about this, I guess we only want to set this to True for the
opcodes that are explicit numeric conversions, that is, the ones we
generate right after "# Generate all of the numeric conversion
opcodes". I am saying this because even if we have unop_convert(), that
is also used for things like unpack opcodes, but_count, etc that are
not real conversions. I was thinking about creating a new
unop_numeric_convert() helper and have all other helpers set this new
field to False. Sounds good?
> > > > + continue;
> > > >
> > > > +
> > > >
> > > > + progress = lower_instr(&b, alu) || progress;
> > > >
> > > > + }
> > > >
> > > > + }
> > > >
> > > > +
> > > >
> > > > + if (progress) {
> > > >
> > > > + nir_metadata_preserve(impl, nir_metadata_block_index |
> > > >
> > > > + nir_metadata_dominance);
> > > >
> > > > + }
> > > >
> > > > +
> > > >
> > > > + return progress;
> > > >
> > > > +}
> > > >
> > > > +
> > > >
> > > > +bool
> > > >
> > > > +brw_nir_lower_conversions(nir_shader *shader)
> > > >
> > > > +{
> > > >
> > > > + bool progress = false;
> > > >
> > > > +
> > > >
> > > > + nir_foreach_function(function, shader) {
> > > >
> > > > + if (function->impl)
> > > >
> > > > + progress |= lower_impl(function->impl);
> > > >
> > > > + }
> > > >
> > > > +
> > > >
> > > > + return progress;
> > > >
> > > > +}
> > > >
> > > > diff --git a/src/intel/compiler/meson.build
> > > > b/src/intel/compiler/meson.build
> > > >
> > > > index f8e5e2518fe..9daf2a94260 100644
> > > >
> > > > --- a/src/intel/compiler/meson.build
> > > >
> > > > +++ b/src/intel/compiler/meson.build
> > > >
> > > > @@ -76,6 +76,7 @@ libintel_compiler_files = files(
> > > >
> > > > 'brw_nir_analyze_boolean_resolves.c',
> > > >
> > > > 'brw_nir_analyze_ubo_ranges.c',
> > > >
> > > > 'brw_nir_attribute_workarounds.c',
> > > >
> > > > + 'brw_nir_lower_conversions.c',
> > > >
> > > > 'brw_nir_lower_cs_intrinsics.c',
> > > >
> > > > 'brw_nir_lower_image_load_store.c',
> > > >
> > > > 'brw_nir_lower_mem_access_bit_sizes.c',
> > > >
>
>
>
>
>
>
>
>
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