On Tue, 2017-03-28 at 08:28 -0700, Jason Ekstrand wrote:
> Sorry I haven't gotten back on this. It got lost somehow.
>
> On Fri, Mar 10, 2017 at 1:56 AM, Iago Toral <ito...@igalia.com>
> wrote:
> > On Thu, 2017-03-09 at 14:05 -0800, Jason Ekstrand wrote:
> > > ---
> > > src/compiler/nir/nir.h | 4 ++++
> > > src/compiler/nir/nir_constant_expressions.py | 16
> > +++++++++++++++-
> > > src/compiler/nir/nir_opcodes.py | 6 +++++-
> > > 3 files changed, 24 insertions(+), 2 deletions(-)
> > >
> > > diff --git a/src/compiler/nir/nir.h b/src/compiler/nir/nir.h
> > > index 57b8be3..eaa103d 100644
> > > --- a/src/compiler/nir/nir.h
> > > +++ b/src/compiler/nir/nir.h
> > > @@ -105,6 +105,10 @@ typedef enum {
> > > typedef union {
> > > float f32[4];
> > > double f64[4];
> > > + int8_t i8[4];
> > > + uint8_t u8[4];
> > > + int16_t i16[4];
> > > + uint16_t u16[4];
> > > int32_t i32[4];
> > > uint32_t u32[4];
> > > int64_t i64[4];
> > >
> > > diff --git a/src/compiler/nir/nir_constant_expressions.py
> > > b/src/compiler/nir/nir_constant_expressions.py
> > > index aecca8b..cbda4b1 100644
> > > --- a/src/compiler/nir/nir_constant_expressions.py
> > > +++ b/src/compiler/nir/nir_constant_expressions.py
> > > @@ -14,8 +14,10 @@ def type_size(type_):
> > > def type_sizes(type_):
> > > if type_has_size(type_):
> > > return [type_size(type_)]
> > > + elif type_ == 'float':
> > > + return [16, 32, 64]
> > > else:
> > > - return [32, 64]
> > > + return [8, 16, 32, 64]
> > >
> > > def type_add_size(type_, size):
> > > if type_has_size(type_):
> > > @@ -34,6 +36,8 @@ def op_bit_sizes(op):
> > > def get_const_field(type_):
> > > if type_ == "bool32":
> > > return "u32"
> > > + elif type_ == "float16":
> > > + return "u16"
> >
> > I was wondering why not have a f16 field with type float16_t
> > in nir_const_value instead, but reading the rest of the patch it
> > seems
> > we really want to work with 32-bit floats and then encode results
> > back to 16-bit values? Is it because there are some operations that
> > we can't implement directly with half-floats?
> >
> Yes. CPUs cannot, in general, work with 16-bit floats so there is no
> actual float16_t type in C. We typedef float to float16_t below just
> because it makes the codegen easier. In reality, all 16-bit
> operations have to be done in 32-bit with a manual conversion to/from
> 16-bit float on both sides.
Thanks for the explanation, it makes sense:
Reviewed-by: Iago Toral Quiroga <ito...@igalia.com>
> > Iago
> >
> > > else:
> > > m = type_split_re.match(type_)
> > > if not m:
> > > @@ -246,6 +250,7 @@ unpack_half_1x16(uint16_t u)
> > > }
> > >
> > > /* Some typed vector structures to make things like src0.y work
> > */
> > > +typedef float float16_t;
> > > typedef float float32_t;
> > > typedef double float64_t;
> > > typedef bool bool32_t;
> > > @@ -297,6 +302,8 @@ evaluate_${name}(MAYBE_UNUSED unsigned
> > > num_components, unsigned bit_size,
> > > % for k in range(op.input_sizes[j]):
> > > % if input_types[j] == "bool32":
> > > _src[${j}].u32[${k}] != 0,
> > > + % elif input_types[j] == "float16":
> > > + _mesa_half_to_float(_src[${j}].u16[${k}]),
> > > % else:
> > >
> > _src[${j}].${get_const_field(input_types[j])}[${k}]
> > ,
> > > % endif
> > > @@ -322,6 +329,9 @@ evaluate_${name}(MAYBE_UNUSED unsigned
> > > num_components, unsigned bit_size,
> > > <% continue %>
> > > % elif input_types[j] == "bool32":
> > > const bool src${j} = _src[${j}].u32[_i] != 0;
> > > + % elif input_types[j] == "float16":
> > > + const float src${j} =
> > > + _mesa_half_to_float(_src[${j}].u16[_i]);
> > > % else:
> > > const ${input_types[j]}_t src${j} =
> > >
> > _src[${j}].${get_const_field(input_types[j])}
> > [_
> > > i];
> > > @@ -344,6 +354,8 @@ evaluate_${name}(MAYBE_UNUSED unsigned
> > > num_components, unsigned bit_size,
> > > % if output_type == "bool32":
> > > ## Sanitize the C value to a proper NIR bool
> > > _dst_val.u32[_i] = dst ? NIR_TRUE : NIR_FALSE;
> > > + % elif output_type == "float16":
> > > + _dst_val.u16[_i] = _mesa_float_to_half(dst);
> > > % else:
> > > _dst_val.${get_const_field(output_type)}[_i] =
> > dst;
> > > % endif
> > > @@ -371,6 +383,8 @@ evaluate_${name}(MAYBE_UNUSED unsigned
> > > num_components, unsigned bit_size,
> > > % if output_type == "bool32":
> > > ## Sanitize the C value to a proper NIR bool
> > > _dst_val.u32[${k}] = dst.${"xyzw"[k]} ? NIR_TRUE
> > :
> > > NIR_FALSE;
> > > + % elif output_type == "float16":
> > > + _dst_val.u16[${k}] =
> > > _mesa_float_to_half(dst.${"xyzw"[k]});
> > > % else:
> > > _dst_val.${get_const_field(output_type)}[${k}] =
> > > dst.${"xyzw"[k]};
> > > % endif
> > > diff --git a/src/compiler/nir/nir_opcodes.py
> > > b/src/compiler/nir/nir_opcodes.py
> > > index 53e9aff..37c655b 100644
> > > --- a/src/compiler/nir/nir_opcodes.py
> > > +++ b/src/compiler/nir/nir_opcodes.py
> > > @@ -175,7 +175,11 @@ for src_t in [tint, tuint, tfloat]:
> > > dst_types = [tint, tuint, tfloat]
> > >
> > > for dst_t in dst_types:
> > > - for bit_size in [32, 64]:
> > > + if dst_t == tfloat:
> > > + bit_sizes = [16, 32, 64]
> > > + else:
> > > + bit_sizes = [8, 16, 32, 64]
> > > + for bit_size in bit_sizes:
> > > unop_convert("{}2{}{}".format(src_t[0], dst_t[0],
> > > bit_size),
> > > dst_t + str(bit_size), src_t, "src0")
> > >
> >
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