[Mesa-dev] [PATCH 3/9] glsl, nir: Make ir_quadop_bitfield_insert a vectorized operation.

[Ilia Mirkin]

On Mon, Jan 11, 2016 at 5:48 PM, Matt Turner <mattst88 at gmail.com> wrote:
> From: Kenneth Graunke <kenneth at whitecape.org>
>
> We would like to be able to combine
>
>    result.x = bitfieldInsert(src0.x, src1.x, src2.x, src3.x);
>    result.y = bitfieldInsert(src0.y, src1.y, src2.y, src3.y);
>    result.z = bitfieldInsert(src0.z, src1.z, src2.z, src3.z);
>    result.w = bitfieldInsert(src0.w, src1.w, src2.w, src3.w);
>
> into a single ivec4 bitfieldInsert operation.  This should be possible
> with most drivers.
>
> This patch changes the offset and bits parameters from scalar ints
> to ivecN or uvecN.  The type of all four operands will be the same,
> for simplicity.
>
> Signed-off-by: Kenneth Graunke <kenneth at whitecape.org>
> Reviewed-by: Matt Turner <mattst88 at gmail.com>
> ---
> [mattst88] v2:
>         Use swizzle(expr, SWIZZLE_XXXX, type->vector_elements) instead of
>         swizzle_for_size(expr, type->vector_elements). The latter does not
>         provide the wanted operation of expanding a scalar.
>
>         Expand arguments to bitfield_insert() in ldexp() lowering passes.
>
>  src/glsl/builtin_functions.cpp      | 8 +++++++-
>  src/glsl/ir.h                       | 1 -
>  src/glsl/ir_constant_expression.cpp | 6 +++---
>  src/glsl/ir_validate.cpp            | 5 +++--
>  src/glsl/lower_instructions.cpp     | 8 ++++----
>  src/glsl/nir/nir_opcodes.py         | 4 ++--
>  6 files changed, 19 insertions(+), 13 deletions(-)
>
> diff --git a/src/glsl/builtin_functions.cpp b/src/glsl/builtin_functions.cpp
> index 602852a..38383bc 100644
> --- a/src/glsl/builtin_functions.cpp
> +++ b/src/glsl/builtin_functions.cpp
> @@ -4902,13 +4902,19 @@ builtin_builder::_bitfieldExtract(const glsl_type *type)
>  ir_function_signature *
>  builtin_builder::_bitfieldInsert(const glsl_type *type)
>  {
> +   bool is_uint = type->base_type == GLSL_TYPE_UINT;
>     ir_variable *base   = in_var(type, "base");
>     ir_variable *insert = in_var(type, "insert");
>     ir_variable *offset = in_var(glsl_type::int_type, "offset");
>     ir_variable *bits   = in_var(glsl_type::int_type, "bits");
>     MAKE_SIG(type, gpu_shader5_or_es31, 4, base, insert, offset, bits);
>
> -   body.emit(ret(bitfield_insert(base, insert, offset, bits)));
> +   operand cast_offset = is_uint ? i2u(offset) : operand(offset);
> +   operand cast_bits = is_uint ? i2u(bits) : operand(bits);
> +
> +   body.emit(ret(bitfield_insert(base, insert,
> +      swizzle(cast_offset, SWIZZLE_XXXX, type->vector_elements),
> +      swizzle(cast_bits, SWIZZLE_XXXX, type->vector_elements))));
>
>     return sig;
>  }
> diff --git a/src/glsl/ir.h b/src/glsl/ir.h
> index a2eb508..9af2fc1 100644
> --- a/src/glsl/ir.h
> +++ b/src/glsl/ir.h
> @@ -1710,7 +1710,6 @@ public:
>               operation == ir_triop_vector_insert ||
>               operation == ir_quadop_vector ||
>               /* TODO: these can't currently be vectorized */
> -             operation == ir_quadop_bitfield_insert ||
>               operation == ir_triop_bitfield_extract;
>     }
>
> diff --git a/src/glsl/ir_constant_expression.cpp b/src/glsl/ir_constant_expression.cpp
> index 38b6dd5..f5b5bd8 100644
> --- a/src/glsl/ir_constant_expression.cpp
> +++ b/src/glsl/ir_constant_expression.cpp
> @@ -1710,10 +1710,10 @@ ir_expression::constant_expression_value(struct hash_table *variable_context)
>     }
>
>     case ir_quadop_bitfield_insert: {
> -      int offset = op[2]->value.i[0];
> -      int bits = op[3]->value.i[0];
> -
>        for (unsigned c = 0; c < components; c++) {
> +         int offset = op[2]->value.i[c];
> +         int bits = op[3]->value.i[c];
> +
>           if (bits == 0)
>              data.u[c] = op[0]->value.u[c];
>           else if (offset < 0 || bits < 0)
> diff --git a/src/glsl/ir_validate.cpp b/src/glsl/ir_validate.cpp
> index a4d6182..fea9b76 100644
> --- a/src/glsl/ir_validate.cpp
> +++ b/src/glsl/ir_validate.cpp
> @@ -647,10 +647,11 @@ ir_validate::visit_leave(ir_expression *ir)
>        break;
>
>     case ir_quadop_bitfield_insert:
> +      assert(ir->type->is_integer());
>        assert(ir->operands[0]->type == ir->type);
>        assert(ir->operands[1]->type == ir->type);
> -      assert(ir->operands[2]->type == glsl_type::int_type);
> -      assert(ir->operands[3]->type == glsl_type::int_type);
> +      assert(ir->operands[2]->type == ir->type);
> +      assert(ir->operands[3]->type == ir->type);

This will break lower_packing_builtins::pack_uvec2_to_uint and the
such. (In other news, I highly encourage you to set
LOWER_PACK_USE_BFI/BFE).

  -ilia