On Tue, Mar 13, 2018 at 5:40 AM, Samuel Iglesias Gonsálvez <
sigles...@igalia.com> wrote:
> OpSConvert interprets the MSB of the unsigned value as the sign bit and
> extends it to the new type. If we want to preserve the value, we need
> to use OpUConvert opcode.
>
> v2:
> - No need to check dst type.
> - Fix typo in comment.
>
> v3:
> - Use src/dst bitsize to get the proper conversion opcode. (Jason)
>
> Signed-off-by: Samuel Iglesias Gonsálvez <sigles...@igalia.com>
> ---
> src/compiler/spirv/vtn_alu.c | 11 ++++++++++-
> 1 file changed, 10 insertions(+), 1 deletion(-)
>
> diff --git a/src/compiler/spirv/vtn_alu.c b/src/compiler/spirv/vtn_alu.c
> index d0c9e316935..9dcd183a48d 100644
> --- a/src/compiler/spirv/vtn_alu.c
> +++ b/src/compiler/spirv/vtn_alu.c
> @@ -354,10 +354,19 @@ vtn_nir_alu_op_for_spirv_opcode(struct vtn_builder
> *b,
> case SpvOpConvertFToS:
> case SpvOpConvertSToF:
> case SpvOpConvertUToF:
>
We probably need to fix SToF and UToF as well.
I'm starting to wonder if we don't want to do them all at once. Maybe
something like this:
nir_alu_type src_type;
switch (opcode) {
case SpvOpConvertFToS:
case SpvOpConvertFToU:
case SpvOpFConvert:
src_type = nir_type_float;
break;
case SpvOpConvertSToF:
case SpvOpSConvert:
src_type = nir_type_int;
break;
case SpvOpConvertUToF:
case SpvOpUConvert:
src_type = nir_type_uint;
break;
default:
unreachable("Invalid opcode");
}
src_type |= nir_alu_type_get_type_size(src);
nir_alu_type dst_type;
switch (opcode) {
...
default:
unreachable("Invalid opcode");
}
dst_type |= nir_alu_type_get_type_size(dst);
While we're at it, since types don't really matter (only bit sizes), maybe
nir_alu_op_for_spirv_opcode should just take bit sizes instead of types.
It would make things simpler and make it more obvious what data actually
gets used.
Sorry I didn't notice the other conversion opcodes earlier. :-(
> - case SpvOpSConvert:
> case SpvOpFConvert:
> return nir_type_conversion_op(src, dst, nir_rounding_mode_undef);
>
> + case SpvOpSConvert: {
> + /* SPIR-V expects to interpret the unsigned value as signed and
> + * sign extend. Return the opcode accordingly.
> + */
> + unsigned src_bit_size = nir_alu_type_get_type_size(src);
> + nir_alu_type src_type = nir_type_int | src_bit_size;
>
+ unsigned dst_bit_size = nir_alu_type_get_type_size(dst);
> + nir_alu_type dst_type = nir_type_int | dst_bit_size;
> + return nir_type_conversion_op(src_type, dst_type,
> nir_rounding_mode_undef);
> + }
> /* Derivatives: */
> case SpvOpDPdx: return nir_op_fddx;
> case SpvOpDPdy: return nir_op_fddy;
> --
> 2.14.1
>
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