[Mesa-dev] [PATCH] spirv: fix OpSConvert when the source is unsigned

[Samuel Iglesias Gonsálvez]

Please ignore this patch. I am going to send a v2 of it, together with a
fix for OpUConvert.

Thanks,

Sam


On 05/03/18 11:18, Samuel Iglesias Gonsálvez 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.
>
> Signed-off-by: Samuel Iglesias Gonsálvez <siglesias at igalia.com>
> ---
>  src/compiler/spirv/vtn_alu.c | 19 ++++++++++++++++++-
>  1 file changed, 18 insertions(+), 1 deletion(-)
>
> diff --git a/src/compiler/spirv/vtn_alu.c b/src/compiler/spirv/vtn_alu.c
> index d0c9e316935..32b4f70d229 100644
> --- a/src/compiler/spirv/vtn_alu.c
> +++ b/src/compiler/spirv/vtn_alu.c
> @@ -354,10 +354,27 @@ vtn_nir_alu_op_for_spirv_opcode(struct vtn_builder *b,
>     case SpvOpConvertFToS:
>     case SpvOpConvertSToF:
>     case SpvOpConvertUToF:
> -   case SpvOpSConvert:
>     case SpvOpFConvert:
>        return nir_type_conversion_op(src, dst, nir_rounding_mode_undef);
>  
> +   case SpvOpSConvert: {
> +      nir_alu_type src_base = (nir_alu_type) nir_alu_type_get_base_type(src);
> +      nir_alu_type dst_base = (nir_alu_type) nir_alu_type_get_base_type(dst);
> +      if (src_base == nir_type_uint && dst_base == nir_type_int) {
> +         /* SPIR-V expects to interpret the unsigned value as signed and
> +          * to sign extend. Return the opcode accordingly.
> +          */
> +         unsigned dst_bit_size = nir_alu_type_get_type_size(dst);
> +         switch (dst_bit_size) {
> +         case 16:   return nir_op_i2i16;
> +         case 32:   return nir_op_i2i32;
> +         case 64:   return nir_op_i2i64;
> +         default:
> +            vtn_fail("Invalid nir alu bit size");
> +         }
> +      }
> +      return nir_type_conversion_op(src, dst, nir_rounding_mode_undef);
> +   }
>     /* Derivatives: */
>     case SpvOpDPdx:         return nir_op_fddx;
>     case SpvOpDPdy:         return nir_op_fddy;


-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 801 bytes
Desc: OpenPGP digital signature
URL: <https://lists.freedesktop.org/archives/mesa-dev/attachments/20180305/fae26d01/attachment.sig>