[Mesa-dev] [PATCH 19/29] nir: fix up bit sizes for undefined alu sources

[Jason Ekstrand]

On Mon, Mar 21, 2016 at 5:05 AM, Samuel Iglesias Gonsálvez <
siglesias at igalia.com> wrote:

> From: Iago Toral Quiroga <itoral at igalia.com>
>
> Undefined sources in alu operations don't have a valid bit size because
> they are uninitialized. Simply ignoring undefined sources for bit size
> validation is not enough since drivers can check and operate with the
> bit-size and that can lead to issues later on. Instead, fix undefined
> sources to always have a compatible bit size.
>

I'm not sure what I think about this.  I think I'd rather have undefs
simply have the right bitsize.


> v2 (Sam):
> - Use helper to get type size from nir_alu_type.
> ---
>  src/compiler/nir/nir_validate.c | 10 ++++++++++
>  1 file changed, 10 insertions(+)
>
> diff --git a/src/compiler/nir/nir_validate.c
> b/src/compiler/nir/nir_validate.c
> index 9f18d1c..645c15a 100644
> --- a/src/compiler/nir/nir_validate.c
> +++ b/src/compiler/nir/nir_validate.c
> @@ -180,9 +180,11 @@ validate_alu_src(nir_alu_instr *instr, unsigned
> index, validate_state *state)
>
>     unsigned num_components;
>     unsigned src_bit_size;
> +   bool is_undef = false;
>     if (src->src.is_ssa) {
>        src_bit_size = src->src.ssa->bit_size;
>        num_components = src->src.ssa->num_components;
> +      is_undef = src->src.ssa->parent_instr->type ==
> nir_instr_type_ssa_undef;
>     } else {
>        src_bit_size = src->src.reg.reg->bit_size;
>        if (src->src.reg.reg->is_packed)
> @@ -205,12 +207,20 @@ validate_alu_src(nir_alu_instr *instr, unsigned
> index, validate_state *state)
>
>     if (nir_alu_type_get_type_size(src_type)) {
>        /* This source has an explicit bit size */
> +      if (is_undef) {
> +         src_bit_size = nir_alu_type_get_type_size(src_type);
> +         src->src.ssa->bit_size = src_bit_size;
> +      }
>        assert(nir_alu_type_get_type_size(src_type) == src_bit_size);
>     } else {
>        if
> (!nir_alu_type_get_type_size(nir_op_infos[instr->op].output_type)) {
>           unsigned dest_bit_size =
>              instr->dest.dest.is_ssa ? instr->dest.dest.ssa.bit_size
>                                      : instr->dest.dest.reg.reg->bit_size;
> +         if (is_undef) {
> +            src_bit_size = dest_bit_size;
> +            src->src.ssa->bit_size = dest_bit_size;
> +         }
>           assert(dest_bit_size == src_bit_size);
>        }
>     }
> --
> 2.5.0
>
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