[Mesa-dev] [PATCH] nir/search: Save/restore the variables_seen bitmask when matching

[Jason Ekstrand]

On Fri, May 8, 2015 at 11:53 AM, Jason Ekstrand <jason at jlekstrand.net> wrote:
> total instructions in shared programs: 7152330 -> 7137006 (-0.21%)
> instructions in affected programs:     1330548 -> 1315224 (-1.15%)
> helped:                                5797
> HURT:                                  76

I'm doing some looking into the hurt programs.  It seems as if there
are some very strange interatctions between flrp and ffma.  I'm still
working out exactly how to fix it up.
--Jason

> GAINED:                                0
> LOST:                                  8
> ---
>  src/glsl/nir/nir_search.c | 11 +++++++++++
>  1 file changed, 11 insertions(+)
>
> diff --git a/src/glsl/nir/nir_search.c b/src/glsl/nir/nir_search.c
> index d86655b..4c83349 100644
> --- a/src/glsl/nir/nir_search.c
> +++ b/src/glsl/nir/nir_search.c
> @@ -199,6 +199,10 @@ match_expression(const nir_search_expression *expr, nir_alu_instr *instr,
>        }
>     }
>
> +   /* Stash off the current variables_seen bitmask.  This way we can
> +    * restore it prior to matching in the commutative case below. */
> +   unsigned variables_seen_stash = state->variables_seen;
> +
>     bool matched = true;
>     for (unsigned i = 0; i < nir_op_infos[instr->op].num_inputs; i++) {
>        /* If the source is an explicitly sized source, then we need to reset
> @@ -221,6 +225,13 @@ match_expression(const nir_search_expression *expr, nir_alu_instr *instr,
>
>     if (nir_op_infos[instr->op].algebraic_properties & NIR_OP_IS_COMMUTATIVE) {
>        assert(nir_op_infos[instr->op].num_inputs == 2);
> +
> +      /* Restore the variables_seen bitmask.  If we don't do this, then we
> +       * could end up with an erroneous failure due to variables found in the
> +       * first match attempt above not matching those in the second.
> +       */
> +      state->variables_seen = variables_seen_stash;
> +
>        if (!match_value(expr->srcs[0], instr, 1, num_components,
>                         swizzle, state))
>           return false;
> --
> 2.4.0
>