[Mesa-dev] [PATCH] nir/algebraic: Only replace an instruction once

[Connor Abbott]

Reviewed-by: Connor Abbott <cwabbott0 at gmail.com>

Just curious, how did this come about?

On Wed, Jan 14, 2015 at 10:15 PM, Jason Ekstrand <jason at jlekstrand.net> wrote:
> Without the break, it was possible that an instruction would match multiple
> expressions.  If this happened, you could end up trying to replace it
> multiple times and get a segfault.  This makes it so that, after a
> successful replacement, it moves on to the next instruction.
> ---
>  src/glsl/nir/nir_algebraic.py | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/src/glsl/nir/nir_algebraic.py b/src/glsl/nir/nir_algebraic.py
> index 72703be..f9b246d 100644
> --- a/src/glsl/nir/nir_algebraic.py
> +++ b/src/glsl/nir/nir_algebraic.py
> @@ -192,8 +192,10 @@ ${pass_name}_block(nir_block *block, void *void_state)
>           for (unsigned i = 0; i < ARRAY_SIZE(${pass_name}_${opcode}_xforms); i++) {
>              if (nir_replace_instr(alu, ${pass_name}_${opcode}_xforms[i].search,
>                                    ${pass_name}_${opcode}_xforms[i].replace,
> -                                  state->mem_ctx))
> +                                  state->mem_ctx)) {
>                 state->progress = true;
> +               break;
> +            }
>           }
>           break;
>        % endfor
> --
> 2.2.1
>
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