[Mesa-dev] [PATCH] nir/builder: Use nir_after_instr to advance the cursor

[Kenneth Graunke]

On Monday, August 31, 2015 04:55:51 PM Jason Ekstrand wrote:
> This *should* ensure that the cursor gets properly advanced in all cases.
> We had a problem before where, if the cursor was created using
> nir_after_cf_node on a non-block cf_node, that would call nir_before_block
> on the block following the cf node.  Instructions would then get inserted
> in backwards order at the top of the block which is not at all what you
> would expect from nir_after_cf_node.  By just resetting to after_instr, we
> avoid all these problems.
> ---
>  src/glsl/nir/nir_builder.h | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
> 
> diff --git a/src/glsl/nir/nir_builder.h b/src/glsl/nir/nir_builder.h
> index 3aa0efd..295a209 100644
> --- a/src/glsl/nir/nir_builder.h
> +++ b/src/glsl/nir/nir_builder.h
> @@ -49,8 +49,7 @@ nir_builder_instr_insert(nir_builder *build, nir_instr *instr)
>     nir_instr_insert(build->cursor, instr);
>  
>     /* Move the cursor forward. */
> -   if (build->cursor.option == nir_cursor_after_instr)
> -      build->cursor.instr = instr;
> +   build->cursor = nir_after_instr(instr);
>  }
>  
>  static inline void
> 

This seems like the right behavior for the builder to take.

Sorry for the breakage - I hadn't thought through how the
nir_{before,after}_cf_{node,list} functions translate to blocks.
Thanks for fixing it.

Reviewed-by: Kenneth Graunke <kenneth at whitecape.org>

You've regression tested this, I assume?

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