[Mesa-dev] [PATCH] i965: Gen4/5: use IEEE floating point mode for GLSL shaders.

[Kenneth Graunke]

On 07/10/2013 02:56 PM, Chris Forbes wrote:
> Fixes isinf(), isnan() from GLSL 1.30
>
> Signed-off-by: Chris Forbes <chrisf at ijw.co.nz>
> ---
>   src/mesa/drivers/dri/i965/brw_vs_state.c |  9 ++++++++-
>   src/mesa/drivers/dri/i965/brw_wm_state.c | 10 +++++++++-
>   2 files changed, 17 insertions(+), 2 deletions(-)
>
> diff --git a/src/mesa/drivers/dri/i965/brw_vs_state.c b/src/mesa/drivers/dri/i965/brw_vs_state.c
> index 54ff754..4dda522 100644
> --- a/src/mesa/drivers/dri/i965/brw_vs_state.c
> +++ b/src/mesa/drivers/dri/i965/brw_vs_state.c
> @@ -55,7 +55,14 @@ brw_upload_vs_unit(struct brw_context *brw)
>   			brw->vs.prog_offset +
>   			(vs->thread0.grf_reg_count << 1)) >> 6;
>
> -   vs->thread1.floating_point_mode = BRW_FLOATING_POINT_NON_IEEE_754;
> +   /* Use ALT floating point mode for ARB vertex programs, because they
> +    * require 0^0 == 1.
> +    */
> +   if (brw->ctx.Shader.CurrentVertexProgram == NULL)
> +      vs->thread1.floating_point_mode = BRW_FLOATING_POINT_NON_IEEE_754;
> +   else
> +      vs->thread1.floating_point_mode = BRW_FLOATING_POINT_IEEE_754;
> +
>      /* Choosing multiple program flow means that we may get 2-vertex threads,
>       * which will have the channel mask for dwords 4-7 enabled in the thread,
>       * and those dwords will be written to the second URB handle when we
> diff --git a/src/mesa/drivers/dri/i965/brw_wm_state.c b/src/mesa/drivers/dri/i965/brw_wm_state.c
> index f221846..631f351 100644
> --- a/src/mesa/drivers/dri/i965/brw_wm_state.c
> +++ b/src/mesa/drivers/dri/i965/brw_wm_state.c
> @@ -110,7 +110,15 @@ brw_upload_wm_unit(struct brw_context *brw)
>   			(wm->wm9.grf_reg_count_2 << 1)) >> 6;
>
>      wm->thread1.depth_coef_urb_read_offset = 1;
> -   wm->thread1.floating_point_mode = BRW_FLOATING_POINT_NON_IEEE_754;
> +   /* Use ALT floating point mode for ARB fragment programs, because they
> +    * require 0^0 == 1.  Even though _CurrentFragmentProgram is used for
> +    * rendering, CurrentFragmentProgram is used for this check to
> +    * differentiate between the GLSL and non-GLSL cases.
> +    */
> +   if (ctx->Shader.CurrentFragmentProgram == NULL)
> +      wm->thread1.floating_point_mode = BRW_FLOATING_POINT_NON_IEEE_754;
> +   else
> +      wm->thread1.floating_point_mode = BRW_FLOATING_POINT_IEEE_754;
>
>      wm->thread1.binding_table_entry_count = 0;

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