[Mesa-dev] [PATCH 11/15] i965: abort linking if we exhaust the registers

[Ian Romanick]

On 04/28/2016 01:40 PM, Antia Puentes wrote:
> From: "Juan A. Suarez Romero" <jasuarez at igalia.com>
> 
> Even when the number of vertex attributes is under the limit, for
> shaders that use a high number of them, we can quickly exhaust the
> number of hardware registers.

Were you able to construct a case where this actually occurs?  Limits
exposed by the driver and enforced by the GLSL linker should prevent this.

> In this case, just abort the linking.
> ---
>  src/mesa/drivers/dri/i965/brw_fs.cpp | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/src/mesa/drivers/dri/i965/brw_fs.cpp b/src/mesa/drivers/dri/i965/brw_fs.cpp
> index 4b8835d..387a266 100644
> --- a/src/mesa/drivers/dri/i965/brw_fs.cpp
> +++ b/src/mesa/drivers/dri/i965/brw_fs.cpp
> @@ -1857,6 +1857,12 @@ fs_visitor::convert_attr_sources_to_hw_regs(fs_inst *inst)
>                     inst->src[i].nr +
>                     inst->src[i].reg_offset;
>  
> +         if (grf >= 128) {
> +            fail("Failure to register allocate.  Reduce the number of "
> +                 "vertex input attributes to avoid this.");
> +            return;
> +         }
> +
>           unsigned exec_size;
>           /* As explained at brw_reg_from_fs_reg, From the Haswell PRM:
>            *
>