[Mesa-dev] [PATCH 2/3] i965/fs: Don't generate saturates over existing variable values.

[Kenneth Graunke]

On 11/27/2012 12:12 AM, Eric Anholt wrote:
> Fixes a crash in http://workshop.chromeexperiments.com/stars/ on i965,
> and the new piglit test glsl-fs-clamp-5.
> We were trying to emit a saturating move into a uniform, which the code
> generator appropriately choked on.  This was broken in the change in
> 32ae8d3b321185a85b73ff703d8fc26bd5f48fa7.
>
> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=57166
> ---
>   src/mesa/drivers/dri/i965/brw_fs_visitor.cpp |    1 +
>   1 file changed, 1 insertion(+)
>
> diff --git a/src/mesa/drivers/dri/i965/brw_fs_visitor.cpp b/src/mesa/drivers/dri/i965/brw_fs_visitor.cpp
> index b6f7771..48ffc83 100644
> --- a/src/mesa/drivers/dri/i965/brw_fs_visitor.cpp
> +++ b/src/mesa/drivers/dri/i965/brw_fs_visitor.cpp
> @@ -217,6 +217,7 @@ fs_visitor::try_emit_saturate(ir_expression *ir)
>       */
>      fs_inst *modify = get_instruction_generating_reg(pre_inst, last_inst, src);
>      if (!modify || modify->regs_written() != 1) {
> +      this->result = fs_reg(this, ir->type);
>         fs_inst *inst = emit(MOV(this->result, src));
>         inst->saturate = true;
>      } else {

NOTE: This is a candidate for stable branches.

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