[Mesa-dev] [PATCH] i965: Fix writemask != 0 assertions on Sandybridge.

[Eric Anholt]

Kenneth Graunke <kenneth at whitecape.org> writes:

> This fixes myriads of regressions since commit 169f9c030c16d1247a3a7629
> ("i965: Add an assertion that writemask != NULL for non-ARFs.").
>
> On Sandybridge, our control flow handling (such as brw_IF) does:
>
>    brw_set_dest(p, insn, brw_imm_w(0));
>    insn->bits1.branch_gen6.jump_count = 0;
>
> This results in a IMM destination with zero for the writemask.  IMM
> destinations are rather bizarre (I'm guessing the file is irrelevant),
> but the code has been working for ages, so I'm loathe to change it.
>
> Fixes glxgears on Sandybridge.

The specs were explicit about "this has to be imm word", for mysterious
reasons.

Reviewed-by: Eric Anholt <eric at anholt.net>
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