i965: Port INTEL_PRECISE_TRIG=1 to NIR.

This makes the extra multiply visible to NIR's algebraic optimizations
(for constant reassociation) as well as constant folding.  This means
that when the result of sin/cos are multiplied by an constant, we can
eliminate the extra multiply altogether, reducing the cost of the
workaround.

It also means we only have to implement it one place, rather than in
both backends.

This makes INTEL_PRECISE_TRIG=1 cost nothing on GPUTest/Volplosion,
which has a ton of sin() calls, but always multiplies them by an
immediate constant.  The extra multiply gets folded away.

Signed-off-by: Kenneth Graunke <[email protected]>
Reviewed-by: Eduardo Lima Mitev <[email protected]>
Reviewed-by: Jason Ekstrand <[email protected]>
Reviewed-by: Matt Turner <[email protected]>

1 files changed, 2 insertions, 0 deletions

diff --git a/src/mesa/drivers/dri/i965/brw_nir.h b/src/mesa/drivers/dri/i965/brw_nir.h
index b10c0838fe0..2711606511d 100644
--- a/src/mesa/drivers/dri/i965/brw_nir.h
+++ b/src/mesa/drivers/dri/i965/brw_nir.h
@@ -106,6 +106,8 @@ bool brw_nir_apply_attribute_workarounds(nir_shader *nir,
                                          bool use_legacy_snorm_formula,
                                          const uint8_t *attrib_wa_flags);
 
+bool brw_nir_apply_trig_workarounds(nir_shader *nir);
+
 nir_shader *brw_nir_apply_sampler_key(nir_shader *nir,
                                       const struct brw_device_info *devinfo,
                                       const struct brw_sampler_prog_key_data *key,