nir: add rcp(w) lowering for gl_FragCoord

On some hardware (e.g. Mali400) the shader needs to apply some
transformations for correct gl_FragCoord handling. The lowering
actions look like the following in pseudocode:
   gl_FragCoord.xyz = gl_FragCoord_orig.xyz
   gl_FragCoord.w = 1.0 / gl_FragCoord_orig.w

Add this lowering as a nir pass in preparation for using it in the driver.

Signed-off-by: Andreas Baierl <[email protected]>
Reviewed-by: Qiang Yu <[email protected]>
Reviewed-by: Eric Anholt <[email protected]>

1 files changed, 1 insertions, 0 deletions

diff --git a/src/compiler/nir/nir.h b/src/compiler/nir/nir.h
index e878a63409d..0ba90caad38 100644
--- a/src/compiler/nir/nir.h
+++ b/src/compiler/nir/nir.h
@@ -3159,6 +3159,7 @@ void nir_lower_io_to_scalar(nir_shader *shader, nir_variable_mode mask);
 void nir_lower_io_to_scalar_early(nir_shader *shader, nir_variable_mode mask);
 bool nir_lower_io_to_vector(nir_shader *shader, nir_variable_mode mask);
 
+void nir_lower_fragcoord_wtrans(nir_shader *shader);
 void nir_lower_viewport_transform(nir_shader *shader);
 bool nir_lower_uniforms_to_ubo(nir_shader *shader, int multiplier);