intel/fs: Don't bother checking if load_frag_coord uses interpolation.

This was leftover dead code from 4bb6e6817e ("intel: Use a system value
for gl_FragCoord") -- the sysval doesn't do any interpolation and doesn't
have sources that could use a barycentric.

Reviewed-by: Alyssa Rosenzweig <alyssa@rosenzweig.io>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/25190>

src/intel/compiler/brw_compile_fs.cpp

@@ -765,23 +765,6 @@ calculate_urb_setup(const struct intel_device_info *devinfo,
 
    brw_compute_urb_setup_index(prog_data);
 }
-static bool
-is_used_in_not_interp_frag_coord(nir_def *def)
-{
-   nir_foreach_use_including_if(src, def) {
-      if (nir_src_is_if(src))
-         return true;
-
-      if (nir_src_parent_instr(src)->type != nir_instr_type_intrinsic)
-         return true;
-
-      nir_intrinsic_instr *intrin = nir_instr_as_intrinsic(nir_src_parent_instr(src));
-      if (intrin->intrinsic != nir_intrinsic_load_frag_coord)
-         return true;
-   }
-
-   return false;
-}
 
 /**
  * Return a bitfield where bit n is set if barycentric interpolation mode n
@@ -816,10 +799,6 @@ brw_compute_barycentric_interp_modes(const struct intel_device_info *devinfo,
                continue;
             }
 
-            /* Ignore WPOS; it doesn't require interpolation. */
-            if (!is_used_in_not_interp_frag_coord(&intrin->def))
-               continue;
-
             enum intel_barycentric_mode bary =
                brw_barycentric_mode(key, intrin);
 

src/intel/compiler/elk/elk_fs.cpp

@@ -6361,24 +6361,6 @@ elk_fs_visitor::run_cs(bool allow_spilling)
    return !failed;
 }
 
-static bool
-is_used_in_not_interp_frag_coord(nir_def *def)
-{
-   nir_foreach_use_including_if(src, def) {
-      if (nir_src_is_if(src))
-         return true;
-
-      if (nir_src_parent_instr(src)->type != nir_instr_type_intrinsic)
-         return true;
-
-      nir_intrinsic_instr *intrin = nir_instr_as_intrinsic(nir_src_parent_instr(src));
-      if (intrin->intrinsic != nir_intrinsic_load_frag_coord)
-         return true;
-   }
-
-   return false;
-}
-
 /**
  * Return a bitfield where bit n is set if barycentric interpolation mode n
  * (see enum elk_barycentric_mode) is needed by the fragment shader.
@@ -6411,10 +6393,6 @@ elk_compute_barycentric_interp_modes(const struct intel_device_info *devinfo,
                continue;
             }
 
-            /* Ignore WPOS; it doesn't require interpolation. */
-            if (!is_used_in_not_interp_frag_coord(&intrin->def))
-               continue;
-
             nir_intrinsic_op bary_op = intrin->intrinsic;
             enum elk_barycentric_mode bary =
                elk_barycentric_mode(intrin);