nir: Add a flag to lower_io to force "sample" interpolation

Signed-off-by: Jason Ekstrand <jason@jlekstrand.net>
Reviewed-by: Anuj Phogat <anuj.phogat@gmail.com>
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>

2 files changed, 23 insertions, 7 deletions

diff --git a/src/compiler/nir/nir.h b/src/compiler/nir/nir.h
index 94eae6d303..6f0597200e 100644
--- a/src/compiler/nir/nir.h
+++ b/src/compiler/nir/nir.h
@@ -2397,9 +2397,17 @@ void nir_assign_var_locations(struct exec_list *var_list, unsigned *size,
                               unsigned base_offset,
                               int (*type_size)(const struct glsl_type *));
 
+typedef enum {
+   /* If set, this forces all non-flat fragment shader inputs to be
+    * interpolated as if with the "sample" qualifier.  This requires
+    * nir_shader_compiler_options::use_interpolated_input_intrinsics.
+    */
+   nir_lower_io_force_sample_interpolation = (1 << 1),
+} nir_lower_io_options;
 void nir_lower_io(nir_shader *shader,
                   nir_variable_mode modes,
-                  int (*type_size)(const struct glsl_type *));
+                  int (*type_size)(const struct glsl_type *),
+                  nir_lower_io_options);
 nir_src *nir_get_io_offset_src(nir_intrinsic_instr *instr);
 nir_src *nir_get_io_vertex_index_src(nir_intrinsic_instr *instr);
 
diff --git a/src/compiler/nir/nir_lower_io.c b/src/compiler/nir/nir_lower_io.c
index b36836f6f7..d469b6180f 100644
--- a/src/compiler/nir/nir_lower_io.c
+++ b/src/compiler/nir/nir_lower_io.c
@@ -39,6 +39,7 @@ struct lower_io_state {
    void *mem_ctx;
    int (*type_size)(const struct glsl_type *type);
    nir_variable_mode modes;
+   nir_lower_io_options options;
 };
 
 void
@@ -205,7 +206,8 @@ lower_load(nir_intrinsic_instr *intrin, struct lower_io_state *state,
          assert(vertex_index == NULL);
 
          nir_intrinsic_op bary_op;
-         if (var->data.sample)
+         if (var->data.sample ||
+             (state->options & nir_lower_io_force_sample_interpolation))
             bary_op = nir_intrinsic_load_barycentric_sample;
          else if (var->data.centroid)
             bary_op = nir_intrinsic_load_barycentric_centroid;
@@ -347,7 +349,9 @@ lower_interpolate_at(nir_intrinsic_instr *intrin, struct lower_io_state *state,
    nir_intrinsic_op bary_op;
    switch (intrin->intrinsic) {
    case nir_intrinsic_interp_var_at_centroid:
-      bary_op = nir_intrinsic_load_barycentric_centroid;
+      bary_op = (state->options & nir_lower_io_force_sample_interpolation) ?
+                nir_intrinsic_load_barycentric_sample :
+                nir_intrinsic_load_barycentric_centroid;
       break;
    case nir_intrinsic_interp_var_at_sample:
       bary_op = nir_intrinsic_load_barycentric_at_sample;
@@ -505,7 +509,8 @@ nir_lower_io_block(nir_block *block,
 static void
 nir_lower_io_impl(nir_function_impl *impl,
                   nir_variable_mode modes,
-                  int (*type_size)(const struct glsl_type *))
+                  int (*type_size)(const struct glsl_type *),
+                  nir_lower_io_options options)
 {
    struct lower_io_state state;
 
@@ -513,6 +518,7 @@ nir_lower_io_impl(nir_function_impl *impl,
    state.mem_ctx = ralloc_parent(impl);
    state.modes = modes;
    state.type_size = type_size;
+   state.options = options;
 
    nir_foreach_block(block, impl) {
       nir_lower_io_block(block, &state);
@@ -524,11 +530,13 @@ nir_lower_io_impl(nir_function_impl *impl,
 
 void
 nir_lower_io(nir_shader *shader, nir_variable_mode modes,
-             int (*type_size)(const struct glsl_type *))
+             int (*type_size)(const struct glsl_type *),
+             nir_lower_io_options options)
 {
    nir_foreach_function(function, shader) {
-      if (function->impl)
-         nir_lower_io_impl(function->impl, modes, type_size);
+      if (function->impl) {
+         nir_lower_io_impl(function->impl, modes, type_size, options);
+      }
    }
 }