nir: Add an info bit for uses_sample_qualifier

Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>

src/compiler/nir/glsl_to_nir.cpp

@@ -182,6 +182,7 @@ glsl_to_nir(const struct gl_shader_program *shader_prog,
          (struct gl_fragment_program *)sh->Program;
 
       shader->info.fs.uses_discard = fp->UsesKill;
+      shader->info.fs.uses_sample_qualifier = fp->IsSample != 0;
       shader->info.fs.early_fragment_tests = sh->EarlyFragmentTests;
       shader->info.fs.depth_layout = fp->FragDepthLayout;
       break;

src/compiler/nir/nir.h

@@ -1743,6 +1743,11 @@ typedef struct nir_shader_info {
       struct {
          bool uses_discard;
 
+         /**
+          * Whether any inputs are declared with the "sample" qualifier.
+          */
+         bool uses_sample_qualifier;
+
          /**
           * Whether early fragment tests are enabled as defined by
           * ARB_shader_image_load_store.

src/compiler/nir/nir_gather_info.c

@@ -125,9 +125,15 @@ nir_shader_gather_info(nir_shader *shader, nir_function_impl *entrypoint)
           shader->stage == MESA_SHADER_FRAGMENT ||
           shader->stage == MESA_SHADER_COMPUTE);
 
+   bool uses_sample_qualifier = false;
    shader->info.inputs_read = 0;
-   foreach_list_typed(nir_variable, var, node, &shader->inputs)
+   foreach_list_typed(nir_variable, var, node, &shader->inputs) {
       shader->info.inputs_read |= get_io_mask(var, shader->stage);
+      uses_sample_qualifier |= var->data.sample;
+   }
+
+   if (shader->stage == MESA_SHADER_FRAGMENT)
+      shader->info.fs.uses_sample_qualifier = uses_sample_qualifier;
 
    /* TODO: Some day we may need to add stream support to NIR */
    shader->info.outputs_written = 0;