Mesa (main): glsl/nir: Set sample_shading if a FS output ever shows up as an rvalue

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Module: Mesa
Branch: main
Commit: 1124bee4baba49466d84b2bf274017dbba6360a7
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=1124bee4baba49466d84b2bf274017dbba6360a7

Author: Jason Ekstrand <jason.ekstrand at collabora.com>
Date:   Mon May  2 18:19:30 2022 -0500

glsl/nir: Set sample_shading if a FS output ever shows up as an rvalue

If framebuffer fetch is used, we have to enable sample shading because
the fetched framebuffer value is per-sample.

Reviewed-by: Alyssa Rosenzweig <alyssa.rosenzweig at collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/14020>

---

 src/compiler/glsl/glsl_to_nir.cpp | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/src/compiler/glsl/glsl_to_nir.cpp b/src/compiler/glsl/glsl_to_nir.cpp
index 7dff79114c4..0a8c33aa00a 100644
--- a/src/compiler/glsl/glsl_to_nir.cpp
+++ b/src/compiler/glsl/glsl_to_nir.cpp
@@ -81,6 +81,9 @@ public:
 
    void create_function(ir_function_signature *ir);
 
+   /* True if we have any output rvalues */
+   bool has_output_rvalue;
+
 private:
    void add_instr(nir_instr *instr, unsigned num_components, unsigned bit_size);
    nir_ssa_def *evaluate_rvalue(ir_rvalue *ir);
@@ -271,6 +274,9 @@ glsl_to_nir(const struct gl_constants *consts,
          if (var->data.mode == nir_var_shader_in && var->data.sample)
             shader->info.fs.uses_sample_shading = true;
       }
+
+      if (v1.has_output_rvalue)
+         shader->info.fs.uses_sample_shading = true;
    }
 
    return shader;
@@ -281,6 +287,7 @@ nir_visitor::nir_visitor(const struct gl_constants *consts, nir_shader *shader)
    this->supports_std430 = consts->UseSTD430AsDefaultPacking;
    this->shader = shader;
    this->is_global = true;
+   this->has_output_rvalue = false;
    this->var_table = _mesa_pointer_hash_table_create(NULL);
    this->overload_table = _mesa_pointer_hash_table_create(NULL);
    this->sparse_variable_set = _mesa_pointer_set_create(NULL);
@@ -1838,6 +1845,9 @@ nir_visitor::evaluate_rvalue(ir_rvalue* ir)
 
       enum gl_access_qualifier access = deref_get_qualifier(this->deref);
       this->result = nir_load_deref_with_access(&b, this->deref, access);
+
+      if (nir_deref_mode_is(this->deref, nir_var_shader_out))
+         this->has_output_rvalue = true;
    }
 
    return this->result;