glsl: basic linking support for xfb qualifiers

This adds the initial infrastructure for enabling transform feedback
mode via in shader qualifiers and adds initial buffer support.

Reviewed-by: Dave Airlie <[email protected]>

3 files changed, 52 insertions, 13 deletions

diff --git a/src/compiler/glsl/link_varyings.cpp b/src/compiler/glsl/link_varyings.cpp
index 57c3d217200..33eb7d0e8bc 100644
--- a/src/compiler/glsl/link_varyings.cpp
+++ b/src/compiler/glsl/link_varyings.cpp
@@ -715,7 +715,8 @@ tfeedback_decl::get_num_outputs() const
 bool
 tfeedback_decl::store(struct gl_context *ctx, struct gl_shader_program *prog,
                       struct gl_transform_feedback_info *info,
-                      unsigned buffer, const unsigned max_outputs) const
+                      unsigned buffer, const unsigned max_outputs,
+                      bool has_xfb_qualifiers) const
 {
    assert(!this->next_buffer_separator);
 
@@ -858,7 +859,7 @@ parse_tfeedback_decls(struct gl_context *ctx, struct gl_shader_program *prog,
 bool
 store_tfeedback_info(struct gl_context *ctx, struct gl_shader_program *prog,
                      unsigned num_tfeedback_decls,
-                     tfeedback_decl *tfeedback_decls)
+                     tfeedback_decl *tfeedback_decls, bool has_xfb_qualifiers)
 {
    bool separate_attribs_mode =
       prog->TransformFeedback.BufferMode == GL_SEPARATE_ATTRIBS;
@@ -885,11 +886,12 @@ store_tfeedback_info(struct gl_context *ctx, struct gl_shader_program *prog,
 
    unsigned num_buffers = 0;
 
-   if (separate_attribs_mode) {
+   if (!has_xfb_qualifiers && separate_attribs_mode) {
       /* GL_SEPARATE_ATTRIBS */
       for (unsigned i = 0; i < num_tfeedback_decls; ++i) {
          if (!tfeedback_decls[i].store(ctx, prog, &prog->LinkedTransformFeedback,
-                                       num_buffers, num_outputs))
+                                       num_buffers, num_outputs,
+                                       has_xfb_qualifiers))
             return false;
 
          num_buffers++;
@@ -898,6 +900,9 @@ store_tfeedback_info(struct gl_context *ctx, struct gl_shader_program *prog,
    else {
       /* GL_INVERLEAVED_ATTRIBS */
       int buffer_stream_id = -1;
+      unsigned buffer =
+         num_tfeedback_decls ? tfeedback_decls[0].get_buffer() : 0;
+
       for (unsigned i = 0; i < num_tfeedback_decls; ++i) {
          if (tfeedback_decls[i].is_next_buffer_separator()) {
             num_buffers++;
@@ -920,9 +925,16 @@ store_tfeedback_info(struct gl_context *ctx, struct gl_shader_program *prog,
             return false;
          }
 
+         if (has_xfb_qualifiers) {
+            buffer = tfeedback_decls[i].get_buffer();
+         } else {
+            buffer = num_buffers;
+         }
+
          if (!tfeedback_decls[i].store(ctx, prog,
                                        &prog->LinkedTransformFeedback,
-                                       num_buffers, num_outputs))
+                                       num_buffers, num_outputs,
+                                       has_xfb_qualifiers))
             return false;
       }
       num_buffers++;
diff --git a/src/compiler/glsl/link_varyings.h b/src/compiler/glsl/link_varyings.h
index 339e9cf2f18..7165ecb9184 100644
--- a/src/compiler/glsl/link_varyings.h
+++ b/src/compiler/glsl/link_varyings.h
@@ -98,7 +98,7 @@ public:
    unsigned get_num_outputs() const;
    bool store(struct gl_context *ctx, struct gl_shader_program *prog,
               struct gl_transform_feedback_info *info, unsigned buffer,
-              const unsigned max_outputs) const;
+              const unsigned max_outputs, bool has_xfb_qualifiers) const;
    const tfeedback_candidate *find_candidate(gl_shader_program *prog,
                                              hash_table *tfeedback_candidates);
 
@@ -301,7 +301,8 @@ remove_unused_shader_inputs_and_outputs(bool is_separate_shader_object,
 bool
 store_tfeedback_info(struct gl_context *ctx, struct gl_shader_program *prog,
                      unsigned num_tfeedback_decls,
-                     tfeedback_decl *tfeedback_decls);
+                     tfeedback_decl *tfeedback_decls,
+                     bool has_xfb_qualifiers);
 
 bool
 assign_varying_locations(struct gl_context *ctx,
diff --git a/src/compiler/glsl/linker.cpp b/src/compiler/glsl/linker.cpp
index cd35464eeeb..3ae958cacb7 100644
--- a/src/compiler/glsl/linker.cpp
+++ b/src/compiler/glsl/linker.cpp
@@ -4169,9 +4169,11 @@ link_shaders(struct gl_context *ctx, struct gl_shader_program *prog)
       return;
    }
 
-   tfeedback_decl *tfeedback_decls = NULL;
-   unsigned num_tfeedback_decls = prog->TransformFeedback.NumVarying;
+   unsigned num_tfeedback_decls = 0;
    unsigned int num_explicit_uniform_locs = 0;
+   bool has_xfb_qualifiers = false;
+   char **varying_names = NULL;
+   tfeedback_decl *tfeedback_decls = NULL;
 
    void *mem_ctx = ralloc_context(NULL); // temporary linker context
 
@@ -4481,6 +4483,30 @@ link_shaders(struct gl_context *ctx, struct gl_shader_program *prog)
       goto done;
    }
 
+   /* From the ARB_enhanced_layouts spec:
+    *
+    *    "If the shader used to record output variables for transform feedback
+    *    varyings uses the "xfb_buffer", "xfb_offset", or "xfb_stride" layout
+    *    qualifiers, the values specified by TransformFeedbackVaryings are
+    *    ignored, and the set of variables captured for transform feedback is
+    *    instead derived from the specified layout qualifiers."
+    */
+   for (int i = MESA_SHADER_FRAGMENT - 1; i >= 0; i--) {
+      /* Find last stage before fragment shader */
+      if (prog->_LinkedShaders[i]) {
+         has_xfb_qualifiers =
+            process_xfb_layout_qualifiers(mem_ctx, prog->_LinkedShaders[i],
+                                          &num_tfeedback_decls,
+                                          &varying_names);
+         break;
+      }
+   }
+
+   if (!has_xfb_qualifiers) {
+      num_tfeedback_decls = prog->TransformFeedback.NumVarying;
+      varying_names = prog->TransformFeedback.VaryingNames;
+   }
+
    if (num_tfeedback_decls != 0) {
       /* From GL_EXT_transform_feedback:
        *   A program will fail to link if:
@@ -4497,10 +4523,9 @@ link_shaders(struct gl_context *ctx, struct gl_shader_program *prog)
       }
 
       tfeedback_decls = ralloc_array(mem_ctx, tfeedback_decl,
-                                     prog->TransformFeedback.NumVarying);
+                                     num_tfeedback_decls);
       if (!parse_tfeedback_decls(ctx, prog, mem_ctx, num_tfeedback_decls,
-                                 prog->TransformFeedback.VaryingNames,
-                                 tfeedback_decls))
+                                 varying_names, tfeedback_decls))
          goto done;
    }
 
@@ -4580,7 +4605,8 @@ link_shaders(struct gl_context *ctx, struct gl_shader_program *prog)
       }
    }
 
-   if (!store_tfeedback_info(ctx, prog, num_tfeedback_decls, tfeedback_decls))
+   if (!store_tfeedback_info(ctx, prog, num_tfeedback_decls, tfeedback_decls,
+                             has_xfb_qualifiers))
       goto done;
 
    update_array_sizes(prog);