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-rw-r--r--src/compiler/glsl/link_varyings.cpp157
1 files changed, 157 insertions, 0 deletions
diff --git a/src/compiler/glsl/link_varyings.cpp b/src/compiler/glsl/link_varyings.cpp
index e1a29b03549..317b3f5fd83 100644
--- a/src/compiler/glsl/link_varyings.cpp
+++ b/src/compiler/glsl/link_varyings.cpp
@@ -2373,3 +2373,160 @@ check_against_input_limit(struct gl_context *ctx,
return true;
}
+
+bool
+link_varyings(struct gl_shader_program *prog, unsigned first, unsigned last,
+ struct gl_context *ctx, void *mem_ctx)
+{
+ bool has_xfb_qualifiers = false;
+ unsigned num_tfeedback_decls = 0;
+ char **varying_names = NULL;
+ tfeedback_decl *tfeedback_decls = NULL;
+
+ /* 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:
+ *
+ * * the <count> specified by TransformFeedbackVaryingsEXT is
+ * non-zero, but the program object has no vertex or geometry
+ * shader;
+ */
+ if (first >= MESA_SHADER_FRAGMENT) {
+ linker_error(prog, "Transform feedback varyings specified, but "
+ "no vertex, tessellation, or geometry shader is "
+ "present.\n");
+ return false;
+ }
+
+ tfeedback_decls = rzalloc_array(mem_ctx, tfeedback_decl,
+ num_tfeedback_decls);
+ if (!parse_tfeedback_decls(ctx, prog, mem_ctx, num_tfeedback_decls,
+ varying_names, tfeedback_decls))
+ return false;
+ }
+
+ /* If there is no fragment shader we need to set transform feedback.
+ *
+ * For SSO we also need to assign output locations. We assign them here
+ * because we need to do it for both single stage programs and multi stage
+ * programs.
+ */
+ if (last < MESA_SHADER_FRAGMENT &&
+ (num_tfeedback_decls != 0 || prog->SeparateShader)) {
+ const uint64_t reserved_out_slots =
+ reserved_varying_slot(prog->_LinkedShaders[last], ir_var_shader_out);
+ if (!assign_varying_locations(ctx, mem_ctx, prog,
+ prog->_LinkedShaders[last], NULL,
+ num_tfeedback_decls, tfeedback_decls,
+ reserved_out_slots))
+ return false;
+ }
+
+ if (last <= MESA_SHADER_FRAGMENT) {
+ /* Remove unused varyings from the first/last stage unless SSO */
+ remove_unused_shader_inputs_and_outputs(prog->SeparateShader,
+ prog->_LinkedShaders[first],
+ ir_var_shader_in);
+ remove_unused_shader_inputs_and_outputs(prog->SeparateShader,
+ prog->_LinkedShaders[last],
+ ir_var_shader_out);
+
+ /* If the program is made up of only a single stage */
+ if (first == last) {
+ gl_linked_shader *const sh = prog->_LinkedShaders[last];
+
+ do_dead_builtin_varyings(ctx, NULL, sh, 0, NULL);
+ do_dead_builtin_varyings(ctx, sh, NULL, num_tfeedback_decls,
+ tfeedback_decls);
+
+ if (prog->SeparateShader) {
+ const uint64_t reserved_slots =
+ reserved_varying_slot(sh, ir_var_shader_in);
+
+ /* Assign input locations for SSO, output locations are already
+ * assigned.
+ */
+ if (!assign_varying_locations(ctx, mem_ctx, prog,
+ NULL /* producer */,
+ sh /* consumer */,
+ 0 /* num_tfeedback_decls */,
+ NULL /* tfeedback_decls */,
+ reserved_slots))
+ return false;
+ }
+ } else {
+ /* Linking the stages in the opposite order (from fragment to vertex)
+ * ensures that inter-shader outputs written to in an earlier stage
+ * are eliminated if they are (transitively) not used in a later
+ * stage.
+ */
+ int next = last;
+ for (int i = next - 1; i >= 0; i--) {
+ if (prog->_LinkedShaders[i] == NULL && i != 0)
+ continue;
+
+ gl_linked_shader *const sh_i = prog->_LinkedShaders[i];
+ gl_linked_shader *const sh_next = prog->_LinkedShaders[next];
+
+ const uint64_t reserved_out_slots =
+ reserved_varying_slot(sh_i, ir_var_shader_out);
+ const uint64_t reserved_in_slots =
+ reserved_varying_slot(sh_next, ir_var_shader_in);
+
+ do_dead_builtin_varyings(ctx, sh_i, sh_next,
+ next == MESA_SHADER_FRAGMENT ? num_tfeedback_decls : 0,
+ tfeedback_decls);
+
+ if (!assign_varying_locations(ctx, mem_ctx, prog, sh_i, sh_next,
+ next == MESA_SHADER_FRAGMENT ? num_tfeedback_decls : 0,
+ tfeedback_decls,
+ reserved_out_slots | reserved_in_slots))
+ return false;
+
+ /* This must be done after all dead varyings are eliminated. */
+ if (sh_i != NULL) {
+ unsigned slots_used = _mesa_bitcount_64(reserved_out_slots);
+ if (!check_against_output_limit(ctx, prog, sh_i, slots_used)) {
+ return false;
+ }
+ }
+
+ unsigned slots_used = _mesa_bitcount_64(reserved_in_slots);
+ if (!check_against_input_limit(ctx, prog, sh_next, slots_used))
+ return false;
+
+ next = i;
+ }
+ }
+ }
+
+ if (!store_tfeedback_info(ctx, prog, num_tfeedback_decls, tfeedback_decls,
+ has_xfb_qualifiers))
+ return false;
+
+ return true;
+}