glsl: move to compiler/

Signed-off-by: Emil Velikov <[email protected]>
Acked-by: Matt Turner <[email protected]>
Acked-by: Jose Fonseca <[email protected]>

1 files changed, 197 insertions, 0 deletions

diff --git a/src/compiler/glsl/opt_dead_code.cpp b/src/compiler/glsl/opt_dead_code.cpp
new file mode 100644
index 00000000000..dbdb7de8bb8
--- /dev/null
+++ b/src/compiler/glsl/opt_dead_code.cpp
@@ -0,0 +1,197 @@
+/*
+ * Copyright © 2010 Intel Corporation
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the next
+ * paragraph) shall be included in all copies or substantial portions of the
+ * Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+ * DEALINGS IN THE SOFTWARE.
+ */
+
+/**
+ * \file opt_dead_code.cpp
+ *
+ * Eliminates dead assignments and variable declarations from the code.
+ */
+
+#include "ir.h"
+#include "ir_visitor.h"
+#include "ir_variable_refcount.h"
+#include "compiler/glsl_types.h"
+#include "util/hash_table.h"
+
+static bool debug = false;
+
+/**
+ * Do a dead code pass over instructions and everything that instructions
+ * references.
+ *
+ * Note that this will remove assignments to globals, so it is not suitable
+ * for usage on an unlinked instruction stream.
+ */
+bool
+do_dead_code(exec_list *instructions, bool uniform_locations_assigned)
+{
+   ir_variable_refcount_visitor v;
+   bool progress = false;
+
+   v.run(instructions);
+
+   struct hash_entry *e;
+   hash_table_foreach(v.ht, e) {
+      ir_variable_refcount_entry *entry = (ir_variable_refcount_entry *)e->data;
+
+      /* Since each assignment is a reference, the refereneced count must be
+       * greater than or equal to the assignment count.  If they are equal,
+       * then all of the references are assignments, and the variable is
+       * dead.
+       *
+       * Note that if the variable is neither assigned nor referenced, both
+       * counts will be zero and will be caught by the equality test.
+       */
+      assert(entry->referenced_count >= entry->assigned_count);
+
+      if (debug) {
+	 printf("%s@%p: %d refs, %d assigns, %sdeclared in our scope\n",
+		entry->var->name, (void *) entry->var,
+		entry->referenced_count, entry->assigned_count,
+		entry->declaration ? "" : "not ");
+      }
+
+      if ((entry->referenced_count > entry->assigned_count)
+	  || !entry->declaration)
+	 continue;
+
+      /* Section 7.4.1 (Shader Interface Matching) of the OpenGL 4.5
+       * (Core Profile) spec says:
+       *
+       *    "With separable program objects, interfaces between shader
+       *    stages may involve the outputs from one program object and the
+       *    inputs from a second program object.  For such interfaces, it is
+       *    not possible to detect mismatches at link time, because the
+       *    programs are linked separately. When each such program is
+       *    linked, all inputs or outputs interfacing with another program
+       *    stage are treated as active."
+       */
+      if (entry->var->data.always_active_io)
+         continue;
+
+      if (!entry->assign_list.is_empty()) {
+	 /* Remove all the dead assignments to the variable we found.
+	  * Don't do so if it's a shader or function output, though.
+	  */
+	 if (entry->var->data.mode != ir_var_function_out &&
+	     entry->var->data.mode != ir_var_function_inout &&
+             entry->var->data.mode != ir_var_shader_out &&
+             entry->var->data.mode != ir_var_shader_storage) {
+
+            while (!entry->assign_list.is_empty()) {
+               struct assignment_entry *assignment_entry =
+                  exec_node_data(struct assignment_entry,
+                                 entry->assign_list.head, link);
+
+	       assignment_entry->assign->remove();
+
+	       if (debug) {
+	          printf("Removed assignment to %s@%p\n",
+		         entry->var->name, (void *) entry->var);
+               }
+
+               assignment_entry->link.remove();
+               free(assignment_entry);
+            }
+            progress = true;
+	 }
+      }
+
+      if (entry->assign_list.is_empty()) {
+	 /* If there are no assignments or references to the variable left,
+	  * then we can remove its declaration.
+	  */
+
+	 /* uniform initializers are precious, and could get used by another
+	  * stage.  Also, once uniform locations have been assigned, the
+	  * declaration cannot be deleted.
+	  */
+         if (entry->var->data.mode == ir_var_uniform ||
+             entry->var->data.mode == ir_var_shader_storage) {
+            if (uniform_locations_assigned || entry->var->constant_initializer)
+               continue;
+
+            /* Section 2.11.6 (Uniform Variables) of the OpenGL ES 3.0.3 spec
+             * says:
+             *
+             *     "All members of a named uniform block declared with a
+             *     shared or std140 layout qualifier are considered active,
+             *     even if they are not referenced in any shader in the
+             *     program. The uniform block itself is also considered
+             *     active, even if no member of the block is referenced."
+             *
+             * If the variable is in a uniform block with one of those
+             * layouts, do not eliminate it.
+             */
+            if (entry->var->is_in_buffer_block()) {
+               if (entry->var->get_interface_type()->interface_packing !=
+                   GLSL_INTERFACE_PACKING_PACKED)
+                  continue;
+            }
+
+            if (entry->var->type->is_subroutine())
+               continue;
+         }
+
+	 entry->var->remove();
+	 progress = true;
+
+	 if (debug) {
+	    printf("Removed declaration of %s@%p\n",
+		   entry->var->name, (void *) entry->var);
+	 }
+      }
+   }
+
+   return progress;
+}
+
+/**
+ * Does a dead code pass on the functions present in the instruction stream.
+ *
+ * This is suitable for use while the program is not linked, as it will
+ * ignore variable declarations (and the assignments to them) for variables
+ * with global scope.
+ */
+bool
+do_dead_code_unlinked(exec_list *instructions)
+{
+   bool progress = false;
+
+   foreach_in_list(ir_instruction, ir, instructions) {
+      ir_function *f = ir->as_function();
+      if (f) {
+	 foreach_in_list(ir_function_signature, sig, &f->signatures) {
+	    /* The setting of the uniform_locations_assigned flag here is
+	     * irrelevent.  If there is a uniform declaration encountered
+	     * inside the body of the function, something has already gone
+	     * terribly, terribly wrong.
+	     */
+	    if (do_dead_code(&sig->body, false))
+	       progress = true;
+	 }
+      }
+   }
+
+   return progress;
+}