glsl: Use simpler visitor to determine which UBO and SSBO blocks are used

Very soon this visitor will get more complicated.  The users of the
existing ir_variable_refcount visitor won't need the coming
functionality, and this use doesn't need much of the functionality of
ir_variable_refcount.

v2: ir_array_refcount_visitor::get_variable_entry cannot return NULL, so
don't check it.  Suggested by Timothy.

Signed-off-by: Ian Romanick <ian.d.romanick@intel.com>
Cc: mesa-stable@lists.freedesktop.org
Reviewed-by: Timothy Arceri <timothy.arceri@collabora.com>
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>

src/compiler/Makefile.sources

@@ -29,6 +29,8 @@ LIBGLSL_FILES = \
 	glsl/glsl_to_nir.cpp \
 	glsl/glsl_to_nir.h \
 	glsl/hir_field_selection.cpp \
+	glsl/ir_array_refcount.cpp \
+	glsl/ir_array_refcount.h \
 	glsl/ir_basic_block.cpp \
 	glsl/ir_basic_block.h \
 	glsl/ir_builder.cpp \

src/compiler/glsl/ir_array_refcount.cpp

@@ -0,0 +1,99 @@
+/*
+ * Copyright © 2016 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 ir_array_refcount.cpp
+ *
+ * Provides a visitor which produces a list of variables referenced.
+ */
+
+#include "ir.h"
+#include "ir_visitor.h"
+#include "ir_array_refcount.h"
+#include "compiler/glsl_types.h"
+#include "util/hash_table.h"
+
+ir_array_refcount_visitor::ir_array_refcount_visitor()
+{
+   this->mem_ctx = ralloc_context(NULL);
+   this->ht = _mesa_hash_table_create(NULL, _mesa_hash_pointer,
+                                      _mesa_key_pointer_equal);
+}
+
+static void
+free_entry(struct hash_entry *entry)
+{
+   ir_array_refcount_entry *ivre = (ir_array_refcount_entry *) entry->data;
+   delete ivre;
+}
+
+ir_array_refcount_visitor::~ir_array_refcount_visitor()
+{
+   ralloc_free(this->mem_ctx);
+   _mesa_hash_table_destroy(this->ht, free_entry);
+}
+
+ir_array_refcount_entry::ir_array_refcount_entry(ir_variable *var)
+   : var(var), is_referenced(false)
+{
+   /* empty */
+}
+
+
+ir_array_refcount_entry *
+ir_array_refcount_visitor::get_variable_entry(ir_variable *var)
+{
+   assert(var);
+
+   struct hash_entry *e = _mesa_hash_table_search(this->ht, var);
+   if (e)
+      return (ir_array_refcount_entry *)e->data;
+
+   ir_array_refcount_entry *entry = new ir_array_refcount_entry(var);
+   _mesa_hash_table_insert(this->ht, var, entry);
+
+   return entry;
+}
+
+
+ir_visitor_status
+ir_array_refcount_visitor::visit(ir_dereference_variable *ir)
+{
+   ir_variable *const var = ir->variable_referenced();
+   ir_array_refcount_entry *entry = this->get_variable_entry(var);
+
+   entry->is_referenced = true;
+
+   return visit_continue;
+}
+
+
+ir_visitor_status
+ir_array_refcount_visitor::visit_enter(ir_function_signature *ir)
+{
+   /* We don't want to descend into the function parameters and
+    * dead-code eliminate them, so just accept the body here.
+    */
+   visit_list_elements(this, &ir->body);
+   return visit_continue_with_parent;
+}

src/compiler/glsl/ir_array_refcount.h

@@ -0,0 +1,65 @@
+/*
+ * Copyright © 2016 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 ir_array_refcount.h
+ *
+ * Provides a visitor which produces a list of variables referenced.
+ */
+
+#include "ir.h"
+#include "ir_visitor.h"
+#include "compiler/glsl_types.h"
+
+class ir_array_refcount_entry
+{
+public:
+   ir_array_refcount_entry(ir_variable *var);
+
+   ir_variable *var; /* The key: the variable's pointer. */
+
+   /** Has the variable been referenced? */
+   bool is_referenced;
+};
+
+class ir_array_refcount_visitor : public ir_hierarchical_visitor {
+public:
+   ir_array_refcount_visitor(void);
+   ~ir_array_refcount_visitor(void);
+
+   virtual ir_visitor_status visit(ir_dereference_variable *);
+
+   virtual ir_visitor_status visit_enter(ir_function_signature *);
+
+   /**
+    * Find variable in the hash table, and insert it if not present
+    */
+   ir_array_refcount_entry *get_variable_entry(ir_variable *var);
+
+   /**
+    * Hash table mapping ir_variable to ir_array_refcount_entry.
+    */
+   struct hash_table *ht;
+
+   void *mem_ctx;
+};

src/compiler/glsl/link_uniforms.cpp

@@ -28,7 +28,7 @@
 #include "glsl_symbol_table.h"
 #include "program.h"
 #include "util/string_to_uint_map.h"
-#include "ir_variable_refcount.h"
+#include "ir_array_refcount.h"
 
 /**
  * \file link_uniforms.cpp
@@ -868,11 +868,11 @@ public:
 };
 
 static bool
-variable_is_referenced(ir_variable_refcount_visitor &v, ir_variable *var)
+variable_is_referenced(ir_array_refcount_visitor &v, ir_variable *var)
 {
-   ir_variable_refcount_entry *const entry = v.get_variable_entry(var);
+   ir_array_refcount_entry *const entry = v.get_variable_entry(var);
 
-   return entry->referenced_count > 0;
+   return entry->is_referenced;
 
 }
 
@@ -886,7 +886,7 @@ static void
 link_update_uniform_buffer_variables(struct gl_linked_shader *shader,
                                      unsigned stage)
 {
-   ir_variable_refcount_visitor v;
+   ir_array_refcount_visitor v;
 
    v.run(shader->ir);