glsl: builtin: always return clones of the builtins

Builtins are created once and allocated using their own private ralloc
context. When reparenting IR that includes builtins, we might be steal
bits of builtins. This is problematic because these builtins might now
be freed when the shader that includes then last is disposed. This
might also lead to inconsistent ralloc trees/lists if shaders are
created on multiple threads.

Rather than including builtins directly into a shader's IR, we should
include clones of them in the ralloc context of the shader that
requires them. This fixes double free issues we've been seeing when
running shader-db on a big multicore (72 threads) server.

v2: Also rename _mesa_glsl_find_builtin_function_by_name() to better
    reflect how this function is used. (Ken)

v3: Rename ctx to mem_ctx (Ken)

Signed-off-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>

src/compiler/glsl/ast_to_hir.cpp

@@ -5653,7 +5653,7 @@ ast_function::hir(exec_list *instructions,
    if (state->es_shader && state->language_version >= 300) {
       /* Local shader has no exact candidates; check the built-ins. */
       _mesa_glsl_initialize_builtin_functions();
-      if (_mesa_glsl_find_builtin_function_by_name(name)) {
+      if (_mesa_glsl_has_builtin_function(name)) {
          YYLTYPE loc = this->get_location();
          _mesa_glsl_error(& loc, state,
                           "A shader cannot redefine or overload built-in "

src/compiler/glsl/builtin_functions.cpp

@@ -62,6 +62,7 @@
 #include "program/prog_instruction.h"
 #include <math.h>
 #include "builtin_functions.h"
+#include "util/hash_table.h"
 
 #define M_PIf   ((float) M_PI)
 #define M_PI_2f ((float) M_PI_2)
@@ -6002,21 +6003,32 @@ ir_function_signature *
 _mesa_glsl_find_builtin_function(_mesa_glsl_parse_state *state,
                                  const char *name, exec_list *actual_parameters)
 {
-   ir_function_signature * s;
+   ir_function_signature *s;
    mtx_lock(&builtins_lock);
    s = builtins.find(state, name, actual_parameters);
    mtx_unlock(&builtins_lock);
-   return s;
+
+   if (s == NULL)
+      return NULL;
+
+   struct hash_table *ht =
+      _mesa_hash_table_create(NULL, _mesa_hash_pointer, _mesa_key_pointer_equal);
+   void *mem_ctx = state;
+   ir_function *f = s->function()->clone(mem_ctx, ht);
+   _mesa_hash_table_destroy(ht, NULL);
+
+   return f->matching_signature(state, actual_parameters, true);
 }
 
-ir_function *
-_mesa_glsl_find_builtin_function_by_name(const char *name)
+bool
+_mesa_glsl_has_builtin_function(const char *name)
 {
    ir_function *f;
    mtx_lock(&builtins_lock);
    f = builtins.shader->symbols->get_function(name);
    mtx_unlock(&builtins_lock);
-   return f;
+
+   return f != NULL;
 }
 
 gl_shader *

src/compiler/glsl/builtin_functions.h

@@ -31,8 +31,8 @@ extern ir_function_signature *
 _mesa_glsl_find_builtin_function(_mesa_glsl_parse_state *state,
                                  const char *name, exec_list *actual_parameters);
 
-extern ir_function *
-_mesa_glsl_find_builtin_function_by_name(const char *name);
+extern bool
+_mesa_glsl_has_builtin_function(const char *name);
 
 extern gl_shader *
 _mesa_glsl_get_builtin_function_shader(void);