diff options
| -rw-r--r-- | src/mesa/drivers/dri/i965/brw_program.c | 43 |
1 files changed, 43 insertions, 0 deletions
diff --git a/src/mesa/drivers/dri/i965/brw_program.c b/src/mesa/drivers/dri/i965/brw_program.c index e81f6b15c0a..673dc502ad4 100644 --- a/src/mesa/drivers/dri/i965/brw_program.c +++ b/src/mesa/drivers/dri/i965/brw_program.c @@ -177,6 +177,49 @@ static struct gl_program *brwNewProgram(struct gl_context *ctx, GLenum target, static void brwDeleteProgram( struct gl_context *ctx, struct gl_program *prog ) { + struct brw_context *brw = brw_context(ctx); + + /* Beware! prog's refcount has reached zero, and it's about to be freed. + * + * In brw_upload_pipeline_state(), we compare brw->foo_program to + * ctx->FooProgram._Current, and flag BRW_NEW_FOO_PROGRAM if the + * pointer has changed. + * + * We cannot leave brw->foo_program as a dangling pointer to the dead + * program. malloc() may allocate the same memory for a new gl_program, + * causing us to see matching pointers...but totally different programs. + * + * We cannot set brw->foo_program to NULL, either. If we've deleted the + * active program, Mesa may set ctx->FooProgram._Current to NULL. That + * would cause us to see matching pointers (NULL == NULL), and fail to + * detect that a program has changed since our last draw. + * + * So, set it to a bogus gl_program pointer that will never match, + * causing us to properly reevaluate the state on our next draw. + * + * Getting this wrong causes heisenbugs which are very hard to catch, + * as you need a very specific allocation pattern to hit the problem. + */ + static const struct gl_program deleted_program; + + if (brw->vertex_program == prog) + brw->vertex_program = &deleted_program; + + if (brw->tess_ctrl_program == prog) + brw->tess_ctrl_program = &deleted_program; + + if (brw->tess_eval_program == prog) + brw->tess_eval_program = &deleted_program; + + if (brw->geometry_program == prog) + brw->geometry_program = &deleted_program; + + if (brw->fragment_program == prog) + brw->fragment_program = &deleted_program; + + if (brw->compute_program == prog) + brw->compute_program = &deleted_program; + _mesa_delete_program( ctx, prog ); } |