st/glsl_to_tgsi: be precise about merging scopes

enclosing_scope already contains enclosing_scope_first_read.
What we really want to check here -- not for correctness, but
for speed -- is whether last_read_scope already contains
enclosing_scope.

Reviewed-By: Gert Wollny <gw.fossdev@gmail.com>
Tested-by: Dieter Nützel <Dieter@nuetzel-hh.de>

diff --git a/src/mesa/state_tracker/st_glsl_to_tgsi_temprename.cpp b/src/mesa/state_tracker/st_glsl_to_tgsi_temprename.cpp
index 00ec7e7..c0c0aaa 100644 (file)
--- a/src/mesa/state_tracker/st_glsl_to_tgsi_temprename.cpp
+++ b/src/mesa/state_tracker/st_glsl_to_tgsi_temprename.cpp
@@ -540,8 +540,8 @@ lifetime temp_comp_access::get_required_lifetime()
    if (enclosing_scope_first_write->contains_range_of(*enclosing_scope))
       enclosing_scope = enclosing_scope_first_write;
 
-   if (enclosing_scope_first_read->contains_range_of(*enclosing_scope))
-      enclosing_scope = enclosing_scope_first_read;
+   if (last_read_scope->contains_range_of(*enclosing_scope))
+      enclosing_scope = last_read_scope;
 
    while (!enclosing_scope->contains_range_of(*enclosing_scope_first_write) ||
           !enclosing_scope->contains_range_of(*last_read_scope)) {