[Mesa-dev] [PATCH 1/2] st/glsl_to_tgsi: be precise about merging scopes

[Nicolai Hähnle]

From: Nicolai Hähnle <nicolai.haehnle at amd.com>

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.
---
 src/mesa/state_tracker/st_glsl_to_tgsi_temprename.cpp | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

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 d984184e701..8ba1f5bb0be 100644
--- a/src/mesa/state_tracker/st_glsl_to_tgsi_temprename.cpp
+++ b/src/mesa/state_tracker/st_glsl_to_tgsi_temprename.cpp
@@ -526,22 +526,22 @@ lifetime temp_comp_access::get_required_lifetime()
       enclosing_scope_first_write = conditional->outermost_loop();
    }
 
    /* Evaluate the scope that is shared by all: required first write scope,
     * required first read before write scope, and last read scope.
     */
    const prog_scope *enclosing_scope = enclosing_scope_first_read;
    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)) {
       enclosing_scope = enclosing_scope->parent();
       assert(enclosing_scope);
    }
 
    /* Propagate the last read scope to the target scope */
    while (enclosing_scope->nesting_depth() < last_read_scope->nesting_depth()) {
       /* If the read is in a loop and we have to move up the scope we need to
-- 
2.11.0