[Mesa-stable] [PATCH] glsl: Handle empty if statement encountered during loop analysis.

Paul Berry stereotype441 at gmail.com
Wed Jul 24 08:17:49 PDT 2013


The is_loop_terminator() function was asserting that the following
kind of if statement could never occur:

    if (...) { } else { }

(presumably based on the assumption that such an if statement would be
eliminated by previous optimization stages).  But that isn't the
case--it's possible that previous optimization stages might simplify
more complex code down to this empty if statement, in which case it
won't be eliminated until the next time through the optimization loop.

So is_loop_terminator() needs to handle it.  Fortunately it's easy to
handle--it's not a loop terminator because it does nothing.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=64330
CC: mesa-stable at lists.freedesktop.org
---
 src/glsl/loop_analysis.cpp | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/src/glsl/loop_analysis.cpp b/src/glsl/loop_analysis.cpp
index 191e92d..40897bb 100644
--- a/src/glsl/loop_analysis.cpp
+++ b/src/glsl/loop_analysis.cpp
@@ -503,7 +503,8 @@ is_loop_terminator(ir_if *ir)
 
    ir_instruction *const inst =
       (ir_instruction *) ir->then_instructions.get_head();
-   assert(inst != NULL);
+   if (inst == NULL)
+      return false;
 
    if (inst->ir_type != ir_type_loop_jump)
       return false;
-- 
1.8.3.3



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