On 07/24/2013 08:17 AM, Paul Berry wrote:
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-sta...@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;
Reviewed-by: Kenneth Graunke <kenn...@whitecape.org>
This would have been a bit more obvious if 'diff' had included a few
more lines of context. Immediately above this hunk, there is:
if (!ir->else_instructions.is_empty())
return false;
which already guarantees the else block is empty, so it really is just
the noop "if (...) {} {}" statement.
--Ken
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