For the first basic block in the program 'block->prev()' would return
an incorrectly cast list head sentinel and the subsequent
'prev_block->end()' dereference would read invalid memory. Introduced
in c7deee69ea6f64ea5b563985bf19d9deebe73b5b.
CC: Ian Romanick <ian.d.roman...@intel.com>
---
src/mesa/drivers/dri/i965/brw_dead_control_flow.cpp | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/src/mesa/drivers/dri/i965/brw_dead_control_flow.cpp
b/src/mesa/drivers/dri/i965/brw_dead_control_flow.cpp
index 75c7be3..73aa1a9 100644
--- a/src/mesa/drivers/dri/i965/brw_dead_control_flow.cpp
+++ b/src/mesa/drivers/dri/i965/brw_dead_control_flow.cpp
@@ -43,9 +43,10 @@ dead_control_flow_eliminate(backend_shader *s)
bool progress = false;
foreach_block_safe (block, s->cfg) {
- bblock_t *prev_block = block->prev();
+ bblock_t *const prev_block = block->num ? block->prev() : NULL;
backend_instruction *const inst = block->start();
- backend_instruction *const prev_inst = prev_block->end();
+ backend_instruction *const prev_inst =
+ prev_block ? prev_block->end() : NULL;
/* ENDIF instructions, by definition, can only be found at the start of
* basic blocks.
--
2.7.0
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