[Mesa-dev] [PATCH 2/5] compiler/list: add and use for_range_list_safe

[Nicolai Hähnle]

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

This macro avoids undefined behaviour that crashes gcc's ubsan.
---
 src/compiler/glsl/list.h                  | 13 +++++++++++++
 src/compiler/glsl/opt_dead_code_local.cpp |  7 +------
 src/compiler/glsl/opt_tree_grafting.cpp   |  5 +----
 3 files changed, 15 insertions(+), 10 deletions(-)

diff --git a/src/compiler/glsl/list.h b/src/compiler/glsl/list.h
index 8da9514..12389aa 100644
--- a/src/compiler/glsl/list.h
+++ b/src/compiler/glsl/list.h
@@ -716,4 +716,17 @@ inline void exec_node::insert_before(exec_list *before)
            (((__node) = exec_node_data(__type, __cur, __field)) || true);  \
            __cur = __prev, __prev = __prev->prev)
 
+/**
+ * Iterate over a range [begin, end) of nodes.
+ */
+#define for_range_list_safe(__type, __node, __begin, __end) \
+   for (__type *(__node), **__flag = &(__node); __flag; __flag = NULL) \
+      for (struct exec_node *__cur = (__begin),                        \
+                            *__next = __cur->next,                     \
+                            *__end_stored = (__end);                   \
+           __cur != __end_stored &&                                    \
+           (((__node) = (__type *) __cur) || true);                    \
+           __cur = __next, __next = __next->next)
+
+
 #endif /* LIST_CONTAINER_H */
diff --git a/src/compiler/glsl/opt_dead_code_local.cpp b/src/compiler/glsl/opt_dead_code_local.cpp
index d38fd2b..5dd3bfd 100644
--- a/src/compiler/glsl/opt_dead_code_local.cpp
+++ b/src/compiler/glsl/opt_dead_code_local.cpp
@@ -291,7 +291,6 @@ dead_code_local_basic_block(ir_instruction *first,
 			     ir_instruction *last,
 			     void *data)
 {
-   ir_instruction *ir, *ir_next;
    /* List of avaialble_copy */
    exec_list assignments;
    bool *out_progress = (bool *)data;
@@ -299,8 +298,7 @@ dead_code_local_basic_block(ir_instruction *first,
 
    void *ctx = ralloc_context(NULL);
    /* Safe looping, since process_assignment */
-   for (ir = first, ir_next = (ir_instruction *)first->next;;
-	ir = ir_next, ir_next = (ir_instruction *)ir->next) {
+   for_range_list_safe(ir_instruction, ir, first, last->next) {
       ir_assignment *ir_assign = ir->as_assignment();
 
       if (debug) {
@@ -314,9 +312,6 @@ dead_code_local_basic_block(ir_instruction *first,
 	 kill_for_derefs_visitor kill(&assignments);
 	 ir->accept(&kill);
       }
-
-      if (ir == last)
-	 break;
    }
    *out_progress = progress;
    ralloc_free(ctx);
diff --git a/src/compiler/glsl/opt_tree_grafting.cpp b/src/compiler/glsl/opt_tree_grafting.cpp
index a40e5f7..47fca7d 100644
--- a/src/compiler/glsl/opt_tree_grafting.cpp
+++ b/src/compiler/glsl/opt_tree_grafting.cpp
@@ -347,11 +347,8 @@ tree_grafting_basic_block(ir_instruction *bb_first,
 			  void *data)
 {
    struct tree_grafting_info *info = (struct tree_grafting_info *)data;
-   ir_instruction *ir, *next;
 
-   for (ir = bb_first, next = (ir_instruction *)ir->next;
-	ir != bb_last->next;
-	ir = next, next = (ir_instruction *)ir->next) {
+   for_range_list_safe(ir_instruction, ir, bb_first, bb_last->next) {
       ir_assignment *assign = ir->as_assignment();
 
       if (!assign)
-- 
2.7.4