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util/rb_tree: Stop relying on &iter->field != NULL

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The old version of the iterators relies on a &iter->field != NULL check
which works fine on older GCC but newer GCC versions and clang have
optimizations that break if you do pointer math on a null pointer.  The
correct solution to this is to do the null comparisons before we do any
sort of &iter->field or use rb_node_data to do the reverse operation.

Acked-by: Michel Dänzer <mdaenzer@redhat.com>
Tested-by: Michel Dänzer <mdaenzer@redhat.com>
Reviewed-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
This commit is contained in:
Jason Ekstrand
2019-09-25 10:02:15 -05:00
parent f18aad6dc0
commit 5ca4f57469
1 changed files with 28 additions and 41 deletions
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69
src/util/rb_tree.h
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@@ -227,29 +227,8 @@ struct rb_node *rb_node_next(struct rb_node *node);
/** Get the next previous (to the left) in the tree or NULL */ /** Get the next previous (to the left) in the tree or NULL */
struct rb_node *rb_node_prev(struct rb_node *node); struct rb_node *rb_node_prev(struct rb_node *node);
/** Get the next node if available or the same node again. #define rb_node_next_or_null(n) ((n) == NULL ? NULL : rb_node_next(n))
* #define rb_node_prev_or_null(n) ((n) == NULL ? NULL : rb_node_prev(n))
* \param type The type of the containing data structure
*
* \param node The variable name for current node in the iteration;
* this will be declared as a pointer to \p type
*
* \param field The rb_node field in containing data structure
*/
#define rb_tree_node_next_if_available(type, node, field) \
(&node->field != NULL) ? rb_node_data(type, rb_node_next(&node->field), field) : node
/** Get the previous node if available or the same node again.
*
* \param type The type of the containing data structure
*
* \param node The variable name for current node in the iteration;
* this will be declared as a pointer to \p type
*
* \param field The rb_node field in containing data structure
*/
#define rb_tree_node_prev_if_available(type, node, field) \
(&node->field != NULL) ? rb_node_data(type, rb_node_prev(&node->field), field) : node
/** Iterate over the nodes in the tree /** Iterate over the nodes in the tree
* *
@@ -262,10 +241,11 @@ struct rb_node *rb_node_prev(struct rb_node *node);
* *
* \param field The rb_node field in containing data structure * \param field The rb_node field in containing data structure
*/ */
#define rb_tree_foreach(type, node, T, field) \ #define rb_tree_foreach(type, iter, T, field) \
for (type *node = rb_node_data(type, rb_tree_first(T), field); \ for (type *iter, *__node = (type *)rb_tree_first(T); \
&node->field != NULL; \ __node != NULL && \
node = rb_node_data(type, rb_node_next(&node->field), field)) (iter = rb_node_data(type, (struct rb_node *)__node, field), true); \
__node = (type *)rb_node_next((struct rb_node *)__node))
/** Iterate over the nodes in the tree, allowing the current node to be freed /** Iterate over the nodes in the tree, allowing the current node to be freed
* *
@@ -278,11 +258,14 @@ struct rb_node *rb_node_prev(struct rb_node *node);
* *
* \param field The rb_node field in containing data structure * \param field The rb_node field in containing data structure
*/ */
#define rb_tree_foreach_safe(type, node, T, field) \ #define rb_tree_foreach_safe(type, iter, T, field) \
for (type *node = rb_node_data(type, rb_tree_first(T), field), \ for (type *iter, \
*__next = rb_tree_node_next_if_available(type, node, field); \ *__node = (type *)rb_tree_first(T), \
&node->field != NULL; \ *__next = (type *)rb_node_next_or_null((struct rb_node *)__node); \
node = __next, __next = rb_tree_node_next_if_available(type, node, field)) __node != NULL && \
(iter = rb_node_data(type, (struct rb_node *)__node, field), true); \
__node = __next, \
__next = (type *)rb_node_next_or_null((struct rb_node *)__node))
/** Iterate over the nodes in the tree in reverse /** Iterate over the nodes in the tree in reverse
* *
@@ -295,10 +278,11 @@ struct rb_node *rb_node_prev(struct rb_node *node);
* *
* \param field The rb_node field in containing data structure * \param field The rb_node field in containing data structure
*/ */
#define rb_tree_foreach_rev(type, node, T, field) \ #define rb_tree_foreach_rev(type, iter, T, field) \
for (type *node = rb_node_data(type, rb_tree_last(T), field); \ for (type *iter, *__node = (type *)rb_tree_last(T); \
&node->field != NULL; \ __node != NULL && \
node = rb_node_data(type, rb_node_prev(&node->field), field)) (iter = rb_node_data(type, (struct rb_node *)__node, field), true); \
__node = (type *)rb_node_prev((struct rb_node *)__node))
/** Iterate over the nodes in the tree in reverse, allowing the current node to be freed /** Iterate over the nodes in the tree in reverse, allowing the current node to be freed
* *
@@ -311,11 +295,14 @@ struct rb_node *rb_node_prev(struct rb_node *node);
* *
* \param field The rb_node field in containing data structure * \param field The rb_node field in containing data structure
*/ */
#define rb_tree_foreach_rev_safe(type, node, T, field) \ #define rb_tree_foreach_rev_safe(type, iter, T, field) \
for (type *node = rb_node_data(type, rb_tree_last(T), field), \ for (type *iter, \
*__prev = rb_tree_node_prev_if_available(type, node, field); \ *__node = (type *)rb_tree_last(T), \
&node->field != NULL; \ *__prev = (type *)rb_node_prev_or_null((struct rb_node *)__node); \
node = __prev, __prev = rb_tree_node_prev_if_available(type, node, field)) __node != NULL && \
(iter = rb_node_data(type, (struct rb_node *)__node, field), true); \
__node = __prev, \
__prev = (type *)rb_node_prev_or_null((struct rb_node *)__node))
/** Validate a red-black tree /** Validate a red-black tree
* *