https://gcc.gnu.org/g:51b85dfeb19652bf3e0aaec08828ba7cee1e641c
commit r15-4414-g51b85dfeb19652bf3e0aaec08828ba7cee1e641c
Author: Siddhesh Poyarekar <siddh...@gotplt.org>
Date: Wed Sep 18 22:36:09 2024 -0400
tree-object-size: Fall back to wholesize for non-const offset
Don't bail out early if the offset to a pointer in __builtin_object_size
is a variable, return the wholesize instead since that is a better
fallback for maximum estimate. This should keep checks in place for
fortified functions to constrain overflows to at lesat some extent.
gcc/ChangeLog:
PR middle-end/77608
* tree-object-size.cc (plus_stmt_object_size): Drop check for
constant offset.
gcc/testsuite/ChangeLog:
* gcc.dg/builtin-object-size-1.c (test12): New test.
(main): Call it.
Signed-off-by: Siddhesh Poyarekar <siddh...@gotplt.org>
Diff:
---
gcc/testsuite/gcc.dg/builtin-object-size-1.c | 21 +++++++++++++++++++++
gcc/tree-object-size.cc | 6 +++---
2 files changed, 24 insertions(+), 3 deletions(-)
diff --git a/gcc/testsuite/gcc.dg/builtin-object-size-1.c
b/gcc/testsuite/gcc.dg/builtin-object-size-1.c
index d6d13c5ef7a2..6161adbd1289 100644
--- a/gcc/testsuite/gcc.dg/builtin-object-size-1.c
+++ b/gcc/testsuite/gcc.dg/builtin-object-size-1.c
@@ -712,6 +712,25 @@ test11 (void)
}
#endif
+void
+__attribute__ ((noinline))
+test12 (unsigned off)
+{
+ char *buf2 = malloc (10);
+ char *p;
+ size_t t;
+
+ p = &buf2[off];
+
+#ifdef __builtin_object_size
+ if (__builtin_object_size (p, 0) != 10 - off)
+ FAIL ();
+#else
+ if (__builtin_object_size (p, 0) != 10)
+ FAIL ();
+#endif
+}
+
int
main (void)
{
@@ -730,5 +749,7 @@ main (void)
#ifndef SKIP_STRNDUP
test11 ();
#endif
+ test12 (0);
+ test12 (2);
DONE ();
}
diff --git a/gcc/tree-object-size.cc b/gcc/tree-object-size.cc
index 78faae7ad0d3..0e4bf84fd11c 100644
--- a/gcc/tree-object-size.cc
+++ b/gcc/tree-object-size.cc
@@ -1501,8 +1501,7 @@ plus_stmt_object_size (struct object_size_info *osi, tree
var, gimple *stmt)
return false;
/* Handle PTR + OFFSET here. */
- if (size_valid_p (op1, object_size_type)
- && (TREE_CODE (op0) == SSA_NAME || TREE_CODE (op0) == ADDR_EXPR))
+ if ((TREE_CODE (op0) == SSA_NAME || TREE_CODE (op0) == ADDR_EXPR))
{
if (TREE_CODE (op0) == SSA_NAME)
{
@@ -1528,7 +1527,8 @@ plus_stmt_object_size (struct object_size_info *osi, tree
var, gimple *stmt)
;
else if ((object_size_type & OST_DYNAMIC)
|| bytes != wholesize
- || compare_tree_int (op1, offset_limit) <= 0)
+ || (size_valid_p (op1, object_size_type)
+ && compare_tree_int (op1, offset_limit) <= 0))
bytes = size_for_offset (bytes, op1, wholesize);
/* In the static case, with a negative offset, the best estimate for
minimum size is size_unknown but for maximum size, the wholesize is a
