https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98255
--- Comment #7 from Martin Jambor <jamborm at gcc dot gnu.org> ---
Even our constant folding thinks the unsigned expression wraps around. If I
tell SRA to fold the expression if the base is a string_cst, the invalid
dereference is avoided. My experiment was (I am not proposing this, but it
illustrates the point):
diff --git a/gcc/tree-sra.c b/gcc/tree-sra.c
index d177f1ba11c..d33c0ab63f7 100644
--- a/gcc/tree-sra.c
+++ b/gcc/tree-sra.c
@@ -99,6 +99,7 @@ along with GCC; see the file COPYING3. If not see
#include "dbgcnt.h"
#include "builtins.h"
#include "tree-sra.h"
+#include "gimple-fold.h"
/* Enumeration of all aggregate reductions we can do. */
@@ -1696,6 +1697,14 @@ build_ref_for_model (location_t loc, tree base,
HOST_WIDE_INT offset,
else
{
tree res;
+ if (TREE_CODE (base) == STRING_CST)
+ {
+ res = build_ref_for_offset (loc, base, offset, model->reverse,
+ model->type, gsi, insert_after);
+ res = fold_const_aggregate_ref (res);
+ return res;
+ }
+
if (model->grp_same_access_path
&& !TREE_THIS_VOLATILE (base)
&& (TYPE_ADDR_SPACE (TREE_TYPE (base))
