PR middle-end/95353 - spurious -Wstringop-overflow writing to a trailing array plus offset

Also resolves:
PR middle-end/92939 - missing -Wstringop-overflow on negative index from the end of array

gcc/ChangeLog:

	PR middle-end/95353
	PR middle-end/92939
	* builtins.c (inform_access): New function.
	(check_access): Call it.  Add argument.
	(addr_decl_size): Remove.
	(get_range): New function.
	(compute_objsize): New overload.  Only use compute_builtin_object_size
	with raw memory function.
	(check_memop_access): Pass new argument to compute_objsize and
	check_access.
	(expand_builtin_memchr, expand_builtin_strcat): Same.
	(expand_builtin_strcpy, expand_builtin_stpcpy_1): Same.
	(expand_builtin_stpncpy, check_strncat_sizes): Same.
	(expand_builtin_strncat, expand_builtin_strncpy): Same.
	(expand_builtin_memcmp): Same.
	* builtins.h (check_nul_terminated_array): Declare extern.
	(check_access): Add argument.
	(struct access_ref, struct access_data): New structs.
	* gimple-ssa-warn-restrict.c (clamp_offset): New helper.
	(builtin_access::overlap): Call it.
	* tree-object-size.c (decl_init_size): Declare extern.
	(addr_object_size): Correct offset computation.
	* tree-object-size.h (decl_init_size): Declare.
	* tree-ssa-strlen.c (handle_integral_assign): Remove a call
	to maybe_warn_overflow when assigning to an SSA_NAME.

gcc/testsuite/ChangeLog:

	PR middle-end/95353
	PR middle-end/92939
	* c-c++-common/Wstringop-truncation.c: Remove an xfail.
	* gcc.dg/Warray-bounds-46.c: Remove a bogus warning.
	* gcc.dg/Wrestrict-9.c: Disable -Wstringop-overflow.
	* gcc.dg/Wstringop-overflow-12.c: Remove xfails.
	* gcc.dg/Wstringop-overflow-28.c: Same.
	* gcc.dg/builtin-stringop-chk-4.c: Same.
	* gcc.dg/builtin-stringop-chk-5.c: Same.
	* gcc.dg/builtin-stringop-chk-8.c: Same.
	* gcc.dg/strlenopt-74.c: Avoid buffer overflow.
	* gcc.dg/Wstringop-overflow-34.c: New test.
	* gcc.dg/Wstringop-overflow-35.c: New test.
	* gcc.dg/Wstringop-overflow-36.c: New test.
	* gcc.dg/Wstringop-overflow-37.c: New test.
	* gcc.dg/Wstringop-overflow-38.c: New test.

1 files changed, 30 insertions, 3 deletions

diff --git a/gcc/builtins.h b/gcc/builtins.h
index 73e85d66e9b..8b812ceb2c4 100644
--- a/gcc/builtins.h
+++ b/gcc/builtins.h
@@ -152,12 +152,39 @@ extern bool target_char_cst_p (tree t, char *p);
 extern internal_fn associated_internal_fn (tree);
 extern internal_fn replacement_internal_fn (gcall *);
 
-bool check_nul_terminated_array (tree, tree, tree = NULL_TREE);
+extern bool check_nul_terminated_array (tree, tree, tree = NULL_TREE);
 extern void warn_string_no_nul (location_t, const char *, tree, tree);
 extern tree unterminated_array (tree, tree * = NULL, bool * = NULL);
 extern bool builtin_with_linkage_p (tree);
-extern bool check_access (tree, tree, tree, tree, tree, tree, tree,
-			  bool = true);
 
+/* Describes a reference to an object used in an access.  */
+struct access_ref
+{
+  access_ref (): ref ()
+  {
+    /* Set to valid.  */
+    offrng[0] = offrng[1] = 0;
+    /* Invalidate.   */
+    sizrng[0] = sizrng[1] = -1;
+  }
+
+  /* Reference to the object.  */
+  tree ref;
+
+  /* Range of offsets into and sizes of the object(s).  */
+  offset_int offrng[2];
+  offset_int sizrng[2];
+};
+
+/* Describes a pair of references used in an access by built-in
+   functions like memcpy.  */
+struct access_data
+{
+  /* Destination and source of the access.  */
+  access_ref dst, src;
+};
+
+extern bool check_access (tree, tree, tree, tree, tree, tree, tree,
+			  bool = true, const access_data * = NULL);
 
 #endif /* GCC_BUILTINS_H */