Generalize compute_objsize to return maximum size/offset instead of failing (PR middle-end/97023).

Also resolves:
PR middle-end/97342 - bogus -Wstringop-overflow with nonzero signed and unsigned offsets
PR middle-end/97023 - missing warning on buffer overflow in chained mempcpy
PR middle-end/96384 - bogus -Wstringop-overflow= storing into multidimensional array with index in range

gcc/ChangeLog:

	PR middle-end/97342
	PR middle-end/97023
	PR middle-end/96384
	* builtins.c (access_ref::access_ref): Initialize new member.  Use
	new enum.
	(access_ref::size_remaining): Define new member function.
	(inform_access): Handle expressions referencing objects.
	(gimple_call_alloc_size): Call get_size_range instead of get_range.
	(gimple_call_return_array): New function.
	(get_range): Rename...
	(get_offset_range): ...to this.  Improve detection of ranges from
	types of expressions.
	(gimple_call_return_array): Adjust calls to get_range per above.
	(compute_objsize): Same.  Set maximum size or offset instead of
	failing for unknown objects and handle more kinds of expressions.
	(compute_objsize): Call access_ref::size_remaining.
	(compute_objsize): Have transitional wrapper fail for pointers
	into unknown objects.
	(expand_builtin_strncmp): Call access_ref::size_remaining and
	handle new cases.
	* builtins.h (access_ref::size_remaining): Declare new member function.
	(access_ref::set_max_size_range): Define new member function.
	(access_ref::add_ofset, access_ref::add_max_ofset): Same.
	(access_ref::add_base0): New data member.
	* calls.c (get_size_range): Change argument type.  Handle new
	condition.
	* calls.h (get_size_range): Adjust signature.
	(enum size_range_flags): Define new type.
	* gimple-ssa-warn-restrict.c (builtin_memref::builtin_memref): Correct
	argument to get_size_range.
	* tree-ssa-strlen.c (get_range): Handle anti-ranges.
	(maybe_warn_overflow): Check DECL_P before assuming it's one.

gcc/testsuite/ChangeLog:

	PR middle-end/97342
	PR middle-end/97023
	PR middle-end/96384
	* c-c++-common/Wrestrict.c: Adjust comment.
	* gcc.dg/Wstringop-overflow-34.c: Remove xfail.
	* gcc.dg/Wstringop-overflow-43.c: Remove xfails.  Adjust regex patterns.
	* gcc.dg/pr51683.c: Prune out expected warning.
	* gcc.target/i386/pr60693.c: Same.
	* g++.dg/warn/Wplacement-new-size-8.C: New test.
	* gcc.dg/Wstringop-overflow-41.c: New test.
	* gcc.dg/Wstringop-overflow-44.s: New test.
	* gcc.dg/Wstringop-overflow-45.c: New test.
	* gcc.dg/Wstringop-overflow-46.c: New test.
	* gcc.dg/Wstringop-overflow-47.c: New test.
	* gcc.dg/Wstringop-overflow-49.c: New test.
	* gcc.dg/Wstringop-overflow-50.c: New test.
	* gcc.dg/Wstringop-overflow-51.c: New test.
	* gcc.dg/Wstringop-overflow-52.c: New test.
	* gcc.dg/Wstringop-overflow-53.c: New test.
	* gcc.dg/Wstringop-overflow-54.c: New test.
	* gcc.dg/Wstringop-overflow-55.c: New test.
	* gcc.dg/Wstringop-overread-5.c: New test.

1 files changed, 35 insertions, 6 deletions

diff --git a/gcc/builtins.h b/gcc/builtins.h
index f226c63..c09f36d 100644
--- a/gcc/builtins.h
+++ b/gcc/builtins.h
@@ -180,15 +180,45 @@ struct access_ref
     return offrng[0] == 0 && offrng[1] == 0;
   }
 
-  /* Return true if OFFRNG is bounded to a subrange of possible offset
-     values.  */
+  /* Return true if OFFRNG is bounded to a subrange of offset values
+     valid for the largest possible object.  */
   bool offset_bounded () const;
 
+  /* Return the maximum amount of space remaining and if non-null, set
+     argument to the minimum.  */
+  offset_int size_remaining (offset_int * = NULL) const;
+
+  /* Set the size range to the maximum.  */
+  void set_max_size_range ()
+  {
+    sizrng[0] = 0;
+    sizrng[1] = wi::to_offset (max_object_size ());
+  }
+
+  /* Add OFF to the offset range.  */
+  void add_offset (const offset_int &off)
+  {
+    add_offset (off, off);
+  }
+
+  /* Add the range [MIN, MAX] to the offset range.  */
+  void add_offset (const offset_int &, const offset_int &);
+
+  /* Add the maximum representable offset to the offset range.  */
+  void add_max_offset ()
+  {
+    offset_int maxoff = wi::to_offset (TYPE_MAX_VALUE (ptrdiff_type_node));
+    add_offset (-maxoff - 1, maxoff);
+  }
+
   /* Used to fold integer expressions when called from front ends.  */
   tree (*eval)(tree);
   /* Set if trailing one-element arrays should be treated as flexible
      array members.  */
   bool trail1special;
+  /* Set if valid offsets must start at zero (for declared and allocated
+     objects but not for others referenced by pointers).  */
+  bool base0;
 };
 
 /* Describes a pair of references used in an access by built-in
@@ -216,11 +246,10 @@ class range_query;
 extern tree gimple_call_alloc_size (gimple *, wide_int[2] = NULL,
 				    range_query * = NULL);
 extern tree gimple_parm_array_size (tree, wide_int[2], range_query * = NULL);
+extern tree compute_objsize (tree, int, access_ref *, range_query * = NULL);
 extern tree compute_objsize (tree, int, tree * = NULL, tree * = NULL,
 			     range_query * = NULL);
-extern tree compute_objsize (tree, int, access_ref *, range_query * = NULL);
-
-extern bool check_access (tree, tree, tree, tree, tree, access_mode,
-			  const access_data * = NULL);
+extern bool check_access (tree, tree, tree, tree, tree,
+			  access_mode, const access_data * = NULL);
 
 #endif /* GCC_BUILTINS_H */