middle-end/70090: Dynamic sizes for -fsanitize=object-size

Use __builtin_dynamic_object_size to get object sizes for ubsan.

gcc/ChangeLog:

	PR middle-end/70090
	* ubsan.cc (ubsan_expand_objsize_ifn): Allow non-constant SIZE.
	(instrument_object_size): Get dynamic object size expression.

gcc/testsuite/ChangeLog:

	PR middle-end/70090
	* gcc.dg/ubsan/object-size-dyn.c: New test.

Signed-off-by: Siddhesh Poyarekar <siddhesh@gotplt.org>

2 files changed, 52 insertions, 6 deletions

diff --git a/gcc/testsuite/gcc.dg/ubsan/object-size-dyn.c b/gcc/testsuite/gcc.dg/ubsan/object-size-dyn.c
new file mode 100644
index 0000000..0159f5b
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/ubsan/object-size-dyn.c
@@ -0,0 +1,45 @@
+/* { dg-do run } */
+/* { dg-skip-if "" { *-*-* } { "*" } { "-O2" } } */
+/* { dg-options "-fsanitize=undefined" } */
+#include <stdio.h>
+
+int
+__attribute__ ((noinline))
+dyn (int size, int i)
+{
+  __builtin_printf ("dyn\n");
+  fflush (stdout);
+  int *alloc = __builtin_calloc (size, sizeof (int));
+  int ret = alloc[i];
+  __builtin_free (alloc);
+  return ret;
+}
+
+int
+__attribute__ ((noinline))
+off (int size, int i, int ret)
+{
+  char *mem = __builtin_alloca (size);
+  mem += size - 1;
+
+  return (int) mem[i] & ret;
+}
+
+int
+main (void)
+{
+  int ret = dyn (2, 2);
+
+  ret |= off (4, 4, 0);
+
+  return ret;
+}
+
+/* { dg-output "load of address \[^\n\r]* with insufficient space for an object of type 'int'\[^\n\r]*(\n|\r\n|\r)" } */
+/* { dg-output "\[^\n\r]*note: pointer points here\[^\n\r]*(\n|\r\n|\r)" } */
+/* { dg-output "\[^\n\r]*\[^\n\r]*(\n|\r\n|\r)" } */
+/* { dg-output "\[^\n\r]*\\^\[^\n\r]*(\n|\r\n|\r)" } */
+/* { dg-output "\[^\n\r]*load of address \[^\n\r]* with insufficient space for an object of type 'char'\[^\n\r]*(\n|\r\n|\r)" } */
+/* { dg-output "\[^\n\r]*note: pointer points here\[^\n\r]*(\n|\r\n|\r)" } */
+/* { dg-output "\[^\n\r]*\[^\n\r]*(\n|\r\n|\r)" } */
+/* { dg-output "\[^\n\r]*\\^" } */
diff --git a/gcc/ubsan.cc b/gcc/ubsan.cc
index 0f5b372..f74929d 100644
--- a/gcc/ubsan.cc
+++ b/gcc/ubsan.cc
@@ -942,8 +942,8 @@ ubsan_expand_objsize_ifn (gimple_stmt_iterator *gsi)
   gimple *g;
 
   /* See if we can discard the check.  */
-  if (TREE_CODE (size) != INTEGER_CST
-      || integer_all_onesp (size))
+  if (TREE_CODE (size) == INTEGER_CST
+      && integer_all_onesp (size))
     /* Yes, __builtin_object_size couldn't determine the
        object size.  */;
   else if (TREE_CODE (offset) == INTEGER_CST
@@ -2162,14 +2162,14 @@ instrument_object_size (gimple_stmt_iterator *gsi, tree t, bool is_lhs)
   if (decl_p)
     base_addr = build1 (ADDR_EXPR,
 			build_pointer_type (TREE_TYPE (base)), base);
-  if (compute_builtin_object_size (base_addr, 0, &sizet))
+  if (compute_builtin_object_size (base_addr, OST_DYNAMIC, &sizet))
     ;
   else if (optimize)
     {
       if (LOCATION_LOCUS (loc) == UNKNOWN_LOCATION)
 	loc = input_location;
-      /* Generate __builtin_object_size call.  */
-      sizet = builtin_decl_explicit (BUILT_IN_OBJECT_SIZE);
+      /* Generate __builtin_dynamic_object_size call.  */
+      sizet = builtin_decl_explicit (BUILT_IN_DYNAMIC_OBJECT_SIZE);
       sizet = build_call_expr_loc (loc, sizet, 2, base_addr,
 				   integer_zero_node);
       sizet = force_gimple_operand_gsi (gsi, sizet, false, NULL_TREE, true,
@@ -2226,7 +2226,8 @@ instrument_object_size (gimple_stmt_iterator *gsi, tree t, bool is_lhs)
       && !TREE_ADDRESSABLE (base))
     mark_addressable (base);
 
-  if (bos_stmt && gimple_call_builtin_p (bos_stmt, BUILT_IN_OBJECT_SIZE))
+  if (bos_stmt
+      && gimple_call_builtin_p (bos_stmt, BUILT_IN_DYNAMIC_OBJECT_SIZE))
     ubsan_create_edge (bos_stmt);
 
   /* We have to emit the check.  */