Add support for detecting mismatched allocation/deallocation calls.

PR c++/90629 - Support for -Wmismatched-new-delete
PR middle-end/94527 - Add an __attribute__ that marks a function as freeing an object

gcc/ChangeLog:

	PR c++/90629
	PR middle-end/94527
	* builtins.c (access_ref::access_ref): Initialize new member.
	(compute_objsize): Use access_ref::deref.  Handle simple pointer
	assignment.
	(expand_builtin): Remove handling of the free built-in.
	(call_dealloc_argno): Same.
	(find_assignment_location): New function.
	(fndecl_alloc_p): Same.
	(gimple_call_alloc_p): Same.
	(call_dealloc_p): Same.
	(matching_alloc_calls_p): Same.
	(warn_dealloc_offset): Same.
	(maybe_emit_free_warning): Same.
	* builtins.h (struct access_ref): Declare new member.
	(maybe_emit_free_warning): Make extern.  Make use of access_ref.
	Handle -Wmismatched-new-delete.
	* calls.c (initialize_argument_information): Call
	maybe_emit_free_warning.
	* doc/extend.texi (attribute malloc): Update.
	* doc/invoke.texi (-Wfree-nonheap-object): Expand documentation.
	(-Wmismatched-new-delete): Document new option.
	(-Wmismatched-dealloc): Document new option.

gcc/c-family/ChangeLog:

	PR c++/90629
	PR middle-end/94527
	* c-attribs.c (handle_dealloc_attribute): New function.
	(handle_malloc_attribute): Handle argument forms of attribute.
	* c.opt (-Wmismatched-dealloc): New option.
	(-Wmismatched-new-delete): New option.

gcc/testsuite/ChangeLog:

	PR c++/90629
	PR middle-end/94527
	* g++.dg/asan/asan_test.cc: Fix a bug.
	* g++.dg/warn/delete-array-1.C: Add expected warning.
	* g++.old-deja/g++.other/delete2.C: Add expected warning.
	* g++.dg/warn/Wfree-nonheap-object-2.C: New test.
	* g++.dg/warn/Wfree-nonheap-object.C: New test.
	* g++.dg/warn/Wmismatched-new-delete.C: New test.
	* g++.dg/warn/Wmismatched-dealloc-2.C: New test.
	* g++.dg/warn/Wmismatched-dealloc.C: New test.
	* gcc.dg/Wmismatched-dealloc.c: New test.
	* gcc.dg/analyzer/malloc-1.c: Prune out expected warning.
	* gcc.dg/attr-malloc.c: New test.
	* gcc.dg/free-1.c: Adjust text of expected warning.
	* gcc.dg/free-2.c: Same.
	* gcc.dg/torture/pr71816.c: Prune out expected warning.
	* gcc.dg/tree-ssa/pr19831-2.c: Add an expected warning.
	* gcc.dg/Wfree-nonheap-object-2.c: New test.
	* gcc.dg/Wfree-nonheap-object-3.c: New test.
	* gcc.dg/Wfree-nonheap-object.c: New test.

libstdc++-v3/ChangeLog:

	* testsuite/ext/vstring/modifiers/clear/56166.cc: Suppress a false
	positive warning.

1 files changed, 273 insertions, 0 deletions

diff --git a/gcc/testsuite/gcc.dg/Wfree-nonheap-object.c b/gcc/testsuite/gcc.dg/Wfree-nonheap-object.c
new file mode 100644
index 0000000..bb222cc
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/Wfree-nonheap-object.c
@@ -0,0 +1,273 @@
+/* PR ????? - No warning on attempts to access free object
+   Verify that freeing unallocated objects referenced either directly
+   or through pointers is diagnosed.  In most cases this doesn't require
+   optimization.
+   { dg-do compile }
+   { dg-options "-Wall -Wfree-nonheap-object" }  */
+
+typedef __INTPTR_TYPE__ intptr_t;
+typedef __SIZE_TYPE__   size_t;
+
+extern void free (void*);
+extern void* malloc (size_t);
+extern void* realloc (void *p, size_t);
+
+void sink (void*, ...);
+
+extern char ecarr[];
+extern void* eparr[];
+
+extern char *eptr;
+
+void* source (void);
+
+void nowarn_free (void *p, void **pp, size_t n, intptr_t iptr)
+{
+  free (p);
+
+  p = 0;
+  free (p);
+
+  p = malloc (n);
+  sink (p);
+  free (p);
+
+  p = malloc (n);
+  sink (p);
+
+  p = realloc (p, n * 2);
+  sink (p);
+  free (p);
+
+  free ((void*)iptr);
+
+  p = source ();
+  free (p);
+
+  p = source ();
+  p = (char*)p - 1;
+  free (p);
+
+  free (*pp);
+}
+
+void warn_free_extern_arr (void)
+{
+  free (ecarr);               // { dg-warning "\\\[-Wfree-nonheap-object" }
+}
+
+void warn_free_extern_arr_offset (int i)
+{
+  char *p = ecarr + i;
+  free (p);                   // { dg-warning "\\\[-Wfree-nonheap-object" }
+}
+
+
+void warn_free_cstint (void)
+{
+  void *p = (void*)1;
+  sink (p);
+  free (p);                   // { dg-warning "\\\[-Wfree-nonheap-object" }
+}
+
+
+void warn_free_func (void)
+{
+  void *p = warn_free_func;
+  sink (p);
+  free (p);                   // { dg-warning "\\\[-Wfree-nonheap-object" }
+}
+
+
+void warn_free_string (int i)
+{
+  {
+    char *p = "123";
+    sink (p);
+    free (p);                 // { dg-warning "\\\[-Wfree-nonheap-object" }
+  }
+  {
+    char *p = "234" + 1;
+    sink (p);
+    free (p);                 // { dg-warning "\\\[-Wfree-nonheap-object" }
+  }
+  {
+    char *p = "345" + i;
+    sink (p);
+    free (p);                 // { dg-warning "\\\[-Wfree-nonheap-object" }
+  }
+
+  if (i >= 0)
+    {
+      char *p = "456" + i;
+      sink (p);
+      free (p);               // { dg-warning "\\\[-Wfree-nonheap-object" }
+    }
+}
+
+void warn_free_local_arr (int i)
+{
+  {
+    char a[4];
+    sink (a);
+    free (a);                 // { dg-warning "\\\[-Wfree-nonheap-object" }
+  }
+  {
+    char b[5];
+    sink (b);
+
+    char *p = b + 1;
+    free (p);                 // { dg-warning "\\\[-Wfree-nonheap-object" }
+  }
+  {
+    char c[6];
+    sink (c);
+
+    char *p = c + i;
+    free (p);                 // { dg-warning "\\\[-Wfree-nonheap-object" }
+  }
+}
+
+
+void warn_free_vla (int n, int i)
+{
+  {
+    int vla[n], *p = vla;
+    sink (p);
+    free (p);                 // { dg-warning "\\\[-Wfree-nonheap-object" }
+  }
+
+  {
+    int vla[n + 1], *p = vla + 1;
+    sink (p);
+    free (p);                 // { dg-warning "\\\[-Wfree-nonheap-object" }
+  }
+  {
+    int vla[n + 2], *p = vla + i;
+    sink (p);
+    free (p);                 // { dg-warning "\\\[-Wfree-nonheap-object" }
+  }
+}
+
+
+void nowarn_free_extern_ptrarr (void)
+{
+  free (*eparr);
+}
+
+void nowarn_free_extern_ptrarr_offset (int i)
+{
+  char *p = eparr[i];
+  free (p);
+}
+
+
+void warn_free_extern_ptrarr (void)
+{
+  free (eparr);               // { dg-warning "\\\[-Wfree-nonheap-object" }
+}
+
+void warn_free_extern_ptrarr_offset (int i)
+{
+  void *p = &eparr[i];
+  free (p);                   // { dg-warning "\\\[-Wfree-nonheap-object" }
+}
+
+
+void nowarn_free_local_ptrarr (int i)
+{
+  void* a[4];
+  sink (a);
+  free (a[0]);
+  free (a[1]);
+  free (a[i]);
+}
+
+
+void nowarn_free_extern_ptr (void)
+{
+  free (eptr);
+}
+
+void nowarn_free_extern_ptr_offset (int i)
+{
+  char *p = eptr + i;
+  free (p);
+}
+
+void nowarn_free_parm_offset (char *p, int i)
+{
+  char *q = p + i;
+  free (q);
+}
+
+void nowarn_free_parm_neg_offset (char *p, int i)
+{
+  if (i >= 0)
+    i = -1;
+
+  char *q = p + i;
+  free (q);
+}
+
+struct Members
+{
+  char a[4], *p, *q;
+};
+
+extern struct Members em;
+
+void nowarn_free_member_ptr (struct Members *pm, int i)
+{
+  char *p = em.p;
+  free (p);
+  p = em.q + i;
+  free (p);
+
+  free (pm->q);
+  p = pm->p;
+  free (pm);
+  free (p);
+}
+
+void nowarn_free_struct_cast (intptr_t *p)
+{
+  struct Members *q = (struct Members*)*p;
+  if (q->p == 0)
+    free (q);                 // { dg-bogus "\\\[-Wfree-nonheap-object" }
+}
+
+
+void warn_free_member_array (void)
+{
+  char *p = em.a;
+  free (p);                   // { dg-warning "\\\[-Wfree-nonheap-object" }
+}
+
+void warn_free_member_array_off (int i)
+{
+  char *p = em.a + i;
+  free (p);                   // { dg-warning "\\\[-Wfree-nonheap-object" }
+}
+
+
+// Range information requires optimization.
+#pragma GCC optimize "1"
+
+void warn_free_extern_ptr_pos_offset (int i)
+{
+  if (i <= 0)
+    i = 1;
+
+  char *q = eptr + i;
+  free (q);                   // { dg-warning "\\\[-Wfree-nonheap-object" }
+}
+
+void warn_free_parm_pos_offset (char *p, int i)
+{
+  if (i <= 0)
+    i = 1;
+
+  char *q = p + i;
+  free (q);                   // { dg-warning "\\\[-Wfree-nonheap-object" }
+}