On Tue, May 9, 2017 at 10:52 PM, <tbsaunde+...@tbsaunde.org> wrote:
> From: Trevor Saunders <tbsaunde+...@tbsaunde.org>
>
> There's two groups of changes here, first taking a sbitmap &, so that we
> can assign null to the pointer after freeing the sbitmap to prevent use
> after free through that pointer. Second we define overloads of
> sbitmap_free and bitmap_free taking auto_sbitmap and auto_bitmap
> respectively, so that you can't double free the bitmap owned by a
> auto_{s,}bitmap.
Looks good - but what do you need the void *& overload for?! That at least
needs a comment.
Richard.
> gcc/ChangeLog:
>
> 2017-05-09 Trevor Saunders <tbsaunde+...@tbsaunde.org>
>
> * bitmap.h (BITMAP_FREE): Convert from macro to inline function
> and add overloaded decl for auto_bitmap.
> * sbitmap.h (inline void sbitmap_free): Add overload for
> auto_sbitmap, and change sbitmap to point to null.
> ---
> gcc/bitmap.h | 21 +++++++++++++++++++--
> gcc/sbitmap.h | 7 ++++++-
> 2 files changed, 25 insertions(+), 3 deletions(-)
>
> diff --git a/gcc/bitmap.h b/gcc/bitmap.h
> index f158b447357..7508239cff9 100644
> --- a/gcc/bitmap.h
> +++ b/gcc/bitmap.h
> @@ -129,6 +129,8 @@ along with GCC; see the file COPYING3. If not see
>
> #include "obstack.h"
>
> + class auto_bitmap;
> +
> /* Bitmap memory usage. */
> struct bitmap_usage: public mem_usage
> {
> @@ -372,8 +374,23 @@ extern hashval_t bitmap_hash (const_bitmap);
> #define BITMAP_GGC_ALLOC() bitmap_gc_alloc ()
>
> /* Do any cleanup needed on a bitmap when it is no longer used. */
> -#define BITMAP_FREE(BITMAP) \
> - ((void) (bitmap_obstack_free ((bitmap) BITMAP), (BITMAP) = (bitmap)
> NULL))
> +inline void
> +BITMAP_FREE (bitmap &b)
> +{
> + bitmap_obstack_free ((bitmap) b);
> + b = NULL;
> +}
> +
> +inline void
> +BITMAP_FREE (void *&b)
> +{
> + bitmap_obstack_free ((bitmap) b);
> + b = NULL;
> +}
> +
> +/* Intentionally unimplemented to ensure it is never called with an
> + auto_bitmap argument. */
> +void BITMAP_FREE (auto_bitmap);
>
> /* Iterator for bitmaps. */
>
> diff --git a/gcc/sbitmap.h b/gcc/sbitmap.h
> index ce4d27d927c..cba0452cdb9 100644
> --- a/gcc/sbitmap.h
> +++ b/gcc/sbitmap.h
> @@ -82,6 +82,8 @@ along with GCC; see the file COPYING3. If not see
> #define SBITMAP_ELT_BITS (HOST_BITS_PER_WIDEST_FAST_INT * 1u)
> #define SBITMAP_ELT_TYPE unsigned HOST_WIDEST_FAST_INT
>
> +class auto_sbitmap;
> +
> struct simple_bitmap_def
> {
> unsigned int n_bits; /* Number of bits. */
> @@ -208,11 +210,14 @@ bmp_iter_next (sbitmap_iterator *i, unsigned *bit_no
> ATTRIBUTE_UNUSED)
> bmp_iter_next (&(ITER), &(BITNUM)))
> #endif
>
> -inline void sbitmap_free (sbitmap map)
> +inline void sbitmap_free (sbitmap &map)
> {
> free (map);
> + map = NULL;
> }
>
> +void sbitmap_free (auto_sbitmap);
> +
> inline void sbitmap_vector_free (sbitmap * vec)
> {
> free (vec);
> --
> 2.11.0
>
