On Wed, May 10, 2017 at 10:14:17AM +0200, Richard Biener wrote:
> 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.
yeah, its gross, I put it in to be compatible with the previous macro.
The first problem with removing it is that cfgexpand.c:663 and
presumably other places do BITMAP_FREE(bb->aux) which of course
depends on being able to pass in a void *. I'll add a comment and try
and look into removing it.
Trev
>
> 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
> >
