Re: [PATCH 03/13] store the bitmap_head within the auto_bitmap

[Richard Biener <richard dot guenther at gmail dot com>]

On Tue, May 9, 2017 at 10:52 PM,  <tbsaunde+gcc@tbsaunde.org> wrote:
> From: Trevor Saunders <tbsaunde+gcc@tbsaunde.org>
>
> This gets rid of one allocation per bitmap.  Often the bitmap_head is
> now on the stack, when it isn't its part of some other struct on the
> heap instead of being refered to by that struct.  On 64 bit platforms
> this will increase the size of such structs by 24 bytes, but its an over
> all win since we don't need an 8 byte pointer pointing at the
> bitmap_head.  Given that the auto_bitmap owns the bitmap_head anyway we
> know there would never be a place where two auto_bitmaps would refer to
> the same bitmap_head object.

Ok.

Richard.

> gcc/ChangeLog:
>
> 2017-05-07  Trevor Saunders  <tbsaunde+gcc@tbsaunde.org>
>
>         * bitmap.h (class auto_bitmap): Change type of m_bits to
> bitmap_head, and adjust ctor / dtor and member operators.
> ---
>  gcc/bitmap.h | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/gcc/bitmap.h b/gcc/bitmap.h
> index 7508239cff9..49aec001cb0 100644
> --- a/gcc/bitmap.h
> +++ b/gcc/bitmap.h
> @@ -823,10 +823,10 @@ bmp_iter_and_compl (bitmap_iterator *bi, unsigned *bit_no)
>  class auto_bitmap
>  {
>   public:
> -  auto_bitmap () { bits = BITMAP_ALLOC (NULL); }
> -  ~auto_bitmap () { BITMAP_FREE (bits); }
> +  auto_bitmap () { bitmap_initialize (&m_bits, &bitmap_default_obstack); }
> +  ~auto_bitmap () { bitmap_clear (&m_bits); }
>    // Allow calling bitmap functions on our bitmap.
> -  operator bitmap () { return bits; }
> +  operator bitmap () { return &m_bits; }
>
>   private:
>    // Prevent making a copy that references our bitmap.
> @@ -837,7 +837,7 @@ class auto_bitmap
>    auto_bitmap &operator = (auto_bitmap &&);
>  #endif
>
> -  bitmap bits;
> +  bitmap_head m_bits;
>  };
>
>  #endif /* GCC_BITMAP_H */
> --
> 2.11.0
>