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

[tbsaunde+gcc@tbsaunde.org]

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.

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