提交 02602a18 编写于 作者: K Konstantin Khlebnikov 提交者: Linus Torvalds

bug: completely remove code generated by disabled VM_BUG_ON()

Even if CONFIG_DEBUG_VM=n gcc genereates code for some VM_BUG_ON()

for example VM_BUG_ON(!PageCompound(page) || !PageHead(page)); in
do_huge_pmd_wp_page() generates 114 bytes of code.

But they mostly disappears when I split this VM_BUG_ON into two:

  -VM_BUG_ON(!PageCompound(page) || !PageHead(page));
  +VM_BUG_ON(!PageCompound(page));
  +VM_BUG_ON(!PageHead(page));

weird... but anyway after this patch code disappears completely.

  add/remove: 0/0 grow/shrink: 7/97 up/down: 135/-1784 (-1649)
Signed-off-by: NKonstantin Khlebnikov <khlebnikov@openvz.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Cong Wang <xiyou.wangcong@gmail.com>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
上级 baf05aa9
......@@ -4,7 +4,7 @@
#ifdef CONFIG_DEBUG_VM
#define VM_BUG_ON(cond) BUG_ON(cond)
#else
#define VM_BUG_ON(cond) do { (void)(cond); } while (0)
#define VM_BUG_ON(cond) BUILD_BUG_ON_INVALID(cond)
#endif
#ifdef CONFIG_DEBUG_VIRTUAL
......
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