[Mesa-dev] [PATCH] util/macros: Simplify DIV_ROUND_UP() definition

[Nanley Chery]

On Thu, Dec 17, 2015 at 12:05:46PM +0100, Glenn Kennard wrote:
> On Wed, 16 Dec 2015 20:57:51 +0100, Nanley Chery <nanleychery at gmail.com> wrote:
> 
> >From: Nanley Chery <nanley.g.chery at intel.com>
> >
> >Commit 64880d073ab21ae1abad0c049ea2d6a1169a3cfa consolidated two
> >DIV_ROUND_UP() definitions to one, but chose the more
> >compute-intensive version in the process. Use the simpler version
> >instead. Reduces .text size by 1360 bytes.
> >
> >Output of `size lib/i965_dri.so`:
> >      text    data     bss     dec     hex filename
> >   7850440  219264   27240 8096944  7b8cb0 lib/i965_dri.so (before)
> >   7849080  219264   27240 8095584  7b8760 lib/i965_dri.so (after)
> >
> >Cc: Axel Davy <axel.davy at ens.fr>
> >Signed-off-by: Nanley Chery <nanley.g.chery at intel.com>
> >---
> > src/util/macros.h | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> >diff --git a/src/util/macros.h b/src/util/macros.h
> >index 0c8958f..53a98a0 100644
> >--- a/src/util/macros.h
> >+++ b/src/util/macros.h
> >@@ -211,6 +211,6 @@ do {                       \
> > #endif
> >/** Compute ceiling of integer quotient of A divided by B. */
> >-#define DIV_ROUND_UP( A, B )  ( (A) % (B) == 0 ? (A)/(B) : (A)/(B)+1 )
> >+#define DIV_ROUND_UP(A, B)  (((A) + (B) - 1) / (B))
> >#endif /* UTIL_MACROS_H */
> 
> I'll point out that these are not equivalent, one can overflow and the other doesn't. You
> probably want to check if the call sites have sufficient checks for that before
> substituting one for the other.
> 

Good point. As I mentioned in another email, I'll leave the current
macro untouched.

Thanks,
Nanley

> 
> /Glenn