Patchwork [03/10] hbitmap: Use non-bitops ctzl

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Submitter Richard Henderson
Date Feb. 14, 2013, 1:47 a.m.
Message ID <1360806463-23632-4-git-send-email-rth@twiddle.net>
Download mbox | patch
Permalink /patch/220343/
State New
Headers show

Comments

Richard Henderson - Feb. 14, 2013, 1:47 a.m.
Both uses of ctz have already eliminated zero, and thus the difference
in edge conditions between the two routines is irrelevant.

Signed-off-by: Richard Henderson <rth@twiddle.net>
---
 include/qemu/hbitmap.h | 3 ++-
 util/hbitmap.c         | 3 ++-
 2 files changed, 4 insertions(+), 2 deletions(-)
Paolo Bonzini - Feb. 14, 2013, 3:03 p.m.
Il 14/02/2013 02:47, Richard Henderson ha scritto:
> Both uses of ctz have already eliminated zero, and thus the difference
> in edge conditions between the two routines is irrelevant.
> 
> Signed-off-by: Richard Henderson <rth@twiddle.net>
> ---
>  include/qemu/hbitmap.h | 3 ++-
>  util/hbitmap.c         | 3 ++-
>  2 files changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/include/qemu/hbitmap.h b/include/qemu/hbitmap.h
> index 250de03..550d7ce 100644
> --- a/include/qemu/hbitmap.h
> +++ b/include/qemu/hbitmap.h
> @@ -16,6 +16,7 @@
>  #include <stdint.h>
>  #include <stdbool.h>
>  #include "bitops.h"
> +#include "host-utils.h"
>  
>  typedef struct HBitmap HBitmap;
>  typedef struct HBitmapIter HBitmapIter;
> @@ -170,7 +171,7 @@ static inline int64_t hbitmap_iter_next(HBitmapIter *hbi)
>  
>      /* The next call will resume work from the next bit.  */
>      hbi->cur[HBITMAP_LEVELS - 1] = cur & (cur - 1);
> -    item = ((uint64_t)hbi->pos << BITS_PER_LEVEL) + bitops_ctzl(cur);
> +    item = ((uint64_t)hbi->pos << BITS_PER_LEVEL) + ctzl(cur);
>  
>      return item << hbi->granularity;
>  }
> diff --git a/util/hbitmap.c b/util/hbitmap.c
> index a0df5d3..d936831 100644
> --- a/util/hbitmap.c
> +++ b/util/hbitmap.c
> @@ -126,7 +126,8 @@ unsigned long hbitmap_iter_skip_words(HBitmapIter *hbi)
>           * The index of this word's least significant set bit provides
>           * the low-order bits.
>           */
> -        pos = (pos << BITS_PER_LEVEL) + bitops_ctzl(cur);
> +        assert(cur);
> +        pos = (pos << BITS_PER_LEVEL) + ctzl(cur);
>          hbi->cur[i] = cur & (cur - 1);
>  
>          /* Set up next level for iteration.  */
> 

Acked-by: Paolo Bonzini <pbonzini@redhat.com>

Patch

diff --git a/include/qemu/hbitmap.h b/include/qemu/hbitmap.h
index 250de03..550d7ce 100644
--- a/include/qemu/hbitmap.h
+++ b/include/qemu/hbitmap.h
@@ -16,6 +16,7 @@ 
 #include <stdint.h>
 #include <stdbool.h>
 #include "bitops.h"
+#include "host-utils.h"
 
 typedef struct HBitmap HBitmap;
 typedef struct HBitmapIter HBitmapIter;
@@ -170,7 +171,7 @@  static inline int64_t hbitmap_iter_next(HBitmapIter *hbi)
 
     /* The next call will resume work from the next bit.  */
     hbi->cur[HBITMAP_LEVELS - 1] = cur & (cur - 1);
-    item = ((uint64_t)hbi->pos << BITS_PER_LEVEL) + bitops_ctzl(cur);
+    item = ((uint64_t)hbi->pos << BITS_PER_LEVEL) + ctzl(cur);
 
     return item << hbi->granularity;
 }
diff --git a/util/hbitmap.c b/util/hbitmap.c
index a0df5d3..d936831 100644
--- a/util/hbitmap.c
+++ b/util/hbitmap.c
@@ -126,7 +126,8 @@  unsigned long hbitmap_iter_skip_words(HBitmapIter *hbi)
          * The index of this word's least significant set bit provides
          * the low-order bits.
          */
-        pos = (pos << BITS_PER_LEVEL) + bitops_ctzl(cur);
+        assert(cur);
+        pos = (pos << BITS_PER_LEVEL) + ctzl(cur);
         hbi->cur[i] = cur & (cur - 1);
 
         /* Set up next level for iteration.  */