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[PATCH] x86/bitmap: Even more signed-ness fixes



Further to commit 558e84b7ffec ("xen/bitmap: Consistently use unsigned bits
values"), it turns out that GCC's range analysis isn't good enough to notice
that 'bits / BITS_PER_LONG' is always within the unsigned range of k.

As a consequence, it re-sign-extends 'k' when calculating the pointer holding
'bitmap[k]' on each loop iteration.  Switch all internal variables to unsigned
int, which allows for better-still code generation.

Also clean up the prototypes for __bitmap_{set,clear} and the *_region()
helpers, along with the internal variables.

Bloat-o-meter for a random x86 build reports:
  add/remove: 0/0 grow/shrink: 0/10 up/down: 0/-277 (-277)

No functional change.

Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
---
CC: George Dunlap <George.Dunlap@xxxxxxxxxx>
CC: Jan Beulich <JBeulich@xxxxxxxx>
CC: Stefano Stabellini <sstabellini@xxxxxxxxxx>
CC: Wei Liu <wl@xxxxxxx>
CC: Julien Grall <julien@xxxxxxx>

Full bloat-o-meter details:

  add/remove: 0/0 grow/shrink: 0/10 up/down: 0/-277 (-277)
  Function                                     old     new   delta
  __bitmap_equal                               105     102      -3
  bitmap_find_free_region                      135     129      -6
  __bitmap_subset                              121     115      -6
  __bitmap_intersects                          105      99      -6
  __bitmap_full                                 91      85      -6
  __bitmap_empty                                90      84      -6
  bitmap_release_region                         68      45     -23
  bitmap_allocate_region                       104      72     -32
  __bitmap_clear                               136      43     -93
  __bitmap_set                                 136      40     -96
  Total: Before=4063985, After=4063708, chg -0.01%

Other functions have changes, but no net change.
---
 xen/common/bitmap.c      | 76 ++++++++++++++++++++++------------------
 xen/include/xen/bitmap.h | 15 ++++----
 2 files changed, 50 insertions(+), 41 deletions(-)

diff --git a/xen/common/bitmap.c b/xen/common/bitmap.c
index 9d9ff09f3dde..18e23e2f0e18 100644
--- a/xen/common/bitmap.c
+++ b/xen/common/bitmap.c
@@ -57,7 +57,8 @@ static void clamp_last_byte(uint8_t *bp, unsigned int nbits)
 
 int __bitmap_empty(const unsigned long *bitmap, unsigned int bits)
 {
-       int k, lim = bits/BITS_PER_LONG;
+       unsigned int k, lim = bits / BITS_PER_LONG;
+
        for (k = 0; k < lim; ++k)
                if (bitmap[k])
                        return 0;
@@ -72,7 +73,8 @@ EXPORT_SYMBOL(__bitmap_empty);
 
 int __bitmap_full(const unsigned long *bitmap, unsigned int bits)
 {
-       int k, lim = bits/BITS_PER_LONG;
+       unsigned int k, lim = bits / BITS_PER_LONG;
+
        for (k = 0; k < lim; ++k)
                if (~bitmap[k])
                        return 0;
@@ -88,7 +90,8 @@ EXPORT_SYMBOL(__bitmap_full);
 int __bitmap_equal(const unsigned long *bitmap1,
                    const unsigned long *bitmap2, unsigned int bits)
 {
-       int k, lim = bits/BITS_PER_LONG;
+       unsigned int k, lim = bits / BITS_PER_LONG;
+
        for (k = 0; k < lim; ++k)
                if (bitmap1[k] != bitmap2[k])
                        return 0;
@@ -103,7 +106,8 @@ EXPORT_SYMBOL(__bitmap_equal);
 
 void __bitmap_complement(unsigned long *dst, const unsigned long *src, 
unsigned int bits)
 {
-       int k, lim = bits/BITS_PER_LONG;
+       unsigned int k, lim = bits / BITS_PER_LONG;
+
        for (k = 0; k < lim; ++k)
                dst[k] = ~src[k];
 
@@ -115,8 +119,7 @@ EXPORT_SYMBOL(__bitmap_complement);
 void __bitmap_and(unsigned long *dst, const unsigned long *bitmap1,
                   const unsigned long *bitmap2, unsigned int bits)
 {
-       int k;
-       int nr = BITS_TO_LONGS(bits);
+       unsigned int k, nr = BITS_TO_LONGS(bits);
 
        for (k = 0; k < nr; k++)
                dst[k] = bitmap1[k] & bitmap2[k];
@@ -126,8 +129,7 @@ EXPORT_SYMBOL(__bitmap_and);
 void __bitmap_or(unsigned long *dst, const unsigned long *bitmap1,
                  const unsigned long *bitmap2, unsigned int bits)
 {
-       int k;
-       int nr = BITS_TO_LONGS(bits);
+       unsigned int k, nr = BITS_TO_LONGS(bits);
 
        for (k = 0; k < nr; k++)
                dst[k] = bitmap1[k] | bitmap2[k];
@@ -137,8 +139,7 @@ EXPORT_SYMBOL(__bitmap_or);
 void __bitmap_xor(unsigned long *dst, const unsigned long *bitmap1,
                   const unsigned long *bitmap2, unsigned int bits)
 {
-       int k;
-       int nr = BITS_TO_LONGS(bits);
+       unsigned int k, nr = BITS_TO_LONGS(bits);
 
        for (k = 0; k < nr; k++)
                dst[k] = bitmap1[k] ^ bitmap2[k];
@@ -148,8 +149,7 @@ EXPORT_SYMBOL(__bitmap_xor);
 void __bitmap_andnot(unsigned long *dst, const unsigned long *bitmap1,
                      const unsigned long *bitmap2, unsigned int bits)
 {
-       int k;
-       int nr = BITS_TO_LONGS(bits);
+       unsigned int k, nr = BITS_TO_LONGS(bits);
 
        for (k = 0; k < nr; k++)
                dst[k] = bitmap1[k] & ~bitmap2[k];
@@ -159,7 +159,8 @@ EXPORT_SYMBOL(__bitmap_andnot);
 int __bitmap_intersects(const unsigned long *bitmap1,
                         const unsigned long *bitmap2, unsigned int bits)
 {
-       int k, lim = bits/BITS_PER_LONG;
+       unsigned int k, lim = bits / BITS_PER_LONG;
+
        for (k = 0; k < lim; ++k)
                if (bitmap1[k] & bitmap2[k])
                        return 1;
@@ -174,7 +175,8 @@ EXPORT_SYMBOL(__bitmap_intersects);
 int __bitmap_subset(const unsigned long *bitmap1,
                     const unsigned long *bitmap2, unsigned int bits)
 {
-       int k, lim = bits/BITS_PER_LONG;
+       unsigned int k, lim = bits / BITS_PER_LONG;
+
        for (k = 0; k < lim; ++k)
                if (bitmap1[k] & ~bitmap2[k])
                        return 0;
@@ -200,11 +202,11 @@ unsigned int __bitmap_weight(const unsigned long *bitmap, 
unsigned int bits)
 }
 EXPORT_SYMBOL(__bitmap_weight);
 
-void __bitmap_set(unsigned long *map, unsigned int start, int len)
+void __bitmap_set(unsigned long *bitmap, unsigned int start, unsigned int len)
 {
-       unsigned long *p = map + BIT_WORD(start);
+       unsigned long *p = bitmap + BIT_WORD(start);
        const unsigned int size = start + len;
-       int bits_to_set = BITS_PER_LONG - (start % BITS_PER_LONG);
+       unsigned int bits_to_set = BITS_PER_LONG - (start % BITS_PER_LONG);
        unsigned long mask_to_set = BITMAP_FIRST_WORD_MASK(start);
 
        while (len - bits_to_set >= 0) {
@@ -220,11 +222,11 @@ void __bitmap_set(unsigned long *map, unsigned int start, 
int len)
        }
 }
 
-void __bitmap_clear(unsigned long *map, unsigned int start, int len)
+void __bitmap_clear(unsigned long *bitmap, unsigned int start, unsigned int 
len)
 {
-       unsigned long *p = map + BIT_WORD(start);
+       unsigned long *p = bitmap + BIT_WORD(start);
        const unsigned int size = start + len;
-       int bits_to_clear = BITS_PER_LONG - (start % BITS_PER_LONG);
+       unsigned int bits_to_clear = BITS_PER_LONG - (start % BITS_PER_LONG);
        unsigned long mask_to_clear = BITMAP_FIRST_WORD_MASK(start);
 
        while (len - bits_to_clear >= 0) {
@@ -255,11 +257,11 @@ void __bitmap_clear(unsigned long *map, unsigned int 
start, int len)
  *
  * Returns either beginning of region or negative error
  */
-int bitmap_find_free_region(unsigned long *bitmap, int bits, int order)
+int bitmap_find_free_region(unsigned long *bitmap, unsigned int bits, unsigned 
int order)
 {
        unsigned long mask;
-       int pages = 1 << order;
-       int i;
+       unsigned int pages = 1 << order;
+       unsigned int i;
 
        if(pages > BITS_PER_LONG)
                return -EINVAL;
@@ -270,8 +272,9 @@ int bitmap_find_free_region(unsigned long *bitmap, int 
bits, int order)
 
        /* run up the bitmap pages bits at a time */
        for (i = 0; i < bits; i += pages) {
-               int index = i/BITS_PER_LONG;
-               int offset = i - (index * BITS_PER_LONG);
+               unsigned int index = i / BITS_PER_LONG;
+               unsigned int offset = i - (index * BITS_PER_LONG);
+
                if((bitmap[index] & (mask << offset)) == 0) {
                        /* set region in bimap */
                        bitmap[index] |= (mask << offset);
@@ -291,23 +294,26 @@ EXPORT_SYMBOL(bitmap_find_free_region);
  * This is the complement to __bitmap_find_free_region and releases
  * the found region (by clearing it in the bitmap).
  */
-void bitmap_release_region(unsigned long *bitmap, int pos, int order)
+void bitmap_release_region(unsigned long *bitmap, unsigned int pos,
+                          unsigned int order)
 {
-       int pages = 1 << order;
+       unsigned int pages = 1 << order;
        unsigned long mask = (1ul << (pages - 1));
-       int index = pos/BITS_PER_LONG;
-       int offset = pos - (index * BITS_PER_LONG);
+       unsigned int index = pos / BITS_PER_LONG;
+       unsigned int offset = pos - (index * BITS_PER_LONG);
+
        mask += mask - 1;
        bitmap[index] &= ~(mask << offset);
 }
 EXPORT_SYMBOL(bitmap_release_region);
 
-int bitmap_allocate_region(unsigned long *bitmap, int pos, int order)
+int bitmap_allocate_region(unsigned long *bitmap, unsigned int pos,
+                          unsigned int order)
 {
-       int pages = 1 << order;
+       unsigned int pages = 1 << order;
        unsigned long mask = (1ul << (pages - 1));
-       int index = pos/BITS_PER_LONG;
-       int offset = pos - (index * BITS_PER_LONG);
+       unsigned int index = pos/BITS_PER_LONG;
+       unsigned int offset = pos - (index * BITS_PER_LONG);
 
        /* We don't do regions of pages > BITS_PER_LONG.  The
         * algorithm would be a simple look for multiple zeros in the
@@ -328,7 +334,7 @@ static void bitmap_long_to_byte(uint8_t *bp, const unsigned 
long *lp,
                                unsigned int nbits)
 {
        unsigned long l;
-       int i, j, b;
+       unsigned int i, j, b;
 
        for (i = 0, b = 0; nbits > 0; i++, b += sizeof(l)) {
                l = lp[i];
@@ -345,7 +351,7 @@ static void bitmap_byte_to_long(unsigned long *lp, const 
uint8_t *bp,
                                unsigned int nbits)
 {
        unsigned long l;
-       int i, j, b;
+       unsigned int i, j, b;
 
        for (i = 0, b = 0; nbits > 0; i++, b += sizeof(l)) {
                l = 0;
diff --git a/xen/include/xen/bitmap.h b/xen/include/xen/bitmap.h
index b9f980e91930..4e71b4350f59 100644
--- a/xen/include/xen/bitmap.h
+++ b/xen/include/xen/bitmap.h
@@ -85,12 +85,15 @@ int __bitmap_intersects(const unsigned long *bitmap1,
 int __bitmap_subset(const unsigned long *bitmap1,
                     const unsigned long *bitmap2, unsigned int bits);
 unsigned int __bitmap_weight(const unsigned long *bitmap, unsigned int bits);
-extern void __bitmap_set(unsigned long *map, unsigned int start, int len);
-extern void __bitmap_clear(unsigned long *map, unsigned int start, int len);
-
-extern int bitmap_find_free_region(unsigned long *bitmap, int bits, int order);
-extern void bitmap_release_region(unsigned long *bitmap, int pos, int order);
-extern int bitmap_allocate_region(unsigned long *bitmap, int pos, int order);
+void __bitmap_set(unsigned long *bitmap, unsigned int start, unsigned int len);
+void __bitmap_clear(unsigned long *bitmap, unsigned int start, unsigned int 
len);
+
+int bitmap_find_free_region(unsigned long *bitmap, unsigned int bits,
+                            unsigned int order);
+void bitmap_release_region(unsigned long *bitmap, unsigned int pos,
+                           unsigned int order);
+int bitmap_allocate_region(unsigned long *bitmap, unsigned int pos,
+                           unsigned int order);
 
 #define BITMAP_LAST_WORD_MASK(nbits)                                   \
 (                                                                      \
-- 
2.30.2




 


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