From: Bart Van Assche <bvanassche@acm.org>
Date: Tue, 25 Mar 2008 17:19:20 +0000 (+0000)
Subject: Minor optimization of bm_clear().
X-Git-Tag: svn/VALGRIND_3_4_0~798
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=042a682ed1728cef83c30f55255e8d9d2e5be9e3;p=thirdparty%2Fvalgrind.git

Minor optimization of bm_clear().

git-svn-id: svn://svn.valgrind.org/valgrind/trunk@7788
---

diff --git a/exp-drd/drd_bitmap.c b/exp-drd/drd_bitmap.c
index 62e17edae1..9d21a1de5c 100644
--- a/exp-drd/drd_bitmap.c
+++ b/exp-drd/drd_bitmap.c
@@ -379,28 +379,6 @@ UWord bm_has_1(const struct bitmap* const bm,
   return 0;
 }
 
-static __inline__
-void bm1_clear(struct bitmap1* const bm1, const Addr a1, const Addr a2)
-{
-  UWord idx;
-  UWord mask;
-
-#if 0
-  /* Commented out the statements below because of performance reasons. */
-  tl_assert(a1);
-  tl_assert(a1 <= a2);
-  tl_assert(UWORD_MSB(a1) == UWORD_MSB(a2)
-            || UWORD_MSB(a1) == UWORD_MSB(a2 - 1));
-#endif
-
-  idx = (a1 & ADDR0_MASK) >> BITS_PER_BITS_PER_UWORD;
-  /* mask: a contiguous series of one bits. The first bit set is bit */
-  /* UWORD_LSB(a2-1), and the last bit set is UWORD_LSB(a1).         */
-  mask = UWORD_LSB(a2) ? bm0_mask(a2) - bm0_mask(a1) : - bm0_mask(a1);
-  bm1->bm0_r[idx] &= ~mask;
-  bm1->bm0_w[idx] &= ~mask;
-}
-
 void bm_clear(const struct bitmap* const bm,
               const Addr a1,
               const Addr a2)
@@ -425,14 +403,14 @@ void bm_clear(const struct bitmap* const bm,
     {
       Addr c = b;
       /* If the first address in the bitmap that must be cleared does not */
-      /* start on an UWord boundary, start clearing the first addresses   */
-      /* by calling bm1_clear().                                          */
+      /* start on an UWord boundary, start clearing the first addresses.  */
       if (UWORD_LSB(c))
       {
         Addr c_next = UWORD_MSB(c) + BITS_PER_UWORD;
         if (c_next > b_next)
           c_next = b_next;
-        bm1_clear(&p2->bm1, c, c_next);
+        bm0_clear_range(p2->bm1.bm0_r, c & ADDR0_MASK, c_next - c);
+        bm0_clear_range(p2->bm1.bm0_w, c & ADDR0_MASK, c_next - c);
         c = c_next;
       }
       /* If some UWords have to be cleared entirely, do this now. */
@@ -452,12 +430,10 @@ void bm_clear(const struct bitmap* const bm,
         }
       }
       /* If the last address in the bitmap that must be cleared does not */
-      /* fall on an UWord boundary, clear the last addresses by calling  */
-      /* bm1_clear().                                                    */
-      if (c != b_next)
-      {
-        bm1_clear(&p2->bm1, c, b_next);
-      }
+      /* fall on an UWord boundary, clear the last addresses.            */
+      /* tl_assert(c <= b_next); */
+      bm0_clear_range(p2->bm1.bm0_r, c & ADDR0_MASK, b_next - c);
+      bm0_clear_range(p2->bm1.bm0_w, c & ADDR0_MASK, b_next - c);
     }
   }
 }
diff --git a/exp-drd/drd_bitmap.h b/exp-drd/drd_bitmap.h
index 3ed3f9a71f..7f3b77a154 100644
--- a/exp-drd/drd_bitmap.h
+++ b/exp-drd/drd_bitmap.h
@@ -124,6 +124,20 @@ static __inline__ void bm0_clear(UWord* bm0, const Addr a)
   bm0[a >> BITS_PER_BITS_PER_UWORD] &= ~((UWord)1 << UWORD_LSB(a));
 }
 
+/** Clear all of the addresses in range [ a1 .. a1 + size [ in bitmap bm0. */
+static __inline__ void bm0_clear_range(UWord* bm0,
+                                       const Addr a1, const SizeT size)
+{
+#if 0
+  tl_assert(a1 < ADDR0_COUNT);
+  tl_assert(size > 0);
+  tl_assert(a1 + size <= ADDR0_COUNT);
+  tl_assert(UWORD_MSB(a1) == UWORD_MSB(a1 + size - 1));
+#endif
+  bm0[a1 >> BITS_PER_BITS_PER_UWORD]
+    &= ~(((UWord)1 << size) - 1) << UWORD_LSB(a1);
+}
+
 static __inline__ UWord bm0_is_set(const UWord* bm0, const Addr a)
 {
   //tl_assert(a < ADDR0_COUNT);