fix generic ctz/clz

microsoft · Dec 10, 2024 · ed31847 · ed31847
1 parent c8607a8
commit ed31847
Showing 1 changed file with 34 additions and 23 deletions.
diff --git a/include/mimalloc/internal.h b/include/mimalloc/internal.h
@@ -873,16 +873,18 @@ static inline size_t mi_ctz(uintptr_t x) {
 }
 
 #else
-static inline size_t mi_ctz32(uint32_t x) {
+
+static inline size_t mi_ctz_generic32(uint32_t x) {
   // de Bruijn multiplication, see <http://supertech.csail.mit.edu/papers/debruijn.pdf>
-  static const unsigned char debruijn[32] = {
+  static const uint8_t debruijn[32] = {
     0, 1, 28, 2, 29, 14, 24, 3, 30, 22, 20, 15, 25, 17, 4, 8,
     31, 27, 13, 23, 21, 19, 16, 7, 26, 12, 18, 6, 11, 5, 10, 9
   };
   if (x==0) return 32;
-  return debruijn[((x & -(int32_t)x) * 0x077CB531UL) >> 27];
+  return debruijn[(uint32_t)((x & -(int32_t)x) * (uint32_t)(0x077CB531U)) >> 27];
 }
-static inline size_t mi_clz32(uint32_t x) {
+
+static inline size_t mi_clz_generic32(uint32_t x) {
   // de Bruijn multiplication, see <http://supertech.csail.mit.edu/papers/debruijn.pdf>
   static const uint8_t debruijn[32] = {
     31, 22, 30, 21, 18, 10, 29, 2, 20, 17, 15, 13, 9, 6, 28, 1,
@@ -894,28 +896,37 @@ static inline size_t mi_clz32(uint32_t x) {
   x |= x >> 4;
   x |= x >> 8;
   x |= x >> 16;
-  return debruijn[(uint32_t)(x * 0x07C4ACDDUL) >> 27];
+  return debruijn[(uint32_t)(x * (uint32_t)(0x07C4ACDDU)) >> 27];
 }
 
-static inline size_t mi_clz(uintptr_t x) {
-  if (x==0) return MI_INTPTR_BITS;
-#if (MI_INTPTR_BITS <= 32)
-  return mi_clz32((uint32_t)x);
-#else
-  size_t count = mi_clz32((uint32_t)(x >> 32));
-  if (count < 32) return count;
-  return (32 + mi_clz32((uint32_t)x));
-#endif
+static inline size_t mi_ctz(size_t x) {
+  if (x==0) return MI_SIZE_BITS;
+  #if (MI_SIZE_BITS <= 32)
+    return mi_ctz_generic32((uint32_t)x);
+  #else
+    const uint32_t lo = (uint32_t)x;
+    if (lo != 0) {
+      return mi_ctz_generic32(lo);
+    }
+    else {
+      return (32 + mi_ctz_generic32((uint32_t)(x>>32)));
+    }
+  #endif
 }
-static inline size_t mi_ctz(uintptr_t x) {
-  if (x==0) return MI_INTPTR_BITS;
-#if (MI_INTPTR_BITS <= 32)
-  return mi_ctz32((uint32_t)x);
-#else
-  size_t count = mi_ctz32((uint32_t)x);
-  if (count < 32) return count;
-  return (32 + mi_ctz32((uint32_t)(x>>32)));
-#endif
+
+static inline size_t mi_clz(size_t x) {
+  if (x==0) return MI_SIZE_BITS;
+  #if (MI_SIZE_BITS <= 32)
+    return mi_clz_generic32((uint32_t)x);
+  #else
+    const uint32_t hi = (uint32_t)(x>>32);
+    if (hi != 0) {
+      return mi_clz_generic32(hi);
+    }
+    else {
+      return 32 + mi_clz_generic32((uint32_t)x);
+    }
+  #endif
 }
 
 #endif