Optimize zend_mm_small_size_to_bin()

It removes a cmov operation and has a much faster branch for small allocations (especially when handling strings) (<= 64 bytes)

1 files changed, 13 insertions, 11 deletions

diff --git a/Zend/zend_alloc.c b/Zend/zend_alloc.c
index bf147f55e5..bd3fe0ebcc 100644
--- a/Zend/zend_alloc.c
+++ b/Zend/zend_alloc.c
@@ -1202,17 +1202,19 @@ static zend_always_inline int zend_mm_small_size_to_bin(size_t size)
 	n = zend_mm_small_size_to_bit(size - 1);
 	return ((size-1) >> f1[n]) + f2[n];
 #else
-	int t1, t2, t3;
-
-	if (UNEXPECTED(size <= 8)) return 0;
-	t1 = (int)(size - 1);
-	t2 = zend_mm_small_size_to_bit(t1);
-	t3 = t2 - 6;
-	t3 = (t3 < 0) ? 0 : t3;
-	t2 = t3 + 3;
-	t1 = t1 >> t2;
-	t3 = t3 << 2;
-	return t1 + t3;
+	unsigned int t1, t2;
+
+	if (size <= 64) {
+		/* we need to support size == 0 ... */
+		return (size - !!size) >> 3;
+	} else {
+		t1 = size - 1;
+		t2 = zend_mm_small_size_to_bit(t1) - 3;
+		t1 = t1 >> t2;
+		t2 = t2 - 3;
+		t2 = t2 << 2;
+		return (int)(t1 + t2);
+	}
 #endif
 }