Add size class computation capability.
Add size class computation capability, currently used only as validation
of the size class lookup tables. Generalize the size class spacing used
for bins, for eventual use throughout the full range of allocation
sizes.
diff --git a/configure.ac b/configure.ac
index 58f6289..5852249 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1201,6 +1201,29 @@
fi
dnl ============================================================================
+dnl Check for __builtin_clz() and __builtin_clzl().
+
+AC_CACHE_CHECK([for __builtin_clz],
+ [je_cv_builtin_clz],
+ [AC_LINK_IFELSE([AC_LANG_PROGRAM([],
+ [
+ {
+ unsigned x = 0;
+ int y = __builtin_clz(x);
+ }
+ {
+ unsigned long x = 0;
+ int y = __builtin_clzl(x);
+ }
+ ])],
+ [je_cv_builtin_clz=yes],
+ [je_cv_builtin_clz=no])])
+
+if test "x${je_cv_builtin_clz}" = "xyes" ; then
+ AC_DEFINE([JEMALLOC_HAVE_BUILTIN_CLZ], [ ])
+fi
+
+dnl ============================================================================
dnl Check for spinlock(3) operations as provided on Darwin.
JE_COMPILABLE([Darwin OSSpin*()], [