bit_util: Add fls_ functions; "find last set".

These simplify a lot of the bit_util module, which had grown bits and pieces of this functionality across a variety of places over the years. While we're here, kill off BIT_UTIL_INLINE and don't do reentrancy testing for bit_util.
ziyuyouxia · Jul 30, 2020 · 22da836 · 22da836
1 parent 1ed0288
commit 22da836
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diff --git a/configure.ac b/configure.ac
@@ -2118,7 +2118,7 @@ esac
 fi
 
 dnl ============================================================================
-dnl Check for __builtin_clz() and __builtin_clzl().
+dnl Check for __builtin_clz(), __builtin_clzl(), and __builtin_clzll().
 
 AC_CACHE_CHECK([for __builtin_clz],
                [je_cv_builtin_clz],
@@ -2132,6 +2132,10 @@ AC_CACHE_CHECK([for __builtin_clz],
                                                         unsigned long x = 0;
                                                         int y = __builtin_clzl(x);
                                                 }
+                                                {
+                                                        unsigned long long x = 0;
+                                                        int y = __builtin_clzll(x);
+                                                }
                                                 ])],
                                [je_cv_builtin_clz=yes],
                                [je_cv_builtin_clz=no])])