[hackers] [libzahl] Cleaner workaround for clang bug || Mattias Andrée

[git]

commit c26e0082091065db907d76b6e560c6d87dfd3fb0
Author:     Mattias Andrée <maand...@kth.se>
AuthorDate: Mon Mar 14 00:31:10 2016 +0100
Commit:     Mattias Andrée <maand...@kth.se>
CommitDate: Mon Mar 14 00:31:10 2016 +0100

    Cleaner workaround for clang bug
    
    Signed-off-by: Mattias Andrée <maand...@kth.se>

diff --git a/src/allocator.c b/src/allocator.c
index fd821a9..e75546f 100644
--- a/src/allocator.c
+++ b/src/allocator.c
@@ -1,44 +1,27 @@
 /* See LICENSE file for copyright and license details. */
 #include "internals.h"
-#include <stdio.h>
-
-
-/* Find r such that r is a minimal power of 2 ≥ n. */
-#define NEXT_2POW(n)\
-       do if (likely((n & (~n + 1)) != n)) {\
-               size_t x;\
-               n |= n >> 1;\
-               n |= n >> 2;\
-               n |= n >> 4;\
-               for (i = sizeof(n), x = 8; i; i >>= 1, x <<= 1)\
-                       n |= n >> x;\
-               n += 1;\
-       } while (0)
-
-
-#if defined(__clang__)
-static inline __attribute__((optnone)) size_t
-clang_warkaround_next_2pow(size_t need)
-{
-       size_t i;
-       NEXT_2POW(need);
-       return need;
-}
-#endif
 
 
 void
 libzahl_realloc(z_t a, size_t need)
 {
-       size_t i;
-       zahl_char_t *new;
-
-#if defined(__clang__)
-       /* https://llvm.org/bugs/show_bug.cgi?id=26930 */
-       need = clang_warkaround_next_2pow(need);
+#if defined(__clang__) /* https://llvm.org/bugs/show_bug.cgi?id=26930 */
+       volatile size_t j;
 #else
-       NEXT_2POW(need);
+# define j  i
 #endif
+       size_t i, x;
+       zahl_char_t *new;
+
+       /* Find n such that n is a minimal power of 2 ≥ need. */
+       if (likely((need & (~need + 1)) != need)) {
+               need |= need >> 1;
+               need |= need >> 2;
+               need |= need >> 4;
+               for (j = sizeof(need), x = 8; j; j >>= 1, x <<= 1)
+                       need |= need >> x;
+               need += 1;
+       }
 
        i = libzahl_msb_nz_zu(need);