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authordim <dim@FreeBSD.org>2015-01-08 19:47:10 +0000
committerdim <dim@FreeBSD.org>2015-01-08 19:47:10 +0000
commitab328f15cea04a45750ef56019d2b3d971e033f3 (patch)
treef47eabbd2a48be6d6fec3ddeeefae5b4aeb87dbc /contrib/compiler-rt/lib/builtins/clzsi2.c
parent8189659be8e499f37c87fdd05ef5ec9f88619d56 (diff)
parent2f1c5cc1039d86db0037cb086bd58f4b90dc6f66 (diff)
downloadFreeBSD-src-ab328f15cea04a45750ef56019d2b3d971e033f3.zip
FreeBSD-src-ab328f15cea04a45750ef56019d2b3d971e033f3.tar.gz
Update compiler-rt to trunk r224034. This brings a number of new
builtins, and also the various sanitizers. Support for these will be added in a later commit.
Diffstat (limited to 'contrib/compiler-rt/lib/builtins/clzsi2.c')
-rw-r--r--contrib/compiler-rt/lib/builtins/clzsi2.c53
1 files changed, 53 insertions, 0 deletions
diff --git a/contrib/compiler-rt/lib/builtins/clzsi2.c b/contrib/compiler-rt/lib/builtins/clzsi2.c
new file mode 100644
index 0000000..25b8ed2
--- /dev/null
+++ b/contrib/compiler-rt/lib/builtins/clzsi2.c
@@ -0,0 +1,53 @@
+/* ===-- clzsi2.c - Implement __clzsi2 -------------------------------------===
+ *
+ * The LLVM Compiler Infrastructure
+ *
+ * This file is dual licensed under the MIT and the University of Illinois Open
+ * Source Licenses. See LICENSE.TXT for details.
+ *
+ * ===----------------------------------------------------------------------===
+ *
+ * This file implements __clzsi2 for the compiler_rt library.
+ *
+ * ===----------------------------------------------------------------------===
+ */
+
+#include "int_lib.h"
+
+/* Returns: the number of leading 0-bits */
+
+/* Precondition: a != 0 */
+
+COMPILER_RT_ABI si_int
+__clzsi2(si_int a)
+{
+ su_int x = (su_int)a;
+ si_int t = ((x & 0xFFFF0000) == 0) << 4; /* if (x is small) t = 16 else 0 */
+ x >>= 16 - t; /* x = [0 - 0xFFFF] */
+ su_int r = t; /* r = [0, 16] */
+ /* return r + clz(x) */
+ t = ((x & 0xFF00) == 0) << 3;
+ x >>= 8 - t; /* x = [0 - 0xFF] */
+ r += t; /* r = [0, 8, 16, 24] */
+ /* return r + clz(x) */
+ t = ((x & 0xF0) == 0) << 2;
+ x >>= 4 - t; /* x = [0 - 0xF] */
+ r += t; /* r = [0, 4, 8, 12, 16, 20, 24, 28] */
+ /* return r + clz(x) */
+ t = ((x & 0xC) == 0) << 1;
+ x >>= 2 - t; /* x = [0 - 3] */
+ r += t; /* r = [0 - 30] and is even */
+ /* return r + clz(x) */
+/* switch (x)
+ * {
+ * case 0:
+ * return r + 2;
+ * case 1:
+ * return r + 1;
+ * case 2:
+ * case 3:
+ * return r;
+ * }
+ */
+ return r + ((2 - x) & -((x & 2) == 0));
+}
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