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-rw-r--r--lib/ffsti2.c35
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diff --git a/lib/ffsti2.c b/lib/ffsti2.c
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+//===-- ffsti2.c - Implement __ffsti2 -------------------------------------===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file implements __ffsti2 for the compiler_rt library.
+//
+//===----------------------------------------------------------------------===//
+
+#if __x86_64
+
+#include "int_lib.h"
+
+// Returns: the index of the least significant 1-bit in a, or
+// the value zero if a is zero. The least significant bit is index one.
+
+si_int
+__ffsti2(ti_int a)
+{
+ twords x;
+ x.all = a;
+ if (x.low == 0)
+ {
+ if (x.high == 0)
+ return 0;
+ return __builtin_ctzll(x.high) + (1 + sizeof(di_int) * CHAR_BIT);
+ }
+ return __builtin_ctzll(x.low) + 1;
+}
+
+#endif