Edward O'Callaghan | 2bf6272 | 2009-08-05 04:02:56 +0000 | [diff] [blame] | 1 | /* ===-- clzdi2.c - Implement __clzdi2 -------------------------------------=== |
| 2 | * |
Anton Korobeynikov | 1c5f89b | 2011-04-19 17:52:09 +0000 | [diff] [blame] | 3 | * The LLVM Compiler Infrastructure |
Edward O'Callaghan | 2bf6272 | 2009-08-05 04:02:56 +0000 | [diff] [blame] | 4 | * |
Howard Hinnant | 9ad441f | 2010-11-16 22:13:33 +0000 | [diff] [blame] | 5 | * This file is dual licensed under the MIT and the University of Illinois Open |
| 6 | * Source Licenses. See LICENSE.TXT for details. |
Edward O'Callaghan | 2bf6272 | 2009-08-05 04:02:56 +0000 | [diff] [blame] | 7 | * |
| 8 | * ===----------------------------------------------------------------------=== |
| 9 | * |
| 10 | * This file implements __clzdi2 for the compiler_rt library. |
| 11 | * |
| 12 | * ===----------------------------------------------------------------------=== |
| 13 | */ |
Daniel Dunbar | b3a6901 | 2009-06-26 16:47:03 +0000 | [diff] [blame] | 14 | |
| 15 | #include "int_lib.h" |
| 16 | |
Edward O'Callaghan | 2bf6272 | 2009-08-05 04:02:56 +0000 | [diff] [blame] | 17 | /* Returns: the number of leading 0-bits */ |
Daniel Dunbar | b3a6901 | 2009-06-26 16:47:03 +0000 | [diff] [blame] | 18 | |
Edward O'Callaghan | 2bf6272 | 2009-08-05 04:02:56 +0000 | [diff] [blame] | 19 | /* Precondition: a != 0 */ |
Daniel Dunbar | b3a6901 | 2009-06-26 16:47:03 +0000 | [diff] [blame] | 20 | |
Anton Korobeynikov | 1c5f89b | 2011-04-19 17:52:09 +0000 | [diff] [blame] | 21 | COMPILER_RT_ABI si_int |
Daniel Dunbar | b3a6901 | 2009-06-26 16:47:03 +0000 | [diff] [blame] | 22 | __clzdi2(di_int a) |
| 23 | { |
| 24 | dwords x; |
| 25 | x.all = a; |
Edward O'Callaghan | 8bf1e09 | 2009-08-09 18:41:02 +0000 | [diff] [blame] | 26 | const si_int f = -(x.s.high == 0); |
| 27 | return __builtin_clz((x.s.high & ~f) | (x.s.low & f)) + |
Daniel Dunbar | b3a6901 | 2009-06-26 16:47:03 +0000 | [diff] [blame] | 28 | (f & ((si_int)(sizeof(si_int) * CHAR_BIT))); |
| 29 | } |