diff options
author | Dimitry Andric <dim@FreeBSD.org> | 2019-08-22 19:26:11 +0000 |
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committer | Dimitry Andric <dim@FreeBSD.org> | 2019-08-22 19:26:11 +0000 |
commit | 14a0b2859e9d76204ca897de961b36344ce1e775 (patch) | |
tree | 08901f9a2645ad5ec5813f4b15bdc92620e1f7e4 /contrib/compiler-rt/lib/builtins/popcountdi2.c | |
parent | 580d4aa65a2dadf52a0abc9451ab25918cb25125 (diff) | |
parent | 8f3cadc28cb2bb9e8f9d69eeaaea1f57f2f7b2ab (diff) |
Merge compiler-rt trunk r366426, resolve conflicts, and add
FREEBSD-Xlist.
Notes
Notes:
svn path=/projects/clang900-import/; revision=351401
Diffstat (limited to 'contrib/compiler-rt/lib/builtins/popcountdi2.c')
-rw-r--r-- | contrib/compiler-rt/lib/builtins/popcountdi2.c | 58 |
1 files changed, 27 insertions, 31 deletions
diff --git a/contrib/compiler-rt/lib/builtins/popcountdi2.c b/contrib/compiler-rt/lib/builtins/popcountdi2.c index 5e8a62f075eb..9bbc39c6608a 100644 --- a/contrib/compiler-rt/lib/builtins/popcountdi2.c +++ b/contrib/compiler-rt/lib/builtins/popcountdi2.c @@ -1,36 +1,32 @@ -/* ===-- popcountdi2.c - Implement __popcountdi2 ----------------------------=== - * - * 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 __popcountdi2 for the compiler_rt library. - * - * ===----------------------------------------------------------------------=== - */ +//===-- popcountdi2.c - Implement __popcountdi2 ---------------------------===// +// +// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. +// See https://llvm.org/LICENSE.txt for license information. +// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception +// +//===----------------------------------------------------------------------===// +// +// This file implements __popcountdi2 for the compiler_rt library. +// +//===----------------------------------------------------------------------===// #include "int_lib.h" -/* Returns: count of 1 bits */ +// Returns: count of 1 bits -COMPILER_RT_ABI si_int -__popcountdi2(di_int a) -{ - du_int x2 = (du_int)a; - x2 = x2 - ((x2 >> 1) & 0x5555555555555555uLL); - /* Every 2 bits holds the sum of every pair of bits (32) */ - x2 = ((x2 >> 2) & 0x3333333333333333uLL) + (x2 & 0x3333333333333333uLL); - /* Every 4 bits holds the sum of every 4-set of bits (3 significant bits) (16) */ - x2 = (x2 + (x2 >> 4)) & 0x0F0F0F0F0F0F0F0FuLL; - /* Every 8 bits holds the sum of every 8-set of bits (4 significant bits) (8) */ - su_int x = (su_int)(x2 + (x2 >> 32)); - /* The lower 32 bits hold four 16 bit sums (5 significant bits). */ - /* Upper 32 bits are garbage */ - x = x + (x >> 16); - /* The lower 16 bits hold two 32 bit sums (6 significant bits). */ - /* Upper 16 bits are garbage */ - return (x + (x >> 8)) & 0x0000007F; /* (7 significant bits) */ +COMPILER_RT_ABI si_int __popcountdi2(di_int a) { + du_int x2 = (du_int)a; + x2 = x2 - ((x2 >> 1) & 0x5555555555555555uLL); + // Every 2 bits holds the sum of every pair of bits (32) + x2 = ((x2 >> 2) & 0x3333333333333333uLL) + (x2 & 0x3333333333333333uLL); + // Every 4 bits holds the sum of every 4-set of bits (3 significant bits) (16) + x2 = (x2 + (x2 >> 4)) & 0x0F0F0F0F0F0F0F0FuLL; + // Every 8 bits holds the sum of every 8-set of bits (4 significant bits) (8) + su_int x = (su_int)(x2 + (x2 >> 32)); + // The lower 32 bits hold four 16 bit sums (5 significant bits). + // Upper 32 bits are garbage + x = x + (x >> 16); + // The lower 16 bits hold two 32 bit sums (6 significant bits). + // Upper 16 bits are garbage + return (x + (x >> 8)) & 0x0000007F; // (7 significant bits) } |