From 655378bb3dd91f8a437ea1ae76418d3bc7a9ce81 Mon Sep 17 00:00:00 2001 From: Pascal Stumpf Date: Mon, 5 Sep 2016 11:36:24 +0000 Subject: Import libcompiler_rt 3.9.0, LLVM's replacement for libgcc. This is the lib/builtin directory of the compiler-rt source tarball. comments/ok patrick@, ok kettenis@ --- lib/libcompiler_rt/popcountdi2.c | 36 ++++++++++++++++++++++++++++++++++++ 1 file changed, 36 insertions(+) create mode 100644 lib/libcompiler_rt/popcountdi2.c (limited to 'lib/libcompiler_rt/popcountdi2.c') diff --git a/lib/libcompiler_rt/popcountdi2.c b/lib/libcompiler_rt/popcountdi2.c new file mode 100644 index 00000000000..5e8a62f075e --- /dev/null +++ b/lib/libcompiler_rt/popcountdi2.c @@ -0,0 +1,36 @@ +/* ===-- 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. + * + * ===----------------------------------------------------------------------=== + */ + +#include "int_lib.h" + +/* 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) */ +} -- cgit v1.2.3