1*4ba319b5SDimitry Andric /*===-- int128_builtins.cpp - Implement __muloti4 --------------------------=== 2*4ba319b5SDimitry Andric * 3*4ba319b5SDimitry Andric * The LLVM Compiler Infrastructure 4*4ba319b5SDimitry Andric * 5*4ba319b5SDimitry Andric * This file is dual licensed under the MIT and the University of Illinois Open 6*4ba319b5SDimitry Andric * Source Licenses. See LICENSE.TXT for details. 7*4ba319b5SDimitry Andric * 8*4ba319b5SDimitry Andric * ===----------------------------------------------------------------------=== 9*4ba319b5SDimitry Andric * 10*4ba319b5SDimitry Andric * This file implements __muloti4, and is stolen from the compiler_rt library. 11*4ba319b5SDimitry Andric * 12*4ba319b5SDimitry Andric * FIXME: we steal and re-compile it into filesystem, which uses __int128_t, 13*4ba319b5SDimitry Andric * and requires this builtin when sanitized. See llvm.org/PR30643 14*4ba319b5SDimitry Andric * 15*4ba319b5SDimitry Andric * ===----------------------------------------------------------------------=== 16*4ba319b5SDimitry Andric */ 17*4ba319b5SDimitry Andric #include "__config" 18*4ba319b5SDimitry Andric #include "climits" 19*4ba319b5SDimitry Andric 20*4ba319b5SDimitry Andric #if !defined(_LIBCPP_HAS_NO_INT128) 21*4ba319b5SDimitry Andric 22*4ba319b5SDimitry Andric extern "C" __attribute__((no_sanitize("undefined"))) __muloti4(__int128_t a,__int128_t b,int * overflow)23*4ba319b5SDimitry Andric__int128_t __muloti4(__int128_t a, __int128_t b, int* overflow) { 24*4ba319b5SDimitry Andric const int N = (int)(sizeof(__int128_t) * CHAR_BIT); 25*4ba319b5SDimitry Andric const __int128_t MIN = (__int128_t)1 << (N - 1); 26*4ba319b5SDimitry Andric const __int128_t MAX = ~MIN; 27*4ba319b5SDimitry Andric *overflow = 0; 28*4ba319b5SDimitry Andric __int128_t result = a * b; 29*4ba319b5SDimitry Andric if (a == MIN) { 30*4ba319b5SDimitry Andric if (b != 0 && b != 1) 31*4ba319b5SDimitry Andric *overflow = 1; 32*4ba319b5SDimitry Andric return result; 33*4ba319b5SDimitry Andric } 34*4ba319b5SDimitry Andric if (b == MIN) { 35*4ba319b5SDimitry Andric if (a != 0 && a != 1) 36*4ba319b5SDimitry Andric *overflow = 1; 37*4ba319b5SDimitry Andric return result; 38*4ba319b5SDimitry Andric } 39*4ba319b5SDimitry Andric __int128_t sa = a >> (N - 1); 40*4ba319b5SDimitry Andric __int128_t abs_a = (a ^ sa) - sa; 41*4ba319b5SDimitry Andric __int128_t sb = b >> (N - 1); 42*4ba319b5SDimitry Andric __int128_t abs_b = (b ^ sb) - sb; 43*4ba319b5SDimitry Andric if (abs_a < 2 || abs_b < 2) 44*4ba319b5SDimitry Andric return result; 45*4ba319b5SDimitry Andric if (sa == sb) { 46*4ba319b5SDimitry Andric if (abs_a > MAX / abs_b) 47*4ba319b5SDimitry Andric *overflow = 1; 48*4ba319b5SDimitry Andric } else { 49*4ba319b5SDimitry Andric if (abs_a > MIN / -abs_b) 50*4ba319b5SDimitry Andric *overflow = 1; 51*4ba319b5SDimitry Andric } 52*4ba319b5SDimitry Andric return result; 53*4ba319b5SDimitry Andric } 54*4ba319b5SDimitry Andric 55*4ba319b5SDimitry Andric #endif 56