/* ===-- mulvti3.c - Implement __mulvti3 -----------------------------------=== * * 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 __mulvti3 for the compiler_rt library. * * ===----------------------------------------------------------------------=== */ #include "int_lib.h" #ifdef CRT_HAS_128BIT /* Returns: a * b */ /* Effects: aborts if a * b overflows */ COMPILER_RT_ABI ti_int __mulvti3(ti_int a, ti_int b) { const int N = (int)(sizeof(ti_int) * CHAR_BIT); const ti_int MIN = (ti_int)1 << (N-1); const ti_int MAX = ~MIN; if (a == MIN) { if (b == 0 || b == 1) return a * b; compilerrt_abort(); } if (b == MIN) { if (a == 0 || a == 1) return a * b; compilerrt_abort(); } ti_int sa = a >> (N - 1); ti_int abs_a = (a ^ sa) - sa; ti_int sb = b >> (N - 1); ti_int abs_b = (b ^ sb) - sb; if (abs_a < 2 || abs_b < 2) return a * b; if (sa == sb) { if (abs_a > MAX / abs_b) compilerrt_abort(); } else { if (abs_a > MIN / -abs_b) compilerrt_abort(); } return a * b; } #endif /* CRT_HAS_128BIT */ |