1214152Sed/* ===-- mulvti3.c - Implement __mulvti3 -----------------------------------=== 2214152Sed * 3214152Sed * The LLVM Compiler Infrastructure 4214152Sed * 5222656Sed * This file is dual licensed under the MIT and the University of Illinois Open 6222656Sed * Source Licenses. See LICENSE.TXT for details. 7214152Sed * 8214152Sed * ===----------------------------------------------------------------------=== 9214152Sed * 10214152Sed * This file implements __mulvti3 for the compiler_rt library. 11214152Sed * 12214152Sed * ===----------------------------------------------------------------------=== 13214152Sed */ 14214152Sed 15239138Sandrew#include "int_lib.h" 16239138Sandrew 17263763Sdim#ifdef CRT_HAS_128BIT 18214152Sed 19214152Sed/* Returns: a * b */ 20214152Sed 21214152Sed/* Effects: aborts if a * b overflows */ 22214152Sed 23214152Sedti_int 24214152Sed__mulvti3(ti_int a, ti_int b) 25214152Sed{ 26214152Sed const int N = (int)(sizeof(ti_int) * CHAR_BIT); 27214152Sed const ti_int MIN = (ti_int)1 << (N-1); 28214152Sed const ti_int MAX = ~MIN; 29214152Sed if (a == MIN) 30214152Sed { 31214152Sed if (b == 0 || b == 1) 32214152Sed return a * b; 33214152Sed compilerrt_abort(); 34214152Sed } 35214152Sed if (b == MIN) 36214152Sed { 37214152Sed if (a == 0 || a == 1) 38214152Sed return a * b; 39214152Sed compilerrt_abort(); 40214152Sed } 41214152Sed ti_int sa = a >> (N - 1); 42214152Sed ti_int abs_a = (a ^ sa) - sa; 43214152Sed ti_int sb = b >> (N - 1); 44214152Sed ti_int abs_b = (b ^ sb) - sb; 45214152Sed if (abs_a < 2 || abs_b < 2) 46214152Sed return a * b; 47214152Sed if (sa == sb) 48214152Sed { 49214152Sed if (abs_a > MAX / abs_b) 50214152Sed compilerrt_abort(); 51214152Sed } 52214152Sed else 53214152Sed { 54214152Sed if (abs_a > MIN / -abs_b) 55214152Sed compilerrt_abort(); 56214152Sed } 57214152Sed return a * b; 58214152Sed} 59214152Sed 60263763Sdim#endif /* CRT_HAS_128BIT */ 61