13cab2bb3Spatrick //===-- clzdi2.c - Implement __clzdi2 -------------------------------------===// 23cab2bb3Spatrick // 33cab2bb3Spatrick // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 43cab2bb3Spatrick // See https://llvm.org/LICENSE.txt for license information. 53cab2bb3Spatrick // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 63cab2bb3Spatrick // 73cab2bb3Spatrick //===----------------------------------------------------------------------===// 83cab2bb3Spatrick // 93cab2bb3Spatrick // This file implements __clzdi2 for the compiler_rt library. 103cab2bb3Spatrick // 113cab2bb3Spatrick //===----------------------------------------------------------------------===// 123cab2bb3Spatrick 133cab2bb3Spatrick #include "int_lib.h" 143cab2bb3Spatrick 153cab2bb3Spatrick // Returns: the number of leading 0-bits 163cab2bb3Spatrick 173cab2bb3Spatrick #if !defined(__clang__) && \ 183cab2bb3Spatrick ((defined(__sparc__) && defined(__arch64__)) || defined(__mips64) || \ 193cab2bb3Spatrick (defined(__riscv) && __SIZEOF_POINTER__ >= 8)) 203cab2bb3Spatrick // On 64-bit architectures with neither a native clz instruction nor a native 213cab2bb3Spatrick // ctz instruction, gcc resolves __builtin_clz to __clzdi2 rather than 223cab2bb3Spatrick // __clzsi2, leading to infinite recursion. 233cab2bb3Spatrick #define __builtin_clz(a) __clzsi2(a) 24*1f9cb04fSpatrick extern int __clzsi2(si_int); 253cab2bb3Spatrick #endif 263cab2bb3Spatrick 273cab2bb3Spatrick // Precondition: a != 0 283cab2bb3Spatrick __clzdi2(di_int a)29*1f9cb04fSpatrickCOMPILER_RT_ABI int __clzdi2(di_int a) { 303cab2bb3Spatrick dwords x; 313cab2bb3Spatrick x.all = a; 323cab2bb3Spatrick const si_int f = -(x.s.high == 0); 33*1f9cb04fSpatrick return clzsi((x.s.high & ~f) | (x.s.low & f)) + 343cab2bb3Spatrick (f & ((si_int)(sizeof(si_int) * CHAR_BIT))); 353cab2bb3Spatrick } 36