diff options
author | Dimitry Andric <dimitry@andric.com> | 2017-04-06 18:12:02 +0000 |
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committer | Dimitry Andric <dimitry@andric.com> | 2017-04-06 18:12:02 +0000 |
commit | 35c61d8119e5a2ecce5c93dc15e143d3f1910033 (patch) | |
tree | e64a7828b52e62bc6422cd56ec30bcaf695d7f28 | |
parent | 0536342a37dcd79009a74983d0d265bc2585d686 (diff) |
Add __ffssi2 implementation to compiler-rt builtins
Summary:
During MIPS implementation work for FreeBSD, John Baldwin (jhb@FreeBSD.org)
found that gcc 6.x emits calls to __ffssi2() when compiling libc and some
userland programs in the base system.
Add it to compiler-rt's builtins, based off of the existing __ffsdi2()
implementation. Also update the CMake files and add a test case.
Reviewers: howard.hinnant, weimingz, rengolin, compnerd
Reviewed By: weimingz
Subscribers: dberris, mgorny, llvm-commits, emaste
Differential Revision: https://reviews.llvm.org/D31721
git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@299675 91177308-0d34-0410-b5e6-96231b3b80d8
-rw-r--r-- | lib/builtins/CMakeLists.txt | 1 | ||||
-rw-r--r-- | lib/builtins/README.txt | 1 | ||||
-rw-r--r-- | lib/builtins/ffssi2.c | 29 | ||||
-rw-r--r-- | test/builtins/Unit/ffssi2_test.c | 57 |
4 files changed, 88 insertions, 0 deletions
diff --git a/lib/builtins/CMakeLists.txt b/lib/builtins/CMakeLists.txt index 3f648dcb3..28901034e 100644 --- a/lib/builtins/CMakeLists.txt +++ b/lib/builtins/CMakeLists.txt @@ -71,6 +71,7 @@ set(GENERIC_SOURCES extendsfdf2.c extendhfsf2.c ffsdi2.c + ffssi2.c ffsti2.c fixdfdi.c fixdfsi.c diff --git a/lib/builtins/README.txt b/lib/builtins/README.txt index ad36e4e52..b3d083614 100644 --- a/lib/builtins/README.txt +++ b/lib/builtins/README.txt @@ -45,6 +45,7 @@ si_int __ctzsi2(si_int a); // count trailing zeros si_int __ctzdi2(di_int a); // count trailing zeros si_int __ctzti2(ti_int a); // count trailing zeros +si_int __ffssi2(si_int a); // find least significant 1 bit si_int __ffsdi2(di_int a); // find least significant 1 bit si_int __ffsti2(ti_int a); // find least significant 1 bit diff --git a/lib/builtins/ffssi2.c b/lib/builtins/ffssi2.c new file mode 100644 index 000000000..e5180eff5 --- /dev/null +++ b/lib/builtins/ffssi2.c @@ -0,0 +1,29 @@ +/* ===-- ffssi2.c - Implement __ffssi2 -------------------------------------=== + * + * 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 __ffssi2 for the compiler_rt library. + * + * ===----------------------------------------------------------------------=== + */ + +#include "int_lib.h" + +/* Returns: the index of the least significant 1-bit in a, or + * the value zero if a is zero. The least significant bit is index one. + */ + +COMPILER_RT_ABI si_int +__ffssi2(si_int a) +{ + if (a == 0) + { + return 0; + } + return __builtin_ctz(a) + 1; +} diff --git a/test/builtins/Unit/ffssi2_test.c b/test/builtins/Unit/ffssi2_test.c new file mode 100644 index 000000000..5d96b9636 --- /dev/null +++ b/test/builtins/Unit/ffssi2_test.c @@ -0,0 +1,57 @@ +// RUN: %clang_builtins %s %librt -o %t && %run %t +//===-- ffssi2_test.c - Test __ffssi2 -------------------------------------===// +// +// 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 tests __ffssi2 for the compiler_rt library. +// +//===----------------------------------------------------------------------===// + +#include "int_lib.h" +#include <stdio.h> + +// Returns: the index of the least significant 1-bit in a, or +// the value zero if a is zero. The least significant bit is index one. + +COMPILER_RT_ABI si_int __ffssi2(si_int a); + +int test__ffssi2(si_int a, si_int expected) +{ + si_int x = __ffssi2(a); + if (x != expected) + printf("error in __ffssi2(0x%X) = %d, expected %d\n", a, x, expected); + return x != expected; +} + +int main() +{ + if (test__ffssi2(0x00000000, 0)) + return 1; + if (test__ffssi2(0x00000001, 1)) + return 1; + if (test__ffssi2(0x00000002, 2)) + return 1; + if (test__ffssi2(0x00000003, 1)) + return 1; + if (test__ffssi2(0x00000004, 3)) + return 1; + if (test__ffssi2(0x00000005, 1)) + return 1; + if (test__ffssi2(0x0000000A, 2)) + return 1; + if (test__ffssi2(0x10000000, 29)) + return 1; + if (test__ffssi2(0x20000000, 30)) + return 1; + if (test__ffssi2(0x60000000, 30)) + return 1; + if (test__ffssi2(0x80000000u, 32)) + return 1; + + return 0; +} |