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Add an implementation of __ffssi2() derived from __ffsdi2().

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Newer versions of GCC include an __ffssi2() symbol in libgcc and the
compiler can emit calls to it in generated code.  This is true for at
least GCC 6.2 when compiling world for mips and mips64.

Reviewed by:	jmallett, dim
Sponsored by:	DARPA / AFRL
Differential Revision:	https://reviews.freebsd.org/D10086
This commit is contained in:
John Baldwin 2017-04-05 02:40:53 +00:00
parent 2e2e26d14e
commit 813b8a9e89
3 changed files with 31 additions and 0 deletions
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1
contrib/compiler-rt/lib/builtins/README.txt
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@ -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

29
contrib/compiler-rt/lib/builtins/ffssi2.c Normal file
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@ -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;
}

1
lib/libcompiler_rt/Makefile.inc
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@ -38,6 +38,7 @@ SRCF+= divxc3
SRCF+= enable_execute_stack
SRCF+= eprintf
SRCF+= extendhfsf2
SRCF+= ffssi2
SRCF+= ffsdi2
SRCF+= ffsti2
SRCF+= fixdfdi