Re: [PATCH] Use __builtin_ffs instead of libc provided ffs in vm_map.c

[Samuel Thibault]

Applied, thanks!

Flavio Cruz, le mer. 14 déc. 2022 02:35:47 -0500, a ecrit:
> We already this built in in other places and this will move us closer to
> being able to build the kernel without libc.
> ---
>  Makefile.am | 4 ++--
>  vm/vm_map.c | 4 ++--
>  2 files changed, 4 insertions(+), 4 deletions(-)
> 
> diff --git a/Makefile.am b/Makefile.am
> index 684344e2..33f770f6 100644
> --- a/Makefile.am
> +++ b/Makefile.am
> @@ -167,13 +167,13 @@ gnumach_o_LINK = $(LD) $(LDFLAGS) -u _start -r -o $@
>  noinst_PROGRAMS += \
>       gnumach.o
>  
> -# This is the list of routines we decide is OK to steal from the C library.
> +# This is the list of routines we decide is OK to steal from the C library 
> or libgcc.
>  clib_routines := htonl htons ntohl ntohs                     \
>                udivdi3 __udivdi3 __udivmoddi4 __umoddi3       \
>                __divdi3 __moddi3                              \
>                __rel_iplt_start __rel_iplt_end                \
>                __rela_iplt_start __rela_iplt_end              \
> -              __ffsdi2 ffs                                   \
> +              __ffsdi2                                       \
>                _START _start etext _edata end _end # actually ld magic, not 
> libc.
>  gnumach-undef: gnumach.$(OBJEXT)
>       $(NM_V) $(NM) -u $< | sed 's/  *U  *//' | sort -u > $@
> diff --git a/vm/vm_map.c b/vm/vm_map.c
> index ceeb91ee..4200a239 100644
> --- a/vm/vm_map.c
> +++ b/vm/vm_map.c
> @@ -685,10 +685,10 @@ vm_map_find_entry_anywhere(struct vm_map *map,
>       if (((mask + 1) & mask) != 0) {
>               /* We have high bits in addition to the low bits */
>  
> -             int first0 = ffs(~mask);                /* First zero after low 
> bits */
> +             int first0 = __builtin_ffs(~mask);              /* First zero 
> after low bits */
>               vm_offset_t lowmask = (1UL << (first0-1)) - 1;          /* low 
> bits */
>               vm_offset_t himask = mask - lowmask;                    /* high 
> bits */
> -             int second1 = ffs(himask);              /* First one after low 
> bits */
> +             int second1 = __builtin_ffs(himask);            /* First one 
> after low bits */
>  
>               max = 1UL << (second1-1);
>  
> -- 
> 2.37.2
> 
>