klibc - Jun 2006 - __builtin_clz in klibc

Hi,

I just got a bug report that klibc doesn't compile on s390:

  KLIBCCC usr/klibc/libgcc/__clzsi2.o
  KLIBCCC usr/klibc/libgcc/__clzdi2.o
usr/klibc/libgcc/__clzdi2.c: In function `__clzdi2':
usr/klibc/libgcc/__clzdi2.c:24: warning: implicit declaration of function
`__builtin_clz'

This looks like a common problem, because __builtin_clz is available since
gcc 3.4, while the kernel should compile even with gcc 3.2.
Looks like counting the zero bits should be done differently...

Heiko Carstens wrote:
> Hi,
> 
> I just got a bug report that klibc doesn't compile on s390:
> 
>   KLIBCCC usr/klibc/libgcc/__clzsi2.o
>   KLIBCCC usr/klibc/libgcc/__clzdi2.o
> usr/klibc/libgcc/__clzdi2.c: In function `__clzdi2':
> usr/klibc/libgcc/__clzdi2.c:24: warning: implicit declaration of function
`__builtin_clz'
> 
> This looks like a common problem, because __builtin_clz is available since
> gcc 3.4, while the kernel should compile even with gcc 3.2.
> Looks like counting the zero bits should be done differently...
That's a warning, though, and shouldn't keep anything from compiling, so
if that happens there is problem elsewhere.

__clzdi2 isn't actually needed by klibc itself (it uses __clzsi2, but 
not __clzdi2), so simply removing __clzdi2.o from the list of modules 
should take care of the problme.

	-hpa

Heiko Carstens wrote:
> Hi,
> 
> I just got a bug report that klibc doesn't compile on s390:
> 
>   KLIBCCC usr/klibc/libgcc/__clzsi2.o
>   KLIBCCC usr/klibc/libgcc/__clzdi2.o
> usr/klibc/libgcc/__clzdi2.c: In function `__clzdi2':
> usr/klibc/libgcc/__clzdi2.c:24: warning: implicit declaration of function
`__builtin_clz'
> 
> This looks like a common problem, because __builtin_clz is available since
> gcc 3.4, while the kernel should compile even with gcc 3.2.
> Looks like counting the zero bits should be done differently...
Just drop __clzdi2.o; it's not used by anything (__clzsi2.o is, however...)

	-hpa

Heiko Carstens wrote:
> Hi,
> 
> I just got a bug report that klibc doesn't compile on s390:
> 
>   KLIBCCC usr/klibc/libgcc/__clzsi2.o
>   KLIBCCC usr/klibc/libgcc/__clzdi2.o
> usr/klibc/libgcc/__clzdi2.c: In function `__clzdi2':
> usr/klibc/libgcc/__clzdi2.c:24: warning: implicit declaration of function
`__builtin_clz'
> 
> This looks like a common problem, because __builtin_clz is available since
> gcc 3.4, while the kernel should compile even with gcc 3.2.
> Looks like counting the zero bits should be done differently...
Just drop __clzdi2.o; it's not used by anything (__clzsi2.o is, however...)

	-hpa

Heiko Carstens wrote:
> Hi,
> 
> I just got a bug report that klibc doesn't compile on s390:
> 
>   KLIBCCC usr/klibc/libgcc/__clzsi2.o
>   KLIBCCC usr/klibc/libgcc/__clzdi2.o
> usr/klibc/libgcc/__clzdi2.c: In function `__clzdi2':
> usr/klibc/libgcc/__clzdi2.c:24: warning: implicit declaration of function
`__builtin_clz'
> 
> This looks like a common problem, because __builtin_clz is available since
> gcc 3.4, while the kernel should compile even with gcc 3.2.
> Looks like counting the zero bits should be done differently...
Just drop __clzdi2.o; it's not used by anything (__clzsi2.o is, however...)

	-hpa

Heiko Carstens wrote:
> Hi,
> 
> I just got a bug report that klibc doesn't compile on s390:
> 
>   KLIBCCC usr/klibc/libgcc/__clzsi2.o
>   KLIBCCC usr/klibc/libgcc/__clzdi2.o
> usr/klibc/libgcc/__clzdi2.c: In function `__clzdi2':
> usr/klibc/libgcc/__clzdi2.c:24: warning: implicit declaration of function
`__builtin_clz'
> 
> This looks like a common problem, because __builtin_clz is available since
> gcc 3.4, while the kernel should compile even with gcc 3.2.
> Looks like counting the zero bits should be done differently...
Just drop __clzdi2.o; it's not used by anything (__clzsi2.o is, 
however...)  I just pushed out 1.4.7 which does this.

	-hpa