Re: LT_PATH_NM uses too strict a check

[Ximin Luo]

some version info:

the bug exists both in 2.2.6 (what I have) and 2.2.10 (I checked the .deb
package from debian experimental)

X

On 21/12/10 22:31, Ximin Luo wrote:
> I have a core2 system, and have been trying to compile GMP 5.0.1 optimised for
> other x86 CPUs, by doing (e.g.)
> 
> $ ./configure --host=pentium4-$(./config.guess | cut -d- -f2-)
> 
> However, these fail with an obscure error message about `link -dump -symbols`
> (see snippet 1). After a convoluted path of debugging, I've worked out that 
> the
> cause is ./configure not detecting the presence of "/usr/bin/nm -B", in the
> case where $build != $host.
> 
> The responsible code is the following snippet:
>   if test -n "$ac_tool_prefix" && test "$build" = "$host"; then
> 
> which occurs twice in GMP 5.0.1's ./configure, the ultimate source being the
> LT_PATH_NM macro from libtool.m4. If you remove all occurrences of the second
> test, the build works fine.
> 
> (I have some test code at [1]. Removing the WORKAROUND on line 232 will cause
> builds such as `./build-all-multi.sh pentium4` to fail when run on a core2.)
> 
> I don't know much about how libtool works, but it seems to me that the check 
> is
> too strict - nm shouldn't change with the CPU. If really necessary, maybe only
> the last part of $build/$host could be matched instead?
> 
> Ximin
> 
> [1]
> https://github.com/freenet/contrib-staging/blob/master/NativeBigInteger/build-all-multi.sh
> 
> ----> snippet 1 <----
> 
> checking if globals are prefixed by underscore... link: invalid option -- 'd'
> Try `link --help' for more information.
> unknown
> configure: WARNING: 
> +----------------------------------------------------------
> configure: WARNING: | Cannot determine global symbol prefix.
> configure: WARNING: | link -dump -symbols output doesn't contain a global data
> symbol.
> configure: WARNING: | Will proceed with no underscore.
> configure: WARNING: | If this is wrong then you'll get link errors referring
> configure: WARNING: | to ___gmpn_add_n (note three underscores).
> configure: WARNING: | In this case do a fresh build with an override,
> configure: WARNING: |     ./configure gmp_cv_asm_underscore=yes
> configure: WARNING: 
> +----------------------------------------------------------
> checking how to switch to read-only data section...   .section        .rodata
> checking for assembler .type directive... .type       $1, <at> $2
> checking for assembler .size directive... .size       $1,$2
> checking for assembler local label prefix... configure: WARNING: "link -dump
> -symbols" failure
> configure: WARNING: cannot determine local label, using default L
> L
> checking for assembler byte directive... .byte
> checking how to define a 32-bit word... link: invalid option -- 'd'
> Try `link --help' for more information.
> link: invalid option -- 'd'
> Try `link --help' for more information.
> configure: error: cannot determine how to define a 32-bit word
> 
> Failed to configure for libjbigi-linux-pentium4; maybe it isn't supported on
> your build environment.
> 
> Error building libjbigi-linux-pentium4!
> 


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