[PATHCH] Disable inline asm for in-tree mpfr (PR69134)

[Bernd Edlinger]

Hi,

On 05.01.2016 13:58, Bernd Schmidt wrote:
> On 01/05/2016 09:44 AM, Bernd Edlinger wrote:
>> an in-tree mpfr build enables inline asm code, which makes the 
>> mips-bootstrap fail,
>> because at least mpfr 2.4.2 uses the "=h" constraint but in 
>> config/mips/constraints.md
>> we find: "Formerly the @code{hi} register.  This constraint is no 
>> longer supported.".
>>
>> Using asm code is generally not desirable for in-tree mpfr builds.
>
> Why not?

for the same reason why we disable the asm code for in-tree gmp.

If we think mpfr is fine to use assembler, why don't we let gmp use the 
assember code too?

When we boot-strap to a different architecture we certainly do not want 
to fiddle with inline-assember bugs, unless absolutely necessary.


>
>> So I looked for a way
>> to disable the asm code, and found it can be done, but differently 
>> than for in-tree gmp.
>> See the attached patch.
>
> Fix mpfr instead not to use that constraint?
>

I don't think we should start to patch mpfr release-tarballs.

The only alternative I see, how a mips-compiler could be boot-strapped 
today would be to set CFLAGS="-g -O2 -DNO_ASM" on the gcc configure 
line, but this will then be used everywhere, and I have no idea if that 
define has some side effects on libgcc for instance (my boot-strap did 
not reach that point).


Bernd.