GMP and clang bugginess

Marc Glisse marc.glisse at
Thu May 21 20:33:19 UTC 2015

On Thu, 21 May 2015, Torbjörn Granlund wrote:

> GMP triggers bugs in clang on every platform where we tried this
> compiler.  Some configs work, though.
> To see how bad it is, please take a look here:
> I think we would help our users by making it hard to use clang with the
> next release.  What do you think?
> My idea is to reject clang with an error message along these lines:
> error: clang is not able to correctly compile GMP.  To override, use
> --enable-clang.  Make sure to run "make check" and don't use the library
> of this fails.

It is your call, but that seems a bit excessive to me. I just did a few 
tests with clang-3.6. It seems to work fine on x86_64, so probably on 
macs, where it is the default compiler and a large part of the user base 

On powerpc-linux-gnu, clang complains about the bc+ instruction, and 
indeed I can't find that in IBM's documentation. After removing 
divrem_2.asm, it compiles fine and passes the testsuite.

aarch64-linux-gnu and arm-linux-gnueabihf are working fine for me.

powerpc64le-linux-gnu seems broken indeed.

I tend to consider that the usual "run the testsuite" message is 
sufficient, possibly with extra warnings in the release notes or some such 
place. But again, your call.

Marc Glisse

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