No support for modes KF/KC cause failures to compile math.h with -mfloat128 on PPC

[nemanjai]

Bugzilla Link	46068
Version	10.0
OS	All
Blocks	#44654
CC	@zygoloid,@tstellar
Fixed by commit(s)	f9e94eb 9021ce9

Extended Description

The following test case does not compile with clang (and also causes failures to configure projects when -mfloat128 is in the FLAGS):

#include <math.h>
__CFLOAT128 testkf(__CFLOAT128 a, __CFLOAT128 b) {
return a + b;
}

$ clang -I /opt/at12.0/include -S -mfloat128 -mcpu=power9 noKC.c -O
In file included from noKC.c:1:
In file included from /opt/at12.0/include/math.h:43:
/opt/at12.0/include/bits/floatn.h:82:52: error: unknown machine mode 'KC'
typedef _Complex float __cfloat128 attribute ((mode (KC)));
^
1 error generated.

[nemanjai]

Fix proposed in: https://reviews.llvm.org/D80374

This fix also depends on https://reviews.llvm.org/D80533
for its tests.

[tstellar]

It looks like the fix has been committed, but the header changes modify the API. They would need to be re-written to preserve the existing function signatures.

[tstellar]

Is anyone planning to rewrite the patch for the release/10.x branch?

[nemanjai]

Sorry, I completely missed this.
Can you clarify which header changes are not compatible with 10.x?

In any case, since I missed this I presume that we can't get this fixed for 10.x at this point so maybe this is moot.

If there is any point to doing so at this time, I can try to provide a patch for 10.x. Otherwise, this is just going to be part of 11.0.