[llvm-dev] '__builtin_nanl' and soft-FP64 support

[Martin J. O'Riordan via llvm-dev]

I am seeing failures in two tests after migrating to v5.0 final, these are:

std/language.support/support.limits/limits/numeric.limits.members/quiet_NaN.
pass.cpp

and:

std/language.support/support.limits/limits/numeric.limits.members/signaling_
NaN.pass.cpp

However, these are new tests and it turns out that the underlying problem is
that the builtin '__builtin_nanl("")' is returning the value
0x0000000000000000.  I tested this builtin with our v4.0 compiler and it has
the same problem, so this is not a regression but rather an existing bug
exposed by the new LibC++ implementation of '<limits>'.

 

But our implementation of FP64 is a software only implementation using the
FP64 support functions in 'compiler-rt' and we have no lowering actions of
our own.

 

Where should I be looking to find out how to fix this?  Is it a CLang issue
of an LLVM issue?

 

Thanks,

 

            MartinO

 

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