[PATCH] D54313: [compiler-rt][builtins][PowerPC] Add floattitf builtin compiler-rt method support for PowerPC

[Robert Enenkel via Phabricator via llvm-commits]

renenkel added a comment.

Regarding Nemanjai's comment, "I would have expected that every __int128_t value is a number (i.e. not a NAN) and none of them produce an infinity."  Correct.  No 128-bit int converted to a long double should produce NaN or Inf.  However, we have to decide what should happen when a long double NaN or Inf gets converted to a 128-bit int.  It seems reasonable that +-Inf gets converted to the largest/smallest int128 of the same sign.  But there is not really any natural value for NaN.  Unless there is a standard governing this, I would suggest it should be undefined.  We've chosen to retain the same bit pattern of the long double NaN in the converted int128. The gcc conversion produces a strange arbitrary number 0x80...080...080...080...0.  I'm not sure what the value would be in matching this, but it would be possible with a special case, should that be deemed necessary.


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  https://reviews.llvm.org/D54313/new/

https://reviews.llvm.org/D54313