Undefined Behavior in lib/msun/src/e_pow.c (was Re: New math library from ARM)

[Pedro Giffuni]

Hmm ...

Looking at the changes in musl's libc I found this issue which seems 
real (although somewhat theoretical):

https://git.musl-libc.org/cgit/musl/commit/src/math?id=688d3da0f1730daddbc954bbc2d27cc96ceee04c

Is the attached patch acceptable?


Also, their code is bit different here:

https://git.musl-libc.org/cgit/musl/commit/src/math?id=282b1cd26649d69de038111f5876853df6ddc345

but we may also have to check fmaf(-0x1.26524ep-54, -0x1.cb7868p+11, 
0x1.d10f5ep-29).

Cheers,

Pedro.

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