[PATCH] D28479: [SimplifyLibCalls] pow(x, -0.5) -> 1.0 / sqrt(x)

[David Majnemer via Phabricator via llvm-commits]

majnemer added inline comments.


================
Comment at: lib/Transforms/Utils/SimplifyLibCalls.cpp:1084-1085
+
+      // Here we cannot lower to an intrinsic because C99 sqrt() and llvm.sqrt
+      // are not guaranteed to have the same semantics.
+      Value *Sqrt = emitUnaryFloatFnCall(Op1, TLI->getName(LibFunc::sqrt), B,
----------------
davide wrote:
> majnemer wrote:
> > Doesn't hasUsnafeAlgebra make this irrelevant?
> Does it? I'm not entirely sure of the implications, see e.g. http://lists.llvm.org/pipermail/llvm-commits/Week-of-Mon-20160808/380416.html @hfinkel 
> (I'd leave the lowering to an intrinsic as a follow-up).
Of course... Sorry about that!


https://reviews.llvm.org/D28479