[PATCH] D79321: [SLC] Allow llvm.pow(2**n,x) -> llvm.exp2(n*x) even if no exp2 lib func

[Eli Friedman via Phabricator via llvm-commits]

efriedma added a comment.

When we're compiling C code, we can't blindly generate floating-point intrinsics.  Even if we're confident the transform is correct, the backend has limited capabilities.  If the corresponding libfunc doesn't exist, and the target doesn't have any special capabilities, the backed is stuck: we need to generate a function call, but the function doesn't exist.

We could potentially add some TTI query to ask about the intrinsic, specifically, as opposed to the library function.  But we can't just bypass the check.


Repository:
  rG LLVM Github Monorepo

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  https://reviews.llvm.org/D79321/new/

https://reviews.llvm.org/D79321