[llvm] SimplifyLibCalls: Don't require ldexp to emit intrinsic in exp2 combine (PR #92707)

[Eli Friedman via llvm-commits]

efriedma-quic wrote:

It looks like the lowering for llvm.ldexp currently doesn't respect "no-builtin-ldexp" etc.; we should probably fix that first.

Long-term, we really need a better approach for managing the codesize explosion that comes from expanding everything inline.

https://github.com/llvm/llvm-project/pull/92707