[libclc] [libclc] Move several 'native' builtins to CLC library (PR #129679)

[Fraser Cormack via cfe-commits]

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@@ -0,0 +1,3 @@
+_CLC_OVERLOAD _CLC_DEF __CLC_GENTYPE __clc_native_log(__CLC_GENTYPE val) {
+  return __clc_native_log2(val) * (1.0f / M_LOG2E_F);
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frasercrmck wrote:

We now apply `-fapprox-func`, as of #133119.

If I change this PR to remove the AMDGPU definitions of `__clc_native_log`, and instead rely on the generic one, we see, e.g., in `amdgcn--amdhsa.bc`:

``` llvm
; Function Attrs: alwaysinline mustprogress nofree norecurse nosync nounwind willreturn memory(none)
define linkonce_odr hidden noundef <2 x float> @_Z10native_logDv2_f(<2 x float> noundef %a) local_unnamed_addr #13 {
entry:
  %elt.log.i = tail call afn noundef <2 x float> @llvm.log.v2f32(<2 x float> %a)
  ret <2 x float> %elt.log.i
}
```

Is this what you had in mind?

https://github.com/llvm/llvm-project/pull/129679