[llvm] [SampleFDO] Support enabling sample loader pass in O0 mode (PR #113985)

[Lei Wang via llvm-commits]

wlei-llvm wrote:

> Should we flatten the profile first for O0 profile loading?

`DisableSampleLoaderInlining` does some flattening(merge the un-inline profile to the outline function) things, was thinking to improve it later.

OK, that seems not a big change, will update in this patch.


https://github.com/llvm/llvm-project/pull/113985