r344199 - Add a flag to remap manglings when reading profile data information.

[Friedman, Eli via cfe-commits]

On 10/10/2018 4:13 PM, Richard Smith via cfe-commits wrote:
> Author: rsmith
> Date: Wed Oct 10 16:13:35 2018
> New Revision: 344199
>
> URL: http://llvm.org/viewvc/llvm-project?rev=344199&view=rev
> Log:
> Add a flag to remap manglings when reading profile data information.
>
> This can be used to preserve profiling information across codebase
> changes that have widespread impact on mangled names, but across which
> most profiling data should still be usable. For example, when switching
> from libstdc++ to libc++, or from the old libstdc++ ABI to the new ABI,
> or even from a 32-bit to a 64-bit build.
>
> The user can provide a remapping file specifying parts of mangled names
> that should be treated as equivalent (eg, std::__1 should be treated as
> equivalent to std::__cxx11), and profile data will be treated as
> applying to a particular function if its name is equivalent to the name
> of a function in the profile data under the provided equivalences. See
> the documentation change for a description of how this is configured.
>
> Remapping is supported for both sample-based profiling and instruction
> profiling. We do not support remapping indirect branch target
> information, but all other profile data should be remapped
> appropriately.
>
> Support is only added for the new pass manager. If someone wants to also
> add support for this for the old pass manager, doing so should be
> straightforward.

Should the documentation mention this limitation?

-Eli

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