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Uniuqe Names for Internal Linkage Symbols.

Authored by tmsriram on May 7 2020, 6:18 PM.

Description

Uniuqe Names for Internal Linkage Symbols.

This is a standalone patch and this would help Propeller do a better job of code
layout as it can accurately attribute the profiles to the right internal linkage
function.

This also helps SampledFDO/AutoFDO correctly associate sampled profiles to the
right internal function. Currently, if there is more than one internal symbol
foo, their profiles are aggregated by SampledFDO.

This patch adds a new clang option, -funique-internal-funcnames, to generate
unique names for functions with internal linkage. This patch appends the md5
hash of the module name to the function symbol as a best effort to generate a
unique name for symbols with internal linkage.

Differential Revision: https://reviews.llvm.org/D73307

Details