[compiler-rt] [llvm] [TypeProf][InstrFDO]Implement more efficient comparison sequence for indirect-call-promotion with vtable profiles. (PR #81442)

[Mingming Liu via llvm-commits]

minglotus-6 wrote:

> Can we rely on instcombine to do the sinking?

Good question. https://gcc.godbolt.org/z/G7Paj7h37 has two examples, `instcombine` can sink the first but cannot see through the second. I filed https://github.com/llvm/llvm-project/issues/88960 to discuss this, and I think it's more reliable to interleave the instruction sink with vtable transformations. I do think it's very preferred to re-use the helper functions like `tryToSinkInstructionDbgValues` and `tryToSinkInstructionDbgVariableRecords`.

https://github.com/llvm/llvm-project/pull/81442