[PATCH] D104431: [lld] Add lto-cspgo-warn-mismatch option for COFF

Tue Jun 22 01:30:47 PDT 2021

YolandaCY added a comment.

@tejohnson Yes, I think the same issue exists for ELF. I just submit this for COFF to make sure the general process works, and may submit a seperate patch for ELF if necessary.
I verified the -mllvm or /mllvm option works for both COFF and ELF. Thank you for the suggestion!

@xur The mismatch happens for both PGO and CSPGO in my case. The PGO pass may catch it firstly when compile to object files, and then CSPGO will catch it again during post-link ThinLTO. We have root-caused that some of these mismatches are due to some specialization code when generate the profiles but disabled later for profile use. 
Please find discussions on these warnings in Chromium bug: https://bugs.chromium.org/p/chromium/issues/detail?id=978401

Do you think we still need an explicit linker option to turn off the warnings (actually errors for lld link)?

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https://reviews.llvm.org/D104431