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Revert "[PM/CC1] Add -f[no-]split-cold-code CC1 option to toggle splitting"

Authored by hans on Oct 19 2020, 3:23 AM.

Description

Revert "[PM/CC1] Add -f[no-]split-cold-code CC1 option to toggle splitting"

This broke Chromium's PGO build, it seems because hot-cold-splitting got turned
on unintentionally. See comment on the code review for repro etc.

This patch adds -f[no-]split-cold-code CC1 options to clang. This allows
the splitting pass to be toggled on/off. The current method of passing
-mllvm -hot-cold-split=true to clang isn't ideal as it may not compose
correctly (say, with -O0 or -Oz).

To implement the -fsplit-cold-code option, an attribute is applied to
functions to indicate that they may be considered for splitting. This
removes some complexity from the old/new PM pipeline builders, and
behaves as expected when LTO is enabled.

Co-authored by: Saleem Abdulrasool <compnerd@compnerd.org>
Differential Revision: https://reviews.llvm.org/D57265
Reviewed By: Aditya Kumar, Vedant Kumar
Reviewers: Teresa Johnson, Aditya Kumar, Fedor Sergeev, Philip Pfaffe, Vedant Kumar

This reverts commit 273c299d5d649a0222fbde03c9a41e41913751b4.