Currently we have quadratic complexity in LowerTypeTests because
ScopedSaveAliaseesAndUsed loops over all aliases for each disjoint
set, and the number of aliases and number of disjoint sets is
roughly proportional to the program size. Fix that by moving
ScopedSaveAliaseesAndUsed to LowerTypeTestsModule::lower() so that
we do this only once.
Reland of #135875 with fix for bug that caused check-lld test failures.
The fix is to only remove functions from llvm.used/llvm.compiler.used
because buildBitSetsFromGlobalVariables, which now runs while
ScopedSaveAliaseesAndUsed is in scope, will delete global variables,
which would otherwise lead to a use-after-free when they are added
back to llvm.used or llvm.compiler.used.
Reviewers: fmayer, vitalybuka
Reviewed By: fmayer
Pull Request: https://github.com/llvm/llvm-project/pull/136053
218531821a