When run under valgrind, or with a malloc that poisons freed memory,
this can lead to segfaults or other problems.
To avoid modifying the AdditionalUsers DenseMap while still iterating,
save the instructions to be notified in a separate SmallPtrSet, and use
this to later call OperandChangedState on each instruction.
Fixes PR49582.
clang-tidy: warning: invalid case style for variable 'toNotify' [readability-identifier-naming]
not useful