Later stages use the name to disambiguate variables and this amgiguity
can lead to incorrect debug info that crashes LLVM. This also makes
the artificial variable names visible in textual SIL output.
rdar://82313550
In https://reviews.llvm.org/D95617 LLVM stopped to emit debug values without a
location as an optimization for inlined functions. Because Swift is emitting
dbg.values(undef) for sizeless variables even at -Onone, we need to make sure
all local variables are preserved even at -Onone.
rdar://82038523
Switch statements generate at least one anonymous match variable per
case, which consumes both a lot of stack space and an explosion of
range extension depencies due to the way case statements are scoped.
rdar://problem/34326355
Most tests were using %swift or similar substitutions, which did not
include the target triple and SDK. The driver was defaulting to the
host OS. Thus, we could not run the tests when the standard library was
not built for OS X.
Swift SVN r24504
This is needed for tests which define internal functions which should not be eliminated.
So far this was not needed because of a hack which prevented whole-module-optimizations for tests.
Swift SVN r22658
