[PATCH] Introduce GlobalAlias::mayBeResolved().

[Peter Collingbourne]

  > Needs a testcase.

  Hmm.  I wonder where the test case should live, then. The purpose of the test case should be to check that no (standard) pass resolves the alias, so I don't think it should belong to a specific pass, such as globalopt.  For now I added it under test/Other. (Existing globalopt tests already check that aliases are resolved when they should be, so my test only checks that aliases aren't resolved when they shouldn't be.)

  > I don' think "may" is the best term in here. Resolving an alias should be legal. It only causes problem in very special cases (like the got not being available yet ). The question is if it is profitable to do so.

  Well, the choice of whether to resolve an alias can also affect the semantics of symbol interpositioning.  While we normally don't care about interpositioning semantics, I think that if the user has gone to the trouble of creating an alias whose visibility differs from the aliasee, that's a pretty strong signal that the user cares about those semantics, and we should respect the user's wishes.

http://llvm-reviews.chandlerc.com/D606