[LLD][AArch64] Detach Landing Pad creation from Thunk creation (#116402)

Move Landing Pad Creation to a new function that checks each thunk every
pass to see if it needs a landing pad. This permits a thunk to be
created without needing a landing pad, but later needing one due to
drifting out of direct branch range and requiring an indirect branch.

We record all the Thunks created so far in a new vector rather than
trying to iterate over the DenseMap as we need a deterministic order of
adding LandingPadThunks due to the short branch fall through. We cannot
use normalizeExistingThunk() either as that only iterates through live
thunks.

Fixes: https://crbug.com/377438309
Original PR: https://github.com/llvm/llvm-project/pull/108989

Sending without a new test case to fix existing test. A new regression
test will come in a separate PR as coming up with a small enough
reproducer for this case is non-trivial.

0 files changed, 0 insertions, 0 deletions