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Austin Seipp authored
This basically cleans a lot of GCTDecl up - I found it quite hard to read and a bit confusing. The changes are mostly cosmetic: better delineation between the alternative cases and light touchups, and tries to make every branch as consistent as possible. However, this patch does have one significant effect: it will ensure that any LLVM-based compilers will use __thread if they support it. Before, they would simply always use pthread_getspecific and pthread_setspecific, which are almost surely even *more* inefficient. The details are a bit too long and boring to go into here; see #7602. After talking with Simon, we decided to play it safe - __thread can at least be optimized by future clang releases even further on OS X if they choose, and it's safer until we can investigate the pthread implementation further on Mavericks. For Linux, the story isn't so bleak if you use Clang (for whatever reason) - Linux directly writes to `%fs` for __thread slots (while OS X will perform a load followed by an indirect call.) So it should still be fairly competitive, speed-wise. Signed-off-by: Austin Seipp <austin@well-typed.com>
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