This patch adds the necessary hacks to support global constructors and
destructors. This is an incredibly hacky process caused by the primary
fact that Nvidia does not provide any binary tools and very little
linker support. We first had to emit references to these functions and
their priority in D149451. Then we dig them out of the module once it's
loaded to manually create the list that the linker should have made for
us. This patch also contains a few Nvidia specific hacks, but it passes
the test, albeit with a stack size warning from `ptxas` for the
callback. But this should be fine given the resource usage of a common
test.
This also adds a dependency on LLVM to the NVPTX loader, which hopefully doesn't
cause problems with our CUDA buildbot.
Depends on D149451
Reviewed By: tra
Differential Revision: https://reviews.llvm.org/D149527
2e1c0ec629