Teach `-dgc2stack` to promote GC allocations in simple loops to stack allocations too. (A "simple" loop is one where the allocation isn't used in a subsequent iteration) This also means it's no longer necessary to run this pass multiple times. Running it once after inlining should now catch all cases.

LLVM D Compiler (LDC)

This compiler is based on the Digital Mars D (DMD) compiler frontend, and
the LLVM compiler toolkit. See LICENSE for licensing information.

For more information, including build instructions, visit the LDC website:

http://www.dsource.org/projects/ldc