We inline a function (e.g. a struct initializer) into a global init function if the result is part of the initialized global.
Now, also handle functions with indirect return values. Such function can result from not-reabstracted generic specializations.
Handle cases where the result is stored into a temporary alloc_stack or directly stored to (a part) of the global variable.
Before this change, if a global variable is required to be statically initialized (e.g. due to @_section attribute), we don't allow its type to be a struct, only a scalar type works. This change improves on that by teaching MandatoryPerformanceOptimizations pass to inline struct initializer calls into initializer of globals, as long as they are simple enough so that we can be sure that we don't trigger recursive/infinite inlining.
Generic specialization drops metatype arguments and therefore exposes opportunities to remove dead metatype instructions.
Instead of removing dead metatype instructions before specialization, try to remove them after specialization.
