Enable most simplify-cfg optimizations as long as the block arguments
have trivial types. Enable most simplify CFG unit tests cases.
This massively reduces the size of the CFG during OSSA passes.
Test cases that aren't supported in OSSA yet have been moved to a
separate test file for disabled OSSA tests,
Full simplify-cfg support is currently blocked on OSSA utilities which
I haven't checked in yet.
This is needed for non-OSSA SIL: in case we see a destroyArray builtin, we can safely remove the otherwise dead array.
This optimization kicks in later in the pipeline, after array semantics are already inlined (for early SIL, DeadObjectElimination can remove arrays based on semantics).
rdar://73569282
https://bugs.swift.org/browse/SR-14100
One of the subtests cannot be fully optimized without
swift_stdlib_no_asserts because, with runtime verification
enabled, "array.finalize" becomes a mutating operation, preventing
SILCombine from deleting it when it removes dead pure
instructions. After inlining, DeadObjectElimination is still
unable to remove the array because a second array is initialized
by copying the first. This problem can be overcome by handling
non-trivial stores in OSSA, as described here:
[OSSA] Improve DeadObjectElimination to handle array copies
https://bugs.swift.org/browse/SR-13782
semantics attribute that is used by the top-level array initializer (in ArrayShared.swift),
which is the entry point used by the compiler to initialize array from array literals.
This initializer is early-inlined so that other optimizations can work on its body.
Fix DeadObjectElimination and ArrayCOWOpts optimization passes to work with this
semantics attribute in addition to "array.uninitialized", which they already use.
Refactor mapInitializationStores function from ArrayElementValuePropagation.cpp to
ArraySemantic.cpp so that the array-initialization pattern matching functionality
implemented by the function can be reused by other optimizations.
