* add `BasicBlockSet`
* add `BasicBlockWorklist`
* add `BasicBlockRange`, which defines a range of blocks from a common dominating “begin” block to a set of “end” blocks.
* add `InstructionRange`, which is similar to `BasicBlockRange`, just on instruction level. It can be used for value lifetime analysis.
* rename `StackList` -> `Stack` and move it to `Optimizer/DataStructures`
* rename `PassContext.passContext` to `PassContext._bridged`
* add notify-functions to PassContext
Use the include search path for the header search rather than
constructing the path using relative paths. This is important for
getting the interop to work properly as well.
Fixes a couple of compiler warnings that occur frequently when building the compiler:
- Copy the nullability annotation definitions from `Visibility.h` to `BridgedSwiftObject.h` and wrap all code that contains nullability annotations in `SWIFT_BEGIN_NULLABILITY_ANNOTATIONS` and `SWIFT_END_NULLABILITY_ANNOTATIONS` (supressing the warning `type nullability specifier '_Nullable' is a Clang extension [-Wnullability-extension]`)
- Suppress warnings about using `$` (mangling prefix) as an identifier using pragmas (supressing the warning `'$' in identifier [-Wdollar-in-identifier-extension]`)
- Change the macro condition of `SWIFT_NODISCARD` from `__cplusplus >= 201402l` (which checked for >= C++14) to `__cplusplus > 201402l`. This appears to have been a copy-paste error from `LLVM_NODISCARD` (supressing the warning `use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-extensions]`)
* unify FunctionPassContext and InstructionPassContext
* add a modification API: PassContext.setOperand
* automatic invalidation notifications when the SIL is modified
Instruction passes are basically visit functions in SILCombine for a specific instruction type.
With the macro SWIFT_INSTRUCTION_PASS such a pass can be declared in Passes.def.
SILCombine then calls the run function of the pass in libswift.
With the macro SWIFT_FUNCTION_PASS a new libswift function pass can be defined in Passes.def.
The SWIFT_FUNCTION_PASS_WITH_LEGACY is similar, but it allows to keep an original C++ “legacy” implementation of the pass, which is used if the compiler is not built with libswift.
