Add support for static symbols and GOT #60
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This tests compilation of relocatable calls.
So far each label symbol (`TRLabelSymbol`) has been associated with block (`TRILBlock`). This commits relaxes this association - every label now may or may not be associated with block. This allows labels to be also used in "local control flows" (local meaning within one evaluator). It will also allow to unify labels with other symbol types (such as function symbols or statics). Technically, a `TRLabelSymbol` the association is still from symbol to block. I have tried to make it the other way round, from block to it's symbol, but that made code managing CFG bit ugly so I decided to keep it like this for time being.
Static symbols represent data stored on the heap (as opposed to data stored in frame which are represented by `TRRegisterMappedSymbol`s) and therefore have a single unique absolute address. The address however may not be known in advance so code individual code generators must always generate proper relocations when accessing static symbols. Jump labels and functions are special kind of static symbols.
This commit adds `TRTarget >> endian` which can be used by various parts when reading from / writing to (target) memory. As of now, both RISC-V and POWER targets are hard-coded as little endian even thought this is not always true. This may be fixes in the future. The rest of Tinyrossa code should consult `TRTarget >> endian` wherever necessary.
Commit b32bc8e added `TRDataType >> #sizeInBytes`. While it is convenient and looks like a good OO design, it does not really work. The size of `Address` (pointer) is architecture-dependent. This commit deprecates `TRDataType >> #sizeInBytes` in favour of `TRTarget >> sizeInBytesOf:` and updates users. Note, that `TRDataType >> #sizeInBytes` has been kept there as "should-not-implement" with comment to prevent future myself to make this tempting mistake again.
This commit adds support for GOT-based accesses (for loading / storing values from / to static symbols). This is implemented by handling `AcRelocationRequestGOTEntry`.
This commit changes `TRRV64GSystemLinkage` to compile relocatable calls using pair of `auipc` and `jalr` with `R_RISCV_CALL_PLT` relocation.
This commit implements loads and stores for static symbols using 32bit PC-relative addressing. In the future, we should use GOT access to allow static symbols to be located anywhere in address space, but this needs to wait for GOT (and PLT) support in code cache.
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This PR adds support for static symbols and for loading/storing into them via GOT. This is implemented by handling
AcRelocationRequestGOTEntryinTRCodeCache >> #link. GOT entries are allocated from the "end" of the code cache.