This allows creation of TCCStates and operation with API
calls independently from each other, even from threads.
Frontend (option parsing/libtcc.c) and backend (linker/tccelf.c)
now depend only on the TCCState (s1) argument.
Compilation per se (tccpp.c, tccgen.c) is still using
globals for convenience. There is only one entry point
to this section which is tcc_compile() which is protected
by a semaphore.
There are some hacks involved to avoid too many changes,
as well as some changes in order to avoid too many hacks ;)
The test libtcc_test_mt.c shows the feature. Except this
new file the patch adds 87 lines overall.
relocs against defined symbols are replaced by relative
relocs, when a GOT slot is created. But code relocs (usually
calls via PLT) use the plt_offset member of attr, not the got_offset
member, so the "huh" warning was triggered in the case of calls to
static functions (the code still worked).
So, for now just use the AUTO_GOT_PLT mechanism. We could also
emit a non-PLT reloc in the backend for calls to VT_STATIC functions
(like the x86-64 backend does) and do the same as for x86-64 in
build_got_entries (which transforms PLT32 into PC32 relocs, riscv
would transform CALL_PLT into CALL relocs). Maybe later.
* support loading sym addresses from GOT: important for weak syms,
fixes 104_inline. This is still incomplete, it only works
for taking the sym address, not for directly loading/storing into
such symbols (i.e. not for VT_LVAL)
* another op: '%'
* ELF flags: add EF_RISCV_FLOAT_ABI_DOUBLE, which is our ABI.
* implement compares, gtst and gsym/gjmp and add
* implement stores (simple cases)
* fix arg passing with more than one register arg, fix
loads to not always use 8byte loads
* add some predefined macros: __riscv, __riscv_xlen,
__SIZEOF_POINTER__ (needed by glibc header)
The first 5 tests of tests2 run now.
this is enough to let me link a tcctest.c compiled by GCC
using some current debian sid riscv64 system. It needs
linking against libgcc.a for various floating point TFmode
routines. The result runs.
