When building with link time optimization enabled it is possible both
gc_collect() and gc_collect_regs_and_stack() get inlined into gc_alloc()
which can result in the regs variable being pushed on the stack earlier
than some of the registers. Depending on the calling convention, those
registers might however contain pointers to blocks which have just been
allocated in the caller of gc_alloc(). Then those pointers end up higher on
the stack than regs, aren't marked by gc_collect_root() and hence get
sweeped, even though they're still in use.
As reported in #4652 this happened for in 32-bit msvc release builds:
mp_lexer_new() does two consecutive allocations and the latter triggered a
gc_collect() which would sweep the memory of the first allocation again.
This is to keep the top-level directory clean, to make it clear what is
core and what is a port, and to allow the repository to grow with new ports
in a sustainable way.
This allows the mp_obj_t type to be configured to something other than a
pointer-sized primitive type.
This patch also includes additional changes to allow the code to compile
when sizeof(mp_uint_t) != sizeof(void*), such as using size_t instead of
mp_uint_t, and various casts.
Now, if we build for an architecture which doesn't have dedicated support
for getting registers for GC scanning, fallback to setjmp-based method
automatically. It's still possible to force setjmp-based implementation
on archs with dedicated support (e.g. for testing, or for peculiar calling
conventions/optimizations).
Native code has GC-heap pointers in it so it must be scanned. But on
unix port memory for native functions is mmap'd, and so it must have
explicit code to scan it for root pointers.
This patch consolidates all global variables in py/ core into one place,
in a global structure. Root pointers are all located together to make
GC tracing easier and more efficient.
gc.enable/disable are now the same as CPython: they just control whether
automatic garbage collection is enabled or not. If disabled, you can
still allocate heap memory, and initiate a manual collection.
As I suspected for a long time, for x86, register helper doesn't really make
any difference - there's simply not enough register to keep anything in
them for any prolonged time. Anything gets pushed on stack anyway. So, on
x86, uPy passed all tests even with empty reg helper. So, this setjmp
implementation goes as "untested".
Blanket wide to all .c and .h files. Some files originating from ST are
difficult to deal with (license wise) so it was left out of those.
Also merged modpyb.h, modos.h, modstm.h and modtime.h in stmhal/.
stijn
Damien George
Alexander Steffen
Jan Pochyla
Paul Sokolovsky
stijn
Antonin ENFRUN
xbe