Undo commit c220b0a5d0: '__close' is not called again in case of
errors. (Upvalue is removed from the list before the call.) The
common error that justified that change was C stack overflows, which
are much rarer with the stackless implementation.
* Avoids multiple definitions of 'lua_assert' in test file.
* Smaller C-stack limit in test mode.
* Note in the manual about the use of false
* Extra test for constant reuse.
References were using both 0 indices and nils as values in arrays.
Both do not fit in the concept of a sequence, which is the kind
of use that guides all Lua optimizations.
When a stack grows, its extra area can be in use, and it becomes part
of the common area. So, the extra area must be kept correct all the
times. (Bug introduced by commit 5aa36e894f5.)
The allocation of a userdata for the state of the warn system can
cause a panic if it fails; 'luaL_ref' also can fail. This commit
re-implements the warn system so that it does not need an explicit
state. Instead, the system uses different functions to represent
the different states.
Fixed the bug that a key removed from a table might not be found
again by 'next'. (This is needed to allow keys to be removed during a
traversal.) This bug was introduced in commit 73ec04fc.
Hashes for long strings are computed only when they are used as keys
in a table, not a too common case. And, in that case, it is to easy to
force collisions changing only the characters which are not part of the
hash.
- After converting a generic GCObject to a specific type ('gco2*'),
avoid using the original GCObject (to reduce aliasing).
- Small corrections in comments in 'lopcodes.h'
- Added tests about who calls __close metamethods
The stack size is derived from 'stack_last', when needed. Moreover,
the handling of stack sizes is more consistent, always excluding the
extra space except when allocating/deallocating the array.
Shrink a stack only when the final stack size can be at most 2/3 the
previous size with half of its entries empty. This commit also
improves the clarity of 'luaD_growstack'.
The previous stackless implementations marked all 'luaV_execute'
invocations as fresh. However, re-entering 'luaV_execute' when
resuming a coroutine should not be a fresh invocation. (It works
because 'unroll' called 'luaV_execute' for each call entry, but
it was slower than letting 'luaV_execute' finish all non-fresh
invocations.)
A "with stack" implementation gains too little in performance to be
worth all the noise from C-stack overflows.
This commit is almost a sketch, to test performance. There are several
pending stuff:
- review control of C-stack overflow and error messages;
- what to do with setcstacklimit;
- review comments;
- review unroll of Lua calls.
When "undumping" a long string, the function 'loadVector' can call the
reader function, which can run the garbage collector, which can collect
the string being read. So, the string must be anchored during the call
to 'loadVector'.
Avoid turning an object to gray except at the moment it is inserted in a
gray list or in the explicit exceptional cases such as open upvalues and
fixed strings.
- Macro 'gray2black' was renamed 'nw2black' (Non-White to black), as it
was already being used on objects that could be already black.
- Macros 'white2gray' and 'black2gray' were unified in 'set2gray'; no
reason to have two macros when one will do and, again, 'black2gray' was
already being used on objects that could be already gray.
Moreover, macros 'maskcolors' and 'maskgcbits' were negated to have
ones in the described bits, instead of zeros. (This naming seems more
intuitive.)
