New functions to reset/kill a thread/coroutine, mainly (only?) to
close any pending to-be-closed variable. ('lua_resetthread' also
allows a thread to be reused...)
(Long time without testing with '-DHARDSTACKTESTS'...)
With the introduction of to-be-closed variables, calls to 'luaF_close'
can move the stack, but some call sites where keeping pointers to the
stack without correcting them.
Sometimes it is useful to mark to-be-closed an index that is not
at the top of the stack (e.g., if the value to be closed came from
a function call returning multiple values).
The new syntax is <local *toclose x = f()>. The mark '*' allows other
attributes to be added later without the need of new keywords; it
also allows better error messages. The API function was also renamed
('lua_tobeclosed' -> 'lua_toclose').
The mechanism of "caching the last closure created for a prototype to
try to reuse it the next time a closure for that prototype is created"
was removed. There are several reasons:
- It is hard to find a natural example where this cache has a measurable
impact on performance.
- Programmers already perceive closure creation as something slow,
so they tend to avoid it inside hot paths. (Any case where the cache
could reuse a closure can be rewritten predefining the closure in some
variable and using that variable.)
- The implementation was somewhat complex, due to a bad interaction
with the generational collector. (Typically, new closures are new,
while prototypes are old. So, the cache breaks the invariant that
old objects should not point to new ones.)
Added restriction that, when a label is created, there cannot be
another label with the same name visible. That allows backward goto's
to be resolved when they are read. Backward goto's get a close if
they jump out of the scope of some variable; labels get a close only
if previous goto to it jumps out of the scope of some upvalue.
Start of the implementation of "scoped variables" or "to be closed"
variables, local variables whose '__close' (or themselves) are called
when they go out of scope. This commit implements the syntax, the
opcode, and the creation of the corresponding upvalue, but it still
does not call the finalizations when the variable goes out of scope
(the most important part).
Currently, the syntax is 'local scoped name = exp', but that will
probably change.
When creating code for a jump on a 'not' condition, the code generator
was removing an instruction (the OP_NOT) without adjusting its
corresponding line information.
This fix also added tests for this case and extra functionality in
the test library to debug line info. structures.
The array with the names of the opcodes was moved to a header file
('lopnames.h'), as it is not used by the Lua kernel. Files that need
that array ('luac.c' and 'ltests.c') include the header file to get
a private (static) copy.
values, so that the array can use bytes instead of ints, reducing
its size. (A new array 'abslineinfo' is used when line differences
do not fit in a byte.)
if the key is dead, it cannot be given to 'next'. Instead, we now
use a 'table' tag without the collectable bit, which makes it
a unique tag good enough to reserve space.
Roberto Ierusalimschy