In 'lundump.c', when loading the upvalues of a function, there can be
a read error if the chunk is truncated. In that case, the creation
of the error message can trigger an emergency collection while the
prototype is still anchored. So, the prototype must be GC consistent
before loading the upvales, which implies that it the 'name' fields
must be filled with NULL before the reading.
The parser were mixing compiler indices of variables with stack indices,
so that when a to-be-closed variable was used inside the scope of
compile-time constants (which may be optimized away), it might be closed
in the wrong place. (See new tests for examples.)
Besides fixing the bugs, this commit also changed comments and variable
names to avoid that kind of confusion and added tests.
(Undoing part of commit f53eabeed8.) It is better to keep this encoding
stable, so that all Lua versions can read at least the version of a
binary file.
Instead of an explicit value (field 'b'), true and false use different
tag variants. This avoids reading an extra field and results in more
direct code. (Most code that uses booleans needs to distinguish between
true and false anyway.)
The initial "\n\t" to properly indent a searcher message is being added
by 'findloader' when building the error message, instead of being
included in the original message by each searcher itself.
- Several details in 'lcode.c'
- A few more tests for code generation
- Bug in assert in 'lcode.c' ("=" x "==")
- Comments in 'lopcodes.h' and 'ltable.c'
The difference in performance between immediate operands and K operands
does not seem to justify all those extra opcodes. We only keep OP_ADDI,
due to its ubiquity and because the difference is a little more relevant.
(Later, OP_SUBI will be implemented by OP_ADDI, negating the constant.)
In arithmetic/bitwise operators, the call to metamethods is made
in a separate opcode following the main one. (The main
opcode skips this next one when the operation succeeds.) This
change reduces slightly the size of the binary and the complexity
of the arithmetic/bitwise opcodes. It also simplfies the treatment
of errors and yeld/resume in these operations, as there are much
fewer cases to consider. (Only OP_MMBIN/OP_MMBINI/OP_MMBINK,
instead of all variants of all arithmetic/bitwise operators.)
The family of opcodes OP_ADDK (arithmetic operators with K constant)
were not being handled in 'luaV_finishOp', which completes their
task after an yield.
When using warn-mode '@store', from the test library, the tests ensure
not only that the expected warnings were issued, but also that there was
no extra warnings.
The macro 'luaL_pushfail' documents all places in the standard libraries
that return nil to signal some kind of failure. It is defined as
'lua_pushnil'. The manual also got a notation (@fail) to document those
returns. The tests were changed to be agnostic regarding whether 'fail'
is 'nil' or 'false'.
Added the concept of control messages to the warning system, plus the
implementation of the controls "@on"/"@off" to turn warnings on/off.
Moreover, the warning system in the test library adds some other
controls to ease the test of warnings.
When initializing a to-be-closed variable, check whether it has a
'__close' metamethod (or is a false value) and raise an error if
if it hasn't. This produces more accurate error messages. (The
check before closing still need to be done: in the C API, the value
is not constant; and the object may lose its '__close' metamethod
during the block.)
The test "to-be-closed variables in main chunk" was broken,
as it used the removed feature of functions as to-be-closed values.
The error was not detected because its expected result had no lines
to be checked (due to missing new lines).
Attributes changed to posfixed ('x <const>', instead of '<const> x'),
and "toclose" renamed to "close". Posfixed attributes seem to make it
clearer that it applies to only one variable when there are multiple
variables.
Instead of updating 'L->top' in every place that may call a
metamethod, the metamethod functions themselves (luaT_trybinTM and
luaT_callorderTM) correct the top. (When calling metamethods from
the C API, however, the callers must preserve 'L->top'.)
- OP_NEWTABLE can use 'ra + 1' to set top (instead of ci->top);
- OP_CLOSE doesn't need to set top ('Protect' already does that);
- OP_TFORCALL must use 'ProtectNT', to preserve the top already set.
(That was a small bug, because iterators could be called with
extra parameters besides the state and the control variable.)
- Comments and an extra test for the bug in previous item.
As an example, 'print(string.format("%.99f", 1e70))' may have a
lot of garbage after the number.
The old test to ensure that 'string.format("%.99f", n)' was not too
large, 'fabs(n) < 1e100', assumes that the number will fit in the 99
bytes; but the 99 is not the space for the number, it is the added
extra zeros. The option worked for smaller numbers because of the
extra space added to MAX_ITEM.
The addresses of static variables may be different for different
instances of Lua, making these instances incompatible if they use
these addresses as unique keys in the registry (or other tables).
- Macro 'checkliveness' (for debug) always uses 'L', to avoid warnings.
- Some old 'while' changed to 'for' in 'testes/gc.lua'.
- In 'testes/libs/makefile', do not make files depend on 'ltests.h',
which may not even exist.
This commit brings a new implementation for HARDMEMTESTS, which forces
an emergency GC whenever possible. It also fixes some issues detected
with this option:
- A small bug in lvm.c: a closure could be collected by an emergency
GC while being initialized.
- Some tests: a memory address can be immediatly reused after a GC;
for instance, two consecutive '{}' expressions can return exactly the
same address, if the first one is not anchored.
Constants directly assigned to other constants were not propagating:
For instance, in
local <const> k1 = 10
local <const> k2 = k1
'k2' were not treated as a compile-time constant.
String literal expressions have their own kind VKSTR, instead of the
generic VK. This allows strings to "cross" functions without entering
their constant tables (e.g., if they are used only by some nested
function).
An error in a closing method may be caused by a lack of resources,
such as memory or stack space, and the error may free enough resources
(by unwinding the stack) to allow the method to work if called again.
If the closing method is already running after some error (including
its own), it is not called again.
Opcodes OP_NEWTABLE and OP_SETLIST use the same representation to
store the size of the array part of a table. This new representation
can go up to 2^33 (8 + 25 bits).
OP_NEWTABLE is followed by an OP_EXTRAARG, so that it can keep
the exact size of the array part of the table to be created.
(Functions 'luaO_int2fb'/'luaO_fb2int' were removed.)
In the generic for loop, it is simpler for OP_TFORLOOP to use the
same 'ra' as OP_TFORCALL. Moreover, the internal names of the loop
temporaries "(for ...)" don't need to leak internal details (even
because the numerical for loop doesn't have a fixed role for each of
its temporaries).
VLOCAL expressions keep a reference to their corresponding 'Vardesc',
and 'Upvaldesc' (for upvalues) has a field 'ro' (read-only). So, it is
easier to check whether a variable is read-only. The decoupling in
VLOCAL between 'vidx' ('Vardesc' index) and 'sidx' (stack index)
should also help the forthcoming implementation of compile-time
constant propagation.
The syntax for local attributes ('const'/'toclose') was unified with
the regular syntax for local variables, so that we can have variables
with attributes in local definitions with multiple names; for instance:
local <toclose> f, <const> err = io.open(fname)
This new syntax does not implement constant propagation, yet.
This commit also has some small improvements to the manual.
