This commit combines the sweep step with moving objects. With this
commit, we can do:
```ruby
GC.start(compact: true)
```
This code will do the following 3 steps:
1. Fully mark the heap
2. Sweep + Move objects
3. Update references
By default, this will compact in order that heap pages are allocated.
In other words, objects will be packed towards older heap pages (as
opposed to heap pages with more pinned objects like `GC.compact` does).
If a module has an origin, and that module is included in another
module or class, previously the iclass created for the module had
an origin pointer to the module's origin instead of the iclass's
origin.
Setting the origin pointer correctly requires using a stack, since
the origin iclass is not created until after the iclass itself.
Use a hidden ruby array to implement that stack.
Correctly assigning the origin pointers in the iclass caused a
use-after-free in GC. If a module with an origin is included
in a class, the iclass shares a method table with the module
and the iclass origin shares a method table with module origin.
Mark iclass origin with a flag that notes that even though the
iclass is an origin, it shares a method table, so the method table
should not be garbage collected. The shared method table will be
garbage collected when the module origin is garbage collected.
I've tested that this does not introduce a memory leak.
This change caused a VM assertion failure, which was traced to callable
method entries using the incorrect defined_class. Update
rb_vm_check_redefinition_opt_method and find_defined_class_by_owner
to treat iclass origins different than class origins to avoid this
issue.
This also includes a fix for Module#included_modules to skip
iclasses with origins.
Fixes [Bug #16736]
If a module has an origin, and that module is included in another
module or class, previously the iclass created for the module had
an origin pointer to the module's origin instead of the iclass's
origin.
Setting the origin pointer correctly requires using a stack, since
the origin iclass is not created until after the iclass itself.
Use a hidden ruby array to implement that stack.
Correctly assigning the origin pointers in the iclass caused a
use-after-free in GC. If a module with an origin is included
in a class, the iclass shares a method table with the module
and the iclass origin shares a method table with module origin.
Mark iclass origin with a flag that notes that even though the
iclass is an origin, it shares a method table, so the method table
should not be garbage collected. The shared method table will be
garbage collected when the module origin is garbage collected.
I've tested that this does not introduce a memory leak.
This also includes a fix for Module#included_modules to skip
iclasses with origins.
Fixes [Bug #16736]
Ruby's GC is incremental, meaning that during the mark phase (and also
the sweep phase) programs are allowed to run. This means that programs
can allocate objects before the mark or sweep phase have actually
completed. Those objects may not have had a chance to be marked, so we
can't know if they are movable or not. Something that references the
newly created object might have called the pinning function during the
mark phase, but since the mark phase hasn't run we can't know if there
is a "pinning" relationship.
To be conservative, we must only allow objects that are not pinned but
also marked to move.
This patch allows global variables that have been assigned in Ruby to
move. I added a new function for the GC to call that will update
global references and introduced a new callback in the global variable
struct for updating references.
Only pure Ruby global variables are supported right now, other
references will be pinned.
No objects should ever reference a `T_MOVED` slot. If they do, it's
absolutely a bug. If we kill the process when `T_MOVED` is pushed on
the mark stack it will make it easier to identify which object holds a
reference that hasn't been updated.
We only need to loop `T_MASK` times once. Also, not every value between
0 and `T_MASK` is an actual Ruby type. Before this change, some
integers were being added to the result hash even though they aren't
actual types. This patch omits considered / moved entries that total 0,
cleaning up the result hash and eliminating these "fake types".
This compile-time option has been broken for years (at least since
commit 49369ef173, according to git
bisect). Let's delete codes that no longer works.
ISO/IEC 9899:1999 section 6.10.3 paragraph 11 explicitly states that
"If there are sequences of preprocessing tokens within the list of
arguments that would otherwise act as preprocessing directives, the
behavior is undefined."
rb_str_new_cstr is in fact a macro. We cannot do this.
This patch contains several ideas:
(1) Disposable inline method cache (IMC) for race-free inline method cache
* Making call-cache (CC) as a RVALUE (GC target object) and allocate new
CC on cache miss.
* This technique allows race-free access from parallel processing
elements like RCU.
(2) Introduce per-Class method cache (pCMC)
* Instead of fixed-size global method cache (GMC), pCMC allows flexible
cache size.
* Caching CCs reduces CC allocation and allow sharing CC's fast-path
between same call-info (CI) call-sites.
(3) Invalidate an inline method cache by invalidating corresponding method
entries (MEs)
* Instead of using class serials, we set "invalidated" flag for method
entry itself to represent cache invalidation.
* Compare with using class serials, the impact of method modification
(add/overwrite/delete) is small.
* Updating class serials invalidate all method caches of the class and
sub-classes.
* Proposed approach only invalidate the method cache of only one ME.
See [Feature #16614] for more details.
Now, rb_call_info contains how to call the method with tuple of
(mid, orig_argc, flags, kwarg). Most of cases, kwarg == NULL and
mid+argc+flags only requires 64bits. So this patch packed
rb_call_info to VALUE (1 word) on such cases. If we can not
represent it in VALUE, then use imemo_callinfo which contains
conventional callinfo (rb_callinfo, renamed from rb_call_info).
iseq->body->ci_kw_size is removed because all of callinfo is VALUE
size (packed ci or a pointer to imemo_callinfo).
To access ci information, we need to use these functions:
vm_ci_mid(ci), _flag(ci), _argc(ci), _kwarg(ci).
struct rb_call_info_kw_arg is renamed to rb_callinfo_kwarg.
rb_funcallv_with_cc() and rb_method_basic_definition_p_with_cc()
is temporary removed because cd->ci should be marked.
On s390x, TestFiber#test_stack_size fails with SEGV.
20200205T223421Z.fail.html.gz
```
TestFiber#test_stack_size [/home/chkbuild/build/20200205T223421Z/ruby/test/ruby/test_fiber.rb:356]:
pid 23844 killed by SIGABRT (signal 6) (core dumped)
| -e:1:in `times': stack level too deep (SystemStackError)
| from -e:1:in `rec'
| from -e:1:in `block (3 levels) in rec'
| from -e:1:in `times'
| from -e:1:in `block (2 levels) in rec'
| from -e:1:in `times'
| from -e:1:in `block in rec'
| from -e:1:in `times'
| from -e:1:in `rec'
| ... 172 levels...
| from -e:1:in `block in rec'
| from -e:1:in `times'
| from -e:1:in `rec'
| from -e:1:in `block in <main>'
| -e: [BUG] Segmentation fault at 0x0000000000000000
```
This change tries a similar fix with
ef64ab917e and
3ddbba84b5.
Saves comitters' daily life by avoid #include-ing everything from
internal.h to make each file do so instead. This would significantly
speed up incremental builds.
We take the following inclusion order in this changeset:
1. "ruby/config.h", where _GNU_SOURCE is defined (must be the very
first thing among everything).
2. RUBY_EXTCONF_H if any.
3. Standard C headers, sorted alphabetically.
4. Other system headers, maybe guarded by #ifdef
5. Everything else, sorted alphabetically.
Exceptions are those win32-related headers, which tend not be self-
containing (headers have inclusion order dependencies).
One day, I could not resist the way it was written. I finally started
to make the code clean. This changeset is the beginning of a series of
housekeeping commits. It is a simple refactoring; split internal.h into
files, so that we can divide and concur in the upcoming commits. No
lines of codes are either added or removed, except the obvious file
headers/footers. The generated binary is identical to the one before.
