Exception raising can now be controlled by the caller.
The main purpose on this patch is:
- Suppress exceptions from `obj_free()` in `src/gc.c` with `mrb_env_unshare()`.
- Consider the possibility that calls to `mrb_malloc()` may cause `e` objects to be subject to GC.
When control is returned to `mrb_env_unshare()`, `struct free_obj::next` in the same offset as `struct REnv::stack` is rewritten.
Unexpected results then occur when the object is reused.
Also, if `mrb_heap_page` containing an `e` object is freed, it may cause `SIGSEGV` at that point.
- Protects the value of the stack on `callinfo` that just exits if GC occurs inside `mrb_env_unshare()`.
```ruby
def m
b = -> { b }
end
p m.call
# => print block object, not nil
```
This patch does not raise a `NoMemoryError` exception in `mrb_env_unshare()` and can detect that error.
Thus, the problem fixed in # 3087 is not resurrected.
Also, it may seem that this patch should suppress exceptions raised by `cipop()` during `mrb_protect_error()` and `mrb_vm_exec()` unwinds.
However, `mrb_callinfo::u.env` by `CINFO_DIRECT` is not seen to be set.
So in that case `mrb_env_unshare()` is assumed to be originally exception-free.
The mrbgem guide (`doc/guides/mrbgems.md`) documents the `path:`
argument for `conf.gem` as being used to point to the root directory
of a gem when that gem is retrieved via git but is located in a
subdirectory of the checkout.
The actual code does not do this. Instead, it treats path as (mostly)
identical to the `gemdir:` argument; that is, it points to a local
directory containing the gem.
This change fixes this by making `path:` behave as documented.
This was the cause of the command line flag being affected by changes in the parent build.
So, for example, if `mruby-rational` was included, even the automatically added `mrbc` builds included `MRB_USE_RATIONAL`.
Each build target can be explicitly disabled from benchmarking with `MRuby::Build#disable_benchmark`.
Also, the build target "host", which was previously excluded, is now included in the benchmark.
- Converted LoadGems::load_special_path_gems() into a class, then
subdivided the various types of gem dependencies into smaller
private methods.
- Added class GemDepDetails to hold the relationship between a gem's
location on the local disk and its upstream repository. This will
be used later.
- Removed the last remains of the '--pull-gems' option from the code
base and documentation. This is no longer present and the dead code
is clutter.
Gracefully handle the case where multiple gems use the same git checkout path.
Previously, if two gems had the same directory name when cloning them
from git, mrbgems would assume they were the same gem. This also
applied to different branches and/or commits of the same repository.
This led to a strange situation where the first `conf.gem` statement
"won" in cloning the repository but the last `conf.gem` ended up
choosing the branch/commit-id to use.
This change detects this situation and makes it an error. It also
allows the config writer to explicitly specify a gem checkout to use
in place of the others.
This adds a build_config that will cross-build a Windows executable
using the MinGW cross-compiler and will also run the unit (i.e.
'rake test') using Wine.
For this to work, I made some modifications to the underlying test
scripts as well as some minor changes to a couple of the tests
themselves.
When `disable_cdump` is declared on a Mrbgem spec, the procedure for
loading MRuby code from the gem's `mrblib` directory is slightly
different; instead of loading the mrblib code as a Proc built from the
compiled irep, the compiled irep is loaded directly. The header files
`mruby.h` and `mruby/proc.h` are needed only when the irep is loaded
directly. They are currently included only when presym is disabled, they
should be included whenever either presym is disabled *or* when
`disable_cdump` is called. The `cdump?` predicate method happens to
return true in either case (presym disabled *or* cdump disabled), so
this change should be safe.
If I break out of a block given to `MRuby::Build.new` with `break` or `throw`, I will get a seemingly inexplicable error because the `presym`-related initialization is not done.
```console
% cat build_config1.rb
MRuby::Build.new do
toolchain
break
end
% rake CONFIG=build_config1.rb
rake aborted!
external mrbc or mruby-bin-mrbc gem in current('host') or 'host' build is required
/var/tmp/mruby/lib/mruby/build.rb:332:in `mrbcfile'
/var/tmp/mruby/tasks/mrblib.rake:9:in `block in <top (required)>'
/var/tmp/mruby/lib/mruby/build.rb:18:in `instance_eval'
/var/tmp/mruby/lib/mruby/build.rb:18:in `block in each_target'
/var/tmp/mruby/lib/mruby/build.rb:17:in `each'
/var/tmp/mruby/lib/mruby/build.rb:17:in `each_target'
/var/tmp/mruby/tasks/mrblib.rake:1:in `<top (required)>'
/var/tmp/mruby/Rakefile:27:in `load'
/var/tmp/mruby/Rakefile:27:in `<top (required)>'
(See full trace by running task with --trace)
```
If a non-exceptional global jump occurs, it can be initialized by `ensure` to solve this problem.
If the current directory is different from `MRUBY_ROOT` and it has` conf.build_dir` and `conf.enable_cxx_exception` set, it was generating a pathname outside of` build_dir`.
As a result, in some cases files unrelated to mruby could be linked.
```console
% pwd
/tmp/mruby/1/2/3/4/5/6
% mruby_dir=/tmp/mruby/a/b/c/d/mruby
% cat my_config.rb
MRuby::Build.new("host", "build/to/custom/directory") do
toolchain
enable_cxx_exception
end
% rake MRUBY_CONFIG=my_config.rb -f $mruby_dir/Rakefile > logs
% grep CXX logs
CXX a/b/c/d/mruby/src/error-cxx.cxx -> a/b/c/d/mruby/src/error-cxx.o
CXX a/b/c/d/mruby/src/gc-cxx.cxx -> a/b/c/d/mruby/src/gc-cxx.o
CXX a/b/c/d/mruby/src/vm-cxx.cxx -> a/b/c/d/mruby/src/vm-cxx.o
CXX a/b/c/d/mruby/mrbgems/mruby-compiler/core/codegen-cxx.cxx -> a/b/c/d/mruby/mrbgems/mruby-compiler/core/codegen-cxx.o
CXX a/b/c/d/mruby/mrbgems/mruby-compiler/core/y.tab-cxx.cxx -> a/b/c/d/mruby/mrbgems/mruby-compiler/core/y.tab-cxx.o
CXX ../a/b/c/d/mruby/src/error-cxx.cxx -> ../a/b/c/d/mruby/src/error-cxx.o
CXX ../a/b/c/d/mruby/src/gc-cxx.cxx -> ../a/b/c/d/mruby/src/gc-cxx.o
CXX ../a/b/c/d/mruby/src/vm-cxx.cxx -> ../a/b/c/d/mruby/src/vm-cxx.o
```
Prevents the auto-generated mrbc target source code from being compiled under host conditions.
This is because a build error occurred when `conf.enable_cxx_exception` was set.
If we modify an option that may have been specified by users, we may
make unintended changes, so it is better not to modify it as much as
possible, IMO.
Because a structure that is an element of `presym_table` has padding, split
it into individual arrays for name and length.
#### Result (64-bit CPU with full-core gembox)
| | mruby | libmruby.a |
|--------|------------|------------|
| Before | 1,087,444B | 1,476,872B |
| After | 1,079,340B | 1,469,784B |
With this change, the test code will not be built unless `rake test` is
run, so there will be almost no side effects even if `enable_test` is
always set (but, gems specified by `add_test_dependency` are included
in `libmruby.a`).
Also added are `test: build` task, which only builds the test code
(including the main code), and `test: run` task, which only runs tests
independent of build. Therefore, the idiom for building in parallel and
not running tests in parallel is `rake -m test:build && rake test:run`.
The accuracy is greatly improved by using the C preprocessor to scan C
sources for presym. C preprocessor can perfectly interpret all comments and
preprocessor directives, so it can detect all symbols defined, for example
`mrbgems/mruby-socket/src/const.cstub`.
Also, as described later, this change will greatly improve the accuracy of
presym detection from Ruby sources.
## Result
The number of lines in the `presym` file for all gems is as follows:
```console
Previous: 999 (false positive = 89, undetected = 297)
New: 1207
```
## Build process
The new build process (with presym) is as follows:
1. Build `mrbc` without presym (more on building without presym later).
2. Compile Ruby sources to C struct format with the `mrbc` created in
step 1, and create` mrblib.c` and `gem_init.c`. Note that the symbols
in the created files are output as `MRB_SYM` family macros or
`mrb_intern_lit` instead of IDs (details will be described later).
3. C preprocessor processes C sources including the created files of
step 2 and outputs them as `.i` files. In these files, for example,
`MRB_IVSYM(foo)` is converted to `<@! "@" "foo" !@>` and
`mrb_define_module(mrb, "Foo")` is converted to `<@! "Foo" !@>`.
4. Scan the files created in step 3 and create `presym` and` presym.inc`
files.
The files created in step 2 should output all static symbols defined in Ruby
sources, including local variables, so we can detect all presyms by just
scanning C sources without scanning Ruby sources directly.
Further, by this process, the files to be scanned becomes the same as the
files to be compiled, so that there is no excess or deficiency.
## Related changes
The following changes have been made in relation to realizing this feature.
### Allow build without presym
It enables build without presym to achieve the "Build process: 1". This
incorporates #5202, see its issue for details.
Note that when presym is enabled, even adding a local variable to a Ruby
source may change contents of presym and require recompilation of almost
all C sources. This is inconvenient, especially during trial and error in
development, but this feature is also useful because it does not cause
this problem if presym is disabled.
### Automatically create build target for `mrbc` without presym
The `mrbc` used in the "Build process: 1" will be built by automatically
creating a build target for it. The build name is `SOURCE_BUILD_NAME/mrbc`.
### Constantize output of C struct format by `mrbc`
To realizing the "Build process: 2", as mentioned above, symbol IDs are not
output directly in C struct format output by `mrbc`. As a result, the output
becomes constant regardless of the state of presym at the time of `mrbc`
build, and it is possible to detect symbols of Ruby sources in the same way
as other C sources.
Note that `mrb_intern_lit` is used for symbols that do not become presym,
but in this state, the corresponding element in the symbol array cannot be
statically initialized, so it is initialized at run time (therefore, in this
case, the `const` qualifier is not added to the symbol array).
### Specify arbitrary `mrbc` file
To realizing the "Build process: 2", enabled to specify `mrbc` created by
another build target or pre-built` mrbc`. Use `MRuby::Build#mrbcfile =` to
specify it explicitly. You can omit the "Build process: 1" by specifying
pre-built `mrbc`, and you can always use an optimized build to compile Ruby
sources faster. I think changes that affect the output of `mrbc` are rare,
so in many cases it helps to improve efficiency.
With presym, the build will be a little slower due to more build steps, but
this feature will improve it a bit.
### Create presym files for each build target
This feature was proposed at #5194 and merged once, but was reverted in
5c205e6e due to problems especially with cross-compilation. It has been
introduced again because this change solves the problem.
The presym files will be created below.
* `build/NAME/presym`
* `build/NAME/include/mruby/presym.inc`
### Other changes
* Because presym detection accuracy is greatly improved as mentioned above,
`MRuby::Gem::Specification#cdump?` is set to true by default, and
`disable_cdump` is added instead of `enable_cdump`. Also, support for gem
specific presym files has been discontinued (https://github.com/mruby/mruby/issues/5151#issuecomment-730967232).
* Previously, `mrbc` was automatically created for the `host` build, but it
will not be created if the build target for `mrbc` mentioned above is
automatically created. At this time, `mrbc` file of the `mrbc` build is
copied to` bin/`.
* Two types of `.d` files will be created, `.o.d` and `.i.d`. oThis is
because if `.i` depends on `presym.inc`, the dependency will circulate, so
the `.d` file cannot be shared.
* Changed file created with `enable_cxx_exception` to `X-cxx.cxx` from
`X.cxx` to use the mruby standard Rake rule.
### Note
Almost all C sources will need to be recompiled if there are any changes to
`persym.inc` (if not recompiled properly, it will often result in run-time
error). If `gcc` toolchain is used, dependencies are resolved by the `.d`
file, so it become automatically recompile target, but if not (e.g. MSVC),
it is necessary to manually make it recompile target.
Also, even if `gcc` toolchain is used, it may not become recompile target if
external gems does not use the mruby standard Rake rule. In particular, if
the standard rule is overwritten, such as
https://github.com/mruby/mruby/pull/5112/files, `.d` file will not be read,
so be careful.
Previously, `libmruby.a` was created even if only `mruby-bin-mrbc` or`
mruby-compiler` was specified for gem, but by specifying `disable_libmruby`,
the creation of `libmruby.a` can be suppressed.
### Note
The https://github.com/mruby/mruby/pull/5084#issuecomment-723521971
incompatibility seems to be difficult for users to avoid, so the original
behavior has been restored. Therefore, if we need `mrbc` other than the
`host` build, we need to explicitly specify `mruby-bin-mrbc` gem.
Due to the above changes, `build_config/boxing.rb` etc. will not work, but I
have added` mruby-bin-mrbc` to `default.gembox` to fix it. I don't think
this change is a big deal because originally `mruby-compiler` was included.
John Bampton