In December 2021, we opened an [issue] to solicit feedback regarding the
porting of the YJIT codebase from C99 to Rust. There were some
reservations, but this project was given the go ahead by Ruby core
developers and Matz. Since then, we have successfully completed the port
of YJIT to Rust.
The new Rust version of YJIT has reached parity with the C version, in
that it passes all the CRuby tests, is able to run all of the YJIT
benchmarks, and performs similarly to the C version (because it works
the same way and largely generates the same machine code). We've even
incorporated some design improvements, such as a more fine-grained
constant invalidation mechanism which we expect will make a big
difference in Ruby on Rails applications.
Because we want to be careful, YJIT is guarded behind a configure
option:
```shell
./configure --enable-yjit # Build YJIT in release mode
./configure --enable-yjit=dev # Build YJIT in dev/debug mode
```
By default, YJIT does not get compiled and cargo/rustc is not required.
If YJIT is built in dev mode, then `cargo` is used to fetch development
dependencies, but when building in release, `cargo` is not required,
only `rustc`. At the moment YJIT requires Rust 1.60.0 or newer.
The YJIT command-line options remain mostly unchanged, and more details
about the build process are documented in `doc/yjit/yjit.md`.
The CI tests have been updated and do not take any more resources than
before.
The development history of the Rust port is available at the following
commit for interested parties:
1fd9573d8b
Our hope is that Rust YJIT will be compiled and included as a part of
system packages and compiled binaries of the Ruby 3.2 release. We do not
anticipate any major problems as Rust is well supported on every
platform which YJIT supports, but to make sure that this process works
smoothly, we would like to reach out to those who take care of building
systems packages before the 3.2 release is shipped and resolve any
issues that may come up.
[issue]: https://bugs.ruby-lang.org/issues/18481
Co-authored-by: Maxime Chevalier-Boisvert <maximechevalierb@gmail.com>
Co-authored-by: Noah Gibbs <the.codefolio.guy@gmail.com>
Co-authored-by: Kevin Newton <kddnewton@gmail.com>
Commit dde164e968 decoupled incremental
marking from page sizes. This commit changes Ruby heap page sizes to
64KiB. Doing so will have several benefits:
1. We can use compaction on systems with 64KiB system page sizes (e.g.
PowerPC).
2. Larger page sizes will allow Variable Width Allocation to increase
slot sizes and embed larger objects.
3. Since commit 002fa28599, macOS has 64
KiB pages. Making page sizes 64 KiB will bring these systems to
parity.
I have attached some bechmark results below.
Discourse:
On Discourse, we saw much better p99 performance (e.g. for "categories"
it went from 214ms on master to 134ms on branch, for "home" it went
from 265ms to 251ms). We don’t see much change in p60, p75, and p90
performance. We also see a slight decrease in memory usage by 1.04x.
Branch RSS: 354.9MB
Master RSS: 368.2MB
railsbench:
On rails bench, we don’t see a big change in RPS or p99
performance. We don’t see a big difference in memory usage.
Branch RPS: 826.27
Master RPS: 824.85
Branch p99: 1.67
Master p99: 1.72
Branch RSS: 88.72MB
Master RSS: 88.48MB
liquid:
We don’t see a significant change in liquid performance.
Branch parse & render: 28.653 I/s
Master parse & render: 28.563 i/s
Previously, YJIT assumed that basic blocks never consume more than
1 KiB of memory. This assumption does not hold for long Ruby methods
such as the one in the following:
```ruby
eval(<<RUBY)
def set_local_a_lot
#{'_=0;'*0x40000}
end
RUBY
set_local_a_lot
```
For low `--yjit-exec-mem-size` values, one basic block could exhaust the
entire buffer.
Introduce a new field `codeblock_t::dropped_bytes` that the assembler
sets whenever it runs out of space. Check this field in
gen_single_block() to respond to out of memory situations and other
error conditions. This design avoids making the control flow graph of
existing code generation functions more complex.
Use POSIX shell in misc/test_yjit_asm.sh since bash is expanding
`0%/*/*` differently.
Co-authored-by: Aaron Patterson <tenderlove@ruby-lang.org>
Some platforms don't want memory to be marked as writeable and
executable at the same time. When we write to the code block, we
calculate the OS page that the buffer position maps to. Then we call
`mprotect` to allow writes on that particular page. As an optimization,
we cache the "last written" aligned page which allows us to amortize the
cost of the `mprotect` call. In other words, sequential writes to the
same page will only call `mprotect` on the page once.
When we're done writing, we call `mprotect` on the entire JIT buffer.
This means we don't need to keep track of which pages were marked as
writeable, we let the OS take care of that.
Co-authored-by: John Hawthorn <john@hawthorn.email>
* YJIT: use shorter encoding for mov(r64,imm) when unambiguous
Previously, for small constants such as `mov(RAX, imm_opnd(Qundef))`,
we emit an instruction with an 8-byte immediate. This form commonly
gets the `movabs` mnemonic.
In 64-bit mode, 32-bit operands get zero extended to 64-bit to fill the
register, so when the immediate is small enough, we can save 4 bytes by
using the `mov` variant that takes a 32-bit immediate and does a zero
extension.
Not implement with this change, there is an imm32 variant of `mov` that
does sign extension we could use. When the constant is negative, we
fallback to the `movabs` form.
In railsbench, this change yields roughly a 12% code size reduction for
the outlined block.
Co-authored-by: Jemma Issroff <jemmaissroff@gmail.com>
* [ci skip] comment edit. Please squash.
Co-authored-by: Jemma Issroff <jemmaissroff@gmail.com>
* New code page allocation logic
* Fix leaked globals
* Fix leaked symbols, yjit asm tests
* Make COUNTED_EXIT take a jit argument, so we can eliminate global ocb
* Remove extra whitespace
* Change block start_pos/end_pos to be pointers instead of uint32_t
* Change branch end_pos and start_pos to end_addr, start_addr
On non RUBY_DEBUG builds, assert() compiles to nothing and the compiler
warns about uninitialized variables in those code paths. Replace
those asserts with rb_bug() to fix the warnings and do the assert in
all builds. Since yjit_asm_tests.c compiles outside of Ruby, it needed
a distinct version of rb_bug().
Also put YJIT_STATS check for function delcaration that is only defined
in YJIT_STATS builds.
This script is an lldb helper that just loops through all the comments
stored and prints out the comment along with the address corresponding
to the comment.
For example, I'm crashing in JIT code at address 0x0000000110000168.
Using the `lc` helper I can see that it's probably crashing inside the
exit back to the interpreter
```
(lldb) bt 5
* thread #1, queue = 'com.apple.main-thread', stop reason = EXC_BAD_ACCESS (code=1, address=0x22220021)
frame #0: 0x0000000110000168
* frame #1: 0x00000001002b5ff5 miniruby`invoke_block_from_c_bh [inlined] invoke_block(ec=0x0000000100e05350, iseq=0x0000000100c1ff10, self=0x0000000100c76cc0, captured=<unavailable>, cref=0x0000000000000000, type=<unavailable>, opt_pc=<unavailable>) at vm.c:1268:12
frame #2: 0x00000001002b5f7d miniruby`invoke_block_from_c_bh [inlined] invoke_iseq_block_from_c(ec=<unavailable>, captured=<unavailable>, self=0x0000000100c76cc0, argc=2, argv=<unavailable>, kw_splat=0, passed_block_handler=0x0000000000000000, cref=0x0000000000000000, is_lambda=<unavailable>, me=0x0000000000000000) at vm.c:1340
frame #3: 0x00000001002b5e14 miniruby`invoke_block_from_c_bh(ec=<unavailable>, block_handler=<unavailable>, argc=<unavailable>, argv=<unavailable>, kw_splat=0, passed_block_handler=0x0000000000000000, cref=0x0000000000000000, is_lambda=<unavailable>, force_blockarg=0) at vm.c:1358
frame #4: 0x000000010029860b miniruby`rb_yield_values(n=<unavailable>) at vm_eval.c:0
(lldb) lc
0x11000006d "putobject_INT2FIX_1_"
0x110000083 "leave"
0x110000087 "check for interrupts"
0x110000087 "RUBY_VM_CHECK_INTS(ec)"
0x110000098 "check for finish frame"
0x1100000ed "getlocal_WC_0"
0x110000107 "getlocal_WC_1"
0x11000012a "opt_send_without_block"
0x110000139 "opt_send_without_block"
0x11000013c "exit to interpreter"
```
This commits implements size classes in the GC for the Variable Width
Allocation feature. Unless `USE_RVARGC` compile flag is set, only a
single size class is created, maintaining current behaviour. See the
redmine ticket for more details.
Co-authored-by: Aaron Patterson <tenderlove@ruby-lang.org>
This commit removes T_PAYLOAD since the new VWA implementation no longer
requires T_PAYLOAD types.
Co-authored-by: Aaron Patterson <tenderlove@ruby-lang.org>
This commits implements size classes in the GC for the Variable Width
Allocation feature. Unless `USE_RVARGC` compile flag is set, only a
single size class is created, maintaining current behaviour. See the
redmine ticket for more details.
Co-authored-by: Aaron Patterson <tenderlove@ruby-lang.org>
This commit removes T_PAYLOAD since the new VWA implementation no longer
requires T_PAYLOAD types.
Co-authored-by: Aaron Patterson <tenderlove@ruby-lang.org>
rather than having to do this in a two step process:
1. heap_page obj
2. dump_page $2 (or whatever lldb variable heap_page set)
we can now just
dump_page_rvalue obj
Jemma Issroff
Alan Wu
Peter Zhu
Aaron Patterson
Matt Valentine-House
Nobuyoshi Nakada
Alan Wu
Maxime Chevalier-Boisvert
Hiroshi SHIBATA
Alexander Popov