* YJIT: Add --yjit-mem-size option * Improve --help * s/the region/this virtual memory region/ Co-authored-by: Maxime Chevalier-Boisvert <maxime.chevalierboisvert@shopify.com> --------- Co-authored-by: Maxime Chevalier-Boisvert <maxime.chevalierboisvert@shopify.com>
* Returning an iterator instead of a vec * Avoid changing the meaning of end_page --------- Co-authored-by: Takashi Kokubun <takashikkbn@gmail.com>
This change implements a fallback mode for the `--yjit-dump-disasm`
development command-line option to make it usable in release builds.
Previously, using the option with release builds of YJIT yielded only
a warning asking the user to build with `--enable-yjit=dev`.
While builds that use the `disasm` feature still give the best output,
just having the comments is useful enough for many kinds of debugging.
Having it usable in release builds is nice for new hackers, too, since
this allows for tinkering without having to learn how to build YJIT in
development mode.
Sample output on A64:
```
# regenerate_branch
# Insn: 0001 opt_send_without_block (stack_size: 1)
# guard known object with singleton class
0x11f7e0034: 4b 00 00 58 03 00 00 14 08 ce 9c 04 01 00 00
0x11f7e0043: 00 3f 00 0b eb 81 06 01 54 1f 20 03 d5
# RUBY_VM_CHECK_INTS(ec)
0x11f7e0050: 8b 02 42 b8 cb 07 01 35
# stack overflow check
0x11f7e0058: ab 62 02 91 7f 02 0b eb 69 07 01 54
# save PC to CFP
0x11f7e0064: 0b 3b 9a d2 2b 2f a0 f2 0b 00 cc f2 6b 02 00
0x11f7e0073: f8 ab 82 00 91
```
To ensure this feature doesn't incur too much cost when running without
the `--yjit-dump-disasm` option, I checked that there is no significant
impact to compile time and memory usage with the `compile_time_ns` and
`yjit_alloc_size` entry in `RubyVM::YJIT.runtime_stats`. For each
sample, I ran 3 iterations of the `lobsters` YJIT benchmark. The
statistics summary and done with the `summary` function in R.
Compile time, sample size of 60, lower is better:
```
Before After
Min. :2.054e+09 Min. :2.028e+09
1st Qu.:2.069e+09 1st Qu.:2.044e+09
Median :2.081e+09 Median :2.060e+09
Mean :2.089e+09 Mean :2.066e+09
3rd Qu.:2.109e+09 3rd Qu.:2.085e+09
Max. :2.146e+09 Max. :2.144e+09
```
Allocation size, sample size of 20, lower is better:
```
Before After
Min. :21804742 Min. :21794082
1st Qu.:21826682 1st Qu.:21816282
Median :21844042 Median :21826814
Mean :21960664 Mean :22026291
3rd Qu.:21861228 3rd Qu.:22040439
Max. :22587426 Max. :22930614
```
The `yjit_alloc_size` samples are noisy, but since the average increased
by only 0.3%, and the median is lower, I feel safe saying that there is
no significant change.
Use a special breakpoint address if one isn't explicitly supplied in order to support natural line stepping. ARM64 will not increment the program counter (PC) upon hitting a breakpoint instruction. Consequently, stepping through code with a debugger ends up looping back to the breakpoint instruction. LLDB has a special breakpoint address of 0xf000 that will increment the PC and allow the debugger to work as expected. This change makes it possible to debug YJIT generated code on ARM64. More details at: https://discourse.llvm.org/t/stepping-over-a-brk-instruction-on-arm64/69766/8 Co-authored-by: Aaron Patterson <tenderlove@ruby-lang.org>
Mostly putting angle brackets around links to follow markdown syntax.
* YJIT: A64: Add CBZ and CBNZ encoding functions * YJIT: A64: Use CBZ/CBNZ to check for zero Instead of emitting `cmp x0, #0` plus `b.z #target`, A64 offers Compare and Branch on Zero for us to just do `cbz x0, #target`. This commit utilizes that and the related CBNZ instruction when appropriate. We check for zero most commonly in interrupt checks: ```diff # Insn: 0003 leave (stack_size: 1) # RUBY_VM_CHECK_INTS(ec) ldur w11, [x20, #0x20] -tst w11, w11 -b.ne #0x109002164 +cbnz w11, #0x1049021d0 ``` * fix copy paste error Co-authored-by: Randy Stauner <randy@r4s6.net> --------- Co-authored-by: Randy Stauner <randy@r4s6.net>
* YJIT: A64: Use ADDS/SUBS/CMP (immediate) when possible We were loading 1 into a register and then doing ADDS/SUBS previously. That was particularly bad since those come up in fixnum operations. ```diff # integer left shift with rhs=1 - mov x11, #1 - subs x11, x1, x11 + subs x11, x1, #1 lsl x12, x11, #1 asr x13, x12, #1 cmp x13, x11 - b.ne #0x106ab60f8 - mov x11, #1 - adds x12, x12, x11 + b.ne #0x10903a0f8 + adds x12, x12, #1 mov x1, x12 ``` Note that it's fine to cast between i64 and u64 since the bit pattern is preserved, and the add/sub themselves don't care about the signedness of the operands. CMP is just another mnemonic for SUBS. * YJIT: A64: Split asm.mul() with immediates properly There is in fact no MUL on A64 that takes an immediate, so this instruction was using the wrong split method. No current usages of this form in YJIT. --------- Co-authored-by: Maxime Chevalier-Boisvert <maxime.chevalierboisvert@shopify.com>
Helps understand page switching