If `--disable-jit-support` is passed to configure, then `jit_func` is
removed from the iseq body and we can't compile YJIT. This commit
detects when the JIT function pointer is gone and disables YJIT in that
case.
Methods with optional parameters don't always start executing at the
first PC, but we compile all methods assuming that they do. This commit
adds a guard to ensure that we're actually starting at the first PC for
methods with optional params
Always using `ret` to return to the interpreter means that we never have
to check the VM_FRAME_FLAG_FINISH flag.
In the case that we return `Qundef`, the interpreter will execute the
cfp. We can take advantage of this by setting the PC to the instruction
we can't handle, and let the interpreter pick up the ball from there.
If we return a value other than Qundef, the interpreter will take that
value as the "return value" from the JIT and push that to the SP of the
caller
The leave instruction puts the return value on the top of the calling
frame's stack. YJIT does the same thing for leave instructions.
However, when we're returning back to the interpreter, the leave
instruction _should not_ put the return value on the top of the stack,
but put it in RAX and use RET. This commit pops the last value from the
stack pointer and puts it in RAX so that the interpreter is happy with
SP.
We clear locals when we know their values might change (ex. when
performing a method call). However previously values on the stack which
were originally pushed from a local would still point back to that
local.
With this commit, when clearing locals, we'll now iterate over the
mappings of the stack and copy the known type from the local to the
stack mapping, removing the association to the local.
This should mean both that we'll retain any information we already know
about the local type, and that if a local is modified we won't
incorrectly infer it's new type from the existing value on the stack.
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"
```
In jit_guard_known_klass whenever we encounter a new class should
recompile the current instruction.
However, previously once jit_guard_known_klass had guarded for a heap
object it would not recompile for any immediate (special const) objects
arriving afterwards and would take a plain side-exit instead of a chain
guard.
This commit uses jit_chain_guard inside jit_guard_known_klass instead of
the plain side exit, so that we can recompile for any special constants
arriving afterwards.
I'm looking through the places where YJIT needs notifications. It looks
like these changes to gc.c and vm_callinfo.h have become unnecessary
since 84ab77ba59. This commit just makes the diff against upstream
smaller, but otherwise shouldn't change any behavior.
Aaron Patterson
Noah Gibbs
John Hawthorn
Kevin Newton
Maxime Chevalier-Boisvert
Maxime Chevalier-Boisvert
Kevin Deisz