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YJIT: Fix tailcall and JIT entry eating up FINISH frames (#9729)

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Suppose YJIT runs a rb_vm_opt_send_without_block()
fallback and the control frame stack looks like:

```
will_tailcall_bar [FINISH]
caller_that_used_fallback
```

will_tailcall_bar() runs in the interpreter and sets up a tailcall.
Right before JIT_EXEC() in the `send` instruction, the stack will look like:

```
bar [FINISH]
caller_that_used_fallback
```

Previously, JIT_EXEC() ran bar() in JIT code, which caused the `FINISH`
flag to return to the interpreter instead of to the JIT code running
caller_that_used_fallback(), causing code to run twice and probably
crash. Recent flaky failures on CI about "each stub expects a particular
iseq" are probably due to leaving methods twice in
`test_optimizations.rb`.

Only run JIT code from the interpreter if a new frame is pushed.
This commit is contained in:
Alan Wu 2024-01-29 12:21:17 -05:00 • committed by GitHub
parent 9a5a11f3d0
commit b0711b1cf1
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2 changed files with 13 additions and 1 deletions
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3
vm_exec.h
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@ -176,7 +176,8 @@ default: \
// Run the JIT from the interpreter
#define JIT_EXEC(ec, val) do { \
rb_jit_func_t func; \
if (val == Qundef && (func = jit_compile(ec))) { \
/* don't run tailcalls since that breaks FINISH */ \
if (val == Qundef && GET_CFP() != ec->cfp && (func = jit_compile(ec))) { \
val = func(ec, ec->cfp); \
RESTORE_REGS(); /* fix cfp for tailcall */ \
if (ec->tag->state) THROW_EXCEPTION(val); \