We should only clear the JIT function when the entry point is
invalidated. Right now we only support compiling functions with a PC
offset of zero (functions that take optional parameters can start at
non-zero PC), so this patch just checks that the index is 0 before
clearing the jit function
This change fixes some cases where YJIT fails to fire tracing events.
Most of the situations YJIT did not handle correctly involves enabling
tracing while running inside generated code.
A new operation to invalidate all generated code is added, which uses
patching to make generated code exit at the next VM instruction
boundary. A new routine called `jit_prepare_routine_call()` is
introduced to facilitate this and should be used when generating code
that could allocate, or could otherwise use `RB_VM_LOCK_ENTER()`.
The `c_return` event is fired in the middle of an instruction as opposed
to at an instruction boundary, so it requires special handling. C method
call return points are patched to go to a fucntion which does everything
the interpreter does, including firing the `c_return` event. The
generated code for C method calls normally does not fire the event.
Invalided code should not change after patching so the exits are not
clobbered. A new variable is introduced to track the region of code that
should not change.
RUBY_DEBUG have a very significant performance overhead. Enough that
YJIT with RUBY_DEBUG is noticeably slower than the interpreter without
RUBY_DEBUG.
This makes it hard to collect yjit-stats in production environments.
By allowing to collect JIT statistics without the RUBy_DEBUG overhead,
I hope to make such use cases smoother.
Previously all stack operands would become unknown once the stack grew
beyond a certain size. This worked, but unnecessarily hid available
information.
If we hit this at PC > 0 (ie. with an optional argument) the provided
types and context are likely incorrect and it is likely this block can't
be used.
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
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.
Make sure `opt_getinlinecache` is in a block all on its own, and
invalidate it from the interpreter when `opt_setinlinecache`.
It will recompile with a filled cache the second time around.
This lets YJIT runs well when the IC for constant is cold.
ASAN can catch these type of things for us, but the scraper can't
handle ASAN :/.
To be more resilient to refactoring, extend the lifetime of
`generic_ctx` in branch_stub_hit() too.
Alan Wu
Maxime Chevalier-Boisvert
John Hawthorn
Aaron Patterson
Jean Boussier
Noah Gibbs
Maxime Chevalier-Boisvert