RFR: 8372591: assert(!current->cont_fastpath() || freeze.check_valid_fast_path()) failed

[Patricio Chilano Mateo]

On Thu, 18 Dec 2025 19:05:08 GMT, Richard Reingruber <rrich at openjdk.org> wrote:

> > > @reinrich @TheRealMDoerr Could you verify if this fix is correct for ppc too? Thanks.
> > 
> > 
> > The fix looks correct. Strangely the reproducer didn't work on ppc. Not even with 3x the locals in the osr method. I'll look a little more into it...
> 
> On ppc we reach `OSR_migration_begin` with `_cont_fastpath` that's higher than `sender.sp()` so `push_cont_fastpath(sender.sp())` has no effect. I'm not sure why this is. It might be due to the trimming with i2i calls where the sender is trimmed to a `parent frame` (the top frame always has room for max_stack). The sender is a lambda. Maybe it has done an i2c call as `top frame` (i.e. untrimmed) which set `_cont_fastpath`?
> 
Maybe, but I don't see which compiled method it could be, since methods before `foo` should be interpreted.

> If max_stack of the sender is very large then, due to trimming, unextended_sp < sp is possible and the assertion could also fail.
> 
> Maybe the maximum of unextended_sp and sp could be used?
>
On x64 and AArch64 we build the OSR frame starting from the sender's `unextended_sp` (modulo aligment). Is that not the case for ppc?

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PR Comment: https://git.openjdk.org/jdk/pull/28830#issuecomment-3672131775