Hi, On 2026-04-02 16:20:41 +1300, Thomas Munro wrote: > On Wed, Apr 1, 2026 at 4:25 PM Thomas Munro <[email protected]> wrote: > > Working on this, more shortly... I'm trying to figure out if Anthonin > > and Andres's feedback means the poison approach does nothing useful > > and we might as well just #ifdef out the lifetime.end stuff for LLVM > > >= 22 to fix the breakage today. > > Done. Hopefully midge and Devrim will now turn green :-)
Thanks! > > Either way it looks like we need a patch to use alloca instead, which > > I'll also look into... > > I see a few options, but I need to hack on them for a while to figure > out the tradeoffs, or what I'm missing... after the freeze. I've experimented a bunch with this, it seems we need the larger changes done as part of the patchset for removing pointers from the expressions to actually allow recent-ish LLVM to optimize this. I did verify that what we did didn't have an effect with any other recent LLVM either. The real fix here might be to have a separate calling convention for the very common case of a scalar stable function with 1-3 arguments. We loose a fair bit of efficiency even in interpreted execution due to ferrying arguments, their nullness, and the nullness of the return value through memory. Greetings, Andres Freund
