Re: Add missing JIT inline pass for llvm>=17

Anthonin Bonnefoy <anthonin.bonnefoy@datadoghq.com>

From: Anthonin Bonnefoy <anthonin.bonnefoy@datadoghq.com>
To: Andreas Karlsson <andreas@proxel.se>
Cc: PostgreSQL Hackers <pgsql-hackers@postgresql.org>
Date: 2026-01-15T09:40:37Z
Lists: pgsql-hackers

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On Thu, Jan 15, 2026 at 4:20 AM Andreas Karlsson <andreas@proxel.se> wrote:
> If inline-always does not do anything it should be removed on older LLVM
> versions too. I do not think we should be having pre- and post-LLVM 17
> run different passes. But as Thomas pointed out inline-always is likely
> used for tuple deforming.

Right, I've missed the l_callsite_alwaysinline for varsize_any.
Testing with the following query to trigger a call to varsize_any:

create table test_always_inline(id integer, data text);
select data, id FROM test_always_inline;

The generated bc were identical (attached with the message), with and
without always-inline with varsize_any not being inlined. I think this
is the same issue as with external functions. varsize_any is defined
in postgres/access/common/heaptuple.bc, and the function needs to be
imported for LLVM to be able to inline it. Without going through
llvm_inline and importing the functions, there's no inlining doable.

Maybe the issue is that always-inline functions should be inlined,
even with the non-optimized case (at least, that's what the configured
passes seem to imply)? But that would require calling llvm_inline,
which kind of defeats the purpose of having a dedicated PGJIT_INLINE
flag and threshold.

I've updated the patch with the simplified PGJIT_INLINE check and the
commit message change. I've added a separate patch to remove the
always-inline pass pre-LLVM 17 if we want to go that way.

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  1. jit: Add missing inline pass for LLVM >= 17.