On 2025-09-12 08:36, Peter Eisentraut wrote:
On 08.09.25 15:20, Holger Hoffstätte wrote:
I tried building against LLVM-21 and noticed that a function for symbol
lookup was renamed (without semantic changes), breaking the LLVM JIT.
The following patch fixes this by adding a version guard. It applies equally
to both master and 17.6. Passes the test suite and verified on 17.6 with the
jit example from the documentation.
I can confirm that this change seems correct. See [0] for reference.
Excellent! Thanks for taking a look. This was my first post to pgsql-hackers
and I wasn't sure if I had done something wrong.
[0]:
https://github.com/llvm/llvm-project/commit/d3d856ad84698fa4ec66177d00558b2f5b438d3b
As a small style request, I would flip the conditional around so
that the new code appears first. I see that we don't do this very
consistently in the existing code, but maybe we can start a new
trend. ;-)
I knew this would come up since I pondered the same thing :D
As you said, the existing code is not consistent, but I can switch this
to let the new code appear first, if you prefer.
A new patch is attached.
In my testing with LLVM 21, I'm getting an additional error:
../src/backend/jit/llvm/llvmjit_wrap.cpp:56:18: error: no matching constructor
for initialization of 'llvm::orc::RTDyldObjectLinkingLayer'
56 | return wrap(new llvm::orc::RTDyldObjectLinkingLayer(
| ^
57 | *unwrap(ES), [] { return
std::make_unique<llvm::backport::SectionMemoryManager>(nullptr, true); }));
|
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/opt/homebrew/Cellar/llvm/21.1.0/include/llvm/ExecutionEngine/Orc/RTDyldObjectLinkingLayer.h:58:3:
note: candidate constructor not viable: no known conversion from '(lambda at
../src/backend/jit/llvm/llvmjit_wrap.cpp:57:16)' to 'GetMemoryManagerFunction' (aka
'unique_function<std::unique_ptr<RuntimeDyld::MemoryManager> (const MemoryBuffer
&)>') for 2nd argument
58 | RTDyldObjectLinkingLayer(ExecutionSession &ES,
| ^
59 | GetMemoryManagerFunction GetMemoryManager);
| ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/opt/homebrew/Cellar/llvm/21.1.0/include/llvm/ExecutionEngine/Orc/RTDyldObjectLinkingLayer.h:37:16:
note: candidate constructor (the implicit copy constructor) not viable:
requires 1 argument, but 2 were provided
37 | class LLVM_ABI RTDyldObjectLinkingLayer
| ^~~~~~~~~~~~~~~~~~~~~~~~
I gather you're not seeing that?
I do not - I dropped the patch into my Gentoo package build for 17.6 and
it has been working fine when building with gcc-15.2 and the jit part
with clang-21.1.0. I also just rebuilt everything with clang-21.1.1 (no gcc)
and also do not see the problem. This is on amd64 Linux.
The following commit seems to be involved:
https://github.com/postgres/postgres/commit/9044fc1d45a0212fd123bd8f364eac058f60fed7
which is also in my 17.6 tree. I verified that the new
SectionMemoryManager.cpp is compiled without error.
Since you're using homebrew I guess this is triggered by the
__aarch64__ guard in src/include/jit/llvmjit_backport.h.
Unfortunately this is as far as I can help with this.
Please let me know if there is anything else I can do.
cheers
Holger
>From 699a5aa8f9438c902ac5ad063525193ddf0ebb59 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Holger=20Hoffst=C3=A4tte?= <[email protected]>
Date: Fri, 12 Sep 2025 09:40:31 +0200
Subject: [PATCH] jit: fix build with LLVM-21
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
LLVM-21 renamed llvm::GlobalValue::getGUID() to
getGUIDAssumingExternalLinkage(), so add a version guard.
Signed-off-by: Holger Hoffstätte <[email protected]>
---
src/backend/jit/llvm/llvmjit_inline.cpp | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/src/backend/jit/llvm/llvmjit_inline.cpp b/src/backend/jit/llvm/llvmjit_inline.cpp
index 2764c3bbe2f..51b32cd9f94 100644
--- a/src/backend/jit/llvm/llvmjit_inline.cpp
+++ b/src/backend/jit/llvm/llvmjit_inline.cpp
@@ -238,7 +238,11 @@ llvm_build_inline_plan(LLVMContextRef lc, llvm::Module *mod)
llvm_split_symbol_name(symbolName.data(), &cmodname, &cfuncname);
+#if LLVM_VERSION_MAJOR >= 21
+ funcGUID = llvm::GlobalValue::getGUIDAssumingExternalLinkage(cfuncname);
+#else
funcGUID = llvm::GlobalValue::getGUID(cfuncname);
+#endif
/* already processed */
if (inlineState.processed)
--
2.51.0
