Re: [PATCH] jit: fix build with LLVM-21

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.

[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. ;-)

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?