Re: JIT compiling with LLVM v10.0

On Thu, Feb 8, 2018 at 3:54 AM, Andres Freund <andres@anarazel.de> wrote:
> I've pushed v10.0. The big (and pretty painful to make) change is that
> now all the LLVM specific code lives in src/backend/jit/llvm, which is
> built as a shared library which is loaded on demand.
>
> The layout is now as follows:
>
> src/backend/jit/jit.c:
>     Part of JITing always linked into the server. Supports loading the
>     LLVM using JIT library.
>
> src/backend/jit/llvm/
> Infrastructure:
>  llvmjit.c:
>     General code generation and optimization infrastructure
>  llvmjit_error.cpp, llvmjit_wrap.cpp:
>     Error / backward compat wrappers
>  llvmjit_inline.cpp:
>     Cross module inlining support
> Code-Gen:
>   llvmjit_expr.c
>     Expression compilation
>   llvmjit_deform.c
>     Deform compilation

You are asking LLVM to dlopen(""), which doesn't work on my not-Linux,
explaining the errors I reported in the older thread.  The portable
way to dlopen the main binary is dlopen(NULL), so I think you need to
pass NULL in to LLVMLoadLibraryPermanently(), even though that isn't
really clear from any LLVM documentation I've looked at.

diff --git a/src/backend/jit/llvm/llvmjit.c b/src/backend/jit/llvm/llvmjit.c
index a1bc6449f7..874bddf81e 100644
--- a/src/backend/jit/llvm/llvmjit.c
+++ b/src/backend/jit/llvm/llvmjit.c
@@ -443,7 +443,7 @@ llvm_session_initialize(void)
        cpu = NULL;

        /* force symbols in main binary to be loaded */
-       LLVMLoadLibraryPermanently("");
+       LLVMLoadLibraryPermanently(NULL);

        llvm_opt0_orc = LLVMOrcCreateInstance(llvm_opt0_targetmachine);
        llvm_opt3_orc = LLVMOrcCreateInstance(llvm_opt3_targetmachine);

-- 
Thomas Munro
http://www.enterprisedb.com