[llvm-dev] OrcV1 removal

[Andres Freund via llvm-dev]

Hi,

On 2020-09-30 21:31:33 -0700, Lang Hames wrote:
> I've taken a first shot at hooking RTDyldObjectLinkingLayer up to the
> ResourceTracker API in 7436b2ab2428. Could you let me know whether that
> fixes the leak you were seeing?

It did improve the situation significantly, thanks!

There's still a smaller leak, unfortunately. The function comments for
modules say that:

/**
 * Create a ThreadSafeModule wrapper around the given LLVM module. This takes
 * ownership of the M argument which should not be disposed of or referenced
 * after this function returns.
 *
 * Ownership of the ThreadSafeModule is unique: If it is transferred to the JIT
 * (e.g. by LLVMOrcLLJITAddLLVMIRModule), in which case the client is no longer
 * responsible for it. If it is not transferred to the JIT then the client
 * should call LLVMOrcDisposeThreadSafeModule to dispose of it.
 */
LLVMOrcThreadSafeModuleRef
LLVMOrcCreateNewThreadSafeModule(LLVMModuleRef M,
                                 LLVMOrcThreadSafeContextRef TSCtx);

/**
 * Dispose of a ThreadSafeModule. This should only be called if ownership has
 * not been passed to LLJIT (e.g. because some error prevented the client from
 * adding this to the JIT).
 */
void LLVMOrcDisposeThreadSafeModule(LLVMOrcThreadSafeModuleRef TSM);

but when using -fsanitize-leaks I see:

Direct leak of 9192 byte(s) in 383 object(s) allocated from:
    #0 0x7fe249127670 in operator new(unsigned long) (/lib/x86_64-linux-gnu/liblsan.so.0+0xf670)
    #1 0x7fe1bfc1cbc0 in LLVMOrcCreateNewThreadSafeModule (/home/andres/build/llvm-project/master/debug/install/lib/libLLVMOrcJIT.so.12git+0x38bbc0)
    #2 0x7fe245f6ea6d in llvm_compile_module /home/andres/src/postgresql/src/backend/jit/llvm/llvmjit.c:606
    #3 0x7fe245f6e0b0 in llvm_get_function /home/andres/src/postgresql/src/backend/jit/llvm/llvmjit.c:275
    #4 0x7fe245f809f1 in ExecRunCompiledExpr /home/andres/src/postgresql/src/backend/jit/llvm/llvmjit_expr.c:2410
    #5 0x5633fbb6c17f in ExecEvalExpr /home/andres/src/postgresql/src/include/executor/executor.h:294

for modules which are passed to LLVMOrcLLJITAddLLVMIRModule:
		ts_module = LLVMOrcCreateNewThreadSafeModule(context->module, llvm_ts_context);
		rt = LLVMOrcJITDylibCreateResourceTracker(jd);
		error = LLVMOrcLLJITAddLLVMIRModule(compile_orc, jd, ts_module, rt);

which seems to suggest that somehow there's a reference too many?

Greetings,

Andres Freund