Re: LLVM 16 (opaque pointers)

Andres Freund <andres@anarazel.de>

From: Andres Freund <andres@anarazel.de>
To: Thomas Munro <thomas.munro@gmail.com>
Cc: PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2023-08-11T18:09:37Z
Lists: pgsql-hackers

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →
  1. jit: Adjust back-patch of f90b4a84 to 12 and 13.

  2. Log LLVM library version in configure output.

  3. jit: Changes for LLVM 17.

  4. jit: Supply LLVMGlobalGetValueType() for LLVM < 8.

  5. jit: Support opaque pointers in LLVM 16.

  6. jit: Reference function pointer types via llvmjit_types.c.

Hi,

On 2023-05-21 15:01:41 +1200, Thomas Munro wrote:
> *For anyone working with this type of IR generation code and
> questioning their sanity, I can pass on some excellent advice I got
> from Andres: build LLVM yourself with assertions enabled, as they
> catch some classes of silly mistake that otherwise just segfault
> inscrutably on execution.

Hm. I think we need a buildfarm animal with an assertion enabled llvm 16 once
we merge this. I think after an upgrade my buildfarm machine has the necessary
resources.


> @@ -150,7 +150,7 @@ llvm_compile_expr(ExprState *state)
>  
>  	/* create function */
>  	eval_fn = LLVMAddFunction(mod, funcname,
> -							  llvm_pg_var_func_type("TypeExprStateEvalFunc"));
> +							  llvm_pg_var_func_type("ExecInterpExprStillValid"));

Hm, that's a bit ugly. But ...

> @@ -77,9 +80,44 @@ extern Datum AttributeTemplate(PG_FUNCTION_ARGS);
>  Datum
>  AttributeTemplate(PG_FUNCTION_ARGS)
>  {
> +	PGFunction	fp PG_USED_FOR_ASSERTS_ONLY;
> +
> +	fp = &AttributeTemplate;
>  	PG_RETURN_NULL();
>  }

Other parts of the file do this by putting the functions into
referenced_functions[], i'd copy that here and below.

> +void
> +ExecEvalSubroutineTemplate(ExprState *state,
> +						   struct ExprEvalStep *op,
> +						   ExprContext *econtext)
> +{
> +	ExecEvalSubroutine fp PG_USED_FOR_ASSERTS_ONLY;
> +
> +	fp = &ExecEvalSubroutineTemplate;
> +}
> +
> +extern bool ExecEvalBoolSubroutineTemplate(ExprState *state,
> +										   struct ExprEvalStep *op,
> +										   ExprContext *econtext);
> +bool
> +ExecEvalBoolSubroutineTemplate(ExprState *state,
> +							   struct ExprEvalStep *op,
> +							   ExprContext *econtext)
> +{
> +	ExecEvalBoolSubroutine fp PG_USED_FOR_ASSERTS_ONLY;
> +
> +	fp = &ExecEvalBoolSubroutineTemplate;
> +	return false;
> +}
> +


Thanks for working on this!

Greetings,

Andres Freund