PostgreSQL's JIT
implementation can inline the implementation of operators and functions
(of type C
and internal
). See Section 32.1.3. To do so for functions in extensions, the
definition of these functions needs to be made available. When using PGXS to build an extension against a server
that has been compiled with LLVM support, the relevant files will be
installed automatically.
The relevant files have to be installed into
$pkglibdir/bitcode/$extension/
and a summary of them
to $pkglibdir/bitcode/$extension.index.bc
, where
$pkglibdir
is the directory returned by
pg_config --pkglibdir
and $extension
the basename of the extension's shared library.
For functions built into PostgreSQL itself,
the bitcode is installed into
$pkglibdir/bitcode/postgres
.
PostgreSQL provides a JIT implementation based on LLVM. The interface to the JIT provider is pluggable and the provider can be changed without recompiling. The provider is chosen via the jit_provider GUC.
A JIT provider is loaded by dynamically loading the
named shared library. The normal library search path is used to locate
the library. To provide the required JIT provider
callbacks and to indicate that the library is actually a
JIT provider it needs to provide a function named
_PG_jit_provider_init
. This function is passed a
struct that needs to be filled with the callback function pointers for
individual actions.
struct JitProviderCallbacks { JitProviderResetAfterErrorCB reset_after_error; JitProviderReleaseContextCB release_context; JitProviderCompileExprCB compile_expr; }; extern void _PG_jit_provider_init(JitProviderCallbacks *cb);