Compatibility

Minimum GCCJIT ABI requirement

mlir-gccjit assumes the availability of LIBGCCJIT_ABI_27, which is available in GCC 14.2.0 or higher.

Please refer to ABI and API compatibility for detailed ABI specification of libgccjit.so.

Known Issues

Polyfill of gccjit.alignof

LIBGCCJIT_ABI_28 introduces gcc_jit_context_new_alignof. On targets before such ABI level, we calculate the alignment of a given type T by creating a dummy structure:

struct dummy {
    char __padding;
    T __field;
};

The alignment is then calculate as the offset to __field if a dummy struct is placed at address NULL:

bitcast(&((dummy *)NULL)->__field, size_t)

GCCJIT ICE with Aligned Alloca or Scoped Alloca

When alignment is specified, our lowering pass converts memref.alloca to an intrinsic call to __builtin_alloca_with_align. Unfortunately, due to some implementation details inside GCC, libgccjit currently cannot identidy the type of this builtin function hence would run into an ICE. We have reported this project to upstream and will keep track of the status. Such issues also apply to __builtin_stack_save and __builtin_stack_restore, which are required to implement scoped alloca.