Support new overload for ObjCRuntime.Selector.GetHandle in the AOT compiler

[rolfbjarne]

The AOT compiler supports inlining calls to Selector.GetHandle(string):

runtime/src/mono/mono/mini/intrinsics.c

Lines 1987 to 2027 in 2bdc3cb

	} else if (((!strcmp (cmethod_klass_image->assembly->aname.name, "Xamarin.iOS") ||
	!strcmp (cmethod_klass_image->assembly->aname.name, "Xamarin.TVOS") ||
	!strcmp (cmethod_klass_image->assembly->aname.name, "Xamarin.MacCatalyst") ||
	!strcmp (cmethod_klass_image->assembly->aname.name, "Xamarin.Mac") ||
	!strcmp (cmethod_klass_image->assembly->aname.name, "Microsoft.iOS") ||
	!strcmp (cmethod_klass_image->assembly->aname.name, "Microsoft.tvOS") ||
	!strcmp (cmethod_klass_image->assembly->aname.name, "Microsoft.MacCatalyst") ||
	!strcmp (cmethod_klass_image->assembly->aname.name, "Microsoft.macOS")) &&
	!strcmp (cmethod_klass_name_space, "ObjCRuntime") &&
	!strcmp (cmethod_klass_name, "Selector"))
	) {
	if ((cfg->backend->have_objc_get_selector || cfg->compile_llvm) &&
	!strcmp (cmethod->name, "GetHandle") && fsig->param_count == 1 &&
	(args [0]->opcode == OP_GOT_ENTRY || args [0]->opcode == OP_AOTCONST) &&
	cfg->compile_aot) {
	MonoInst *pi;
	MonoJumpInfoToken *ji;
	char *s;
	if (args [0]->opcode == OP_GOT_ENTRY) {
	pi = (MonoInst *)args [0]->inst_p1;
	g_assert (pi->opcode == OP_PATCH_INFO);
	g_assert (GPOINTER_TO_INT (pi->inst_p1) == MONO_PATCH_INFO_LDSTR);
	ji = (MonoJumpInfoToken *)pi->inst_p0;
	} else {
	g_assert (GPOINTER_TO_INT (args [0]->inst_p1) == MONO_PATCH_INFO_LDSTR);
	ji = (MonoJumpInfoToken *)args [0]->inst_p0;
	}
	NULLIFY_INS (args [0]);
	s = mono_ldstr_utf8 (ji->image, mono_metadata_token_index (ji->token), cfg->error);
	return_val_if_nok (cfg->error, NULL);
	MONO_INST_NEW (cfg, ins, OP_OBJC_GET_SELECTOR);
	ins->dreg = mono_alloc_ireg (cfg);
	// FIXME: Leaks
	ins->inst_p0 = s;
	MONO_ADD_INS (cfg->cbb, ins);
	return ins;
	}

and we'd like to add a new overload: Selector.GetHandle(ReadOnlySpan<byte>), where the constant value would be a UTF8 string:

Selector.GetHandle ("mySelector"u8);

And where the call to the new overload would also be optimized.

Would this be possible to implement?

CC @vargaz

[vargaz]

Here is how the IL looks:

    IL_0000:  ldsflda    int32 '<PrivateImplementationDetails>'::F9E5DF8B4E118810BA431209F1BFB47819AE57578BAADA047095340A3159E7A4
    IL_0005:  ldc.i4.3
    IL_0006:  newobj     instance void valuetype [System.Runtime]System.ReadOnlySpan`1<uint8>::.ctor(void*,
                                                                                                     int32)
    IL_000b:  call       void HelloWorld.Program::foo(valuetype [System.Runtime]System.ReadOnlySpan`1<uint8>)

It might be doable, but not simple.