io interface (first pass)

compiler/lower/lower.odin

@@ -1608,6 +1608,69 @@ lower_global_initializer :: proc(hir_module: ^hir.Module, global: hir.Global, al
 	return state.instructions[:]
 }
 
+append_injected_main :: proc(module: ^ir.Module, hir_module: ^hir.Module, allocator: mem.Allocator) {
+	main_index, main_ok := hir.index(hir_module.injected_main, hir.INVALID_FUNCTION, len(hir_module.functions))
+	provider_index, provider_ok := hir.index(hir_module.io_provider, hir.INVALID_FUNCTION, len(hir_module.functions))
+	if !main_ok || !provider_ok {
+		return
+	}
+
+	instructions: [dynamic]ir.Instruction
+	instructions.allocator = allocator
+	provider_call := ir.instruction_id(len(instructions))
+	append(&instructions, ir.Instruction{
+		op=.Call,
+		type=hir_module.functions[provider_index].result,
+		target=ir.function_ref(ir.Function_Id(provider_index)),
+		a=ir.INVALID_INSTRUCTION,
+		b=ir.INVALID_INSTRUCTION,
+		diagnostic=source.INVALID_DIAGNOSTIC,
+	})
+	args := make([]ir.Instruction_Id, 1, allocator)
+	args[0] = provider_call
+	main_call := ir.instruction_id(len(instructions))
+	append(&instructions, ir.Instruction{
+		op=.Call,
+		type=hir_module.functions[main_index].result,
+		args=args,
+		target=ir.function_ref(ir.Function_Id(main_index)),
+		a=ir.INVALID_INSTRUCTION,
+		b=ir.INVALID_INSTRUCTION,
+		diagnostic=source.INVALID_DIAGNOSTIC,
+	})
+	if types.is_void(hir_module.functions[main_index].result) {
+		append(&instructions, ir.Instruction{
+			op=.Return_Void,
+			type=types.VOID,
+			target=ir.INVALID_REF,
+			a=ir.INVALID_INSTRUCTION,
+			b=ir.INVALID_INSTRUCTION,
+			diagnostic=source.INVALID_DIAGNOSTIC,
+		})
+	} else {
+		append(&instructions, ir.Instruction{
+			op=.Return,
+			type=hir_module.functions[main_index].result,
+			target=ir.INVALID_REF,
+			a=main_call,
+			b=ir.INVALID_INSTRUCTION,
+			diagnostic=source.INVALID_DIAGNOSTIC,
+		})
+	}
+
+	append(&module.functions, ir.Function{
+		link_name=fmt.aprintf("main", allocator=allocator),
+		calling_convention=.C,
+		implementation=.Definition,
+		linkage=.External,
+		is_main=true,
+		result=hir_module.functions[main_index].result,
+		instructions=instructions[:],
+		problematic=hir_module.functions[main_index].problematic ||
+		            hir_module.functions[provider_index].problematic,
+	})
+}
+
 lower :: proc(hir_module: ^hir.Module, allocator := context.allocator) -> ir.Module {
 	module := ir.init_module(hir_module.target, allocator)
 	types.destroy_store(&module.types)
@@ -1649,5 +1712,6 @@ lower :: proc(hir_module: ^hir.Module, allocator := context.allocator) -> ir.Mod
 			problematic=function.problematic,
 		})
 	}
+	append_injected_main(&module, hir_module, allocator)
 	return module
 }