codegen for calling an async function

See #727

src/analyze.cpp

@@ -986,20 +986,25 @@ TypeTableEntry *get_fn_type(CodeGen *g, FnTypeId *fn_type_id) {
     if (!skip_debug_info) {
         bool first_arg_return = calling_convention_does_first_arg_return(fn_type_id->cc) &&
             handle_is_ptr(fn_type_id->return_type);
+        bool is_async = fn_type_id->cc == CallingConventionAsync;
         bool prefix_arg_error_return_trace = g->have_err_ret_tracing &&
             (fn_type_id->return_type->id == TypeTableEntryIdErrorUnion || 
             fn_type_id->return_type->id == TypeTableEntryIdErrorSet);
         // +1 for maybe making the first argument the return value
-        // +1 for maybe last argument the error return trace
+        // +1 for maybe first argument the error return trace
-        LLVMTypeRef *gen_param_types = allocate<LLVMTypeRef>(2 + fn_type_id->param_count);
+        // +2 for maybe arguments async allocator and error code pointer
+        LLVMTypeRef *gen_param_types = allocate<LLVMTypeRef>(4 + fn_type_id->param_count);
         // +1 because 0 is the return type and
         // +1 for maybe making first arg ret val and
-        // +1 for maybe last argument the error return trace
+        // +1 for maybe first argument the error return trace
-        ZigLLVMDIType **param_di_types = allocate<ZigLLVMDIType*>(3 + fn_type_id->param_count);
+        // +2 for maybe arguments async allocator and error code pointer
+        ZigLLVMDIType **param_di_types = allocate<ZigLLVMDIType*>(5 + fn_type_id->param_count);
         param_di_types[0] = fn_type_id->return_type->di_type;
         size_t gen_param_index = 0;
         TypeTableEntry *gen_return_type;
-        if (!type_has_bits(fn_type_id->return_type)) {
+        if (is_async) {
+            gen_return_type = get_pointer_to_type(g, g->builtin_types.entry_u8, false);
+        } else if (!type_has_bits(fn_type_id->return_type)) {
             gen_return_type = g->builtin_types.entry_void;
         } else if (first_arg_return) {
             TypeTableEntry *gen_type = get_pointer_to_type(g, fn_type_id->return_type, false);
@@ -1020,6 +1025,25 @@ TypeTableEntry *get_fn_type(CodeGen *g, FnTypeId *fn_type_id) {
             // after the gen_param_index += 1 because 0 is the return type
             param_di_types[gen_param_index] = gen_type->di_type;
         }
+        if (is_async) {
+            {
+                // async allocator param
+                TypeTableEntry *gen_type = fn_type_id->async_allocator_type;
+                gen_param_types[gen_param_index] = gen_type->type_ref;
+                gen_param_index += 1;
+                // after the gen_param_index += 1 because 0 is the return type
+                param_di_types[gen_param_index] = gen_type->di_type;
+            }
+
+            {
+                // error code pointer
+                TypeTableEntry *gen_type = get_pointer_to_type(g, g->builtin_types.entry_global_error_set, false);
+                gen_param_types[gen_param_index] = gen_type->type_ref;
+                gen_param_index += 1;
+                // after the gen_param_index += 1 because 0 is the return type
+                param_di_types[gen_param_index] = gen_type->di_type;
+            }
+        }
 
         fn_type->data.fn.gen_param_info = allocate<FnGenParamInfo>(fn_type_id->param_count);
         for (size_t i = 0; i < fn_type_id->param_count; i += 1) {

src/codegen.cpp

@@ -2521,13 +2521,12 @@ static LLVMValueRef ir_render_call(CodeGen *g, IrExecutable *executable, IrInstr
     }
 
     FnTypeId *fn_type_id = &fn_type->data.fn.fn_type_id;
-    if (fn_type_id->cc == CallingConventionAsync) {
-        zig_panic("TODO codegen async function call");
-    }
 
     TypeTableEntry *src_return_type = fn_type_id->return_type;
     bool ret_has_bits = type_has_bits(src_return_type);
-    bool first_arg_ret = ret_has_bits && handle_is_ptr(src_return_type);
+
+    bool first_arg_ret = ret_has_bits && handle_is_ptr(src_return_type) &&
+            calling_convention_does_first_arg_return(fn_type->data.fn.fn_type_id.cc);
     bool prefix_arg_err_ret_stack = g->have_err_ret_tracing && (src_return_type->id == TypeTableEntryIdErrorUnion || src_return_type->id == TypeTableEntryIdErrorSet);
     size_t actual_param_count = instruction->arg_count + (first_arg_ret ? 1 : 0) + (prefix_arg_err_ret_stack ? 1 : 0);
     bool is_var_args = fn_type_id->is_var_args;
@@ -2541,6 +2540,15 @@ static LLVMValueRef ir_render_call(CodeGen *g, IrExecutable *executable, IrInstr
         gen_param_values[gen_param_index] = g->cur_err_ret_trace_val;
         gen_param_index += 1;
     }
+    if (instruction->is_async) {
+        gen_param_values[gen_param_index] = ir_llvm_value(g, instruction->async_allocator);
+        gen_param_index += 1;
+
+        LLVMValueRef err_val_ptr = LLVMBuildStructGEP(g->builder, instruction->tmp_ptr, err_union_err_index, "");
+        LLVMBuildStore(g->builder, LLVMConstNull(g->builtin_types.entry_global_error_set->type_ref), err_val_ptr);
+        gen_param_values[gen_param_index] = err_val_ptr;
+        gen_param_index += 1;
+    }
     for (size_t call_i = 0; call_i < instruction->arg_count; call_i += 1) {
         IrInstruction *param_instruction = instruction->args[call_i];
         TypeTableEntry *param_type = param_instruction->value.type;
@@ -2578,6 +2586,12 @@ static LLVMValueRef ir_render_call(CodeGen *g, IrExecutable *executable, IrInstr
         }
     }
 
+    if (instruction->is_async) {
+        LLVMValueRef payload_ptr = LLVMBuildStructGEP(g->builder, instruction->tmp_ptr, err_union_payload_index, "");
+        LLVMBuildStore(g->builder, result, payload_ptr);
+        return instruction->tmp_ptr;
+    }
+
     if (src_return_type->id == TypeTableEntryIdUnreachable) {
         return LLVMBuildUnreachable(g->builder);
     } else if (!ret_has_bits) {

src/ir.cpp

@@ -11775,6 +11775,7 @@ static TypeTableEntry *ir_analyze_fn_call(IrAnalyze *ira, IrInstructionCall *cal
         if (call_instruction->is_async) {
             IrInstruction *result = ir_analyze_async_call(ira, call_instruction, impl_fn, impl_fn->type_entry, fn_ref, casted_args, impl_param_count, async_allocator_inst);
             ir_link_new_instruction(result, &call_instruction->base);
+            ir_add_alloca(ira, result, result->value.type);
             return ir_finish_anal(ira, result->value.type);
         }
 
@@ -11862,6 +11863,7 @@ static TypeTableEntry *ir_analyze_fn_call(IrAnalyze *ira, IrInstructionCall *cal
 
         IrInstruction *result = ir_analyze_async_call(ira, call_instruction, fn_entry, fn_type, fn_ref, casted_args, call_param_count, async_allocator_inst);
         ir_link_new_instruction(result, &call_instruction->base);
+        ir_add_alloca(ira, result, result->value.type);
         return ir_finish_anal(ira, result->value.type);
     }