Commit 72e983670e

Andrew Kelley <andrew@ziglang.org>
2019-07-21 22:21:16
simple async function call working
1 parent 54e716a
src/all_types.hpp
@@ -1251,6 +1251,7 @@ enum ZigTypeId {
     ZigTypeIdBoundFn,
     ZigTypeIdArgTuple,
     ZigTypeIdOpaque,
+    ZigTypeIdCoroFrame,
     ZigTypeIdVector,
     ZigTypeIdEnumLiteral,
 };
@@ -1265,6 +1266,11 @@ struct ZigTypeOpaque {
     Buf *bare_name;
 };
 
+struct ZigTypeCoroFrame {
+    ZigFn *fn;
+    ZigType *locals_struct;
+};
+
 struct ZigType {
     ZigTypeId id;
     Buf name;
@@ -1290,6 +1296,7 @@ struct ZigType {
         ZigTypeBoundFn bound_fn;
         ZigTypeVector vector;
         ZigTypeOpaque opaque;
+        ZigTypeCoroFrame frame;
     } data;
 
     // use these fields to make sure we don't duplicate type table entries for the same type
@@ -1340,6 +1347,7 @@ struct ZigFn {
     ScopeBlock *def_scope; // parent is child_scope
     Buf symbol_name;
     ZigType *type_entry; // function type
+    ZigType *frame_type; // coro frame type
     // in the case of normal functions this is the implicit return type
     // in the case of async functions this is the implicit return type according to the
     // zig source code, not according to zig ir
@@ -1356,6 +1364,7 @@ struct ZigFn {
 
     ZigList<IrInstructionAllocaGen *> alloca_gen_list;
     ZigList<ZigVar *> variable_list;
+    ZigList<IrBasicBlock *> resume_blocks;
 
     Buf *section_name;
     AstNode *set_alignstack_node;
@@ -1365,6 +1374,7 @@ struct ZigFn {
     ZigList<GlobalExport> export_list;
 
     LLVMValueRef valgrind_client_request_array;
+    LLVMBasicBlockRef preamble_llvm_block;
 
     FnInline fn_inline;
     FnAnalState anal_state;
@@ -1512,6 +1522,7 @@ enum PanicMsgId {
     PanicMsgIdBadEnumValue,
     PanicMsgIdFloatToInt,
     PanicMsgIdPtrCastNull,
+    PanicMsgIdBadResume,
 
     PanicMsgIdCount,
 };
@@ -1755,6 +1766,7 @@ struct CodeGen {
         ZigType *entry_global_error_set;
         ZigType *entry_arg_tuple;
         ZigType *entry_enum_literal;
+        ZigType *entry_frame_header;
     } builtin_types;
     ZigType *align_amt_type;
     ZigType *stack_trace_type;
@@ -2119,6 +2131,8 @@ struct IrBasicBlock {
     size_t ref_count;
     // index into the basic block list
     size_t index;
+    // for coroutines, the resume_index which corresponds to this block
+    size_t resume_index;
     LLVMBasicBlockRef llvm_block;
     LLVMBasicBlockRef llvm_exit_block;
     // The instruction that referenced this basic block and caused us to
@@ -2297,6 +2311,8 @@ enum IrInstructionId {
     IrInstructionIdEndExpr,
     IrInstructionIdPtrOfArrayToSlice,
     IrInstructionIdUnionInitNamedField,
+    IrInstructionIdSuspendBegin,
+    IrInstructionIdSuspendBr,
 };
 
 struct IrInstruction {
@@ -3511,6 +3527,18 @@ struct IrInstructionPtrOfArrayToSlice {
     IrInstruction *result_loc;
 };
 
+struct IrInstructionSuspendBegin {
+    IrInstruction base;
+
+    IrBasicBlock *resume_block;
+};
+
+struct IrInstructionSuspendBr {
+    IrInstruction base;
+
+    IrBasicBlock *resume_block;
+};
+
 enum ResultLocId {
     ResultLocIdInvalid,
     ResultLocIdNone,
@@ -3593,6 +3621,8 @@ static const size_t maybe_null_index = 1;
 static const size_t err_union_err_index = 0;
 static const size_t err_union_payload_index = 1;
 
+static const size_t coro_resume_index_index = 0;
+
 // TODO call graph analysis to find out what this number needs to be for every function
 // MUST BE A POWER OF TWO.
 static const size_t stack_trace_ptr_count = 32;
src/analyze.cpp
@@ -228,6 +228,8 @@ AstNode *type_decl_node(ZigType *type_entry) {
             return type_entry->data.enumeration.decl_node;
         case ZigTypeIdUnion:
             return type_entry->data.unionation.decl_node;
+        case ZigTypeIdCoroFrame:
+            return type_entry->data.frame.fn->proto_node;
         case ZigTypeIdOpaque:
         case ZigTypeIdMetaType:
         case ZigTypeIdVoid:
@@ -262,6 +264,20 @@ bool type_is_resolved(ZigType *type_entry, ResolveStatus status) {
             return type_entry->data.structure.resolve_status >= status;
         case ZigTypeIdUnion:
             return type_entry->data.unionation.resolve_status >= status;
+        case ZigTypeIdCoroFrame:
+            switch (status) {
+                case ResolveStatusInvalid:
+                    zig_unreachable();
+                case ResolveStatusUnstarted:
+                case ResolveStatusZeroBitsKnown:
+                    return true;
+                case ResolveStatusAlignmentKnown:
+                case ResolveStatusSizeKnown:
+                    return type_entry->data.frame.locals_struct != nullptr;
+                case ResolveStatusLLVMFwdDecl:
+                case ResolveStatusLLVMFull:
+                    return type_entry->llvm_type != nullptr;
+            }
         case ZigTypeIdEnum:
             switch (status) {
                 case ResolveStatusUnstarted:
@@ -345,6 +361,25 @@ static const char *ptr_len_to_star_str(PtrLen ptr_len) {
     zig_unreachable();
 }
 
+ZigType *get_coro_frame_type(CodeGen *g, ZigFn *fn) {
+    if (fn->frame_type != nullptr) {
+        return fn->frame_type;
+    }
+
+    ZigType *entry = new_type_table_entry(ZigTypeIdCoroFrame);
+    buf_resize(&entry->name, 0);
+    buf_appendf(&entry->name, "@Frame(%s)", buf_ptr(&fn->symbol_name));
+
+    entry->data.frame.fn = fn;
+
+    // Coroutine frames are always non-zero bits because they always have a resume index.
+    entry->abi_size = SIZE_MAX;
+    entry->size_in_bits = SIZE_MAX;
+
+    fn->frame_type = entry;
+    return entry;
+}
+
 ZigType *get_pointer_to_type_extra(CodeGen *g, ZigType *child_type, bool is_const,
         bool is_volatile, PtrLen ptr_len, uint32_t byte_alignment,
         uint32_t bit_offset_in_host, uint32_t host_int_bytes, bool allow_zero)
@@ -1039,6 +1074,7 @@ static Error emit_error_unless_type_allowed_in_packed_struct(CodeGen *g, ZigType
         case ZigTypeIdBoundFn:
         case ZigTypeIdArgTuple:
         case ZigTypeIdOpaque:
+        case ZigTypeIdCoroFrame:
             add_node_error(g, source_node,
                     buf_sprintf("type '%s' not allowed in packed struct; no guaranteed in-memory representation",
                         buf_ptr(&type_entry->name)));
@@ -1127,6 +1163,7 @@ bool type_allowed_in_extern(CodeGen *g, ZigType *type_entry) {
         case ZigTypeIdBoundFn:
         case ZigTypeIdArgTuple:
         case ZigTypeIdVoid:
+        case ZigTypeIdCoroFrame:
             return false;
         case ZigTypeIdOpaque:
         case ZigTypeIdUnreachable:
@@ -1297,6 +1334,7 @@ static ZigType *analyze_fn_type(CodeGen *g, AstNode *proto_node, Scope *child_sc
             case ZigTypeIdUnion:
             case ZigTypeIdFn:
             case ZigTypeIdVector:
+            case ZigTypeIdCoroFrame:
                 switch (type_requires_comptime(g, type_entry)) {
                     case ReqCompTimeNo:
                         break;
@@ -1392,6 +1430,7 @@ static ZigType *analyze_fn_type(CodeGen *g, AstNode *proto_node, Scope *child_sc
         case ZigTypeIdUnion:
         case ZigTypeIdFn:
         case ZigTypeIdVector:
+        case ZigTypeIdCoroFrame:
             switch (type_requires_comptime(g, fn_type_id.return_type)) {
                 case ReqCompTimeInvalid:
                     return g->builtin_types.entry_invalid;
@@ -1825,6 +1864,39 @@ static Error resolve_union_type(CodeGen *g, ZigType *union_type) {
     return ErrorNone;
 }
 
+static Error resolve_coro_frame(CodeGen *g, ZigType *frame_type) {
+    assert(frame_type->data.frame.locals_struct == nullptr);
+
+    ZigFn *fn = frame_type->data.frame.fn;
+    switch (fn->anal_state) {
+        case FnAnalStateInvalid:
+            return ErrorSemanticAnalyzeFail;
+        case FnAnalStateComplete:
+            break;
+        case FnAnalStateReady:
+            analyze_fn_body(g, fn);
+            if (fn->anal_state == FnAnalStateInvalid)
+                return ErrorSemanticAnalyzeFail;
+            break;
+        case FnAnalStateProbing:
+            add_node_error(g, fn->proto_node,
+                    buf_sprintf("cannot resolve '%s': function not fully analyzed yet",
+                        buf_ptr(&frame_type->name)));
+            return ErrorSemanticAnalyzeFail;
+    }
+    // TODO iterate over fn->alloca_gen_list
+    ZigList<ZigType *> field_types = {};
+    ZigList<const char *> field_names = {};
+
+    field_names.append("resume_index");
+    field_types.append(g->builtin_types.entry_usize);
+
+    assert(field_names.length == field_types.length);
+    frame_type->data.frame.locals_struct = get_struct_type(g, buf_ptr(&frame_type->name),
+            field_names.items, field_types.items, field_names.length);
+    return ErrorNone;
+}
+
 static bool type_is_valid_extern_enum_tag(CodeGen *g, ZigType *ty) {
     // Only integer types are allowed by the C ABI
     if(ty->id != ZigTypeIdInt)
@@ -2997,6 +3069,7 @@ ZigType *validate_var_type(CodeGen *g, AstNode *source_node, ZigType *type_entry
         case ZigTypeIdFn:
         case ZigTypeIdBoundFn:
         case ZigTypeIdVector:
+        case ZigTypeIdCoroFrame:
             return type_entry;
     }
     zig_unreachable();
@@ -3496,6 +3569,7 @@ bool is_container(ZigType *type_entry) {
         case ZigTypeIdArgTuple:
         case ZigTypeIdOpaque:
         case ZigTypeIdVector:
+        case ZigTypeIdCoroFrame:
             return false;
     }
     zig_unreachable();
@@ -3552,6 +3626,7 @@ Error resolve_container_type(CodeGen *g, ZigType *type_entry) {
         case ZigTypeIdArgTuple:
         case ZigTypeIdOpaque:
         case ZigTypeIdVector:
+        case ZigTypeIdCoroFrame:
             zig_unreachable();
     }
     zig_unreachable();
@@ -4002,6 +4077,7 @@ bool handle_is_ptr(ZigType *type_entry) {
              return false;
         case ZigTypeIdArray:
         case ZigTypeIdStruct:
+        case ZigTypeIdCoroFrame:
              return type_has_bits(type_entry);
         case ZigTypeIdErrorUnion:
              return type_has_bits(type_entry->data.error_union.payload_type);
@@ -4246,6 +4322,9 @@ static uint32_t hash_const_val(ConstExprValue *const_val) {
         case ZigTypeIdVector:
             // TODO better hashing algorithm
             return 3647867726;
+        case ZigTypeIdCoroFrame:
+            // TODO better hashing algorithm
+            return 675741936;
         case ZigTypeIdBoundFn:
         case ZigTypeIdInvalid:
         case ZigTypeIdUnreachable:
@@ -4310,6 +4389,7 @@ static bool can_mutate_comptime_var_state(ConstExprValue *value) {
         case ZigTypeIdOpaque:
         case ZigTypeIdErrorSet:
         case ZigTypeIdEnum:
+        case ZigTypeIdCoroFrame:
             return false;
 
         case ZigTypeIdPointer:
@@ -4381,6 +4461,7 @@ static bool return_type_is_cacheable(ZigType *return_type) {
         case ZigTypeIdEnum:
         case ZigTypeIdPointer:
         case ZigTypeIdVector:
+        case ZigTypeIdCoroFrame:
             return true;
 
         case ZigTypeIdArray:
@@ -4512,6 +4593,7 @@ OnePossibleValue type_has_one_possible_value(CodeGen *g, ZigType *type_entry) {
         case ZigTypeIdBool:
         case ZigTypeIdFloat:
         case ZigTypeIdErrorUnion:
+        case ZigTypeIdCoroFrame:
             return OnePossibleValueNo;
         case ZigTypeIdUndefined:
         case ZigTypeIdNull:
@@ -4599,6 +4681,7 @@ ReqCompTime type_requires_comptime(CodeGen *g, ZigType *type_entry) {
         case ZigTypeIdFloat:
         case ZigTypeIdVoid:
         case ZigTypeIdUnreachable:
+        case ZigTypeIdCoroFrame:
             return ReqCompTimeNo;
     }
     zig_unreachable();
@@ -4941,6 +5024,8 @@ Error type_resolve(CodeGen *g, ZigType *ty, ResolveStatus status) {
                 return resolve_enum_zero_bits(g, ty);
             } else if (ty->id == ZigTypeIdUnion) {
                 return resolve_union_alignment(g, ty);
+            } else if (ty->id == ZigTypeIdCoroFrame) {
+                return resolve_coro_frame(g, ty);
             }
             return ErrorNone;
         case ResolveStatusSizeKnown:
@@ -4950,6 +5035,8 @@ Error type_resolve(CodeGen *g, ZigType *ty, ResolveStatus status) {
                 return resolve_enum_zero_bits(g, ty);
             } else if (ty->id == ZigTypeIdUnion) {
                 return resolve_union_type(g, ty);
+            } else if (ty->id == ZigTypeIdCoroFrame) {
+                return resolve_coro_frame(g, ty);
             }
             return ErrorNone;
         case ResolveStatusLLVMFwdDecl:
@@ -5144,6 +5231,8 @@ bool const_values_equal(CodeGen *g, ConstExprValue *a, ConstExprValue *b) {
                     return false;
             }
             return true;
+        case ZigTypeIdCoroFrame:
+            zig_panic("TODO");
         case ZigTypeIdUndefined:
             zig_panic("TODO");
         case ZigTypeIdNull:
@@ -5496,6 +5585,10 @@ void render_const_value(CodeGen *g, Buf *buf, ConstExprValue *const_val) {
                 buf_appendf(buf, "(args value)");
                 return;
             }
+        case ZigTypeIdCoroFrame:
+            buf_appendf(buf, "(TODO: coroutine frame value)");
+            return;
+
     }
     zig_unreachable();
 }
@@ -5542,6 +5635,7 @@ uint32_t type_id_hash(TypeId x) {
         case ZigTypeIdFn:
         case ZigTypeIdBoundFn:
         case ZigTypeIdArgTuple:
+        case ZigTypeIdCoroFrame:
             zig_unreachable();
         case ZigTypeIdErrorUnion:
             return hash_ptr(x.data.error_union.err_set_type) ^ hash_ptr(x.data.error_union.payload_type);
@@ -5590,6 +5684,7 @@ bool type_id_eql(TypeId a, TypeId b) {
         case ZigTypeIdBoundFn:
         case ZigTypeIdArgTuple:
         case ZigTypeIdOpaque:
+        case ZigTypeIdCoroFrame:
             zig_unreachable();
         case ZigTypeIdErrorUnion:
             return a.data.error_union.err_set_type == b.data.error_union.err_set_type &&
@@ -5818,10 +5913,12 @@ size_t type_id_index(ZigType *entry) {
             return 20;
         case ZigTypeIdOpaque:
             return 21;
-        case ZigTypeIdVector:
+        case ZigTypeIdCoroFrame:
             return 22;
-        case ZigTypeIdEnumLiteral:
+        case ZigTypeIdVector:
             return 23;
+        case ZigTypeIdEnumLiteral:
+            return 24;
     }
     zig_unreachable();
 }
@@ -5878,6 +5975,8 @@ const char *type_id_name(ZigTypeId id) {
             return "Opaque";
         case ZigTypeIdVector:
             return "Vector";
+        case ZigTypeIdCoroFrame:
+            return "Frame";
     }
     zig_unreachable();
 }
@@ -5947,7 +6046,7 @@ bool type_can_fail(ZigType *type_entry) {
 }
 
 bool fn_type_can_fail(FnTypeId *fn_type_id) {
-    return type_can_fail(fn_type_id->return_type) || fn_type_id->cc == CallingConventionAsync;
+    return type_can_fail(fn_type_id->return_type);
 }
 
 // ErrorNone - result pointer has the type
@@ -6935,12 +7034,12 @@ static void resolve_llvm_types_array(CodeGen *g, ZigType *type) {
             debug_align_in_bits, get_llvm_di_type(g, elem_type), (int)type->data.array.len);
 }
 
-static void resolve_llvm_types_fn(CodeGen *g, ZigType *fn_type) {
+void resolve_llvm_types_fn(CodeGen *g, ZigType *fn_type, ZigFn *fn) {
     if (fn_type->llvm_di_type != nullptr) return;
 
     FnTypeId *fn_type_id = &fn_type->data.fn.fn_type_id;
     bool first_arg_return = want_first_arg_sret(g, fn_type_id);
-    bool is_async = fn_type_id->cc == CallingConventionAsync;
+    bool is_async = fn_type_id->cc == CallingConventionAsync || (fn != nullptr && fn->resume_blocks.length != 0);
     bool is_c_abi = fn_type_id->cc == CallingConventionC;
     bool prefix_arg_error_return_trace = g->have_err_ret_tracing && fn_type_can_fail(fn_type_id);
     // +1 for maybe making the first argument the return value
@@ -6955,7 +7054,7 @@ static void resolve_llvm_types_fn(CodeGen *g, ZigType *fn_type) {
     param_di_types.append(get_llvm_di_type(g, fn_type_id->return_type));
     ZigType *gen_return_type;
     if (is_async) {
-        gen_return_type = get_pointer_to_type(g, g->builtin_types.entry_u8, false);
+        gen_return_type = g->builtin_types.entry_usize;
     } else if (!type_has_bits(fn_type_id->return_type)) {
         gen_return_type = g->builtin_types.entry_void;
     } else if (first_arg_return) {
@@ -6974,13 +7073,10 @@ static void resolve_llvm_types_fn(CodeGen *g, ZigType *fn_type) {
         param_di_types.append(get_llvm_di_type(g, gen_type));
     }
     if (is_async) {
-            // coroutine frame pointer
-            // TODO if we can make this typed a little more it will be better for
-            // debug symbols.
-            // TODO do we need to make this aligned more?
-            ZigType *void_star = get_pointer_to_type(g, g->builtin_types.entry_c_void, false);
-            gen_param_types.append(get_llvm_type(g, void_star));
-            param_di_types.append(get_llvm_di_type(g, void_star));
+        ZigType *frame_type = (fn == nullptr) ? g->builtin_types.entry_frame_header : get_coro_frame_type(g, fn);
+        ZigType *ptr_type = get_pointer_to_type(g, frame_type, false);
+        gen_param_types.append(get_llvm_type(g, ptr_type));
+        param_di_types.append(get_llvm_di_type(g, ptr_type));
     }
 
     fn_type->data.fn.gen_param_info = allocate<FnGenParamInfo>(fn_type_id->param_count);
@@ -7055,6 +7151,17 @@ static void resolve_llvm_types_anyerror(CodeGen *g) {
             get_llvm_di_type(g, g->err_tag_type), "");
 }
 
+static void resolve_llvm_types_coro_frame(CodeGen *g, ZigType *frame_type, ResolveStatus wanted_resolve_status) {
+    if (frame_type->llvm_di_type != nullptr) return;
+
+    resolve_llvm_types_struct(g, frame_type->data.frame.locals_struct, wanted_resolve_status);
+    frame_type->llvm_type = frame_type->data.frame.locals_struct->llvm_type;
+    frame_type->llvm_di_type = frame_type->data.frame.locals_struct->llvm_di_type;
+    frame_type->abi_size = frame_type->data.frame.locals_struct->abi_size;
+    frame_type->abi_align = frame_type->data.frame.locals_struct->abi_align;
+    frame_type->size_in_bits = frame_type->data.frame.locals_struct->size_in_bits;
+}
+
 static void resolve_llvm_types(CodeGen *g, ZigType *type, ResolveStatus wanted_resolve_status) {
     assert(type->id == ZigTypeIdOpaque || type_is_resolved(type, ResolveStatusSizeKnown));
     assert(wanted_resolve_status > ResolveStatusSizeKnown);
@@ -7096,7 +7203,7 @@ static void resolve_llvm_types(CodeGen *g, ZigType *type, ResolveStatus wanted_r
         case ZigTypeIdArray:
             return resolve_llvm_types_array(g, type);
         case ZigTypeIdFn:
-            return resolve_llvm_types_fn(g, type);
+            return resolve_llvm_types_fn(g, type, nullptr);
         case ZigTypeIdErrorSet: {
             if (type->llvm_di_type != nullptr) return;
 
@@ -7115,6 +7222,8 @@ static void resolve_llvm_types(CodeGen *g, ZigType *type, ResolveStatus wanted_r
                     type->abi_align, get_llvm_di_type(g, type->data.vector.elem_type), type->data.vector.len);
             return;
         }
+        case ZigTypeIdCoroFrame:
+            return resolve_llvm_types_coro_frame(g, type, wanted_resolve_status);
     }
     zig_unreachable();
 }
src/analyze.hpp
@@ -16,6 +16,7 @@ ErrorMsg *add_token_error(CodeGen *g, ZigType *owner, Token *token, Buf *msg);
 ErrorMsg *add_error_note(CodeGen *g, ErrorMsg *parent_msg, AstNode *node, Buf *msg);
 void emit_error_notes_for_ref_stack(CodeGen *g, ErrorMsg *msg);
 ZigType *new_type_table_entry(ZigTypeId id);
+ZigType *get_coro_frame_type(CodeGen *g, ZigFn *fn);
 ZigType *get_pointer_to_type(CodeGen *g, ZigType *child_type, bool is_const);
 ZigType *get_pointer_to_type_extra(CodeGen *g, ZigType *child_type, bool is_const,
         bool is_volatile, PtrLen ptr_len,
@@ -247,4 +248,6 @@ void src_assert(bool ok, AstNode *source_node);
 bool is_container(ZigType *type_entry);
 ConstExprValue *analyze_const_value(CodeGen *g, Scope *scope, AstNode *node, ZigType *type_entry, Buf *type_name);
 
+void resolve_llvm_types_fn(CodeGen *g, ZigType *fn_type, ZigFn *fn);
+
 #endif
src/codegen.cpp
@@ -498,7 +498,7 @@ static LLVMValueRef fn_llvm_value(CodeGen *g, ZigFn *fn_table_entry) {
 
     ZigType *fn_type = fn_table_entry->type_entry;
     // Make the raw_type_ref populated
-    (void)get_llvm_type(g, fn_type);
+    resolve_llvm_types_fn(g, fn_type, fn_table_entry);
     LLVMTypeRef fn_llvm_type = fn_type->data.fn.raw_type_ref;
     if (fn_table_entry->body_node == nullptr) {
         LLVMValueRef existing_llvm_fn = LLVMGetNamedFunction(g->module, buf_ptr(symbol_name));
@@ -921,9 +921,8 @@ static bool ir_want_fast_math(CodeGen *g, IrInstruction *instruction) {
     return false;
 }
 
-static bool ir_want_runtime_safety(CodeGen *g, IrInstruction *instruction) {
+static bool ir_want_runtime_safety_scope(CodeGen *g, Scope *scope) {
     // TODO memoize
-    Scope *scope = instruction->scope;
     while (scope) {
         if (scope->id == ScopeIdBlock) {
             ScopeBlock *block_scope = (ScopeBlock *)scope;
@@ -941,6 +940,10 @@ static bool ir_want_runtime_safety(CodeGen *g, IrInstruction *instruction) {
             g->build_mode != BuildModeSmallRelease);
 }
 
+static bool ir_want_runtime_safety(CodeGen *g, IrInstruction *instruction) {
+    return ir_want_runtime_safety_scope(g, instruction->scope);
+}
+
 static Buf *panic_msg_buf(PanicMsgId msg_id) {
     switch (msg_id) {
         case PanicMsgIdCount:
@@ -981,6 +984,8 @@ static Buf *panic_msg_buf(PanicMsgId msg_id) {
             return buf_create_from_str("integer part of floating point value out of bounds");
         case PanicMsgIdPtrCastNull:
             return buf_create_from_str("cast causes pointer to be null");
+        case PanicMsgIdBadResume:
+            return buf_create_from_str("invalid resume of async function");
     }
     zig_unreachable();
 }
@@ -1027,14 +1032,18 @@ static void gen_safety_crash(CodeGen *g, PanicMsgId msg_id) {
     gen_panic(g, get_panic_msg_ptr_val(g, msg_id), nullptr);
 }
 
-static void gen_assertion(CodeGen *g, PanicMsgId msg_id, IrInstruction *source_instruction) {
-    if (ir_want_runtime_safety(g, source_instruction)) {
+static void gen_assertion_scope(CodeGen *g, PanicMsgId msg_id, Scope *source_scope) {
+    if (ir_want_runtime_safety_scope(g, source_scope)) {
         gen_safety_crash(g, msg_id);
     } else {
         LLVMBuildUnreachable(g->builder);
     }
 }
 
+static void gen_assertion(CodeGen *g, PanicMsgId msg_id, IrInstruction *source_instruction) {
+    return gen_assertion_scope(g, msg_id, source_instruction->scope);
+}
+
 static LLVMValueRef get_stacksave_fn_val(CodeGen *g) {
     if (g->stacksave_fn_val)
         return g->stacksave_fn_val;
@@ -2092,6 +2101,10 @@ static LLVMValueRef ir_render_save_err_ret_addr(CodeGen *g, IrExecutable *execut
 }
 
 static LLVMValueRef ir_render_return(CodeGen *g, IrExecutable *executable, IrInstructionReturn *return_instruction) {
+    if (g->cur_fn->resume_blocks.length != 0) {
+        LLVMBuildRet(g->builder, LLVMGetUndef(g->builtin_types.entry_usize->llvm_type));
+        return nullptr;
+    }
     if (want_first_arg_sret(g, &g->cur_fn->type_entry->data.fn.fn_type_id)) {
         if (return_instruction->value == nullptr) {
             LLVMBuildRetVoid(g->builder);
@@ -3375,8 +3388,7 @@ static LLVMValueRef ir_render_elem_ptr(CodeGen *g, IrExecutable *executable, IrI
 static bool get_prefix_arg_err_ret_stack(CodeGen *g, FnTypeId *fn_type_id) {
     return g->have_err_ret_tracing &&
         (fn_type_id->return_type->id == ZigTypeIdErrorUnion ||
-         fn_type_id->return_type->id == ZigTypeIdErrorSet ||
-         fn_type_id->cc == CallingConventionAsync);
+         fn_type_id->return_type->id == ZigTypeIdErrorSet);
 }
 
 static LLVMValueRef get_new_stack_addr(CodeGen *g, LLVMValueRef new_stack) {
@@ -3440,15 +3452,23 @@ static LLVMValueRef ir_render_call(CodeGen *g, IrExecutable *executable, IrInstr
     bool is_var_args = fn_type_id->is_var_args;
     ZigList<LLVMValueRef> gen_param_values = {};
     LLVMValueRef result_loc = instruction->result_loc ? ir_llvm_value(g, instruction->result_loc) : nullptr;
-    if (first_arg_ret) {
+    if (instruction->is_async) {
+        assert(result_loc != nullptr);
+        assert(instruction->fn_entry != nullptr);
+        LLVMValueRef resume_index_ptr = LLVMBuildStructGEP(g->builder, result_loc, coro_resume_index_index, "");
+        LLVMValueRef zero = LLVMConstNull(g->builtin_types.entry_usize->llvm_type);
+        LLVMBuildStore(g->builder, zero, resume_index_ptr);
+
+        if (prefix_arg_err_ret_stack) {
+            zig_panic("TODO");
+        }
+
         gen_param_values.append(result_loc);
-    }
-    if (prefix_arg_err_ret_stack) {
+    } else if (first_arg_ret) {
+        gen_param_values.append(result_loc);
+    } else if (prefix_arg_err_ret_stack) {
         gen_param_values.append(get_cur_err_ret_trace_val(g, instruction->base.scope));
     }
-    if (instruction->is_async) {
-        zig_panic("TODO codegen async call");
-    }
     FnWalk fn_walk = {};
     fn_walk.id = FnWalkIdCall;
     fn_walk.data.call.inst = instruction;
@@ -3489,9 +3509,7 @@ static LLVMValueRef ir_render_call(CodeGen *g, IrExecutable *executable, IrInstr
 
 
     if (instruction->is_async) {
-        LLVMValueRef payload_ptr = LLVMBuildStructGEP(g->builder, result_loc, err_union_payload_index, "");
-        LLVMBuildStore(g->builder, result, payload_ptr);
-        return result_loc;
+        return nullptr;
     }
 
     if (src_return_type->id == ZigTypeIdUnreachable) {
@@ -4921,6 +4939,24 @@ static LLVMValueRef ir_render_assert_non_null(CodeGen *g, IrExecutable *executab
     return nullptr;
 }
 
+static LLVMValueRef ir_render_suspend_begin(CodeGen *g, IrExecutable *executable,
+        IrInstructionSuspendBegin *instruction)
+{
+    LLVMValueRef locals_ptr = g->cur_ret_ptr;
+    LLVMValueRef resume_index_ptr = LLVMBuildStructGEP(g->builder, locals_ptr, coro_resume_index_index, "");
+    LLVMValueRef new_resume_index = LLVMConstInt(g->builtin_types.entry_usize->llvm_type,
+            instruction->resume_block->resume_index, false);
+    LLVMBuildStore(g->builder, new_resume_index, resume_index_ptr);
+    return nullptr;
+}
+
+static LLVMValueRef ir_render_suspend_br(CodeGen *g, IrExecutable *executable,
+        IrInstructionSuspendBr *instruction)
+{
+    LLVMBuildRet(g->builder, LLVMGetUndef(g->builtin_types.entry_usize->llvm_type));
+    return nullptr;
+}
+
 static void set_debug_location(CodeGen *g, IrInstruction *instruction) {
     AstNode *source_node = instruction->source_node;
     Scope *scope = instruction->scope;
@@ -5161,6 +5197,10 @@ static LLVMValueRef ir_render_instruction(CodeGen *g, IrExecutable *executable,
             return ir_render_resize_slice(g, executable, (IrInstructionResizeSlice *)instruction);
         case IrInstructionIdPtrOfArrayToSlice:
             return ir_render_ptr_of_array_to_slice(g, executable, (IrInstructionPtrOfArrayToSlice *)instruction);
+        case IrInstructionIdSuspendBegin:
+            return ir_render_suspend_begin(g, executable, (IrInstructionSuspendBegin *)instruction);
+        case IrInstructionIdSuspendBr:
+            return ir_render_suspend_br(g, executable, (IrInstructionSuspendBr *)instruction);
     }
     zig_unreachable();
 }
@@ -5422,7 +5462,8 @@ static LLVMValueRef pack_const_int(CodeGen *g, LLVMTypeRef big_int_type_ref, Con
                 }
                 return val;
             }
-
+        case ZigTypeIdCoroFrame:
+            zig_panic("TODO bit pack a coroutine frame");
     }
     zig_unreachable();
 }
@@ -5943,7 +5984,8 @@ static LLVMValueRef gen_const_val(CodeGen *g, ConstExprValue *const_val, const c
         case ZigTypeIdArgTuple:
         case ZigTypeIdOpaque:
             zig_unreachable();
-
+        case ZigTypeIdCoroFrame:
+            zig_panic("TODO");
     }
     zig_unreachable();
 }
@@ -6027,12 +6069,20 @@ static void generate_error_name_table(CodeGen *g) {
 static void build_all_basic_blocks(CodeGen *g, ZigFn *fn) {
     IrExecutable *executable = &fn->analyzed_executable;
     assert(executable->basic_block_list.length > 0);
+    LLVMValueRef fn_val = fn_llvm_value(g, fn);
+    LLVMBasicBlockRef first_bb = nullptr;
+    if (fn->resume_blocks.length != 0) {
+        first_bb = LLVMAppendBasicBlock(fn_val, "AsyncSwitch");
+        fn->preamble_llvm_block = first_bb;
+    }
     for (size_t block_i = 0; block_i < executable->basic_block_list.length; block_i += 1) {
         IrBasicBlock *bb = executable->basic_block_list.at(block_i);
-        bb->llvm_block = LLVMAppendBasicBlock(fn_llvm_value(g, fn), bb->name_hint);
+        bb->llvm_block = LLVMAppendBasicBlock(fn_val, bb->name_hint);
+    }
+    if (first_bb == nullptr) {
+        first_bb = executable->basic_block_list.at(0)->llvm_block;
     }
-    IrBasicBlock *entry_bb = executable->basic_block_list.at(0);
-    LLVMPositionBuilderAtEnd(g->builder, entry_bb->llvm_block);
+    LLVMPositionBuilderAtEnd(g->builder, first_bb);
 }
 
 static void gen_global_var(CodeGen *g, ZigVar *var, LLVMValueRef init_val,
@@ -6209,7 +6259,7 @@ static void do_code_gen(CodeGen *g) {
         build_all_basic_blocks(g, fn_table_entry);
         clear_debug_source_node(g);
 
-        if (want_sret) {
+        if (want_sret || fn_table_entry->resume_blocks.length != 0) {
             g->cur_ret_ptr = LLVMGetParam(fn, 0);
         } else if (handle_is_ptr(fn_type_id->return_type)) {
             g->cur_ret_ptr = build_alloca(g, fn_type_id->return_type, "result", 0);
@@ -6357,6 +6407,41 @@ static void do_code_gen(CodeGen *g) {
         fn_walk_init.data.inits.gen_i = gen_i_init;
         walk_function_params(g, fn_table_entry->type_entry, &fn_walk_init);
 
+        if (fn_table_entry->resume_blocks.length != 0) {
+            if (!g->strip_debug_symbols) {
+                AstNode *source_node = fn_table_entry->proto_node;
+                ZigLLVMSetCurrentDebugLocation(g->builder, (int)source_node->line + 1,
+                        (int)source_node->column + 1, get_di_scope(g, fn_table_entry->child_scope));
+            }
+            LLVMTypeRef usize_type_ref = g->builtin_types.entry_usize->llvm_type;
+            LLVMBasicBlockRef bad_resume_block = LLVMAppendBasicBlock(g->cur_fn_val, "BadResume");
+            LLVMPositionBuilderAtEnd(g->builder, bad_resume_block);
+            gen_assertion_scope(g, PanicMsgIdBadResume, fn_table_entry->child_scope);
+
+            LLVMBasicBlockRef get_size_block = LLVMAppendBasicBlock(g->cur_fn_val, "GetSize");
+            LLVMPositionBuilderAtEnd(g->builder, get_size_block);
+            assert(fn_table_entry->frame_type->abi_size != 0);
+            assert(fn_table_entry->frame_type->abi_size != SIZE_MAX);
+            LLVMValueRef size_val = LLVMConstInt(usize_type_ref, fn_table_entry->frame_type->abi_size, false);
+            LLVMBuildRet(g->builder, size_val);
+
+            LLVMPositionBuilderAtEnd(g->builder, fn_table_entry->preamble_llvm_block);
+            LLVMValueRef resume_index_ptr = LLVMBuildStructGEP(g->builder, g->cur_ret_ptr,
+                    coro_resume_index_index, "");
+            LLVMValueRef resume_index = LLVMBuildLoad(g->builder, resume_index_ptr, "");
+            // The +1 is because index 0 is reserved for getting the size.
+            LLVMValueRef switch_instr = LLVMBuildSwitch(g->builder, resume_index, bad_resume_block,
+                    fn_table_entry->resume_blocks.length + 1);
+
+            LLVMValueRef zero = LLVMConstNull(usize_type_ref);
+            LLVMAddCase(switch_instr, zero, get_size_block);
+
+            for (size_t resume_i = 0; resume_i < fn_table_entry->resume_blocks.length; resume_i += 1) {
+                LLVMValueRef case_value = LLVMConstInt(usize_type_ref, resume_i + 1, false);
+                LLVMAddCase(switch_instr, case_value, fn_table_entry->resume_blocks.at(resume_i)->llvm_block);
+            }
+        }
+
         ir_render(g, fn_table_entry);
 
     }
@@ -6644,9 +6729,13 @@ static void define_builtin_types(CodeGen *g) {
 
         g->primitive_type_table.put(&entry->name, entry);
     }
+    {
+        const char *field_names[] = {"resume_index"};
+        ZigType *field_types[] = {g->builtin_types.entry_usize};
+        g->builtin_types.entry_frame_header = get_struct_type(g, "(frame header)", field_names, field_types, 1);
+    }
 }
 
-
 static BuiltinFnEntry *create_builtin_fn(CodeGen *g, BuiltinFnId id, const char *name, size_t count) {
     BuiltinFnEntry *builtin_fn = allocate<BuiltinFnEntry>(1);
     buf_init_from_str(&builtin_fn->name, name);
@@ -7072,6 +7161,7 @@ Buf *codegen_generate_builtin_source(CodeGen *g) {
             "    BoundFn: Fn,\n"
             "    ArgTuple: void,\n"
             "    Opaque: void,\n"
+            "    Frame: void,\n"
             "    Vector: Vector,\n"
             "    EnumLiteral: void,\n"
             "\n\n"
@@ -8335,6 +8425,7 @@ static void prepend_c_type_to_decl_list(CodeGen *g, GenH *gen_h, ZigType *type_e
         case ZigTypeIdArgTuple:
         case ZigTypeIdErrorUnion:
         case ZigTypeIdErrorSet:
+        case ZigTypeIdCoroFrame:
             zig_unreachable();
         case ZigTypeIdVoid:
         case ZigTypeIdUnreachable:
@@ -8518,6 +8609,7 @@ static void get_c_type(CodeGen *g, GenH *gen_h, ZigType *type_entry, Buf *out_bu
         case ZigTypeIdUndefined:
         case ZigTypeIdNull:
         case ZigTypeIdArgTuple:
+        case ZigTypeIdCoroFrame:
             zig_unreachable();
     }
 }
@@ -8685,6 +8777,7 @@ static void gen_h_file(CodeGen *g) {
             case ZigTypeIdOptional:
             case ZigTypeIdFn:
             case ZigTypeIdVector:
+            case ZigTypeIdCoroFrame:
                 zig_unreachable();
             case ZigTypeIdEnum:
                 if (type_entry->data.enumeration.layout == ContainerLayoutExtern) {
src/ir.cpp
@@ -318,6 +318,7 @@ static bool types_have_same_zig_comptime_repr(ZigType *a, ZigType *b) {
         case ZigTypeIdFn:
         case ZigTypeIdArgTuple:
         case ZigTypeIdVector:
+        case ZigTypeIdCoroFrame:
             return false;
     }
     zig_unreachable();
@@ -1026,6 +1027,14 @@ static constexpr IrInstructionId ir_instruction_id(IrInstructionUnionInitNamedFi
     return IrInstructionIdUnionInitNamedField;
 }
 
+static constexpr IrInstructionId ir_instruction_id(IrInstructionSuspendBegin *) {
+    return IrInstructionIdSuspendBegin;
+}
+
+static constexpr IrInstructionId ir_instruction_id(IrInstructionSuspendBr *) {
+    return IrInstructionIdSuspendBr;
+}
+
 template<typename T>
 static T *ir_create_instruction(IrBuilder *irb, Scope *scope, AstNode *source_node) {
     T *special_instruction = allocate<T>(1);
@@ -3183,6 +3192,30 @@ static IrInstruction *ir_build_end_expr(IrBuilder *irb, Scope *scope, AstNode *s
     return &instruction->base;
 }
 
+static IrInstruction *ir_build_suspend_begin(IrBuilder *irb, Scope *scope, AstNode *source_node,
+        IrBasicBlock *resume_block)
+{
+    IrInstructionSuspendBegin *instruction = ir_build_instruction<IrInstructionSuspendBegin>(irb, scope, source_node);
+    instruction->base.value.type = irb->codegen->builtin_types.entry_void;
+    instruction->resume_block = resume_block;
+
+    ir_ref_bb(resume_block);
+
+    return &instruction->base;
+}
+
+static IrInstruction *ir_build_suspend_br(IrBuilder *irb, Scope *scope, AstNode *source_node,
+        IrBasicBlock *resume_block)
+{
+    IrInstructionSuspendBr *instruction = ir_build_instruction<IrInstructionSuspendBr>(irb, scope, source_node);
+    instruction->base.value.type = irb->codegen->builtin_types.entry_unreachable;
+    instruction->resume_block = resume_block;
+
+    ir_ref_bb(resume_block);
+
+    return &instruction->base;
+}
+
 static void ir_count_defers(IrBuilder *irb, Scope *inner_scope, Scope *outer_scope, size_t *results) {
     results[ReturnKindUnconditional] = 0;
     results[ReturnKindError] = 0;
@@ -3286,6 +3319,18 @@ static void ir_set_cursor_at_end_and_append_block(IrBuilder *irb, IrBasicBlock *
     ir_set_cursor_at_end(irb, basic_block);
 }
 
+static ScopeSuspend *get_scope_suspend(Scope *scope) {
+    while (scope) {
+        if (scope->id == ScopeIdSuspend)
+            return (ScopeSuspend *)scope;
+        if (scope->id == ScopeIdFnDef)
+            return nullptr;
+
+        scope = scope->parent;
+    }
+    return nullptr;
+}
+
 static ScopeDeferExpr *get_scope_defer_expr(Scope *scope) {
     while (scope) {
         if (scope->id == ScopeIdDeferExpr)
@@ -3308,14 +3353,9 @@ static IrInstruction *ir_gen_async_return(IrBuilder *irb, Scope *scope, AstNode
 {
     ir_mark_gen(ir_build_add_implicit_return_type(irb, scope, node, return_value));
 
-    bool is_async = exec_is_async(irb->exec);
-    if (!is_async) {
-        IrInstruction *return_inst = ir_build_return(irb, scope, node, return_value);
-        return_inst->is_gen = is_generated_code;
-        return return_inst;
-    }
-
-    zig_panic("TODO async return");
+    IrInstruction *return_inst = ir_build_return(irb, scope, node, return_value);
+    return_inst->is_gen = is_generated_code;
+    return return_inst;
 }
 
 static IrInstruction *ir_gen_return(IrBuilder *irb, Scope *scope, AstNode *node, LVal lval, ResultLoc *result_loc) {
@@ -5393,12 +5433,8 @@ static IrInstruction *ir_gen_fn_call(IrBuilder *irb, Scope *scope, AstNode *node
     }
 
     bool is_async = node->data.fn_call_expr.is_async;
-    if (is_async) {
-        zig_panic("TODO async fn call");
-    }
-
-    IrInstruction *fn_call = ir_build_call_src(irb, scope, node, nullptr, fn_ref, arg_count, args, false, FnInlineAuto,
-            is_async, nullptr, result_loc);
+    IrInstruction *fn_call = ir_build_call_src(irb, scope, node, nullptr, fn_ref, arg_count, args, false,
+            FnInlineAuto, is_async, nullptr, result_loc);
     return ir_lval_wrap(irb, scope, fn_call, lval, result_loc);
 }
 
@@ -7655,7 +7691,45 @@ static IrInstruction *ir_gen_await_expr(IrBuilder *irb, Scope *scope, AstNode *n
 static IrInstruction *ir_gen_suspend(IrBuilder *irb, Scope *parent_scope, AstNode *node) {
     assert(node->type == NodeTypeSuspend);
 
-    zig_panic("TODO ir_gen_suspend");
+    ZigFn *fn_entry = exec_fn_entry(irb->exec);
+    if (!fn_entry) {
+        add_node_error(irb->codegen, node, buf_sprintf("suspend outside function definition"));
+        return irb->codegen->invalid_instruction;
+    }
+    ScopeDeferExpr *scope_defer_expr = get_scope_defer_expr(parent_scope);
+    if (scope_defer_expr) {
+        if (!scope_defer_expr->reported_err) {
+            ErrorMsg *msg = add_node_error(irb->codegen, node, buf_sprintf("cannot suspend inside defer expression"));
+            add_error_note(irb->codegen, msg, scope_defer_expr->base.source_node, buf_sprintf("defer here"));
+            scope_defer_expr->reported_err = true;
+        }
+        return irb->codegen->invalid_instruction;
+    }
+    ScopeSuspend *existing_suspend_scope = get_scope_suspend(parent_scope);
+    if (existing_suspend_scope) {
+        if (!existing_suspend_scope->reported_err) {
+            ErrorMsg *msg = add_node_error(irb->codegen, node, buf_sprintf("cannot suspend inside suspend block"));
+            add_error_note(irb->codegen, msg, existing_suspend_scope->base.source_node, buf_sprintf("other suspend block here"));
+            existing_suspend_scope->reported_err = true;
+        }
+        return irb->codegen->invalid_instruction;
+    }
+
+    IrBasicBlock *resume_block = ir_create_basic_block(irb, parent_scope, "Resume");
+
+    ir_build_suspend_begin(irb, parent_scope, node, resume_block);
+    if (node->data.suspend.block != nullptr) {
+        Scope *child_scope;
+        ScopeSuspend *suspend_scope = create_suspend_scope(irb->codegen, node, parent_scope);
+        suspend_scope->resume_block = resume_block;
+        child_scope = &suspend_scope->base;
+        IrInstruction *susp_res = ir_gen_node(irb, node->data.suspend.block, child_scope);
+        ir_mark_gen(ir_build_check_statement_is_void(irb, child_scope, node->data.suspend.block, susp_res));
+    }
+
+    IrInstruction *result = ir_build_suspend_br(irb, parent_scope, node, resume_block);
+    ir_set_cursor_at_end_and_append_block(irb, resume_block);
+    return result;
 }
 
 static IrInstruction *ir_gen_node_raw(IrBuilder *irb, AstNode *node, Scope *scope,
@@ -7854,13 +7928,6 @@ bool ir_gen(CodeGen *codegen, AstNode *node, Scope *scope, IrExecutable *ir_exec
     // Entry block gets a reference because we enter it to begin.
     ir_ref_bb(irb->current_basic_block);
 
-    ZigFn *fn_entry = exec_fn_entry(irb->exec);
-
-    bool is_async = fn_entry != nullptr && fn_entry->type_entry->data.fn.fn_type_id.cc == CallingConventionAsync;
-    if (is_async) {
-        zig_panic("ir_gen async fn");
-    }
-
     IrInstruction *result = ir_gen_node_extra(irb, node, scope, LValNone, nullptr);
     assert(result);
     if (irb->exec->invalid)
@@ -12659,6 +12726,7 @@ static IrInstruction *ir_analyze_bin_op_cmp(IrAnalyze *ira, IrInstructionBinOp *
         case ZigTypeIdNull:
         case ZigTypeIdErrorUnion:
         case ZigTypeIdUnion:
+        case ZigTypeIdCoroFrame:
             operator_allowed = false;
             break;
         case ZigTypeIdOptional:
@@ -14023,6 +14091,7 @@ static IrInstruction *ir_analyze_instruction_export(IrAnalyze *ira, IrInstructio
                 case ZigTypeIdBoundFn:
                 case ZigTypeIdArgTuple:
                 case ZigTypeIdOpaque:
+                case ZigTypeIdCoroFrame:
                     ir_add_error(ira, target,
                         buf_sprintf("invalid export target '%s'", buf_ptr(&type_value->name)));
                     break;
@@ -14047,6 +14116,7 @@ static IrInstruction *ir_analyze_instruction_export(IrAnalyze *ira, IrInstructio
         case ZigTypeIdArgTuple:
         case ZigTypeIdOpaque:
         case ZigTypeIdEnumLiteral:
+        case ZigTypeIdCoroFrame:
             ir_add_error(ira, target,
                     buf_sprintf("invalid export target type '%s'", buf_ptr(&target->value.type->name)));
             break;
@@ -14553,6 +14623,20 @@ static IrInstruction *ir_analyze_instruction_reset_result(IrAnalyze *ira, IrInst
     return ir_const_void(ira, &instruction->base);
 }
 
+static IrInstruction *ir_analyze_async_call(IrAnalyze *ira, IrInstructionCallSrc *call_instruction, ZigFn *fn_entry,
+        ZigType *fn_type, IrInstruction *fn_ref, IrInstruction **casted_args, size_t arg_count)
+{
+    ir_assert(fn_entry != nullptr, &call_instruction->base);
+
+    ZigType *frame_type = get_coro_frame_type(ira->codegen, fn_entry);
+    IrInstruction *result_loc = ir_resolve_result(ira, &call_instruction->base, call_instruction->result_loc,
+            frame_type, nullptr, true, true);
+    if (result_loc != nullptr && (type_is_invalid(result_loc->value.type) || instr_is_unreachable(result_loc))) {
+        return result_loc;
+    }
+    return ir_build_call_gen(ira, &call_instruction->base, fn_entry, fn_ref, arg_count,
+            casted_args, FnInlineAuto, true, nullptr, result_loc, frame_type);
+}
 static bool ir_analyze_fn_call_inline_arg(IrAnalyze *ira, AstNode *fn_proto_node,
     IrInstruction *arg, Scope **exec_scope, size_t *next_proto_i)
 {
@@ -15366,16 +15450,18 @@ static IrInstruction *ir_analyze_fn_call(IrAnalyze *ira, IrInstructionCallSrc *c
     if (type_is_invalid(return_type))
         return ira->codegen->invalid_instruction;
 
-    if (call_instruction->is_async) {
-        zig_panic("TODO async call");
-    }
-
     if (fn_entry != nullptr && fn_entry->fn_inline == FnInlineAlways && fn_inline == FnInlineNever) {
         ir_add_error(ira, &call_instruction->base,
             buf_sprintf("no-inline call of inline function"));
         return ira->codegen->invalid_instruction;
     }
 
+    if (call_instruction->is_async) {
+        IrInstruction *result = ir_analyze_async_call(ira, call_instruction, fn_entry, fn_type, fn_ref,
+                casted_args, call_param_count);
+        return ir_finish_anal(ira, result);
+    }
+
     IrInstruction *result_loc;
     if (handle_is_ptr(return_type)) {
         result_loc = ir_resolve_result(ira, &call_instruction->base, call_instruction->result_loc,
@@ -15535,7 +15621,7 @@ static Error ir_read_const_ptr(IrAnalyze *ira, CodeGen *codegen, AstNode *source
     zig_unreachable();
 }
 
-static IrInstruction *ir_analyze_maybe(IrAnalyze *ira, IrInstructionUnOp *un_op_instruction) {
+static IrInstruction *ir_analyze_optional_type(IrAnalyze *ira, IrInstructionUnOp *un_op_instruction) {
     Error err;
     IrInstruction *value = un_op_instruction->value->child;
     ZigType *type_entry = ir_resolve_type(ira, value);
@@ -15569,6 +15655,7 @@ static IrInstruction *ir_analyze_maybe(IrAnalyze *ira, IrInstructionUnOp *un_op_
         case ZigTypeIdFn:
         case ZigTypeIdBoundFn:
         case ZigTypeIdArgTuple:
+        case ZigTypeIdCoroFrame:
             return ir_const_type(ira, &un_op_instruction->base, get_optional_type(ira->codegen, type_entry));
         case ZigTypeIdUnreachable:
         case ZigTypeIdOpaque:
@@ -15733,7 +15820,7 @@ static IrInstruction *ir_analyze_instruction_un_op(IrAnalyze *ira, IrInstruction
             return result;
         }
         case IrUnOpOptional:
-            return ir_analyze_maybe(ira, instruction);
+            return ir_analyze_optional_type(ira, instruction);
     }
     zig_unreachable();
 }
@@ -17340,6 +17427,7 @@ static IrInstruction *ir_analyze_instruction_slice_type(IrAnalyze *ira,
         case ZigTypeIdFn:
         case ZigTypeIdBoundFn:
         case ZigTypeIdVector:
+        case ZigTypeIdCoroFrame:
             {
                 ResolveStatus needed_status = (align_bytes == 0) ?
                     ResolveStatusZeroBitsKnown : ResolveStatusAlignmentKnown;
@@ -17454,6 +17542,7 @@ static IrInstruction *ir_analyze_instruction_array_type(IrAnalyze *ira,
         case ZigTypeIdFn:
         case ZigTypeIdBoundFn:
         case ZigTypeIdVector:
+        case ZigTypeIdCoroFrame:
             {
                 if ((err = ensure_complete_type(ira->codegen, child_type)))
                     return ira->codegen->invalid_instruction;
@@ -17504,6 +17593,7 @@ static IrInstruction *ir_analyze_instruction_size_of(IrAnalyze *ira,
         case ZigTypeIdUnion:
         case ZigTypeIdFn:
         case ZigTypeIdVector:
+        case ZigTypeIdCoroFrame:
             {
                 uint64_t size_in_bytes = type_size(ira->codegen, type_entry);
                 return ir_const_unsigned(ira, &size_of_instruction->base, size_in_bytes);
@@ -18067,6 +18157,7 @@ static IrInstruction *ir_analyze_instruction_switch_target(IrAnalyze *ira,
         case ZigTypeIdArgTuple:
         case ZigTypeIdOpaque:
         case ZigTypeIdVector:
+        case ZigTypeIdCoroFrame:
             ir_add_error(ira, &switch_target_instruction->base,
                 buf_sprintf("invalid switch target type '%s'", buf_ptr(&target_type->name)));
             return ira->codegen->invalid_instruction;
@@ -19906,6 +19997,8 @@ static Error ir_make_type_info_value(IrAnalyze *ira, IrInstruction *source_instr
 
                 break;
             }
+        case ZigTypeIdCoroFrame:
+            zig_panic("TODO @typeInfo for coro frames");
     }
 
     assert(result != nullptr);
@@ -21660,6 +21753,7 @@ static IrInstruction *ir_analyze_instruction_align_of(IrAnalyze *ira, IrInstruct
         case ZigTypeIdUnion:
         case ZigTypeIdFn:
         case ZigTypeIdVector:
+        case ZigTypeIdCoroFrame:
             {
                 uint64_t align_in_bytes = get_abi_alignment(ira->codegen, type_entry);
                 return ir_const_unsigned(ira, &instruction->base, align_in_bytes);
@@ -22815,6 +22909,8 @@ static void buf_write_value_bytes(CodeGen *codegen, uint8_t *buf, ConstExprValue
             zig_panic("TODO buf_write_value_bytes fn type");
         case ZigTypeIdUnion:
             zig_panic("TODO buf_write_value_bytes union type");
+        case ZigTypeIdCoroFrame:
+            zig_panic("TODO buf_write_value_bytes coro frame type");
     }
     zig_unreachable();
 }
@@ -22994,6 +23090,8 @@ static Error buf_read_value_bytes(IrAnalyze *ira, CodeGen *codegen, AstNode *sou
             zig_panic("TODO buf_read_value_bytes fn type");
         case ZigTypeIdUnion:
             zig_panic("TODO buf_read_value_bytes union type");
+        case ZigTypeIdCoroFrame:
+            zig_panic("TODO buf_read_value_bytes coro frame type");
     }
     zig_unreachable();
 }
@@ -24021,6 +24119,33 @@ static IrInstruction *ir_analyze_instruction_union_init_named_field(IrAnalyze *i
             union_type, field_name, field_result_loc, result_loc);
 }
 
+static IrInstruction *ir_analyze_instruction_suspend_begin(IrAnalyze *ira, IrInstructionSuspendBegin *instruction) {
+    IrBasicBlock *new_bb = ir_get_new_bb_runtime(ira, instruction->resume_block, &instruction->base);
+    if (new_bb == nullptr)
+        return ir_unreach_error(ira);
+    return ir_build_suspend_begin(&ira->new_irb, instruction->base.scope, instruction->base.source_node, new_bb);
+}
+
+static IrInstruction *ir_analyze_instruction_suspend_br(IrAnalyze *ira, IrInstructionSuspendBr *instruction) {
+    IrBasicBlock *old_dest_block = instruction->resume_block;
+
+    IrBasicBlock *new_bb = ir_get_new_bb_runtime(ira, old_dest_block, &instruction->base);
+    if (new_bb == nullptr)
+        return ir_unreach_error(ira);
+
+    ZigFn *fn_entry = exec_fn_entry(ira->new_irb.exec);
+    ir_assert(fn_entry != nullptr, &instruction->base);
+    fn_entry->resume_blocks.append(new_bb);
+    // This is done after appending the block because resume_index 0 is reserved for querying the size.
+    new_bb->resume_index = fn_entry->resume_blocks.length;
+
+    ir_push_resume_block(ira, old_dest_block);
+
+    IrInstruction *result = ir_build_suspend_br(&ira->new_irb,
+            instruction->base.scope, instruction->base.source_node, new_bb);
+    return ir_finish_anal(ira, result);
+}
+
 static IrInstruction *ir_analyze_instruction_base(IrAnalyze *ira, IrInstruction *instruction) {
     switch (instruction->id) {
         case IrInstructionIdInvalid:
@@ -24304,6 +24429,10 @@ static IrInstruction *ir_analyze_instruction_base(IrAnalyze *ira, IrInstruction
             return ir_analyze_instruction_bit_cast_src(ira, (IrInstructionBitCastSrc *)instruction);
         case IrInstructionIdUnionInitNamedField:
             return ir_analyze_instruction_union_init_named_field(ira, (IrInstructionUnionInitNamedField *)instruction);
+        case IrInstructionIdSuspendBegin:
+            return ir_analyze_instruction_suspend_begin(ira, (IrInstructionSuspendBegin *)instruction);
+        case IrInstructionIdSuspendBr:
+            return ir_analyze_instruction_suspend_br(ira, (IrInstructionSuspendBr *)instruction);
     }
     zig_unreachable();
 }
@@ -24436,6 +24565,8 @@ bool ir_has_side_effects(IrInstruction *instruction) {
         case IrInstructionIdOptionalWrap:
         case IrInstructionIdVectorToArray:
         case IrInstructionIdResetResult:
+        case IrInstructionIdSuspendBegin:
+        case IrInstructionIdSuspendBr:
             return true;
 
         case IrInstructionIdPhi:
src/ir_print.cpp
@@ -1503,6 +1503,16 @@ static void ir_print_union_init_named_field(IrPrint *irp, IrInstructionUnionInit
     fprintf(irp->f, ")");
 }
 
+static void ir_print_suspend_begin(IrPrint *irp, IrInstructionSuspendBegin *instruction) {
+    fprintf(irp->f, "@suspendBegin()");
+}
+
+static void ir_print_suspend_br(IrPrint *irp, IrInstructionSuspendBr *instruction) {
+    fprintf(irp->f, "@suspendBr(");
+    ir_print_other_block(irp, instruction->resume_block);
+    fprintf(irp->f, ")");
+}
+
 static void ir_print_instruction(IrPrint *irp, IrInstruction *instruction) {
     ir_print_prefix(irp, instruction);
     switch (instruction->id) {
@@ -1961,6 +1971,12 @@ static void ir_print_instruction(IrPrint *irp, IrInstruction *instruction) {
         case IrInstructionIdUnionInitNamedField:
             ir_print_union_init_named_field(irp, (IrInstructionUnionInitNamedField *)instruction);
             break;
+        case IrInstructionIdSuspendBegin:
+            ir_print_suspend_begin(irp, (IrInstructionSuspendBegin *)instruction);
+            break;
+        case IrInstructionIdSuspendBr:
+            ir_print_suspend_br(irp, (IrInstructionSuspendBr *)instruction);
+            break;
     }
     fprintf(irp->f, "\n");
 }
CMakeLists.txt
@@ -426,7 +426,6 @@ set(ZIG_MAIN_SRC "${CMAKE_SOURCE_DIR}/src/main.cpp")
 set(ZIG0_SHIM_SRC "${CMAKE_SOURCE_DIR}/src/userland.cpp")
 
 set(ZIG_SOURCES
-    "${CMAKE_SOURCE_DIR}/src/glibc.cpp"
     "${CMAKE_SOURCE_DIR}/src/analyze.cpp"
     "${CMAKE_SOURCE_DIR}/src/ast_render.cpp"
     "${CMAKE_SOURCE_DIR}/src/bigfloat.cpp"
@@ -438,6 +437,7 @@ set(ZIG_SOURCES
     "${CMAKE_SOURCE_DIR}/src/compiler.cpp"
     "${CMAKE_SOURCE_DIR}/src/errmsg.cpp"
     "${CMAKE_SOURCE_DIR}/src/error.cpp"
+    "${CMAKE_SOURCE_DIR}/src/glibc.cpp"
     "${CMAKE_SOURCE_DIR}/src/ir.cpp"
     "${CMAKE_SOURCE_DIR}/src/ir_print.cpp"
     "${CMAKE_SOURCE_DIR}/src/libc_installation.cpp"