Commit 1a51bf63047e9a3cd6ae3273296fded82009235c | zig

author	Andrew Kelley <andrew@ziglang.org> 2019-06-10 11:15:32-04:00
committer	Andrew Kelley <andrew@ziglang.org> 2019-06-10 11:15:32-04:00
log	1a51bf63047e9a3cd6ae3273296fded82009235c
tree	a0ed33775740c091baad17c8dffdc5c9c272cefb
parent	4e2b2822f18577edb614bdc3ec6808a0587662e5
signature	Commit is signed but in an unrecognized format.

hook up result locations for union initializations

```zig
export fn entry() void {
    var x = Foo{ .bar = bar() };
}
```

```llvm
define void @entry() #2 !dbg !44 {
Entry:
  %x = alloca %Foo, align 4
  %0 = getelementptr inbounds %Foo, %Foo* %x, i32 0, i32 1, !dbg !68
  store i1 true, i1* %0, align 1, !dbg !68
  %1 = getelementptr inbounds %Foo, %Foo* %x, i32 0, i32 0, !dbg !68
  %2 = bitcast { i32, [4 x i8] }* %1 to %Bar*, !dbg !68
  call fastcc void @bar(%Bar* sret %2), !dbg !68
  call void @llvm.dbg.declare(metadata %Foo* %x, metadata !48, metadata !DIExpression()), !dbg !69
  ret void, !dbg !70
}
```

5 files changed, 56 insertions(+), 128 deletions(-)

BRANCH_TODO
src

BRANCH_TODO-1

...	@@ -1,7 +1,6 @@	...	@@ -1,7 +1,6 @@
1	Scratch pad for stuff to do before merging master	1	Scratch pad for stuff to do before merging master
2	=================================================	2	=================================================
3		3
4	* union initializations
5	* bitCast	4	* bitCast
6		5
7	look at all the ir_gen_node ir_gen_node_extra calls and make sure result locations are properly propagated	6	look at all the ir_gen_node ir_gen_node_extra calls and make sure result locations are properly propagated

src/all_types.hpp+2-11

 @@ -2204,7 +2204,6 @@ enum IrInstructionId {
     IrInstructionIdResizeSlice,
     IrInstructionIdContainerInitList,
     IrInstructionIdContainerInitFields,
-    IrInstructionIdUnionInit,
     IrInstructionIdUnreachable,
     IrInstructionIdTypeOf,
     IrInstructionIdSetCold,
 @@ -2520,6 +2519,7 @@ struct IrInstructionStorePtr {
 struct IrInstructionFieldPtr {
     IrInstruction base;
+    bool initializing;
     IrInstruction *container_ptr;
     Buf *field_name_buffer;
     IrInstruction *field_name_expr;
 @@ -2536,9 +2536,9 @@ struct IrInstructionStructFieldPtr {
 struct IrInstructionUnionFieldPtr {
     IrInstruction base;
+    bool initializing;
     IrInstruction *union_ptr;
     TypeUnionField *field;
-    bool is_const;
 };
 struct IrInstructionElemPtr {
 @@ -2663,15 +2663,6 @@ struct IrInstructionContainerInitFields {
     IrInstructionContainerInitFieldsField *fields;
 };
-struct IrInstructionUnionInit {
-    IrInstruction base;
-    ZigType *union_type;
-    TypeUnionField *field;
-    IrInstruction *init_value;
-    LLVMValueRef tmp_ptr;
-};
 struct IrInstructionUnreachable {
     IrInstruction base;
 };

src/codegen.cpp+6-43

...	@@ -3859,7 +3859,12 @@ static LLVMValueRef ir_render_union_field_ptr(CodeGen g, IrExecutable executab	...	@@ -3859,7 +3859,12 @@ static LLVMValueRef ir_render_union_field_ptr(CodeGen g, IrExecutable executab
3859	return bitcasted_union_field_ptr;	3859	return bitcasted_union_field_ptr;
3860	}	3860	}
3861		3861
3862	if (ir_want_runtime_safety(g, &instruction->base)) {	3862	if (instruction->initializing) {
		3863	LLVMValueRef tag_field_ptr = LLVMBuildStructGEP(g->builder, union_ptr, union_type->data.unionation.gen_tag_index, "");
		3864	LLVMValueRef tag_value = bigint_to_llvm_const(get_llvm_type(g, union_type->data.unionation.tag_type),
		3865	&field->enum_field->value);
		3866	gen_store_untyped(g, tag_value, tag_field_ptr, 0, false);
		3867	} else if (ir_want_runtime_safety(g, &instruction->base)) {
3863	LLVMValueRef tag_field_ptr = LLVMBuildStructGEP(g->builder, union_ptr, union_type->data.unionation.gen_tag_index, "");	3868	LLVMValueRef tag_field_ptr = LLVMBuildStructGEP(g->builder, union_ptr, union_type->data.unionation.gen_tag_index, "");
3864	LLVMValueRef tag_value = gen_load_untyped(g, tag_field_ptr, 0, false, "");	3869	LLVMValueRef tag_value = gen_load_untyped(g, tag_field_ptr, 0, false, "");
3865		3870
...	@@ -5035,43 +5040,6 @@ static LLVMValueRef ir_render_union_tag(CodeGen g, IrExecutable executable, Ir	...	@@ -5035,43 +5040,6 @@ static LLVMValueRef ir_render_union_tag(CodeGen g, IrExecutable executable, Ir
5035	return get_handle_value(g, tag_field_ptr, tag_type, ptr_type);	5040	return get_handle_value(g, tag_field_ptr, tag_type, ptr_type);
5036	}	5041	}
5037		5042
5038	static LLVMValueRef ir_render_union_init(CodeGen g, IrExecutable executable, IrInstructionUnionInit *instruction) {
5039	TypeUnionField *type_union_field = instruction->field;
5040
5041	if (!type_has_bits(type_union_field->type_entry))
5042	return nullptr;
5043
5044	uint32_t field_align_bytes = get_abi_alignment(g, type_union_field->type_entry);
5045	ZigType *ptr_type = get_pointer_to_type_extra(g, type_union_field->type_entry,
5046	false, false, PtrLenSingle, field_align_bytes,
5047	0, 0, false);
5048
5049	LLVMValueRef uncasted_union_ptr;
5050	// Even if safety is off in this block, if the union type has the safety field, we have to populate it
5051	// correctly. Otherwise safety code somewhere other than here could fail.
5052	ZigType *union_type = instruction->union_type;
5053	if (union_type->data.unionation.gen_tag_index != SIZE_MAX) {
5054	LLVMValueRef tag_field_ptr = LLVMBuildStructGEP(g->builder, instruction->tmp_ptr,
5055	union_type->data.unionation.gen_tag_index, "");
5056
5057	LLVMValueRef tag_value = bigint_to_llvm_const(get_llvm_type(g, union_type->data.unionation.tag_type),
5058	&type_union_field->enum_field->value);
5059	gen_store_untyped(g, tag_value, tag_field_ptr, 0, false);
5060
5061	uncasted_union_ptr = LLVMBuildStructGEP(g->builder, instruction->tmp_ptr,
5062	(unsigned)union_type->data.unionation.gen_union_index, "");
5063	} else {
5064	uncasted_union_ptr = LLVMBuildStructGEP(g->builder, instruction->tmp_ptr, (unsigned)0, "");
5065	}
5066
5067	LLVMValueRef field_ptr = LLVMBuildBitCast(g->builder, uncasted_union_ptr, get_llvm_type(g, ptr_type), "");
5068	LLVMValueRef value = ir_llvm_value(g, instruction->init_value);
5069
5070	gen_assign_raw(g, field_ptr, ptr_type, value);
5071
5072	return instruction->tmp_ptr;
5073	}
5074
5075	static LLVMValueRef ir_render_panic(CodeGen g, IrExecutable executable, IrInstructionPanic *instruction) {	5043	static LLVMValueRef ir_render_panic(CodeGen g, IrExecutable executable, IrInstructionPanic *instruction) {
5076	gen_panic(g, ir_llvm_value(g, instruction->msg), get_cur_err_ret_trace_val(g, instruction->base.scope));	5044	gen_panic(g, ir_llvm_value(g, instruction->msg), get_cur_err_ret_trace_val(g, instruction->base.scope));
5077	return nullptr;	5045	return nullptr;
...	@@ -5659,8 +5627,6 @@ static LLVMValueRef ir_render_instruction(CodeGen g, IrExecutable executable,	...	@@ -5659,8 +5627,6 @@ static LLVMValueRef ir_render_instruction(CodeGen g, IrExecutable executable,
5659	return ir_render_err_wrap_payload(g, executable, (IrInstructionErrWrapPayload *)instruction);	5627	return ir_render_err_wrap_payload(g, executable, (IrInstructionErrWrapPayload *)instruction);
5660	case IrInstructionIdUnionTag:	5628	case IrInstructionIdUnionTag:
5661	return ir_render_union_tag(g, executable, (IrInstructionUnionTag *)instruction);	5629	return ir_render_union_tag(g, executable, (IrInstructionUnionTag *)instruction);
5662	case IrInstructionIdUnionInit:
5663	return ir_render_union_init(g, executable, (IrInstructionUnionInit *)instruction);
5664	case IrInstructionIdPtrCastGen:	5630	case IrInstructionIdPtrCastGen:
5665	return ir_render_ptr_cast(g, executable, (IrInstructionPtrCastGen *)instruction);	5631	return ir_render_ptr_cast(g, executable, (IrInstructionPtrCastGen *)instruction);
5666	case IrInstructionIdBitCastGen:	5632	case IrInstructionIdBitCastGen:
...	@@ -6874,9 +6840,6 @@ static void do_code_gen(CodeGen *g) {	...	@@ -6874,9 +6840,6 @@ static void do_code_gen(CodeGen *g) {
6874	} else if (instruction->id == IrInstructionIdContainerInitList) {	6840	} else if (instruction->id == IrInstructionIdContainerInitList) {
6875	IrInstructionContainerInitList container_init_list_instruction = (IrInstructionContainerInitList )instruction;	6841	IrInstructionContainerInitList container_init_list_instruction = (IrInstructionContainerInitList )instruction;
6876	slot = &container_init_list_instruction->tmp_ptr;	6842	slot = &container_init_list_instruction->tmp_ptr;
6877	} else if (instruction->id == IrInstructionIdUnionInit) {
6878	IrInstructionUnionInit union_init_instruction = (IrInstructionUnionInit )instruction;
6879	slot = &union_init_instruction->tmp_ptr;
6880	} else if (instruction->id == IrInstructionIdSlice) {	6843	} else if (instruction->id == IrInstructionIdSlice) {
6881	IrInstructionSlice slice_instruction = (IrInstructionSlice )instruction;	6844	IrInstructionSlice slice_instruction = (IrInstructionSlice )instruction;
6882	slot = &slice_instruction->tmp_ptr;	6845	slot = &slice_instruction->tmp_ptr;

src/ir.cpp+48-61

 @@ -164,7 +164,7 @@ static IrInstruction *ir_implicit_cast(IrAnalyze *ira, IrInstruction *value, Zig
 static IrInstruction *ir_get_deref(IrAnalyze *ira, IrInstruction *source_instruction, IrInstruction *ptr);
 static ErrorMsg *exec_add_error_node(CodeGen *codegen, IrExecutable *exec, AstNode *source_node, Buf *msg);
 static IrInstruction *ir_analyze_container_field_ptr(IrAnalyze *ira, Buf *field_name,
-    IrInstruction *source_instr, IrInstruction *container_ptr, ZigType *container_type);
+    IrInstruction *source_instr, IrInstruction *container_ptr, ZigType *container_type, bool initializing);
 static IrInstruction *ir_get_var_ptr(IrAnalyze *ira, IrInstruction *instruction, ZigVar *var);
 static ZigType *ir_resolve_atomic_operand_type(IrAnalyze *ira, IrInstruction *op);
 static IrInstruction *ir_lval_wrap(IrBuilder *irb, Scope *scope, IrInstruction *value, LVal lval, ResultLoc *result_loc);
 @@ -616,10 +616,6 @@ static constexpr IrInstructionId ir_instruction_id(IrInstructionRef *) {
     return IrInstructionIdRef;
 }
-static constexpr IrInstructionId ir_instruction_id(IrInstructionUnionInit *) {
-    return IrInstructionIdUnionInit;
-}
 static constexpr IrInstructionId ir_instruction_id(IrInstructionCompileErr *) {
     return IrInstructionIdCompileErr;
 }
 @@ -1312,12 +1308,13 @@ static IrInstruction *ir_build_field_ptr_instruction(IrBuilder *irb, Scope *scop
 }
 static IrInstruction *ir_build_field_ptr(IrBuilder *irb, Scope *scope, AstNode *source_node,
-    IrInstruction *container_ptr, Buf *field_name)
+    IrInstruction *container_ptr, Buf *field_name, bool initializing)
 {
     IrInstructionFieldPtr *instruction = ir_build_instruction<IrInstructionFieldPtr>(irb, scope, source_node);
     instruction->container_ptr = container_ptr;
     instruction->field_name_buffer = field_name;
     instruction->field_name_expr = nullptr;
+    instruction->initializing = initializing;
     ir_ref_instruction(container_ptr, irb->current_basic_block);
 @@ -1337,9 +1334,10 @@ static IrInstruction *ir_build_struct_field_ptr(IrBuilder *irb, Scope *scope, As
 }
 static IrInstruction *ir_build_union_field_ptr(IrBuilder *irb, Scope *scope, AstNode *source_node,
-    IrInstruction *union_ptr, TypeUnionField *field)
+    IrInstruction *union_ptr, TypeUnionField *field, bool initializing)
 {
     IrInstructionUnionFieldPtr *instruction = ir_build_instruction<IrInstructionUnionFieldPtr>(irb, scope, source_node);
+    instruction->initializing = initializing;
     instruction->union_ptr = union_ptr;
     instruction->field = field;
 @@ -1517,19 +1515,6 @@ static IrInstruction *ir_build_container_init_fields(IrBuilder *irb, Scope *scop
     return &container_init_fields_instruction->base;
 }
-static IrInstruction *ir_build_union_init(IrBuilder *irb, Scope *scope, AstNode *source_node,
-        ZigType *union_type, TypeUnionField *field, IrInstruction *init_value)
-{
-    IrInstructionUnionInit *union_init_instruction = ir_build_instruction<IrInstructionUnionInit>(irb, scope, source_node);
-    union_init_instruction->union_type = union_type;
-    union_init_instruction->field = field;
-    union_init_instruction->init_value = init_value;
-    ir_ref_instruction(init_value, irb->current_basic_block);
-    return &union_init_instruction->base;
-}
 static IrInstruction *ir_build_unreachable(IrBuilder *irb, Scope *scope, AstNode *source_node) {
     IrInstructionUnreachable *unreachable_instruction =
         ir_build_instruction<IrInstructionUnreachable>(irb, scope, source_node);
 @@ -4121,7 +4106,7 @@ static IrInstruction *ir_gen_field_access(IrBuilder *irb, Scope *scope, AstNode
     if (container_ref_instruction == irb->codegen->invalid_instruction)
         return container_ref_instruction;
-    return ir_build_field_ptr(irb, scope, node, container_ref_instruction, field_name);
+    return ir_build_field_ptr(irb, scope, node, container_ref_instruction, field_name, false);
 }
 static IrInstruction *ir_gen_overflow_op(IrBuilder *irb, Scope *scope, AstNode *node, IrOverflowOp op) {
 @@ -5594,7 +5579,7 @@ static IrInstruction *ir_gen_container_init_expr(IrBuilder *irb, Scope *scope, A
                 AstNode *expr_node = entry_node->data.struct_val_field.expr;
                 IrInstruction *field_ptr = ir_build_field_ptr(irb, &result_loc->scope_elide->base, expr_node,
-                        container_ptr, name);
+                        container_ptr, name, true);
                 ResultLocInstruction *result_loc_inst = allocate<ResultLocInstruction>(1);
                 result_loc_inst->base.id = ResultLocIdInstruction;
                 result_loc_inst->base.source_instruction = field_ptr;
 @@ -6105,7 +6090,7 @@ static IrInstruction *ir_gen_for_expr(IrBuilder *irb, Scope *parent_scope, AstNo
     IrBasicBlock *continue_block = ir_create_basic_block(irb, parent_scope, "ForContinue");
     Buf *len_field_name = buf_create_from_str("len");
-    IrInstruction *len_ref = ir_build_field_ptr(irb, parent_scope, node, array_val_ptr, len_field_name);
+    IrInstruction *len_ref = ir_build_field_ptr(irb, parent_scope, node, array_val_ptr, len_field_name, false);
     IrInstruction *len_val = ir_build_load_ptr(irb, parent_scope, node, len_ref);
     ir_build_br(irb, parent_scope, node, cond_block, is_comptime);
 @@ -7496,7 +7481,7 @@ static IrInstruction *ir_gen_cancel_target(IrBuilder *irb, Scope *scope, AstNode
     IrInstruction *coro_promise_ptr = ir_build_coro_promise(irb, scope, node, casted_target_inst);
     Buf *atomic_state_field_name = buf_create_from_str(ATOMIC_STATE_FIELD_NAME);
     IrInstruction *atomic_state_ptr = ir_build_field_ptr(irb, scope, node, coro_promise_ptr,
-            atomic_state_field_name);
+            atomic_state_field_name, false);
     // set the is_canceled bit
     IrInstruction *prev_atomic_value = ir_build_atomic_rmw(irb, scope, node,
 @@ -7575,7 +7560,7 @@ static IrInstruction *ir_gen_resume_target(IrBuilder *irb, Scope *scope, AstNode
     IrInstruction *coro_promise_ptr = ir_build_coro_promise(irb, scope, node, casted_target_inst);
     Buf *atomic_state_field_name = buf_create_from_str(ATOMIC_STATE_FIELD_NAME);
     IrInstruction *atomic_state_ptr = ir_build_field_ptr(irb, scope, node, coro_promise_ptr,
-            atomic_state_field_name);
+            atomic_state_field_name, false);
     // clear the is_suspended bit
     IrInstruction *prev_atomic_value = ir_build_atomic_rmw(irb, scope, node,
 @@ -7642,12 +7627,12 @@ static IrInstruction *ir_gen_await_expr(IrBuilder *irb, Scope *scope, AstNode *n
     IrInstruction *coro_promise_ptr = ir_build_coro_promise(irb, scope, node, target_inst);
     Buf *result_ptr_field_name = buf_create_from_str(RESULT_PTR_FIELD_NAME);
-    IrInstruction *result_ptr_field_ptr = ir_build_field_ptr(irb, scope, node, coro_promise_ptr, result_ptr_field_name);
+    IrInstruction *result_ptr_field_ptr = ir_build_field_ptr(irb, scope, node, coro_promise_ptr, result_ptr_field_name, false);
     if (irb->codegen->have_err_ret_tracing) {
         IrInstruction *err_ret_trace_ptr = ir_build_error_return_trace(irb, scope, node, IrInstructionErrorReturnTrace::NonNull);
         Buf *err_ret_trace_ptr_field_name = buf_create_from_str(ERR_RET_TRACE_PTR_FIELD_NAME);
-        IrInstruction *err_ret_trace_ptr_field_ptr = ir_build_field_ptr(irb, scope, node, coro_promise_ptr, err_ret_trace_ptr_field_name);
+        IrInstruction *err_ret_trace_ptr_field_ptr = ir_build_field_ptr(irb, scope, node, coro_promise_ptr, err_ret_trace_ptr_field_name, false);
         ir_build_store_ptr(irb, scope, node, err_ret_trace_ptr_field_ptr, err_ret_trace_ptr);
     }
 @@ -7669,7 +7654,7 @@ static IrInstruction *ir_gen_await_expr(IrBuilder *irb, Scope *scope, AstNode *n
     Buf *atomic_state_field_name = buf_create_from_str(ATOMIC_STATE_FIELD_NAME);
     IrInstruction *atomic_state_ptr = ir_build_field_ptr(irb, scope, node, coro_promise_ptr,
-            atomic_state_field_name);
+            atomic_state_field_name, false);
     IrInstruction *promise_type_val = ir_build_const_type(irb, scope, node, irb->codegen->builtin_types.entry_promise);
     IrInstruction *const_bool_false = ir_build_const_bool(irb, scope, node, false);
 @@ -7723,12 +7708,12 @@ static IrInstruction *ir_gen_await_expr(IrBuilder *irb, Scope *scope, AstNode *n
     ir_set_cursor_at_end_and_append_block(irb, no_suspend_block);
     if (irb->codegen->have_err_ret_tracing) {
         Buf *err_ret_trace_field_name = buf_create_from_str(ERR_RET_TRACE_FIELD_NAME);
-        IrInstruction *src_err_ret_trace_ptr = ir_build_field_ptr(irb, scope, node, coro_promise_ptr, err_ret_trace_field_name);
+        IrInstruction *src_err_ret_trace_ptr = ir_build_field_ptr(irb, scope, node, coro_promise_ptr, err_ret_trace_field_name, false);
         IrInstruction *dest_err_ret_trace_ptr = ir_build_error_return_trace(irb, scope, node, IrInstructionErrorReturnTrace::NonNull);
         ir_build_merge_err_ret_traces(irb, scope, node, coro_promise_ptr, src_err_ret_trace_ptr, dest_err_ret_trace_ptr);
     }
     Buf *result_field_name = buf_create_from_str(RESULT_FIELD_NAME);
-    IrInstruction *promise_result_ptr = ir_build_field_ptr(irb, scope, node, coro_promise_ptr, result_field_name);
+    IrInstruction *promise_result_ptr = ir_build_field_ptr(irb, scope, node, coro_promise_ptr, result_field_name, false);
     // If the type of the result handle_is_ptr then this does not actually perform a load. But we need it to,
     // because we're about to destroy the memory. So we store it into our result variable.
     IrInstruction *no_suspend_result = ir_build_load_ptr(irb, scope, node, promise_result_ptr);
 @@ -8152,7 +8137,7 @@ bool ir_gen(CodeGen *codegen, AstNode *node, Scope *scope, IrExecutable *ir_exec
         build_decl_var_and_init(irb, coro_scope, node, irb->exec->coro_allocator_var, implicit_allocator_ptr,
                 "allocator", const_bool_false);
         Buf *realloc_field_name = buf_create_from_str(ASYNC_REALLOC_FIELD_NAME);
-        IrInstruction *realloc_fn_ptr = ir_build_field_ptr(irb, coro_scope, node, implicit_allocator_ptr, realloc_field_name);
+        IrInstruction *realloc_fn_ptr = ir_build_field_ptr(irb, coro_scope, node, implicit_allocator_ptr, realloc_field_name, false);
         IrInstruction *realloc_fn = ir_build_load_ptr(irb, coro_scope, node, realloc_fn_ptr);
         IrInstruction *maybe_coro_mem_ptr = ir_build_coro_alloc_helper(irb, coro_scope, node, realloc_fn, coro_size);
         IrInstruction *alloc_result_is_ok = ir_build_test_nonnull(irb, coro_scope, node, maybe_coro_mem_ptr);
 @@ -8172,30 +8157,30 @@ bool ir_gen(CodeGen *codegen, AstNode *node, Scope *scope, IrExecutable *ir_exec
         Buf *atomic_state_field_name = buf_create_from_str(ATOMIC_STATE_FIELD_NAME);
         irb->exec->atomic_state_field_ptr = ir_build_field_ptr(irb, scope, node, coro_promise_ptr,
-                atomic_state_field_name);
+                atomic_state_field_name, false);
         IrInstruction *zero = ir_build_const_usize(irb, scope, node, 0);
         ir_build_store_ptr(irb, scope, node, irb->exec->atomic_state_field_ptr, zero);
         Buf *result_field_name = buf_create_from_str(RESULT_FIELD_NAME);
-        irb->exec->coro_result_field_ptr = ir_build_field_ptr(irb, scope, node, coro_promise_ptr, result_field_name);
+        irb->exec->coro_result_field_ptr = ir_build_field_ptr(irb, scope, node, coro_promise_ptr, result_field_name, false);
         result_ptr_field_name = buf_create_from_str(RESULT_PTR_FIELD_NAME);
-        irb->exec->coro_result_ptr_field_ptr = ir_build_field_ptr(irb, scope, node, coro_promise_ptr, result_ptr_field_name);
+        irb->exec->coro_result_ptr_field_ptr = ir_build_field_ptr(irb, scope, node, coro_promise_ptr, result_ptr_field_name, false);
         ir_build_store_ptr(irb, scope, node, irb->exec->coro_result_ptr_field_ptr, irb->exec->coro_result_field_ptr);
         if (irb->codegen->have_err_ret_tracing) {
             // initialize the error return trace
             Buf *return_addresses_field_name = buf_create_from_str(RETURN_ADDRESSES_FIELD_NAME);
-            IrInstruction *return_addresses_ptr = ir_build_field_ptr(irb, scope, node, coro_promise_ptr, return_addresses_field_name);
+            IrInstruction *return_addresses_ptr = ir_build_field_ptr(irb, scope, node, coro_promise_ptr, return_addresses_field_name, false);
             Buf *err_ret_trace_field_name = buf_create_from_str(ERR_RET_TRACE_FIELD_NAME);
-            err_ret_trace_ptr = ir_build_field_ptr(irb, scope, node, coro_promise_ptr, err_ret_trace_field_name);
+            err_ret_trace_ptr = ir_build_field_ptr(irb, scope, node, coro_promise_ptr, err_ret_trace_field_name, false);
             ir_build_mark_err_ret_trace_ptr(irb, scope, node, err_ret_trace_ptr);
             // coordinate with builtin.zig
             Buf *index_name = buf_create_from_str("index");
-            IrInstruction *index_ptr = ir_build_field_ptr(irb, scope, node, err_ret_trace_ptr, index_name);
+            IrInstruction *index_ptr = ir_build_field_ptr(irb, scope, node, err_ret_trace_ptr, index_name, false);
             ir_build_store_ptr(irb, scope, node, index_ptr, zero);
             Buf *instruction_addresses_name = buf_create_from_str("instruction_addresses");
-            IrInstruction *addrs_slice_ptr = ir_build_field_ptr(irb, scope, node, err_ret_trace_ptr, instruction_addresses_name);
+            IrInstruction *addrs_slice_ptr = ir_build_field_ptr(irb, scope, node, err_ret_trace_ptr, instruction_addresses_name, false);
             IrInstruction *slice_value = ir_build_slice(irb, scope, node, return_addresses_ptr, zero, nullptr, false);
             ir_build_store_ptr(irb, scope, node, addrs_slice_ptr, slice_value);
 @@ -8256,7 +8241,7 @@ bool ir_gen(CodeGen *codegen, AstNode *node, Scope *scope, IrExecutable *ir_exec
         }
         if (irb->codegen->have_err_ret_tracing) {
             Buf *err_ret_trace_ptr_field_name = buf_create_from_str(ERR_RET_TRACE_PTR_FIELD_NAME);
-            IrInstruction *err_ret_trace_ptr_field_ptr = ir_build_field_ptr(irb, scope, node, coro_promise_ptr, err_ret_trace_ptr_field_name);
+            IrInstruction *err_ret_trace_ptr_field_ptr = ir_build_field_ptr(irb, scope, node, coro_promise_ptr, err_ret_trace_ptr_field_name, false);
             IrInstruction *dest_err_ret_trace_ptr = ir_build_load_ptr(irb, scope, node, err_ret_trace_ptr_field_ptr);
             ir_build_merge_err_ret_traces(irb, scope, node, coro_promise_ptr, err_ret_trace_ptr, dest_err_ret_trace_ptr);
         }
 @@ -8291,7 +8276,7 @@ bool ir_gen(CodeGen *codegen, AstNode *node, Scope *scope, IrExecutable *ir_exec
         Buf *shrink_field_name = buf_create_from_str(ASYNC_SHRINK_FIELD_NAME);
         IrInstruction *implicit_allocator_ptr = ir_build_get_implicit_allocator(irb, scope, node,
                 ImplicitAllocatorIdLocalVar);
-        IrInstruction *shrink_fn_ptr = ir_build_field_ptr(irb, scope, node, implicit_allocator_ptr, shrink_field_name);
+        IrInstruction *shrink_fn_ptr = ir_build_field_ptr(irb, scope, node, implicit_allocator_ptr, shrink_field_name, false);
         IrInstruction *shrink_fn = ir_build_load_ptr(irb, scope, node, shrink_fn_ptr);
         IrInstruction *zero = ir_build_const_usize(irb, scope, node, 0);
         IrInstruction *coro_mem_ptr_maybe = ir_build_coro_free(irb, scope, node, coro_id, irb->exec->coro_handle);
 @@ -14722,7 +14707,7 @@ static IrInstruction *ir_analyze_async_call(IrAnalyze *ira, IrInstructionCallSrc
     ir_assert(async_allocator_inst->value.type->id == ZigTypeIdPointer, &call_instruction->base);
     ZigType *container_type = async_allocator_inst->value.type->data.pointer.child_type;
     IrInstruction *field_ptr_inst = ir_analyze_container_field_ptr(ira, realloc_field_name, &call_instruction->base,
-            async_allocator_inst, container_type);
+            async_allocator_inst, container_type, false);
     if (type_is_invalid(field_ptr_inst->value.type)) {
         return ira->codegen->invalid_instruction;
     }
 @@ -16580,7 +16565,7 @@ static IrInstruction *ir_analyze_container_member_access_inner(IrAnalyze *ira,
 }
 static IrInstruction *ir_analyze_container_field_ptr(IrAnalyze *ira, Buf *field_name,
-    IrInstruction *source_instr, IrInstruction *container_ptr, ZigType *container_type)
+    IrInstruction *source_instr, IrInstruction *container_ptr, ZigType *container_type, bool initializing)
 {
     Error err;
 @@ -16664,15 +16649,19 @@ static IrInstruction *ir_analyze_container_field_ptr(IrAnalyze *ira, Buf *field_
                     if (type_is_invalid(union_val->type))
                         return ira->codegen->invalid_instruction;
-                    TypeUnionField *actual_field = find_union_field_by_tag(bare_type, &union_val->data.x_union.tag);
+                    if (initializing) {
-                    if (actual_field == nullptr)
+                        bigint_init_bigint(&union_val->data.x_union.tag, &field->enum_field->value);
-                        zig_unreachable();
+                    } else {
+                        TypeUnionField *actual_field = find_union_field_by_tag(bare_type, &union_val->data.x_union.tag);
+                        if (actual_field == nullptr)
+                            zig_unreachable();
-                    if (field != actual_field) {
+                        if (field != actual_field) {
-                        ir_add_error_node(ira, source_instr->source_node,
+                            ir_add_error_node(ira, source_instr->source_node,
-                            buf_sprintf("accessing union field '%s' while field '%s' is set", buf_ptr(field_name),
+                                buf_sprintf("accessing union field '%s' while field '%s' is set", buf_ptr(field_name),
-                                buf_ptr(actual_field->name)));
+                                    buf_ptr(actual_field->name)));
-                        return ira->codegen->invalid_instruction;
+                            return ira->codegen->invalid_instruction;
+                        }
                     }
                     ConstExprValue *payload_val = union_val->data.x_union.payload;
 @@ -16690,7 +16679,8 @@ static IrInstruction *ir_analyze_container_field_ptr(IrAnalyze *ira, Buf *field_
                 }
             }
-            IrInstruction *result = ir_build_union_field_ptr(&ira->new_irb, source_instr->scope, source_instr->source_node, container_ptr, field);
+            IrInstruction *result = ir_build_union_field_ptr(&ira->new_irb, source_instr->scope,
+                    source_instr->source_node, container_ptr, field, initializing);
             result->value.type = get_pointer_to_type_extra(ira->codegen, field->type_entry, is_const, is_volatile,
                     PtrLenSingle, 0, 0, 0, false);
             return result;
 @@ -16826,10 +16816,10 @@ static IrInstruction *ir_analyze_instruction_field_ptr(IrAnalyze *ira, IrInstruc
         if (container_type->id == ZigTypeIdPointer) {
             ZigType *bare_type = container_ref_type(container_type);
             IrInstruction *container_child = ir_get_deref(ira, &field_ptr_instruction->base, container_ptr);
-            IrInstruction *result = ir_analyze_container_field_ptr(ira, field_name, &field_ptr_instruction->base, container_child, bare_type);
+            IrInstruction *result = ir_analyze_container_field_ptr(ira, field_name, &field_ptr_instruction->base, container_child, bare_type, field_ptr_instruction->initializing);
             return result;
         } else {
-            IrInstruction *result = ir_analyze_container_field_ptr(ira, field_name, &field_ptr_instruction->base, container_ptr, container_type);
+            IrInstruction *result = ir_analyze_container_field_ptr(ira, field_name, &field_ptr_instruction->base, container_ptr, container_type, field_ptr_instruction->initializing);
             return result;
         }
     } else if (is_array_ref(container_type)) {
 @@ -18120,7 +18110,7 @@ static IrInstruction *ir_analyze_instruction_switch_var(IrAnalyze *ira, IrInstru
         }
         IrInstruction *result = ir_build_union_field_ptr(&ira->new_irb,
-            instruction->base.scope, instruction->base.source_node, target_value_ptr, field);
+            instruction->base.scope, instruction->base.source_node, target_value_ptr, field, false);
         result->value.type = get_pointer_to_type(ira->codegen, field->type_entry,
                 target_value_ptr->value.type->data.pointer.is_const);
         return result;
 @@ -18386,11 +18376,10 @@ static IrInstruction *ir_analyze_container_init_fields_union(IrAnalyze *ira, IrI
         return result;
     }
-    IrInstruction *new_instruction = ir_build_union_init(&ira->new_irb,
+    // this instruction should not get to codegen
-        instruction->scope, instruction->source_node,
+    IrInstruction *new_instruction = ir_const(ira, instruction, container_type);
-        container_type, type_field, casted_field_value);
+    // this is how we signal to EndExpr the value is not comptime known
-    new_instruction->value.type = container_type;
+    new_instruction->value.special = ConstValSpecialRuntime;
-    ir_add_alloca(ira, new_instruction, container_type);
     return new_instruction;
 }
 @@ -23907,7 +23896,6 @@ static IrInstruction *ir_analyze_instruction_base(IrAnalyze *ira, IrInstruction
     switch (instruction->id) {
         case IrInstructionIdInvalid:
         case IrInstructionIdWidenOrShorten:
-        case IrInstructionIdUnionInit:
         case IrInstructionIdStructFieldPtr:
         case IrInstructionIdUnionFieldPtr:
         case IrInstructionIdOptionalWrap:
 @@ -24353,7 +24341,6 @@ bool ir_has_side_effects(IrInstruction *instruction) {
         case IrInstructionIdCast:
         case IrInstructionIdContainerInitList:
         case IrInstructionIdContainerInitFields:
-        case IrInstructionIdUnionInit:
         case IrInstructionIdFieldPtr:
         case IrInstructionIdElemPtr:
         case IrInstructionIdVarPtr:

src/ir_print.cpp-12

...	@@ -360,15 +360,6 @@ static void ir_print_container_init_fields(IrPrint *irp, IrInstructionContainerI	...	@@ -360,15 +360,6 @@ static void ir_print_container_init_fields(IrPrint *irp, IrInstructionContainerI
360	fprintf(irp->f, "} // container init");	360	fprintf(irp->f, "} // container init");
361	}	361	}
362		362
363	static void ir_print_union_init(IrPrint irp, IrInstructionUnionInit instruction) {
364	Buf *field_name = instruction->field->enum_field->name;
365
366	fprintf(irp->f, "%s {", buf_ptr(&instruction->union_type->name));
367	fprintf(irp->f, ".%s = ", buf_ptr(field_name));
368	ir_print_other_instruction(irp, instruction->init_value);
369	fprintf(irp->f, "} // union init");
370	}
371
372	static void ir_print_unreachable(IrPrint irp, IrInstructionUnreachable instruction) {	363	static void ir_print_unreachable(IrPrint irp, IrInstructionUnreachable instruction) {
373	fprintf(irp->f, "unreachable");	364	fprintf(irp->f, "unreachable");
374	}	365	}
...	@@ -1590,9 +1581,6 @@ static void ir_print_instruction(IrPrint irp, IrInstruction instruction) {	...	@@ -1590,9 +1581,6 @@ static void ir_print_instruction(IrPrint irp, IrInstruction instruction) {
1590	case IrInstructionIdContainerInitFields:	1581	case IrInstructionIdContainerInitFields:
1591	ir_print_container_init_fields(irp, (IrInstructionContainerInitFields *)instruction);	1582	ir_print_container_init_fields(irp, (IrInstructionContainerInitFields *)instruction);
1592	break;	1583	break;
1593	case IrInstructionIdUnionInit:
1594	ir_print_union_init(irp, (IrInstructionUnionInit *)instruction);
1595	break;
1596	case IrInstructionIdUnreachable:	1584	case IrInstructionIdUnreachable:
1597	ir_print_unreachable(irp, (IrInstructionUnreachable *)instruction);	1585	ir_print_unreachable(irp, (IrInstructionUnreachable *)instruction);
1598	break;	1586	break;