Commit dd1338b0e6280b10b9b62ca73bf9ece34bd8524e | zig

author	Andrew Kelley <andrew@ziglang.org> 2018-09-11 12:57:53-04:00
committer	Andrew Kelley <andrew@ziglang.org> 2018-09-11 12:59:39-04:00
log	dd1338b0e6280b10b9b62ca73bf9ece34bd8524e
tree	e9745fe1b7a469cf8859b820c7a73715d76832d1
parent	c4f96ea745ae2aa56ec5cb2c871e5b3d86b04c8f
signature	Commit is signed but in an unrecognized format.

fix incorrect union const value generation

closes #1381

The union was generated as a 3 byte struct when it needed to be
4 bytes so that the packed struct bitcast could work correctly.

Now it recognizes this situation and adds padding bytes to become
the correct size so that it can fit into an array.

3 files changed, 34 insertions(+), 3 deletions(-)

src
- codegen.cpp
test
- behavior.zig
- cases
  - bugs
    1381.zig

src/codegen.cpp+12-3

 @@ -3218,7 +3218,8 @@ static LLVMValueRef ir_render_decl_var(CodeGen *g, IrExecutable *executable,
         assert(var->value->type == init_value->value.type);
         ZigType *var_ptr_type = get_pointer_to_type_extra(g, var->value->type, false, false,
                 PtrLenSingle, var->align_bytes, 0, 0);
-        gen_assign_raw(g, var->value_ref, var_ptr_type, ir_llvm_value(g, init_value));
+        LLVMValueRef llvm_init_val = ir_llvm_value(g, init_value);
+        gen_assign_raw(g, var->value_ref, var_ptr_type, llvm_init_val);
     } else {
         bool want_safe = ir_want_runtime_safety(g, &decl_var_instruction->base);
         if (want_safe) {
 @@ -5863,12 +5864,20 @@ static LLVMValueRef gen_const_val(CodeGen *g, ConstExprValue *const_val, const c
                 LLVMValueRef tag_value = bigint_to_llvm_const(type_entry->data.unionation.tag_type->type_ref,
                         &const_val->data.x_union.tag);
-                LLVMValueRef fields[2];
+                LLVMValueRef fields[3];
                 fields[type_entry->data.unionation.gen_union_index] = union_value_ref;
                 fields[type_entry->data.unionation.gen_tag_index] = tag_value;
                 if (make_unnamed_struct) {
-                    return LLVMConstStruct(fields, 2, false);
+                    LLVMValueRef result = LLVMConstStruct(fields, 2, false);
+                    size_t expected_sz = LLVMStoreSizeOfType(g->target_data_ref, type_entry->type_ref);
+                    size_t actual_sz = LLVMStoreSizeOfType(g->target_data_ref, LLVMTypeOf(result));
+                    if (actual_sz < expected_sz) {
+                        unsigned pad_sz = expected_sz - actual_sz;
+                        fields[2] = LLVMGetUndef(LLVMArrayType(LLVMInt8Type(), pad_sz));
+                        result = LLVMConstStruct(fields, 3, false);
+                    }
+                    return result;
                 } else {
                     return LLVMConstNamedStruct(type_entry->type_ref, fields, 2);
                 }

test/behavior.zig+1

...	@@ -10,6 +10,7 @@ comptime {	...	@@ -10,6 +10,7 @@ comptime {
10	_ = @import("cases/bool.zig");	10	_ = @import("cases/bool.zig");
11	_ = @import("cases/bugs/1111.zig");	11	_ = @import("cases/bugs/1111.zig");
12	_ = @import("cases/bugs/1277.zig");	12	_ = @import("cases/bugs/1277.zig");
		13	_ = @import("cases/bugs/1381.zig");
13	_ = @import("cases/bugs/1421.zig");	14	_ = @import("cases/bugs/1421.zig");
14	_ = @import("cases/bugs/394.zig");	15	_ = @import("cases/bugs/394.zig");
15	_ = @import("cases/bugs/655.zig");	16	_ = @import("cases/bugs/655.zig");

test/cases/bugs/1381.zig created+21

...	@@ -0,0 +1,21 @@
1	const std = @import("std");
2
3	const B = union(enum) {
4	D: u8,
5	E: u16,
6	};
7
8	const A = union(enum) {
9	B: B,
10	C: u8,
11	};
12
13	test "union that needs padding bytes inside an array" {
14	var as = []A{
15	A{ .B = B{ .D = 1 } },
16	A{ .B = B{ .D = 1 } },
17	};
18
19	const a = as[0].B;
20	std.debug.assertOrPanic(a.D == 1);
21	}