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debug safety for unions

master
Andrew Kelley 2017-11-16 21:15:15 -05:00
parent f12d36641f
commit e26ccd5166
4 changed files with 48 additions and 12 deletions
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1
src/all_types.hpp
View File

@ -1317,6 +1317,7 @@ enum PanicMsgId {
PanicMsgIdUnwrapMaybeFail,
PanicMsgIdInvalidErrorCode,
PanicMsgIdIncorrectAlignment,
PanicMsgIdBadUnionField,
PanicMsgIdCount,
};

37
src/codegen.cpp
View File

@ -810,6 +810,8 @@ static Buf *panic_msg_buf(PanicMsgId msg_id) {
return buf_create_from_str("invalid error code");
case PanicMsgIdIncorrectAlignment:
return buf_create_from_str("incorrect alignment");
case PanicMsgIdBadUnionField:
return buf_create_from_str("access of inactive union field");
}
zig_unreachable();
}
@ -2415,6 +2417,23 @@ static LLVMValueRef ir_render_union_field_ptr(CodeGen *g, IrExecutable *executab
return bitcasted_union_field_ptr;
}
if (ir_want_debug_safety(g, &instruction->base)) {
LLVMValueRef tag_field_ptr = LLVMBuildStructGEP(g->builder, union_ptr, union_type->data.unionation.gen_tag_index, "");
LLVMValueRef tag_value = gen_load_untyped(g, tag_field_ptr, 0, false, "");
LLVMValueRef expected_tag_value = LLVMConstInt(union_type->data.unionation.tag_type->type_ref,
field->value, false);
LLVMBasicBlockRef ok_block = LLVMAppendBasicBlock(g->cur_fn_val, "UnionCheckOk");
LLVMBasicBlockRef bad_block = LLVMAppendBasicBlock(g->cur_fn_val, "UnionCheckFail");
LLVMValueRef ok_val = LLVMBuildICmp(g->builder, LLVMIntEQ, tag_value, expected_tag_value, "");
LLVMBuildCondBr(g->builder, ok_val, ok_block, bad_block);
LLVMPositionBuilderAtEnd(g->builder, bad_block);
gen_debug_safety_crash(g, PanicMsgIdBadUnionField);
LLVMPositionBuilderAtEnd(g->builder, ok_block);
}
LLVMValueRef union_field_ptr = LLVMBuildStructGEP(g->builder, union_ptr, union_type->data.unionation.gen_union_index, "");
LLVMValueRef bitcasted_union_field_ptr = LLVMBuildBitCast(g->builder, union_field_ptr, field_type_ref, "");
return bitcasted_union_field_ptr;
@ -3977,21 +3996,17 @@ static LLVMValueRef gen_const_val(CodeGen *g, ConstExprValue *const_val) {
LLVMValueRef union_value_ref;
{
unsigned field_count;
LLVMValueRef fields[2];
fields[0] = correctly_typed_value;
if (pad_bytes == 0) {
field_count = 1;
union_value_ref = correctly_typed_value;
} else {
LLVMValueRef fields[2];
fields[0] = correctly_typed_value;
fields[1] = LLVMGetUndef(LLVMArrayType(LLVMInt8Type(), (unsigned)pad_bytes));
field_count = 2;
}
if (make_unnamed_struct || type_entry->data.unionation.gen_tag_index != SIZE_MAX) {
union_value_ref = LLVMConstStruct(fields, field_count, false);
} else {
union_value_ref = LLVMConstNamedStruct(union_type_ref, fields, field_count);
if (make_unnamed_struct || type_entry->data.unionation.gen_tag_index != SIZE_MAX) {
union_value_ref = LLVMConstStruct(fields, 2, false);
} else {
union_value_ref = LLVMConstNamedStruct(union_type_ref, fields, 2);
}
}
}

2
test/cases/union.zig
View File

@ -41,7 +41,7 @@ const Foo = union {
test "basic unions" {
var foo = Foo { .int = 1 };
assert(foo.int == 1);
foo.float = 12.34;
foo = Foo {.float = 12.34};
assert(foo.float == 12.34);
}

20
test/debug_safety.zig
View File

@ -260,4 +260,24 @@ pub fn addCases(cases: &tests.CompareOutputContext) {
\\ return int_slice[0];
\\}
);
cases.addDebugSafety("bad union field access",
\\pub fn panic(message: []const u8) -> noreturn {
\\ @import("std").os.exit(126);
\\}
\\
\\const Foo = union {
\\ float: f32,
\\ int: u32,
\\};
\\
\\pub fn main() -> %void {
\\ var f = Foo { .int = 42 };
\\ bar(&f);
\\}
\\
\\fn bar(f: &Foo) {
\\ f.float = 12.34;
\\}
);
}