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unions have a secret field for the type

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See #144
This commit is contained in:
Andrew Kelley 2017-11-15 22:52:47 -05:00
parent f276fd0f37
commit 018cbff438
4 changed files with 195 additions and 31 deletions
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12
src/all_types.hpp
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@ -1037,6 +1037,9 @@ struct TypeTableEntryEnumTag {
LLVMValueRef name_table;
};
uint32_t type_ptr_hash(const TypeTableEntry *ptr);
bool type_ptr_eql(const TypeTableEntry *a, const TypeTableEntry *b);
struct TypeTableEntryUnion {
AstNode *decl_node;
ContainerLayout layout;
@ -1044,6 +1047,8 @@ struct TypeTableEntryUnion {
uint32_t gen_field_count;
TypeUnionField *fields;
bool is_invalid; // true if any fields are invalid
TypeTableEntry *tag_type;
LLVMTypeRef union_type_ref;
ScopeDecls *decls_scope;
@ -1057,8 +1062,13 @@ struct TypeTableEntryUnion {
bool zero_bits_known;
uint32_t abi_alignment; // also figured out with zero_bits pass
uint32_t size_bytes;
size_t gen_union_index;
size_t gen_tag_index;
uint32_t union_size_bytes;
TypeTableEntry *most_aligned_union_member;
HashMap<const TypeTableEntry *, uint32_t, type_ptr_hash, type_ptr_eql> distinct_types = {};
};
struct FnGenParamInfo {

140
src/analyze.cpp
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@ -992,26 +992,23 @@ TypeTableEntry *get_partial_container_type(CodeGen *g, Scope *scope, ContainerKi
TypeTableEntryId type_id = container_to_type(kind);
TypeTableEntry *entry = new_container_type_entry(type_id, decl_node, scope);
unsigned dwarf_kind;
switch (kind) {
case ContainerKindStruct:
entry->data.structure.decl_node = decl_node;
entry->data.structure.layout = layout;
dwarf_kind = ZigLLVMTag_DW_structure_type();
break;
case ContainerKindEnum:
entry->data.enumeration.decl_node = decl_node;
entry->data.enumeration.layout = layout;
dwarf_kind = ZigLLVMTag_DW_structure_type();
break;
case ContainerKindUnion:
entry->data.unionation.decl_node = decl_node;
entry->data.unionation.layout = layout;
dwarf_kind = ZigLLVMTag_DW_union_type();
break;
}
size_t line = decl_node ? decl_node->line : 0;
unsigned dwarf_kind = ZigLLVMTag_DW_structure_type();
ImportTableEntry *import = get_scope_import(scope);
entry->type_ref = LLVMStructCreateNamed(LLVMGetGlobalContext(), name);
@ -1873,6 +1870,11 @@ static void resolve_union_type(CodeGen *g, TypeTableEntry *union_type) {
uint64_t biggest_align_in_bits = 0;
uint64_t biggest_size_in_bits = 0;
bool auto_layout = (union_type->data.unionation.layout == ContainerLayoutAuto);
ZigLLVMDIEnumerator **di_enumerators = allocate<ZigLLVMDIEnumerator*>(field_count);
auto distinct_types = &union_type->data.unionation.distinct_types;
distinct_types->init(4);
Scope *scope = &union_type->data.unionation.decls_scope->base;
ImportTableEntry *import = get_scope_import(scope);
@ -1893,6 +1895,11 @@ static void resolve_union_type(CodeGen *g, TypeTableEntry *union_type) {
if (!type_has_bits(field_type))
continue;
size_t distinct_type_index = distinct_types->size();
if (distinct_types->put_unique(field_type, distinct_type_index) == nullptr) {
di_enumerators[i] = ZigLLVMCreateDebugEnumerator(g->dbuilder, buf_ptr(&field_type->name), distinct_type_index);
}
uint64_t store_size_in_bits = 8*LLVMStoreSizeOfType(g->target_data_ref, field_type->type_ref);
uint64_t abi_align_in_bits = 8*LLVMABIAlignmentOfType(g->target_data_ref, field_type->type_ref);
@ -1919,7 +1926,7 @@ static void resolve_union_type(CodeGen *g, TypeTableEntry *union_type) {
// unset temporary flag
union_type->data.unionation.embedded_in_current = false;
union_type->data.unionation.complete = true;
union_type->data.unionation.size_bytes = biggest_size_in_bits / 8;
union_type->data.unionation.union_size_bytes = biggest_size_in_bits / 8;
union_type->data.unionation.most_aligned_union_member = most_aligned_union_member;
if (union_type->data.unionation.is_invalid)
@ -1947,8 +1954,42 @@ static void resolve_union_type(CodeGen *g, TypeTableEntry *union_type) {
assert(most_aligned_union_member != nullptr);
// create llvm type for union
bool want_safety = (distinct_types->size() > 1) && auto_layout;
uint64_t padding_in_bits = biggest_size_in_bits - size_of_most_aligned_member_in_bits;
if (!want_safety) {
if (padding_in_bits > 0) {
TypeTableEntry *u8_type = get_int_type(g, false, 8);
TypeTableEntry *padding_array = get_array_type(g, u8_type, padding_in_bits / 8);
LLVMTypeRef union_element_types[] = {
most_aligned_union_member->type_ref,
padding_array->type_ref,
};
LLVMStructSetBody(union_type->type_ref, union_element_types, 2, false);
} else {
LLVMStructSetBody(union_type->type_ref, &most_aligned_union_member->type_ref, 1, false);
}
union_type->data.unionation.union_type_ref = union_type->type_ref;
union_type->data.unionation.gen_tag_index = SIZE_MAX;
union_type->data.unionation.gen_union_index = SIZE_MAX;
assert(8*LLVMABIAlignmentOfType(g->target_data_ref, union_type->type_ref) >= biggest_align_in_bits);
assert(8*LLVMStoreSizeOfType(g->target_data_ref, union_type->type_ref) >= biggest_size_in_bits);
// create debug type for union
ZigLLVMDIType *replacement_di_type = ZigLLVMCreateDebugUnionType(g->dbuilder,
ZigLLVMFileToScope(import->di_file), buf_ptr(&union_type->name),
import->di_file, (unsigned)(decl_node->line + 1),
biggest_size_in_bits, biggest_align_in_bits, 0, union_inner_di_types,
gen_field_count, 0, "");
ZigLLVMReplaceTemporary(g->dbuilder, union_type->di_type, replacement_di_type);
union_type->di_type = replacement_di_type;
return;
}
LLVMTypeRef union_type_ref;
if (padding_in_bits > 0) {
TypeTableEntry *u8_type = get_int_type(g, false, 8);
TypeTableEntry *padding_array = get_array_type(g, u8_type, padding_in_bits / 8);
@ -1956,20 +1997,87 @@ static void resolve_union_type(CodeGen *g, TypeTableEntry *union_type) {
most_aligned_union_member->type_ref,
padding_array->type_ref,
};
LLVMStructSetBody(union_type->type_ref, union_element_types, 2, false);
union_type_ref = LLVMStructType(union_element_types, 2, false);
} else {
LLVMStructSetBody(union_type->type_ref, &most_aligned_union_member->type_ref, 1, false);
union_type_ref = most_aligned_union_member->type_ref;
}
union_type->data.unionation.union_type_ref = union_type_ref;
assert(8*LLVMABIAlignmentOfType(g->target_data_ref, union_type_ref) >= biggest_align_in_bits);
assert(8*LLVMStoreSizeOfType(g->target_data_ref, union_type_ref) >= biggest_size_in_bits);
// create llvm type for root struct
TypeTableEntry *tag_int_type = get_smallest_unsigned_int_type(g, distinct_types->size() - 1);
TypeTableEntry *tag_type_entry = tag_int_type;
union_type->data.unionation.tag_type = tag_type_entry;
uint64_t align_of_tag_in_bits = 8*LLVMABIAlignmentOfType(g->target_data_ref, tag_int_type->type_ref);
if (align_of_tag_in_bits >= biggest_align_in_bits) {
union_type->data.unionation.gen_tag_index = 0;
union_type->data.unionation.gen_union_index = 1;
} else {
union_type->data.unionation.gen_union_index = 0;
union_type->data.unionation.gen_tag_index = 1;
}
assert(8*LLVMABIAlignmentOfType(g->target_data_ref, union_type->type_ref) >= biggest_align_in_bits);
assert(8*LLVMStoreSizeOfType(g->target_data_ref, union_type->type_ref) >= biggest_size_in_bits);
LLVMTypeRef root_struct_element_types[2];
root_struct_element_types[union_type->data.unionation.gen_tag_index] = tag_type_entry->type_ref;
root_struct_element_types[union_type->data.unionation.gen_union_index] = union_type_ref;
LLVMStructSetBody(union_type->type_ref, root_struct_element_types, 2, false);
// create debug type for root struct
// create debug type for tag
uint64_t tag_debug_size_in_bits = 8*LLVMStoreSizeOfType(g->target_data_ref, tag_type_entry->type_ref);
uint64_t tag_debug_align_in_bits = 8*LLVMABIAlignmentOfType(g->target_data_ref, tag_type_entry->type_ref);
ZigLLVMDIType *tag_di_type = ZigLLVMCreateDebugEnumerationType(g->dbuilder,
ZigLLVMTypeToScope(union_type->di_type), "AnonEnum",
import->di_file, (unsigned)(decl_node->line + 1),
tag_debug_size_in_bits, tag_debug_align_in_bits, di_enumerators, distinct_types->size(),
tag_type_entry->di_type, "");
// create debug type for union
ZigLLVMDIType *replacement_di_type = ZigLLVMCreateDebugUnionType(g->dbuilder,
ZigLLVMFileToScope(import->di_file), buf_ptr(&union_type->name),
ZigLLVMDIType *union_di_type = ZigLLVMCreateDebugUnionType(g->dbuilder,
ZigLLVMTypeToScope(union_type->di_type), "AnonUnion",
import->di_file, (unsigned)(decl_node->line + 1),
biggest_size_in_bits, biggest_align_in_bits, 0, union_inner_di_types,
gen_field_count, 0, "");
uint64_t union_offset_in_bits = 8*LLVMOffsetOfElement(g->target_data_ref, union_type->type_ref,
union_type->data.unionation.gen_union_index);
uint64_t tag_offset_in_bits = 8*LLVMOffsetOfElement(g->target_data_ref, union_type->type_ref,
union_type->data.unionation.gen_tag_index);
ZigLLVMDIType *union_member_di_type = ZigLLVMCreateDebugMemberType(g->dbuilder,
ZigLLVMTypeToScope(union_type->di_type), "union_field",
import->di_file, (unsigned)(decl_node->line + 1),
biggest_size_in_bits,
biggest_align_in_bits,
union_offset_in_bits,
0, union_di_type);
ZigLLVMDIType *tag_member_di_type = ZigLLVMCreateDebugMemberType(g->dbuilder,
ZigLLVMTypeToScope(union_type->di_type), "tag_field",
import->di_file, (unsigned)(decl_node->line + 1),
tag_debug_size_in_bits,
tag_debug_align_in_bits,
tag_offset_in_bits,
0, tag_di_type);
ZigLLVMDIType *di_root_members[2];
di_root_members[union_type->data.unionation.gen_tag_index] = tag_member_di_type;
di_root_members[union_type->data.unionation.gen_union_index] = union_member_di_type;
uint64_t debug_size_in_bits = 8*LLVMStoreSizeOfType(g->target_data_ref, union_type->type_ref);
uint64_t debug_align_in_bits = 8*LLVMABISizeOfType(g->target_data_ref, union_type->type_ref);
ZigLLVMDIType *replacement_di_type = ZigLLVMCreateDebugStructType(g->dbuilder,
ZigLLVMFileToScope(import->di_file),
buf_ptr(&union_type->name),
import->di_file, (unsigned)(decl_node->line + 1),
debug_size_in_bits,
debug_align_in_bits,
0, nullptr, di_root_members, 2, 0, nullptr, "");
ZigLLVMReplaceTemporary(g->dbuilder, union_type->di_type, replacement_di_type);
union_type->di_type = replacement_di_type;
}
@ -5140,3 +5248,11 @@ TypeTableEntry *get_align_amt_type(CodeGen *g) {
}
return g->align_amt_type;
}
uint32_t type_ptr_hash(const TypeTableEntry *ptr) {
return hash_ptr((void*)ptr);
}
bool type_ptr_eql(const TypeTableEntry *a, const TypeTableEntry *b) {
return a == b;
}

61
src/codegen.cpp
View File

@ -2408,9 +2408,15 @@ static LLVMValueRef ir_render_union_field_ptr(CodeGen *g, IrExecutable *executab
LLVMValueRef union_ptr = ir_llvm_value(g, instruction->union_ptr);
LLVMTypeRef field_type_ref = LLVMPointerType(field->type_entry->type_ref, 0);
LLVMValueRef union_field_ptr = LLVMBuildStructGEP(g->builder, union_ptr, 0, "");
LLVMValueRef bitcasted_union_field_ptr = LLVMBuildBitCast(g->builder, union_field_ptr, field_type_ref, "");
if (union_type->data.unionation.gen_tag_index == SIZE_MAX) {
LLVMValueRef union_field_ptr = LLVMBuildStructGEP(g->builder, union_ptr, 0, "");
LLVMValueRef bitcasted_union_field_ptr = LLVMBuildBitCast(g->builder, union_field_ptr, field_type_ref, "");
return bitcasted_union_field_ptr;
}
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;
}
@ -3955,7 +3961,7 @@ static LLVMValueRef gen_const_val(CodeGen *g, ConstExprValue *const_val) {
}
case TypeTableEntryIdUnion:
{
LLVMTypeRef union_type_ref = type_entry->type_ref;
LLVMTypeRef union_type_ref = type_entry->data.unionation.union_type_ref;
ConstExprValue *payload_value = const_val->data.x_union.value;
assert(payload_value != nullptr);
@ -3964,29 +3970,48 @@ static LLVMValueRef gen_const_val(CodeGen *g, ConstExprValue *const_val) {
}
uint64_t field_type_bytes = LLVMStoreSizeOfType(g->target_data_ref, payload_value->type->type_ref);
uint64_t pad_bytes = type_entry->data.unionation.size_bytes - field_type_bytes;
uint64_t pad_bytes = type_entry->data.unionation.union_size_bytes - field_type_bytes;
LLVMValueRef correctly_typed_value = gen_const_val(g, payload_value);
bool make_unnamed_struct = is_llvm_value_unnamed_type(payload_value->type, correctly_typed_value) ||
payload_value->type != type_entry->data.unionation.most_aligned_union_member;
unsigned field_count;
LLVMValueRef fields[2];
fields[0] = correctly_typed_value;
if (pad_bytes == 0) {
field_count = 1;
} else {
LLVMValueRef union_value_ref;
{
unsigned field_count;
LLVMValueRef fields[2];
fields[0] = correctly_typed_value;
fields[1] = LLVMGetUndef(LLVMArrayType(LLVMInt8Type(), (unsigned)pad_bytes));
field_count = 2;
if (pad_bytes == 0) {
field_count = 1;
} else {
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) {
return LLVMConstStruct(fields, field_count, false);
} else {
return LLVMConstNamedStruct(type_entry->type_ref, fields, field_count);
if (type_entry->data.unionation.gen_tag_index == SIZE_MAX) {
return union_value_ref;
}
size_t distinct_type_index = type_entry->data.unionation.distinct_types.get(const_val->data.x_union.value->type);
LLVMValueRef tag_value = LLVMConstInt(type_entry->data.unionation.tag_type->type_ref, distinct_type_index, false);
LLVMValueRef fields[2];
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);
} else {
return LLVMConstNamedStruct(type_entry->type_ref, fields, 2);
}
}
case TypeTableEntryIdEnum:
{

13
test/cases/union.zig
View File

@ -44,3 +44,16 @@ test "basic unions" {
foo.float = 12.34;
assert(foo.float == 12.34);
}
const FooExtern = extern union {
float: f64,
int: i32,
};
test "basic extern unions" {
var foo = FooExtern { .int = 1 };
assert(foo.int == 1);
foo.float = 12.34;
assert(foo.float == 12.34);
}