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comptime: ability to @ptrCast to an extern struct and read fields
This commit is contained in:
Andrew Kelley
parent
f301474531
commit
218a4d4b30
64
src/ir.cpp
64
src/ir.cpp
@ -159,7 +159,7 @@ static ZigType *ir_resolve_atomic_operand_type(IrAnalyze *ira, IrInstruction *op
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static IrInstruction *ir_lval_wrap(IrBuilder *irb, Scope *scope, IrInstruction *value, LVal lval);
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static ZigType *adjust_ptr_align(CodeGen *g, ZigType *ptr_type, uint32_t new_align);
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static ZigType *adjust_slice_align(CodeGen *g, ZigType *slice_type, uint32_t new_align);
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static void buf_read_value_bytes(CodeGen *codegen, uint8_t *buf, ConstExprValue *val);
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static Error buf_read_value_bytes(IrAnalyze *ira, AstNode *source_node, uint8_t *buf, ConstExprValue *val);
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static void buf_write_value_bytes(CodeGen *codegen, uint8_t *buf, ConstExprValue *val);
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static Error ir_read_const_ptr(IrAnalyze *ira, AstNode *source_node,
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ConstExprValue *out_val, ConstExprValue *ptr_val);
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@ -13725,7 +13725,8 @@ static Error ir_read_const_ptr(IrAnalyze *ira, AstNode *source_node,
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Buf buf = BUF_INIT;
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buf_resize(&buf, src_size);
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buf_write_value_bytes(ira->codegen, (uint8_t*)buf_ptr(&buf), pointee);
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buf_read_value_bytes(ira->codegen, (uint8_t*)buf_ptr(&buf), out_val);
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if ((err = buf_read_value_bytes(ira, source_node, (uint8_t*)buf_ptr(&buf), out_val)))
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return err;
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return ErrorNone;
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}
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@ -13759,7 +13760,8 @@ static Error ir_read_const_ptr(IrAnalyze *ira, AstNode *source_node,
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ConstExprValue *elem_val = &array_val->data.x_array.data.s_none.elements[elem_index + i];
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buf_write_value_bytes(ira->codegen, (uint8_t*)buf_ptr(&buf) + (i * elem_size), elem_val);
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}
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buf_read_value_bytes(ira->codegen, (uint8_t*)buf_ptr(&buf), out_val);
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if ((err = buf_read_value_bytes(ira, source_node, (uint8_t*)buf_ptr(&buf), out_val)))
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return err;
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return ErrorNone;
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}
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case ConstPtrSpecialBaseStruct:
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@ -20077,7 +20079,8 @@ static void buf_write_value_bytes(CodeGen *codegen, uint8_t *buf, ConstExprValue
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zig_unreachable();
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}
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static void buf_read_value_bytes(CodeGen *codegen, uint8_t *buf, ConstExprValue *val) {
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static Error buf_read_value_bytes(IrAnalyze *ira, AstNode *source_node, uint8_t *buf, ConstExprValue *val) {
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Error err;
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assert(val->special == ConstValSpecialStatic);
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switch (val->type->id) {
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case ZigTypeIdInvalid:
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@ -20094,30 +20097,60 @@ static void buf_read_value_bytes(CodeGen *codegen, uint8_t *buf, ConstExprValue
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case ZigTypeIdPromise:
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zig_unreachable();
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case ZigTypeIdVoid:
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return;
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return ErrorNone;
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case ZigTypeIdBool:
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val->data.x_bool = (buf[0] != 0);
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return;
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return ErrorNone;
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case ZigTypeIdInt:
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bigint_read_twos_complement(&val->data.x_bigint, buf, val->type->data.integral.bit_count,
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codegen->is_big_endian, val->type->data.integral.is_signed);
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return;
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ira->codegen->is_big_endian, val->type->data.integral.is_signed);
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return ErrorNone;
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case ZigTypeIdFloat:
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float_read_ieee597(val, buf, codegen->is_big_endian);
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return;
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float_read_ieee597(val, buf, ira->codegen->is_big_endian);
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return ErrorNone;
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case ZigTypeIdPointer:
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{
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val->data.x_ptr.special = ConstPtrSpecialHardCodedAddr;
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BigInt bn;
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bigint_read_twos_complement(&bn, buf, codegen->builtin_types.entry_usize->data.integral.bit_count,
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codegen->is_big_endian, false);
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bigint_read_twos_complement(&bn, buf, ira->codegen->builtin_types.entry_usize->data.integral.bit_count,
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ira->codegen->is_big_endian, false);
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val->data.x_ptr.data.hard_coded_addr.addr = bigint_as_unsigned(&bn);
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return;
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return ErrorNone;
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}
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case ZigTypeIdArray:
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zig_panic("TODO buf_read_value_bytes array type");
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case ZigTypeIdStruct:
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zig_panic("TODO buf_read_value_bytes struct type");
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switch (val->type->data.structure.layout) {
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case ContainerLayoutAuto: {
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ErrorMsg *msg = ir_add_error_node(ira, source_node,
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buf_sprintf("non-extern, non-packed struct '%s' cannot have its bytes reinterpreted",
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buf_ptr(&val->type->name)));
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add_error_note(ira->codegen, msg, val->type->data.structure.decl_node,
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buf_sprintf("declared here"));
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return ErrorSemanticAnalyzeFail;
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}
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case ContainerLayoutExtern: {
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size_t src_field_count = val->type->data.structure.src_field_count;
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val->data.x_struct.fields = create_const_vals(src_field_count);
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for (size_t field_i = 0; field_i < src_field_count; field_i += 1) {
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ConstExprValue *field_val = &val->data.x_struct.fields[field_i];
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field_val->special = ConstValSpecialStatic;
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TypeStructField *type_field = &val->type->data.structure.fields[field_i];
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field_val->type = type_field->type_entry;
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if (type_field->gen_index == SIZE_MAX)
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continue;
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size_t offset = LLVMOffsetOfElement(ira->codegen->target_data_ref, val->type->type_ref,
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type_field->gen_index);
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uint8_t *new_buf = buf + offset;
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if ((err = buf_read_value_bytes(ira, source_node, new_buf, field_val)))
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return err;
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}
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return ErrorNone;
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}
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case ContainerLayoutPacked:
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zig_panic("TODO buf_read_value_bytes packed struct");
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}
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zig_unreachable();
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case ZigTypeIdOptional:
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zig_panic("TODO buf_read_value_bytes maybe type");
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case ZigTypeIdErrorUnion:
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@ -20220,7 +20253,8 @@ static IrInstruction *ir_analyze_instruction_bit_cast(IrAnalyze *ira, IrInstruct
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IrInstruction *result = ir_const(ira, &instruction->base, dest_type);
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uint8_t *buf = allocate_nonzero<uint8_t>(src_size_bytes);
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buf_write_value_bytes(ira->codegen, buf, val);
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buf_read_value_bytes(ira->codegen, buf, &result->value);
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if ((err = buf_read_value_bytes(ira, instruction->base.source_node, buf, &result->value)))
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return ira->codegen->invalid_instruction;
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return result;
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}
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@ -15,3 +15,22 @@ fn testReinterpretBytesAsInteger() void {
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};
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assertOrPanic(@ptrCast(*align(1) const u32, bytes[1..5].ptr).* == expected);
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}
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test "reinterpret bytes of an array into an extern struct" {
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testReinterpretBytesAsExternStruct();
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comptime testReinterpretBytesAsExternStruct();
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}
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fn testReinterpretBytesAsExternStruct() void {
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var bytes align(2) = []u8{ 1, 2, 3, 4, 5, 6 };
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const S = extern struct {
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a: u8,
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b: u16,
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c: u8,
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};
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var ptr = @ptrCast(*const S, &bytes);
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var val = ptr.c;
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assertOrPanic(val == 5);
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}
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