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[/] [openrisc/] [trunk/] [gnu-dev/] [or1k-gcc/] [gcc/] [go/] [gofrontend/] [backend.h] - Rev 724
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// backend.h -- Go frontend interface to backend -*- C++ -*- // Copyright 2011 The Go Authors. All rights reserved. // Use of this source code is governed by a BSD-style // license that can be found in the LICENSE file. #ifndef GO_BACKEND_H #define GO_BACKEND_H // Pointers to these types are created by the backend, passed to the // frontend, and passed back to the backend. The types must be // defined by the backend using these names. // The backend representation of a type. class Btype; // The backend represention of an expression. class Bexpression; // The backend representation of a statement. class Bstatement; // The backend representation of a function definition. class Bfunction; // The backend representation of a block. class Bblock; // The backend representation of a variable. class Bvariable; // The backend representation of a label. class Blabel; // The backend interface. This is a pure abstract class that a // specific backend will implement. class Backend { public: virtual ~Backend() { } // Name/type/location. Used for function parameters, struct fields, // interface methods. struct Btyped_identifier { std::string name; Btype* btype; Location location; Btyped_identifier() : name(), btype(NULL), location(UNKNOWN_LOCATION) { } Btyped_identifier(const std::string& a_name, Btype* a_btype, Location a_location) : name(a_name), btype(a_btype), location(a_location) { } }; // Types. // Produce an error type. Actually the backend could probably just // crash if this is called. virtual Btype* error_type() = 0; // Get a void type. This is used in (at least) two ways: 1) as the // return type of a function with no result parameters; 2) // unsafe.Pointer is represented as *void. virtual Btype* void_type() = 0; // Get the unnamed boolean type. virtual Btype* bool_type() = 0; // Get an unnamed integer type with the given signedness and number // of bits. virtual Btype* integer_type(bool is_unsigned, int bits) = 0; // Get an unnamed floating point type with the given number of bits // (32 or 64). virtual Btype* float_type(int bits) = 0; // Get an unnamed complex type with the given number of bits (64 or 128). virtual Btype* complex_type(int bits) = 0; // Get a pointer type. virtual Btype* pointer_type(Btype* to_type) = 0; // Get a function type. The receiver, parameter, and results are // generated from the types in the Function_type. The Function_type // is provided so that the names are available. virtual Btype* function_type(const Btyped_identifier& receiver, const std::vector<Btyped_identifier>& parameters, const std::vector<Btyped_identifier>& results, Location location) = 0; // Get a struct type. virtual Btype* struct_type(const std::vector<Btyped_identifier>& fields) = 0; // Get an array type. virtual Btype* array_type(Btype* element_type, Bexpression* length) = 0; // Create a placeholder pointer type. This is used for a named // pointer type, since in Go a pointer type may refer to itself. // NAME is the name of the type, and the location is where the named // type is defined. This function is also used for unnamed function // types with multiple results, in which case the type has no name // and NAME will be empty. FOR_FUNCTION is true if this is for a Go // function type, which corresponds to a C/C++ pointer to function // type. The return value will later be passed as the first // parameter to set_placeholder_pointer_type or // set_placeholder_function_type. virtual Btype* placeholder_pointer_type(const std::string& name, Location, bool for_function) = 0; // Fill in a placeholder pointer type as a pointer. This takes a // type returned by placeholder_pointer_type and arranges for it to // point to the type that TO_TYPE points to (that is, PLACEHOLDER // becomes the same type as TO_TYPE). Returns true on success, // false on failure. virtual bool set_placeholder_pointer_type(Btype* placeholder, Btype* to_type) = 0; // Fill in a placeholder pointer type as a function. This takes a // type returned by placeholder_pointer_type and arranges for it to // become a real Go function type (which corresponds to a C/C++ // pointer to function type). FT will be something returned by the // function_type method. Returns true on success, false on failure. virtual bool set_placeholder_function_type(Btype* placeholder, Btype* ft) = 0; // Create a placeholder struct type. This is used for a named // struct type, as with placeholder_pointer_type. It is also used // for interface types, in which case NAME will be the empty string. virtual Btype* placeholder_struct_type(const std::string& name, Location) = 0; // Fill in a placeholder struct type. This takes a type returned by // placeholder_struct_type and arranges for it to become a real // struct type. The parameter is as for struct_type. Returns true // on success, false on failure. virtual bool set_placeholder_struct_type(Btype* placeholder, const std::vector<Btyped_identifier>& fields) = 0; // Create a placeholder array type. This is used for a named array // type, as with placeholder_pointer_type, to handle cases like // type A []*A. virtual Btype* placeholder_array_type(const std::string& name, Location) = 0; // Fill in a placeholder array type. This takes a type returned by // placeholder_array_type and arranges for it to become a real array // type. The parameters are as for array_type. Returns true on // success, false on failure. virtual bool set_placeholder_array_type(Btype* placeholder, Btype* element_type, Bexpression* length) = 0; // Return a named version of a type. The location is the location // of the type definition. This will not be called for a type // created via placeholder_pointer_type, placeholder_struct_type, or // placeholder_array_type.. (It may be called for a pointer, // struct, or array type in a case like "type P *byte; type Q P".) virtual Btype* named_type(const std::string& name, Btype*, Location) = 0; // Create a marker for a circular pointer type. Go pointer and // function types can refer to themselves in ways that are not // permitted in C/C++. When a circular type is found, this function // is called for the circular reference. This permits the backend // to decide how to handle such a type. PLACEHOLDER is the // placeholder type which has already been created; if the backend // is prepared to handle a circular pointer type, it may simply // return PLACEHOLDER. FOR_FUNCTION is true if this is for a // function type. // // For "type P *P" the sequence of calls will be // bt1 = placeholder_pointer_type(); // bt2 = circular_pointer_type(bt1, false); // set_placeholder_pointer_type(bt1, bt2); virtual Btype* circular_pointer_type(Btype* placeholder, bool for_function) = 0; // Return whether the argument could be a special type created by // circular_pointer_type. This is used to introduce explicit type // conversions where needed. If circular_pointer_type returns its // PLACEHOLDER parameter, this may safely always return false. virtual bool is_circular_pointer_type(Btype*) = 0; // Return the size of a type. virtual size_t type_size(Btype*) = 0; // Return the alignment of a type. virtual size_t type_alignment(Btype*) = 0; // Return the alignment of a struct field of this type. This is // normally the same as type_alignment, but not always. virtual size_t type_field_alignment(Btype*) = 0; // Return the offset of field INDEX in a struct type. INDEX is the // entry in the FIELDS std::vector parameter of struct_type or // set_placeholder_struct_type. virtual size_t type_field_offset(Btype*, size_t index) = 0; // Expressions. // Return an expression for a zero value of the given type. This is // used for cases such as local variable initialization and // converting nil to other types. virtual Bexpression* zero_expression(Btype*) = 0; // Statements. // Create an error statement. This is used for cases which should // not occur in a correct program, in order to keep the compilation // going without crashing. virtual Bstatement* error_statement() = 0; // Create an expression statement. virtual Bstatement* expression_statement(Bexpression*) = 0; // Create a variable initialization statement. This initializes a // local variable at the point in the program flow where it is // declared. virtual Bstatement* init_statement(Bvariable* var, Bexpression* init) = 0; // Create an assignment statement. virtual Bstatement* assignment_statement(Bexpression* lhs, Bexpression* rhs, Location) = 0; // Create a return statement, passing the representation of the // function and the list of values to return. virtual Bstatement* return_statement(Bfunction*, const std::vector<Bexpression*>&, Location) = 0; // Create an if statement. ELSE_BLOCK may be NULL. virtual Bstatement* if_statement(Bexpression* condition, Bblock* then_block, Bblock* else_block, Location) = 0; // Create a switch statement where the case values are constants. // CASES and STATEMENTS must have the same number of entries. If // VALUE matches any of the list in CASES[i], which will all be // integers, then STATEMENTS[i] is executed. STATEMENTS[i] will // either end with a goto statement or will fall through into // STATEMENTS[i + 1]. CASES[i] is empty for the default clause, // which need not be last. virtual Bstatement* switch_statement(Bexpression* value, const std::vector<std::vector<Bexpression*> >& cases, const std::vector<Bstatement*>& statements, Location) = 0; // Create a single statement from two statements. virtual Bstatement* compound_statement(Bstatement*, Bstatement*) = 0; // Create a single statement from a list of statements. virtual Bstatement* statement_list(const std::vector<Bstatement*>&) = 0; // Blocks. // Create a block. The frontend will call this function when it // starts converting a block within a function. FUNCTION is the // current function. ENCLOSING is the enclosing block; it will be // NULL for the top-level block in a function. VARS is the list of // local variables defined within this block; each entry will be // created by the local_variable function. START_LOCATION is the // location of the start of the block, more or less the location of // the initial curly brace. END_LOCATION is the location of the end // of the block, more or less the location of the final curly brace. // The statements will be added after the block is created. virtual Bblock* block(Bfunction* function, Bblock* enclosing, const std::vector<Bvariable*>& vars, Location start_location, Location end_location) = 0; // Add the statements to a block. The block is created first. Then // the statements are created. Then the statements are added to the // block. This will called exactly once per block. The vector may // be empty if there are no statements. virtual void block_add_statements(Bblock*, const std::vector<Bstatement*>&) = 0; // Return the block as a statement. This is used to include a block // in a list of statements. virtual Bstatement* block_statement(Bblock*) = 0; // Variables. // Create an error variable. This is used for cases which should // not occur in a correct program, in order to keep the compilation // going without crashing. virtual Bvariable* error_variable() = 0; // Create a global variable. PACKAGE_NAME is the name of the // package where the variable is defined. UNIQUE_PREFIX is the // prefix for that package, from the -fgo-prefix option. NAME is // the name of the variable. BTYPE is the type of the variable. // IS_EXTERNAL is true if the variable is defined in some other // package. IS_HIDDEN is true if the variable is not exported (name // begins with a lower case letter). LOCATION is where the variable // was defined. virtual Bvariable* global_variable(const std::string& package_name, const std::string& unique_prefix, const std::string& name, Btype* btype, bool is_external, bool is_hidden, Location location) = 0; // A global variable will 1) be initialized to zero, or 2) be // initialized to a constant value, or 3) be initialized in the init // function. In case 2, the frontend will call // global_variable_set_init to set the initial value. If this is // not called, the backend should initialize a global variable to 0. // The init function may then assign a value to it. virtual void global_variable_set_init(Bvariable*, Bexpression*) = 0; // Create a local variable. The frontend will create the local // variables first, and then create the block which contains them. // FUNCTION is the function in which the variable is defined. NAME // is the name of the variable. TYPE is the type. IS_ADDRESS_TAKEN // is true if the address of this variable is taken (this implies // that the address does not escape the function, as otherwise the // variable would be on the heap). LOCATION is where the variable // is defined. For each local variable the frontend will call // init_statement to set the initial value. virtual Bvariable* local_variable(Bfunction* function, const std::string& name, Btype* type, bool is_address_taken, Location location) = 0; // Create a function parameter. This is an incoming parameter, not // a result parameter (result parameters are treated as local // variables). The arguments are as for local_variable. virtual Bvariable* parameter_variable(Bfunction* function, const std::string& name, Btype* type, bool is_address_taken, Location location) = 0; // Create a temporary variable. A temporary variable has no name, // just a type. We pass in FUNCTION and BLOCK in case they are // needed. If INIT is not NULL, the variable should be initialized // to that value. Otherwise the initial value is irrelevant--the // backend does not have to explicitly initialize it to zero. // ADDRESS_IS_TAKEN is true if the programs needs to take the // address of this temporary variable. LOCATION is the location of // the statement or expression which requires creating the temporary // variable, and may not be very useful. This function should // return a variable which can be referenced later and should set // *PSTATEMENT to a statement which initializes the variable. virtual Bvariable* temporary_variable(Bfunction*, Bblock*, Btype*, Bexpression* init, bool address_is_taken, Location location, Bstatement** pstatement) = 0; // Create a named immutable initialized data structure. This is // used for type descriptors and map descriptors. This returns a // Bvariable because it corresponds to an initialized const global // variable in C. // // NAME is the name to use for the initialized global variable which // this call will create. // // IS_COMMON is true if NAME may be defined by several packages, and // the linker should merge all such definitions. If IS_COMMON is // false, NAME should be defined in only one file. In general // IS_COMMON will be true for the type descriptor of an unnamed type // or a builtin type. // // TYPE will be a struct type; the type of the returned expression // must be a pointer to this struct type. // // We must create the named structure before we know its // initializer, because the initializer may refer to its own // address. After calling this the frontend will call // immutable_struct_set_init. virtual Bvariable* immutable_struct(const std::string& name, bool is_common, Btype* type, Location) = 0; // Set the initial value of a variable created by immutable_struct. // The NAME, IS_COMMON, TYPE, and location parameters are the same // ones passed to immutable_struct. INITIALIZER will be a composite // literal of type TYPE. It will not contain any function calls or // anything else which can not be put into a read-only data section. // It may contain the address of variables created by // immutable_struct. virtual void immutable_struct_set_init(Bvariable*, const std::string& name, bool is_common, Btype* type, Location, Bexpression* initializer) = 0; // Create a reference to a named immutable initialized data // structure defined in some other package. This will be a // structure created by a call to immutable_struct with the same // NAME and TYPE and with IS_COMMON passed as false. This // corresponds to an extern const global variable in C. virtual Bvariable* immutable_struct_reference(const std::string& name, Btype* type, Location) = 0; // Labels. // Create a new label. NAME will be empty if this is a label // created by the frontend for a loop construct. The location is // where the the label is defined. virtual Blabel* label(Bfunction*, const std::string& name, Location) = 0; // Create a statement which defines a label. This statement will be // put into the codestream at the point where the label should be // defined. virtual Bstatement* label_definition_statement(Blabel*) = 0; // Create a goto statement to a label. virtual Bstatement* goto_statement(Blabel*, Location) = 0; // Create an expression for the address of a label. This is used to // get the return address of a deferred function which may call // recover. virtual Bexpression* label_address(Blabel*, Location) = 0; }; // The backend interface has to define this function. extern Backend* go_get_backend(); // FIXME: Temporary helper functions while converting to new backend // interface. extern Btype* tree_to_type(tree); extern Bexpression* tree_to_expr(tree); extern Bstatement* tree_to_stat(tree); extern Bfunction* tree_to_function(tree); extern Bblock* tree_to_block(tree); extern tree type_to_tree(Btype*); extern tree expr_to_tree(Bexpression*); extern tree stat_to_tree(Bstatement*); extern tree block_to_tree(Bblock*); extern tree var_to_tree(Bvariable*); #endif // !defined(GO_BACKEND_H)
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