Definitions and functions for handling the compiler IR. More...

Data Structures
struct	t_label
struct	t_instrArg
struct	t_instruction
struct	t_symbol
struct	t_program

Macros
#define	REG_INVALID ((t_regID)(-1))
	Constant used for invalid register identifiers.
#define	REG_0 ((t_regID)(0))
	Constant identifying a register whose value is always zero.

Typedefs
typedef int	t_regID
	Type for register identifiers.

Enumerations
enum	t_symbolType { TYPE_INT , TYPE_INT_ARRAY }

Construction/destruction of a program
t_program *	newProgram (void)
void	deleteProgram (t_program *program)

Handling of labels
t_label *	createLabel (t_program *program)
void	assignLabel (t_program program, t_label label)
void	setLabelName (t_program program, t_label label, const char *name)
char *	getLabelName (t_label *label)

Generation of instructions
t_regID	getNewRegister (t_program *program)
t_instruction *	genInstruction (t_program program, int opcode, t_regID rd, t_regID rs1, t_regID rs2, t_label label, int immediate)
void	removeInstructionAt (t_program program, t_listNode instrLi)

Handling of symbols
t_symbol *	createSymbol (t_program program, char ID, t_symbolType type, int arraySize)
t_symbol *	getSymbol (t_program program, char ID)
bool	isArray (t_symbol *symbol)

Utility functions
void	genEpilog (t_program *program)
void	programDump (t_program program, FILE fout)

Detailed Description

Definitions and functions for handling the compiler IR.

During the compilation process, the program is built instruction by instruction by the code in the syntactic-directed translator in parser.y. The contents of the program are stored in an intermediate data structure of type t_program.

In successive compilation steps, the instructions and data declarations in the program intermediate representation are modified to make them conform to the requirements of the target machine, and at the end they are written to the output assembly file (see target_asm_print.h).

Data Structure Documentation

◆ t_label

struct t_label

Object representing a label in the output assembly file.

Note: A label object does not uniquely identify a label, its labelID field does. This is used for aliasing multiple label objects to the same physical label if more than one label is assigned to an instruction.

Definition at line 47 of file program.h.

Data Fields
bool	global	True if the label will be defined as 'global'.
bool	isAlias	True if this label object is an alias to another one with the same labelID.
unsigned int	labelID	Unique numeric identifier for the label.
char *	name	Name of the label. If NULL, the name will be automatically generated in the form L<ID>.

◆ t_instrArg

struct t_instrArg

Object representing a register argument to an instruction.

Definition at line 61 of file program.h.

Data Fields
t_regID	ID	The register identifier.
t_listNode *	mcRegWhitelist	The list of machine registers where this argument may be allocated. NULL if any machine register is allowed.

◆ t_instruction

struct t_instruction

Object representing a symbolic assembly instruction.

Definition at line 70 of file program.h.

Data Fields
t_label *	addressParam	Address argument.
char *	comment	A comment string associated with the instruction, or NULL if none.
int	immediate	Immediate argument.
t_label *	label	Label associated with the instruction, or NULL.
int	opcode	Instruction opcode.
t_instrArg *	rDest	Destination argument (or NULL if none).
t_instrArg *	rSrc1	First source argument (or NULL if none).
t_instrArg *	rSrc2	Second source argument (or NULL if none).

◆ t_symbol

struct t_symbol

A structure that represents the properties of a given symbol in the source code.

Definition at line 84 of file program.h.

Data Fields
int	arraySize	For arrays only, the size of the array.
char *	ID	Symbol name (should never be a NULL pointer or an empty string "").
t_label *	label	A label that refers to the location of the variable inside the data segment.
t_symbolType	type	A valid data type.

◆ t_program

struct t_program

Object containing the program's intermediate representation during the compilation process.

Definition at line 98 of file program.h.

Data Fields
unsigned int	firstUnusedLblID	Next unused label ID.
t_regID	firstUnusedReg	Next unused register ID.
t_listNode *	instructions	List of instructions.
t_listNode *	labels	List of all labels.
t_label *	pendingLabel	Next pending label to assign.
t_listNode *	symbols	Symbol table.

Macro Definition Documentation

◆ REG_0

#define REG_0 ((t_regID)(0))

Constant identifying a register whose value is always zero.

Definition at line 33 of file program.h.

◆ REG_INVALID

#define REG_INVALID ((t_regID)(-1))

Constant used for invalid register identifiers.

Definition at line 31 of file program.h.

Typedef Documentation

◆ t_regID

typedef int t_regID

Type for register identifiers.

Definition at line 28 of file program.h.

Enumeration Type Documentation

◆ t_symbolType

enum t_symbolType

Supported data types.

Enumerator
TYPE_INT	‘int’ scalar type.
TYPE_INT_ARRAY	‘int’ array type.

Definition at line 37 of file program.h.

Function Documentation

◆ assignLabel()

void assignLabel	(	t_program *	program,
		t_label *	label )

Assign the given label object to the next instruction to be generated.

Parameters

program	The program where the label belongs.
label	The label to be assigned.

Definition at line 253 of file program.c.

◆ createLabel()

t_label * createLabel ( t_program * program )

Reserve a new label object, unassigned to any instruction.

Parameters

program The program where the label belongs.

Returns: The new label object.

Definition at line 173 of file program.c.

◆ createSymbol()

t_symbol * createSymbol	(	t_program *	program,
		char *	ID,
		t_symbolType	type,
		int	arraySize )

Add a symbol to the program.

Parameters

program	The program where to add the symbol.
ID	The identifier (name) of the new symbol.
type	The data type of the variable associated to the symbol.
arraySize	For arrays, the size of the array.

Returns: A pointer to the newly created symbol object.

Definition at line 406 of file program.c.

◆ deleteProgram()

void deleteProgram ( t_program * program )

Delete a program object.

Parameters

program The program object to delete.

Definition at line 162 of file program.c.

◆ genEpilog()

void genEpilog ( t_program * program )

Generates the final instruction sequence required at the end of a program.

Parameters

program The program to be modified.

Definition at line 475 of file program.c.

◆ genInstruction()

t_instruction * genInstruction	(	t_program *	program,
		int	opcode,
		t_regID	rd,
		t_regID	rs1,
		t_regID	rs2,
		t_label *	label,
		int	immediate )

Add a new instruction at the end the current program's list of instructions.

Parameters

program	The program where to add the instruction.
opcode	Identifier for the operation performed by the instruction.
rd	Identifier of the destination register argument, or REG_INVALID if none.
rs1	Identifier of the first source register argument, or REG_INVALID if none.
rs2	Identifier of the second source register argument, or REG_INVALID if none.
label	Label object representing the label argument, or NULL if none.
immediate	Immediate argument to the instruction, if needed.

Returns: the instruction object added to the instruction list.

Warning: This is a low-level primitive for generating instructions. This function is not aware of the semantic meaning of each operation code, and performs no parameter checking. As a result using this function directly may result in the generation of invalid instructions. Use the helper functions in codegen.h instead for generating instructions.

Definition at line 338 of file program.c.

◆ getLabelName()

char * getLabelName ( t_label * label )

Obtain the name of a given label.

Parameters

label The label.

Returns: A dynamically allocated string. The caller owns the string and is responsible for freeing it.

Definition at line 297 of file program.c.

◆ getNewRegister()

t_regID getNewRegister ( t_program * program )

Obtain a currently unused temporary register identifier.

Parameters

program The program where the register will be used.

Returns: The identifier of the register.

Definition at line 398 of file program.c.

◆ getSymbol()

t_symbol * getSymbol	(	t_program *	program,
		char *	ID )

Lookup a previously added symbol.

Parameters

program	The program where the symbol belongs.
ID	The identifier of the symbol.

Returns: A pointer to the corresponding symbol object, or NULL if the symbol has not been declared yet.

Definition at line 461 of file program.c.

◆ isArray()

bool isArray ( t_symbol * symbol )

Checks if the type of the given symbol is an array type.

Parameters

symbol The symbol object.

Returns: ‘true’ if the type of the symbol is a kind of array, otherwise returns ‘false’.

Definition at line 445 of file program.c.

◆ newProgram()

t_program * newProgram ( void )

Create a new empty program object.

Definition at line 141 of file program.c.

◆ programDump()

void programDump	(	t_program *	program,
		FILE *	fout )

Dumps the current state of a program object to the specified file.

Parameters

program	The program which will be dumped.
fout	The file where to print the dump.

Definition at line 493 of file program.c.

◆ removeInstructionAt()

void removeInstructionAt	(	t_program *	program,
		t_listNode *	instrLi )

Remove an instruction from the program, given its node in the instruction list.

Parameters

program	The program where to remove the instruction.
instrLi	Node in the instruction list to remove.

Definition at line 361 of file program.c.

◆ setLabelName()

void setLabelName	(	t_program *	program,
		t_label *	label,
		const char *	name )

Sets the name of a label to the specified string.

Parameters

program	The program where the label belongs.
label	The label whose name to set.
name	The string which will be used as label name.

Note: If another label with the same name already exists, the name assigned to this label will be modified to remove any ambiguity.

Definition at line 205 of file program.c.

Data Structures

Macros

Typedefs

Enumerations

Construction/destruction of a program

Handling of labels

Generation of instructions

Handling of symbols

Utility functions

Detailed Description

Data Structure Documentation

◆ t_label

◆ t_instrArg

◆ t_instruction

◆ t_symbol

◆ t_program

Macro Definition Documentation

◆ REG_0

◆ REG_INVALID

Typedef Documentation

◆ t_regID

Enumeration Type Documentation

◆ t_symbolType

Function Documentation

◆ assignLabel()

◆ createLabel()

◆ createSymbol()

◆ deleteProgram()

◆ genEpilog()

◆ genInstruction()

◆ getLabelName()

◆ getNewRegister()

◆ getSymbol()

◆ isArray()

◆ newProgram()

◆ programDump()

◆ removeInstructionAt()

◆ setLabelName()