prog_optimize.c File Reference

#include "main/glheader.h"
#include "main/context.h"
#include "main/macros.h"
#include "program.h"
#include "prog_instruction.h"
#include "prog_optimize.h"
#include "prog_print.h"

Data Structures
struct	interval
	A live register interval. More...
struct	interval_list
	A list of register intervals. More...
Defines
#define	MAX_LOOP_NESTING   50
Enumerations
enum	temp_use { READ, WRITE, FLOW, END }
Functions
static GLuint	remove_instructions (struct gl_program *prog, const GLboolean *removeFlags)
	In 'prog' remove instruction[i] if removeFlags[i] == TRUE.
static void	replace_regs (struct gl_program *prog, gl_register_file file, const GLint map[])
	Remap register indexes according to map.
static void	_mesa_consolidate_registers (struct gl_program *prog)
	Consolidate temporary registers to use low numbers.
static void	_mesa_remove_dead_code (struct gl_program *prog)
	Remove dead instructions from the given program.
static enum temp_use	find_next_temp_use (const struct gl_program *prog, GLuint start, GLuint index)
	Scan forward in program from 'start' for the next occurance of TEMP[index].
static void	_mesa_remove_extra_moves (struct gl_program *prog)
	Try to remove extraneous MOV instructions from the given program.
static void	append_interval (struct interval_list *list, const struct interval *inv)
static void	insert_interval_by_end (struct interval_list *list, const struct interval *inv)
	Insert interval inv into list, sorted by interval end.
static void	remove_interval (struct interval_list *list, const struct interval *inv)
	Remove the given interval from the interval list.
static int	compare_start (const void *a, const void *b)
	called by qsort()
static void	sort_interval_list_by_start (struct interval_list *list)
	sort the interval list according to interval starts
static void	update_interval (GLint intBegin[], GLint intEnd[], GLuint index, GLuint ic)
	Update the intermediate interval info for register 'index' and instruction 'ic'.
GLboolean	_mesa_find_temp_intervals (const struct prog_instruction *instructions, GLuint numInstructions, GLint intBegin[MAX_PROGRAM_TEMPS], GLint intEnd[MAX_PROGRAM_TEMPS])
	Find first/last instruction that references each temporary register.
static GLboolean	find_live_intervals (struct gl_program *prog, struct interval_list *liveIntervals)
	Find the live intervals for each temporary register in the program.
static GLint	alloc_register (GLboolean usedRegs[MAX_PROGRAM_TEMPS])
	Scan the array of used register flags to find free entry.
static void	_mesa_reallocate_registers (struct gl_program *prog)
	This function implements "Linear Scan Register Allocation" to reduce the number of temporary registers used by the program.
void	_mesa_optimize_program (GLcontext *ctx, struct gl_program *program)
	Apply optimizations to the given program to eliminate unnecessary instructions, temp regs, etc.
Variables
static GLboolean	dbg = GL_FALSE

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Define Documentation

#define MAX_LOOP_NESTING   50

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Enumeration Type Documentation

enum temp_use

Enumerator:

READ
WRITE
FLOW
END

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Function Documentation

static void _mesa_consolidate_registers

(

struct gl_program *

prog

)

[static]

Consolidate temporary registers to use low numbers.

For example, if the shader only uses temps 4, 5, 8, replace them with 0, 1, 2.

GLboolean _mesa_find_temp_intervals	(	const struct prog_instruction *	instructions,
		GLuint	numInstructions,
		GLint	intBegin[MAX_PROGRAM_TEMPS],
		GLint	intEnd[MAX_PROGRAM_TEMPS]
	)

Find first/last instruction that references each temporary register.

< Start, end instructions of loop

void _mesa_optimize_program	(	GLcontext *	ctx,
		struct gl_program *	program
	)

Apply optimizations to the given program to eliminate unnecessary instructions, temp regs, etc.

static void _mesa_reallocate_registers

(

struct gl_program *

prog

)

[static]

This function implements "Linear Scan Register Allocation" to reduce the number of temporary registers used by the program.

We compute the "live interval" for all temporary registers then examine the overlap of the intervals to allocate new registers. Basically, if two intervals do not overlap, they can use the same register.

static void _mesa_remove_dead_code

(

struct gl_program *

prog

)

[static]

Remove dead instructions from the given program.

This is very primitive for now. Basically look for temp registers that are written to but never read. Remove any instructions that write to such registers. Be careful with condition code setters.

static void _mesa_remove_extra_moves

(

struct gl_program *

prog

)

[static]

Try to remove extraneous MOV instructions from the given program.

static GLint alloc_register

(

GLboolean

usedRegs[MAX_PROGRAM_TEMPS]

)

[static]

Scan the array of used register flags to find free entry.

static void append_interval	(	struct interval_list *	list,
		const struct interval *	inv
	)			[static]

static int compare_start	(	const void *	a,
		const void *	b
	)			[static]

called by qsort()

static GLboolean find_live_intervals	(	struct gl_program *	prog,
		struct interval_list *	liveIntervals
	)			[static]

Find the live intervals for each temporary register in the program.

For register R, the interval [A,B] indicates that R is referenced from instruction A through instruction B. Special consideration is needed for loops and subroutines.

Returns:

GL_TRUE if success, GL_FALSE if we cannot proceed for some reason

static enum temp_use find_next_temp_use	(	const struct gl_program *	prog,
		GLuint	start,
		GLuint	index
	)			[static]

Scan forward in program from 'start' for the next occurance of TEMP[index].

Return READ, WRITE, FLOW or END to indicate the next usage or an indicator that we can't look further.

static void insert_interval_by_end	(	struct interval_list *	list,
		const struct interval *	inv
	)			[static]

Insert interval inv into list, sorted by interval end.

static GLuint remove_instructions	(	struct gl_program *	prog,
		const GLboolean *	removeFlags
	)			[static]

In 'prog' remove instruction[i] if removeFlags[i] == TRUE.

Returns:

number of instructions removed

static void remove_interval	(	struct interval_list *	list,
		const struct interval *	inv
	)			[static]

Remove the given interval from the interval list.

static void replace_regs	(	struct gl_program *	prog,
		gl_register_file	file,
		const GLint	map[]
	)			[static]

Remap register indexes according to map.

Parameters:

	prog	the program to search/replace
	file	the type of register file to search/replace
	map	maps old register indexes to new indexes

static void sort_interval_list_by_start

(

struct interval_list *

list

)

[static]

sort the interval list according to interval starts

static void update_interval	(	GLint	intBegin[],
		GLint	intEnd[],
		GLuint	index,
		GLuint	ic
	)			[static]

Update the intermediate interval info for register 'index' and instruction 'ic'.

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Variable Documentation

GLboolean dbg = GL_FALSE [static]

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