libfirm/irarch.h File Reference

Some machine dependent optimizations. More...

#include "firm_types.h"
#include "begin.h"
#include "end.h"

Go to the source code of this file.

Data Structures
struct	ir_settings_arch_dep_t
	A parameter structure that drives the machine dependent Firm optimizations. More...
Typedefs
typedef int(*	evaluate_costs_func )(insn_kind kind, const ir_mode *mode, ir_tarval *tv)
	A Callback for evaluating the costs of an instruction.
typedef const ir_settings_arch_dep_t *(*	arch_dep_params_factory_t )(void)
	A factory function, that provides architecture parameters for machine dependent optimizations.
Enumerations
enum	insn_kind {   LEA, SHIFT, SUB, ADD,   ZERO, MUL, ROOT }
	The Multiplication replacement can consist of the following instructions. More...
enum	arch_dep_opts_t { arch_dep_none = 0, arch_dep_mul_to_shift = 1, arch_dep_div_by_const = 2, arch_dep_mod_by_const = 4 }
	Optimization flags. More...
Functions
void	arch_dep_set_opts (arch_dep_opts_t opts)
	Sets the optimizations that shall be applied.
ir_node *	arch_dep_replace_mul_with_shifts (ir_node *irn)
	Replaces Muls with Lea/Shifts/Add/Subs if these have smaller costs than the original multiplication.
ir_node *	arch_dep_replace_div_by_const (ir_node *irn)
	Replaces Divs with Shifts and Add/Subs and Mulh.
ir_node *	arch_dep_replace_mod_by_const (ir_node *irn)
	Replaces Mods with Shifts and Add/Subs and Mulh.

---

Detailed Description

Some machine dependent optimizations.

Date:

1.10.2004

Author:

Sebastian Hack

Definition in file irarch.h.

---

Typedef Documentation

typedef const ir_settings_arch_dep_t*(* arch_dep_params_factory_t)(void)

A factory function, that provides architecture parameters for machine dependent optimizations.

Definition at line 80 of file irarch.h.

typedef int(* evaluate_costs_func)(insn_kind kind, const ir_mode *mode, ir_tarval *tv)

A Callback for evaluating the costs of an instruction.

Parameters:

kind	the instruction
mode	the mode of the instruction
tv	for MUL instruction, the multiplication constant

Returns:

the costs of this instruction

Definition at line 54 of file irarch.h.

---

Enumeration Type Documentation

enum arch_dep_opts_t

Optimization flags.

Enumerator:

arch_dep_mul_to_shift	optimize Mul into Shift/Add/Sub
arch_dep_div_by_const	optimize Div into Shift/Add/Mulh
arch_dep_mod_by_const	optimize Mod into Shift/Add/Mulh

Definition at line 85 of file irarch.h.

enum insn_kind

The Multiplication replacement can consist of the following instructions.

Enumerator:

LEA	the LEA instruction
SHIFT	the SHIFT instruction
SUB	the SUB instruction
ADD	the ADD instruction
ZERO	creates a ZERO constant
MUL	the original MUL instruction
ROOT	the ROOT value that is multiplied

Definition at line 35 of file irarch.h.

---

Function Documentation

ir_node* arch_dep_replace_div_by_const

(

ir_node *

irn

)

Replaces Divs with Shifts and Add/Subs and Mulh.

This function is driven by the 3 parameters:

• allow_mulhu
• allow_mulhs
• max_bits_for_mulh

If irn is a Div with a Const, the constant is inspected if it meets the requirements of the variables stated above. If a Shl/Add/Sub/Mulh sequence can be generated that meets these requirements, this expression is returned. In each other case irn is returned unmodified.

Parameters:

irn	The Firm node to inspect.

Returns:

A replacement expression for irn.

ir_node* arch_dep_replace_mod_by_const

(

ir_node *

irn

)

Replaces Mods with Shifts and Add/Subs and Mulh.

This function is driven by the 3 parameters:

• allow_mulhu
• allow_mulhs
• max_bits_for_mulh

If irn is a Mod with a Const, the constant is inspected if it meets the requirements of the variables stated above. If a Shl/Add/Sub/Mulh sequence can be generated that meets these requirements, this expression is returned. In each other case irn is returned unmodified.

Parameters:

irn	The Firm node to inspect.

Returns:

A replacement expression for irn.

ir_node* arch_dep_replace_mul_with_shifts

(

ir_node *

irn

)

Replaces Muls with Lea/Shifts/Add/Subs if these have smaller costs than the original multiplication.

Parameters:

irn	The Firm node to inspect.

Returns:

A replacement expression for irn.

void arch_dep_set_opts

(

arch_dep_opts_t

opts

)

Sets the optimizations that shall be applied.

Parameters:

opts	An optimization bit mask.