/*
* This file is part of libFirm.
* Copyright (C) 2014 Karlsruhe Institute of Technology
*/
/**
* @file
* @brief Some machine dependent optimizations.
* @author Sebastian Hack
*/
#ifndef FIRM_IR_IRARCH_H
#define FIRM_IR_IRARCH_H
#include "firm_types.h"
#include
/**
* The Multiplication replacement can consist of the following instructions.
*/
typedef enum insn_kind {
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 */
} insn_kind;
/**
* A Callback for evaluating the costs of an instruction.
*
* @param kind the instruction
* @param mode the mode of the instruction
* @param tv for MUL instruction, the multiplication constant
*
* @return the costs of this instruction
*/
typedef int (*evaluate_costs_func)(insn_kind kind, const ir_mode *mode, ir_tarval *tv);
/**
* A parameter structure that drives the machine dependent Firm
* optimizations.
*/
typedef struct ir_settings_arch_dep_t {
bool replace_muls : 1;
bool replace_divs : 1;
bool replace_mods : 1;
bool allow_mulhs : 1; /**< Use Mulhs for division by constant */
bool allow_mulhu : 1; /**< Use Mulhu for division by constant */
bool also_use_subs : 1; /**< Use Subs when resolving Muls to shifts */
unsigned maximum_shifts; /**< The maximum number of shifts that shall be inserted for a mul. */
unsigned highest_shift_amount; /**< The highest shift amount you want to
tolerate. Muls which would require a higher
shift constant are left. */
evaluate_costs_func evaluate; /**< Evaluate the costs of a generated instruction. */
/* Div/Mod optimization */
unsigned max_bits_for_mulh; /**< Maximum number of bits the Mulh operation can take.
Modes with higher amount of bits will use Mulh */
} ir_settings_arch_dep_t;
/**
* Replaces Muls with Lea/Shifts/Add/Subs if these
* have smaller costs than the original multiplication.
*
* @param irn The Firm node to inspect.
* @return A replacement expression for irn.
*/
ir_node *arch_dep_replace_mul_with_shifts(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.
*
* @param irn The Firm node to inspect.
* @return A replacement expression for irn.
*/
ir_node *arch_dep_replace_div_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.
*
* @param irn The Firm node to inspect.
* @return A replacement expression for irn.
*/
ir_node *arch_dep_replace_mod_by_const(ir_node *irn);
/**
* Initialize machine dependent mul/div/mod with constant localopts and
* run optimize_graph_df() once to do the replacements.
*/
void ir_arch_lower(ir_settings_arch_dep_t const *settings);
#endif