Commit 371e0a7b authored by Sebastian Hack's avatar Sebastian Hack
Browse files

Added architecture dependent optimizations framework.

A first optimization, replacing muls by shl/add/sub is already present

[r4025]
parent ce1a7aa2
......@@ -17,7 +17,7 @@ subdir := ir/ir
INSTALL_HEADERS = irprog.h irgraph.h irnode.h irmode.h irop.h ircons.h \
irflag.h irvrfy.h irgwalk.h irgmod.h iropt.h irdump.h \
irgopt.h ircgcons.h ircgopt.h irreflect.h
irgopt.h ircgcons.h ircgopt.h irreflect.h irarch.h
SOURCES = $(INSTALL_HEADERS)
......@@ -25,7 +25,7 @@ SOURCES += Makefile.in \
ircons.c ircons_t.h irgmod.c irgraph_t.h irnode.c iropt.c iropt_t.h irvrfy.c \
irgwalk.c irgwalk_blk.c irdump.c irdumptxt.c irgopt.c irnode_t.h \
irmode.c irop.c irprog.c irflag.c irflag_t.h irgraph.c \
irmode_t.h irop_t.h irprog_t.h ircgcons.c ircgopt.c irreflect.c
irmode_t.h irop_t.h irprog_t.h ircgcons.c ircgopt.c irreflect.c irarch.c
include $(topdir)/MakeRules
......
/**
* @file irarch.c
* @date 28.9.2004
* @author Sebastian Hack
* @brief Machine dependent firm optimizations.
*
* $Id$
*/
#include <stdlib.h>
#include <assert.h>
#include "irnode_t.h"
#include "irgraph_t.h"
#include "irmode_t.h"
#include "iropt_t.h"
#include "ircons_t.h"
#include "irgmod.h"
#include "irvrfy.h"
#include "tv.h"
#include "dbginfo_t.h"
#include "iropt_dbg.h"
#include "irflag_t.h"
#include "firmstat.h"
#include "ircons.h"
#include "irarch.h"
#undef DEB
#define MAX_BITSTR 64
/** The params got from the factopry in arch_dep_init(...). */
static const arch_dep_params_t *params = NULL;
/** The bit mask, which optimizations to apply. */
static arch_dep_opts_t opts;
void arch_dep_init(arch_dep_params_factory_t factory)
{
opts = arch_dep_none;
if(factory != NULL)
params = factory();
}
void arch_dep_set_opts(arch_dep_opts_t the_opts) {
opts = the_opts;
}
ir_node *arch_dep_replace_mul_with_shifts(ir_node *irn)
{
ir_node *res = irn;
ir_node *operand = NULL;
ir_node *left, *right;
ir_mode *mode = get_irn_mode(irn);
tarval *tv = NULL;
/* If the architecture dependent optimizations were not initialized
or this optimization was not enabled. */
if(params == NULL || (opts & arch_dep_mul_to_shift) == 0)
return irn;
if(is_ir_node(irn)
&& get_irn_opcode(irn) == iro_Mul
&& mode_is_int(mode)) {
left = get_binop_left(irn);
right = get_binop_right(irn);
/* Look, if one operand is a constant. */
if(get_irn_opcode(left) == iro_Const) {
tv = get_Const_tarval(left);
operand = right;
} else if(get_irn_opcode(right) == iro_Const) {
tv = get_Const_tarval(right);
operand = left;
}
if(tv != NULL) {
int maximum_shifts = params->maximum_shifts;
int also_use_subs = params->also_use_subs;
int highest_shift_amount = params->highest_shift_amount;
char *bitstr = get_tarval_bitpattern(tv);
char *p;
int i, last = 0;
int counter = 0;
int curr_bit;
int compr_len = 0;
char compr[MAX_BITSTR];
int singleton;
int end_of_group;
int shift_with_sub[MAX_BITSTR] = { 0 };
int shift_without_sub[MAX_BITSTR] = { 0 };
int shift_with_sub_pos = 0;
int shift_without_sub_pos = 0;
#if DEB
{
int val = (int) get_tarval_long(tv);
fprintf(stderr, "Found mul with %d(%x) = ", val, val);
for(p = bitstr; *p != '\0'; p++)
printf("%c", *p);
printf("\n");
}
#endif
for(p = bitstr; *p != '\0'; p++) {
int bit = *p != '0';
switch(bit - last) {
case -1: // The last was 1 we are now at 0
case 1: // The last was 0 and we are now at 1
compr[compr_len++] = counter;
counter = 1;
break;
default:
counter++;
}
last = bit;
}
compr[compr_len++] = counter;
#ifdef DEF
{
const char *prefix = "";
for(i = 0; i < compr_len; i++, prefix = ",")
fprintf(stderr, "%s%d", prefix, compr[i]);
fprintf("\n");
}
#endif
// Go over all recorded one groups.
curr_bit = compr[0];
for(i = 1; i < compr_len; i = end_of_group + 2) {
int j, zeros_in_group, ones_in_group;
ones_in_group = compr[i];
zeros_in_group = 0;
// Scan for singular 0s in a sequence
for(j = i + 1; j < compr_len && compr[j] == 1; j += 2) {
zeros_in_group += 1;
ones_in_group += (j + 1 < compr_len ? compr[j + 1] : 0);
}
end_of_group = j - 1;
if(zeros_in_group >= ones_in_group - 1)
end_of_group = i;
#ifdef DEB
fprintf(stderr, " i:%d, eg:%d\n", i, end_of_group);
#endif
singleton = compr[i] == 1 && i == end_of_group;
for(j = i; j <= end_of_group; j += 2) {
int curr_ones = compr[j];
int biased_curr_bit = curr_bit + 1;
int k;
#ifdef DEB
fprintf(stderr, " j:%d, ones:%d\n", j, curr_ones);
#endif
// If this ones group is a singleton group (it has no
// singleton zeros inside
if(singleton)
shift_with_sub[shift_with_sub_pos++] = biased_curr_bit;
else if(j == i)
shift_with_sub[shift_with_sub_pos++] = -biased_curr_bit;
for(k = 0; k < curr_ones; k++)
shift_without_sub[shift_without_sub_pos++] = biased_curr_bit + k;
curr_bit += curr_ones;
biased_curr_bit = curr_bit + 1;
if(!singleton && j == end_of_group)
shift_with_sub[shift_with_sub_pos++] = biased_curr_bit;
else if(j != end_of_group)
shift_with_sub[shift_with_sub_pos++] = -biased_curr_bit;
curr_bit += compr[j + 1];
}
}
{
int *shifts = shift_with_sub;
int n = shift_with_sub_pos;
int highest_shift_wide = 0;
int highest_shift_seq = 0;
int last_shift = 0;
/* If we may not use subs, or we can achive the same with adds,
prefer adds. */
if(!also_use_subs || shift_with_sub_pos >= shift_without_sub_pos) {
shifts = shift_without_sub;
n = shift_without_sub_pos;
}
/* If the number of needed shifts exceeds the given maximum,
use the Mul and exit. */
if(n > maximum_shifts) {
#ifdef DEB
fprintf(stderr, "Only allowed %d shifts, but %d are needed\n",
maximum_shifts, n);
#endif
return irn;
}
/* Compute the highest shift needed for both, the
sequential and wide representations. */
for(i = 0; i < n; i++) {
int curr = abs(shifts[i]);
int curr_seq = curr - last;
highest_shift_wide = curr > highest_shift_wide ? curr
: highest_shift_wide;
highest_shift_seq = curr_seq > highest_shift_seq ? curr_seq
: highest_shift_seq;
last_shift = curr;
}
/* If the highest shift amount is greater than the given limit,
give back the Mul */
if(highest_shift_seq > highest_shift_amount) {
#ifdef DEB
fprintf(stderr, "Shift argument %d exceeds maximum %d\n",
highest_shift_seq, highest_shift_amount);
#endif
return irn;
}
/* If we have subs, we cannot do sequential. */
if(1 /* also_use_subs */) {
if(n > 0) {
ir_node *curr = NULL;
i = n - 1;
do {
int curr_shift = shifts[i];
int sub = curr_shift < 0;
int amount = abs(curr_shift) - 1;
ir_node *aux = operand;
assert(amount >= 0 && "What is a negative shift??");
if(amount != 0) {
tarval *shift_amount = new_tarval_from_long(amount, mode_Iu);
ir_node *cnst = new_Const(mode_Iu, shift_amount);
aux = new_Shl(operand, cnst, mode);
}
if(curr) {
if(sub)
curr = new_Sub(curr, aux, mode);
else
curr = new_Add(curr, aux, mode);
} else
curr = aux;
} while(--i >= 0);
res = curr;
}
}
#ifdef DEB
{
const char *prefix = "";
for(i = 0; i < n; i++) {
fprintf(stderr, "%s%d", prefix, shifts[i]);
prefix = ", ";
}
fprintf(stderr, "\n");
}
#endif
}
if(bitstr)
free(bitstr);
}
}
return res;
}
static const arch_dep_params_t default_params = {
1, /* also use subs */
4, /* maximum shifts */
31 /* maximum shift amount */
};
const arch_dep_params_t *arch_dep_default_factory(void) {
return &default_params;
}
/**
* @file irarch.h
* @date 1.10.2004
* @author Sebastian Hack
* @brief Some machine dependent optimizations.
*
* $Id$
*/
#ifndef __FIRM_IRARCH_H
#define __FIRM_IRARCH_H
#include "irnode.h"
/**
* A parameter structure that drives the machine dependent Firm
* optimizations.
*/
typedef struct {
int also_use_subs : 1; /**< Use also Subs when resolving muls to shifts */
int maximum_shifts; /**< The maximum number of shifts that shall be
inserted for a mul. */
int highest_shift_amount; /**< The highest shift amount you want to
tolerate. Muls which would require a higher
shift constant are left. */
} arch_dep_params_t;
/**
* A factory function, that provides architecture parameters for
* machine dependent optimizations.
*/
typedef const arch_dep_params_t *(*arch_dep_params_factory_t)(void);
/**
* A default parameter factory for testing purposes.
*/
const arch_dep_params_t *arch_dep_default_factory(void);
/**
* Optimization flags.
*/
typedef enum {
arch_dep_none = 0,
arch_dep_mul_to_shift = 1
} arch_dep_opts_t;
/**
* Initialize the machine dependent optimizations.
* @param factory A factory that delivers parameters for these
* optimizations. If NULL is passed, or this method
* is not called, the machine dependent optimizations
* are not enabled at all.
*/
void arch_dep_init(arch_dep_params_factory_t factory);
/**
* Set the optimizations that shall be applied.
* @param opts An optimization bit mask.
*/
void arch_dep_set_opts(arch_dep_opts_t opts);
/**
* Replace Muls with Shifts and Add/Subs.
* This function is driven by the 3 parameters:
* - also_use_subs
* - maximum_shifts
* - highest_shift_amount
*
* If irn is a Mul with a Const, The constant is inspected, if it meets the
* requirements of the three variables stated above. If a Shl/Add/Sub
* 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_mul_with_shifts(ir_node *irn);
#endif
......@@ -26,6 +26,7 @@
# include "iropt_dbg.h"
# include "irflag_t.h"
# include "firmstat.h"
# include "irarch.h"
/* Make types visible to allow most efficient access */
# include "entity_t.h"
......@@ -1046,6 +1047,11 @@ optimize_preds(ir_node *n) {
} /* end switch */
}
static ir_node *transform_node_Mul(ir_node *n)
{
return arch_dep_replace_mul_with_shifts(n);
}
static ir_node *transform_node_Div(ir_node *n)
{
tarval *tv = computed_value(n);
......@@ -1450,6 +1456,7 @@ static ir_op *firm_set_default_transform_node(ir_op *op)
break
switch (op->code) {
CASE(Mul);
CASE(Div);
CASE(Mod);
CASE(DivMod);
......
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