quakeforge/tools/qfcc/source/dags.c
Bill Currie 2bb1a0a76e [qfcc] Search for alias nodes
This doesn't affect the generated code (aliases are free), but does
simplify the dag significantly, thus optimizing the compiler somewhat,
but also makes reading dags much easier and therefore optimizing the
debugging process.
2023-09-02 10:43:32 +09:00

1484 lines
38 KiB
C

/*
dags.c
DAG representation of basic blocks
Copyright (C) 2012 Bill Currie <bill@taniwha.org>
Author: Bill Currie <bill@taniwha.org>
Date: 2012/05/08
This program is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License
as published by the Free Software Foundation; either version 2
of the License, or (at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
See the GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to:
Free Software Foundation, Inc.
59 Temple Place - Suite 330
Boston, MA 02111-1307, USA
*/
#ifdef HAVE_CONFIG_H
# include "config.h"
#endif
#ifdef HAVE_STRING_H
# include <string.h>
#endif
#ifdef HAVE_STRINGS_H
# include <strings.h>
#endif
#include <stdlib.h>
#include <ctype.h>
#include "qfalloca.h"
#include "QF/alloc.h"
#include "QF/dstring.h"
#include "QF/mathlib.h"
#include "QF/set.h"
#include "tools/qfcc/include/dags.h"
#include "tools/qfcc/include/diagnostic.h"
#include "tools/qfcc/include/dot.h"
#include "tools/qfcc/include/flow.h"
#include "tools/qfcc/include/function.h"
#include "tools/qfcc/include/options.h"
#include "tools/qfcc/include/qfcc.h"
#include "tools/qfcc/include/statements.h"
#include "tools/qfcc/include/strpool.h"
#include "tools/qfcc/include/symtab.h"
#include "tools/qfcc/include/type.h"
#include "tools/qfcc/include/value.h"
ALLOC_STATE (daglabel_t, labels);
ALLOC_STATE (dagnode_t, nodes);
ALLOC_STATE (dag_t, dags);
static daglabel_t *daglabel_chain;
static void dagnode_set_edges (dag_t *dag, dagnode_t *n, statement_t *s);
static void dag_live_aliases(operand_t *op);
static int
op_is_identifier (operand_t *op)
{
if (!op)
return 0;
if (op->op_type == op_label)
return 0;
if (op->op_type == op_value)
return 0;
if (op->op_type == op_temp)
return 1;
if (op->op_type != op_def)
return 0;
return 1;
}
static int
op_is_constant (operand_t *op)
{
if (!op)
return 0;
if (op->op_type == op_label)
return 1;
if (op->op_type == op_value)
return 1;
if (op->op_type == op_label)
return op->def->constant;
return 0;
}
static int
op_is_temp (operand_t *op)
{
if (!op)
return 0;
return op->op_type == op_temp;
}
static int
op_is_alias (operand_t *op)
{
if (!op) {
return 0;
}
if (op->op_type == op_temp) {
return !!op->tempop.alias;
}
if (op->op_type == op_def) {
return !!op->def->alias;
}
return 0;
}
static int __attribute__((pure))
op_alias_offset (operand_t *op)
{
if (!op_is_alias (op)) {
internal_error (op->expr, "not an alias op");
}
if (op->op_type == op_temp) {
return op->tempop.offset;
}
internal_error (op->expr, "eh? how?");
}
static operand_t * __attribute__((pure))
unalias_op (operand_t *op)
{
if (!op_is_alias (op)) {
internal_error (op->expr, "not an alias op");
}
if (op->op_type == op_temp) {
return op->tempop.alias;
}
if (op->op_type == op_def) {
// XXX FIXME needed?
return op;
}
internal_error (op->expr, "eh? how?");
}
static void
flush_daglabels (void)
{
while (daglabel_chain) {
operand_t *op;
if ((op = daglabel_chain->op)) {
if (op->op_type == op_def)
op->def->daglabel = 0;
else if (op->op_type == op_temp)
op->tempop.daglabel = 0;
else if (op->op_type == op_value)
op->value->daglabel = 0;
else if (op->op_type == op_label)
op->label->daglabel = 0;
else
internal_error (op->expr, "unexpected operand type");
}
daglabel_chain = daglabel_chain->daglabel_chain;
}
}
static dag_t *
new_dag (void)
{
dag_t *dag;
ALLOC (256, dag_t, dags, dag);
return dag;
}
static daglabel_t *
new_label (dag_t *dag)
{
daglabel_t *label;
ALLOC (256, daglabel_t, labels, label);
label->daglabel_chain = daglabel_chain;
daglabel_chain = label;
label->number = dag->num_labels;
dag->labels[dag->num_labels++] = label;
return label;
}
static dagnode_t *
new_node (dag_t *dag)
{
dagnode_t *node;
ALLOC (256, dagnode_t, nodes, node);
node->parents = set_new ();
node->edges = set_new ();
node->identifiers = set_new ();
node->reachable = set_new ();
node->number = dag->num_nodes;
set_add (dag->roots, node->number); // nodes start out as root nodes
dag->nodes[dag->num_nodes++] = node;
return node;
}
const char *
daglabel_string (daglabel_t *label)
{
static dstring_t *str;
if ((label->opcode && label->op) || (!label->opcode && !label->op))
return "bad label";
if (label->opcode)
return label->opcode;
if (!str)
str = dstring_new ();
// operand_string might use quote_string, which returns a pointer to
// a static variable.
dstring_copystr (str, operand_string (label->op));
#if 0
if (label->op->type) {
dstring_appendstr (str, label->op->type->encoding);
}
#endif
return quote_string (str->str);
}
static daglabel_t *
opcode_label (dag_t *dag, const char *opcode, expr_t *expr)
{
daglabel_t *label;
label = new_label (dag);
label->opcode = opcode;
label->expr = expr;
return label;
}
static daglabel_t *
operand_label (dag_t *dag, operand_t *op)
{
def_t *def = 0;
ex_value_t *val = 0;
daglabel_t *label;
if (!op)
return 0;
if (op->op_type == op_temp) {
//while (op->tempop.alias)
// op = op->tempop.alias;
if (op->tempop.daglabel)
return op->tempop.daglabel;
label = new_label (dag);
label->op = op;
op->tempop.daglabel = label;
} else if (op->op_type == op_def) {
def = op->def;
if (def->daglabel)
return def->daglabel;
label = new_label (dag);
label->op = op;
def->daglabel = label;
} else if (op->op_type == op_value) {
val = op->value;
if (val->daglabel)
return val->daglabel;
label = new_label (dag);
label->op = op;
val->daglabel = label;
} else if (op->op_type == op_label) {
if (op->label->daglabel)
return op->label->daglabel;
label = new_label (dag);
label->op = op;
op->label->daglabel = label;
} else {
internal_error (op->expr, "unexpected operand type: %s", op_type_names[op->op_type]);
}
return label;
}
static dagnode_t *
leaf_node (dag_t *dag, operand_t *op, expr_t *expr)
{
daglabel_t *label;
dagnode_t *node;
if (!op)
return 0;
node = new_node (dag);
node->tl = op->type;
label = operand_label (dag, op);
label->dagnode = node;
label->expr = expr;
node->label = label;
return node;
}
static __attribute__((pure)) dagnode_t *
dag_node (operand_t *op)
{
def_t *def;
dagnode_t *node = 0;
if (!op)
return 0;
if (op->op_type == op_def) {
def = op->def;
if (def->daglabel)
node = def->daglabel->dagnode;
} else if (op->op_type == op_temp) {
if (op->tempop.daglabel)
node = op->tempop.daglabel->dagnode;
} else if (op->op_type == op_value) {
if (op->value->daglabel)
node = op->value->daglabel->dagnode;
} else if (op->op_type == op_label) {
if (op->label->daglabel)
node = op->label->daglabel->dagnode;
}
return node;
}
static int
dagnode_deref_match (const dagnode_t *n, const dagnode_t *search)
{
int i;
auto children = search->children;
for (i = 0; i < 2; i++) {
if (n->children[i] != children[i + 1])
return 0;
}
return 1;
}
static int
dagnode_match (const dagnode_t *n, const dagnode_t *search)
{
int i;
auto op = search->label;
if (n->killed)
return 0;
if (!strcmp (op->opcode, "load")
&& n->label->opcode && !strcmp (n->label->opcode, "store"))
return dagnode_deref_match (n, search);
if (n->label->opcode != op->opcode)
return 0;
for (i = 0; i < 3; i++) {
if (n->children[i] != search->children[i]) {
return 0;
}
if (n->type == st_alias) {
if (n->types[i] != search->types[i]) {
return 0;
}
if (n->offset != search->offset) {
return 0;
}
}
}
return 1;
}
static dagnode_t *
dagnode_search (dag_t *dag, const dagnode_t *search)
{
int i;
for (i = 0; i < dag->num_nodes; i++)
if (dagnode_match (dag->nodes[i], search))
return dag->nodes[i];
return 0;
}
static void
dag_make_leafs (dag_t *dag, statement_t *s, operand_t *operands[FLOW_OPERANDS])
{
int i;
flow_analyze_statement (s, 0, 0, 0, operands);
for (i = 1; i < FLOW_OPERANDS; i++) {
if (!dag_node (operands[i])) {
leaf_node (dag, operands[i], s->expr);
}
}
}
static void
dagnode_set_reachable (dag_t *dag, dagnode_t *node)
{
for (set_iter_t *edge_iter = set_first (node->edges); edge_iter;
edge_iter = set_next (edge_iter)) {
dagnode_t *r = dag->nodes[edge_iter->element];
// The other node is directly reachable
set_add (node->reachable, r->number);
// All nodes reachable by the other node are indirectly reachable
// from this node.
set_union (node->reachable, r->reachable);
}
}
static void
dag_make_children (dag_t *dag, statement_t *s,
operand_t *operands[FLOW_OPERANDS],
dagnode_t *children[3])
{
int i;
flow_analyze_statement (s, 0, 0, 0, operands);
for (i = 0; i < 3; i++) {
operand_t *op = operands[i + 1];
dagnode_t *node = dag_node (op);
dagnode_t *killer = 0;
if (node && (node->killed || s->type == st_address)) {
// If the node has been killed, then a new node is needed
// taking the address of a variable effectively kills the node it's
// attached to. FIXME should this be for only when the variable is
// in the attached identifiers list and is not the node's label?
killer = node->killed;
node = 0;
}
if (!node && op_is_alias (op)) {
operand_t *uop = unalias_op (op);
if (uop != op) {
if (!(node = dag_node (uop))) {
node = leaf_node (dag, uop, s->expr);
}
node->label->live = 1;
dagnode_t *n;
dagnode_t search = {
.type = st_alias,
.label = opcode_label (dag, save_string ("alias"), s->expr),
.children = { node },
.types = { op->type },
.offset = op_alias_offset (op),
};
if (!(n = dagnode_search (dag, &search))) {
n = new_node (dag);
n->type = st_alias;
n->label = search.label;
n->children[0] = node;
n->types[0] = op->type;
n->offset = search.offset;
set_remove (dag->roots, node->number);
set_add (node->parents, n->number);
dagnode_set_edges (dag, n, s);
dagnode_set_reachable (dag, n);
}
node = n;
}
}
if (!node) {
// No valid node found (either first reference to the value,
// or the value's node was killed).
node = leaf_node (dag, op, s->expr);
}
if (killer) {
// When an operand refers to a killed node, it must be
// evaluated AFTER the killing node has been evaluated.
set_add (node->edges, killer->number);
// If killer is set, then node is guaranteed to be a new node
// and thus does not have any parents, so no need to worry about
// updating the reachable sets of any parent nodes.
dagnode_set_reachable (dag, node);
}
children[i] = node;
}
}
static void
dagnode_add_children (dag_t *dag, dagnode_t *n, operand_t *operands[4],
dagnode_t *children[3])
{
int i;
for (i = 0; i < 3; i++) {
dagnode_t *child = children[i];
if ((n->children[i] = child)) {
n->types[i] = operands[i + 1]->type;
set_remove (dag->roots, child->number);
set_add (child->parents, n->number);
}
}
}
static int
dagnode_tempop_set_edges_visit (tempop_t *tempop, void *_node)
{
dagnode_t *node = (dagnode_t *) _node;
daglabel_t *label;
label = tempop->daglabel;
if (label && label->dagnode) {
set_add (node->edges, label->dagnode->number);
label->live = 1;
}
return 0;
}
static int
dagnode_def_set_edges_visit (def_t *def, void *_node)
{
dagnode_t *node = (dagnode_t *) _node;
daglabel_t *label;
label = def->daglabel;
if (label && label->dagnode) {
set_add (node->edges, label->dagnode->number);
label->live = 1;
}
return 0;
}
static int
dag_find_node (def_t *def, void *_daglabel)
{
daglabel_t **daglabel = (daglabel_t **) _daglabel;
if (def->daglabel && def->daglabel->dagnode) {
*daglabel = def->daglabel;
return def->daglabel->dagnode->number + 1; // ensure never 0
}
return 0;
}
static void
dagnode_set_edges (dag_t *dag, dagnode_t *n, statement_t *s)
{
int i;
for (i = 0; i < 3; i++) {
dagnode_t *child = n->children[i];
if (child && n != child)
set_add (n->edges, child->number);
}
if (n->type == st_flow)
return;
for (i = 0; i < 3; i++) {
dagnode_t *child = n->children[i];
if (child) {
if (child->label->op) {
dagnode_t *node = child->label->dagnode;
operand_t *op = child->label->op;
if (node != child && node != n) {
set_add (node->edges, n->number);
}
if (op->op_type == op_value
&& op->value->lltype == ev_ptr
&& op->value->v.pointer.def) {
def_visit_all (op->value->v.pointer.def, 1,
dagnode_def_set_edges_visit, n);
}
if (op->op_type == op_def
&& (op->def->alias || op->def->alias_defs)) {
def_visit_all (op->def, 1,
dagnode_def_set_edges_visit, n);
}
if (op->op_type == op_temp
&& (op->tempop.alias || op->tempop.alias_ops)) {
tempop_visit_all (&op->tempop, 1,
dagnode_tempop_set_edges_visit, n);
}
}
if (n != child)
set_add (n->edges, child->number);
}
}
for (operand_t *use = s->use; use; use = use->next) {
if (use->op_type == op_pseudo) {
continue;
}
daglabel_t *label = operand_label (dag, use);
label->live = 1;
dag_live_aliases (use);
set_add (n->edges, label->dagnode->number);
}
if (n->type == st_func) {
const char *num_params = 0;
int first_param = 0;
function_t *func = dag->flownode->graph->func;
flowvar_t **flowvars = func->vars;
if (!strcmp (n->label->opcode, "call")) {
// nothing to do
} else if (!strncmp (n->label->opcode, "rcall", 5)) {
num_params = n->label->opcode + 6;
first_param = 2;
} else if (!strncmp (n->label->opcode, "call", 4)) {
num_params = n->label->opcode + 5;
} else if (!strcmp (n->label->opcode, "return") && n->children[0]) {
daglabel_t *label = n->children[0]->label;
if (!label->op) {
set_iter_t *lab_i;
for (lab_i = set_first (n->children[0]->identifiers); lab_i;
lab_i = set_next (lab_i)) {
label = dag->labels[lab_i->element];
}
}
label->live = 1;
}
for (int i = 0; i < s->num_use; i++) {
udchain_t ud = func->ud_chains[s->first_use + i];
flowvar_t *var = func->vars[ud.var];
if (var->op->op_type == op_pseudo) {
continue;
}
daglabel_t *l = operand_label (dag, var->op);
if (l) {
l->live = 1;
}
}
// ensure all operations on global variables are completed before
// the st_func statement executes
for (set_iter_t *g = set_first (func->global_vars); g;
g = set_next (g)) {
flowvar_t *var = flowvars[g->element];
dagnode_t *gn = dag_node (var->op);
if (gn) {
set_add (n->edges, gn->number);
set_remove (gn->edges, n->number);
}
}
if (num_params && isdigit ((byte) *num_params)) {
for (i = first_param; i < *num_params - '0'; i++) {
flowvar_t *var = flowvars[i + 1];
def_t *param_def = var->op->def;
daglabel_t *daglabel;
int param_node;
// FIXME hopefully only the one alias :P
param_node = def_visit_all (param_def, 0, dag_find_node,
&daglabel);
if (!param_node) {
bug (n->label->expr, ".param_%d not set for %s", i,
n->label->opcode);
continue;
}
daglabel->live = 1;
set_add (n->edges, param_node - 1);
}
}
}
}
static int
dag_tempop_kill_aliases_visit (tempop_t *tempop, void *_l)
{
daglabel_t *l = (daglabel_t *) _l;
dagnode_t *node = l->dagnode;
daglabel_t *label;
if (tempop == &l->op->tempop)
return 0;
label = tempop->daglabel;
if (label && label->dagnode && !label->dagnode->killed) {
set_add (node->edges, label->dagnode->number);
set_remove (node->edges, node->number);
label->dagnode->killed = node;
}
return 0;
}
static int
dag_def_kill_aliases_visit (def_t *def, void *_l)
{
daglabel_t *l = (daglabel_t *) _l;
dagnode_t *node = l->dagnode;
daglabel_t *label;
if (def == l->op->def)
return 0;
label = def->daglabel;
if (label && label->dagnode && !label->dagnode->killed) {
set_add (node->edges, label->dagnode->number);
set_remove (node->edges, node->number);
label->dagnode->killed = node;
}
return 0;
}
static void
dag_kill_aliases (daglabel_t *l)
{
operand_t *op = l->op;
if (op->op_type == op_temp) {
if (op->tempop.alias || op->tempop.alias_ops) {
tempop_visit_all (&op->tempop, 1,
dag_tempop_kill_aliases_visit, l);
}
} else if (op->op_type == op_def) {
if (op->def->alias || op->def->alias_defs) {
def_visit_all (op->def, 1, dag_def_kill_aliases_visit, l);
}
} else {
internal_error (op->expr, "rvalue assignment?");
}
}
static int
dag_tempop_live_aliases (tempop_t *tempop, void *_t)
{
if (tempop != _t && tempop->daglabel)
tempop->daglabel->live = 1;
return 0;
}
static int
dag_def_live_aliases (def_t *def, void *_d)
{
if (def != _d && def->daglabel)
def->daglabel->live = 1;
return 0;
}
static void
dag_live_aliases(operand_t *op)
{
// FIXME it would be better to propogate the aliasing
if (op->op_type == op_temp
&& (op->tempop.alias || op->tempop.alias_ops)) {
tempop_visit_all (&op->tempop, 1, dag_tempop_live_aliases,
&op->tempop);
}
if (op->op_type == op_def
&& (op->def->alias || op->def->alias_defs)) {
def_visit_all (op->def, 1, dag_def_live_aliases, op->def);
}
}
static void
dag_make_var_live (set_t *live_vars, operand_t *op)
{
flowvar_t *var = 0;
if (op) {
dag_live_aliases (op);
var = flow_get_var (op);
}
if (var)
set_add (live_vars, var->number);
}
static int
dagnode_attach_label (dag_t *dag, dagnode_t *n, daglabel_t *l)
{
if (!l->op)
internal_error (0, "attempt to attach operator label to dagnode "
"identifiers");
if (!op_is_identifier (l->op))
internal_error (l->op->expr,
"attempt to attach non-identifer label to dagnode "
"identifiers");
if (l->dagnode) {
dagnode_t *node = l->dagnode;
set_remove (node->identifiers, l->number);
// If the target node (n) is reachable by the label's node or its
// parents, then attaching the label's node to the target node would
// cause the label's node to be written before it used.
set_t *reachable = set_new ();
set_assign (reachable, node->reachable);
for (set_iter_t *node_iter = set_first (node->parents); node_iter;
node_iter = set_next (node_iter)) {
dagnode_t *p = dag->nodes[node_iter->element];
set_union (reachable, p->reachable);
}
int is_reachable = set_is_member (reachable, n->number);
set_delete (reachable);
if (is_reachable) {
return 0;
}
// this assignment to the variable must come after any previous uses,
// which includes itself and its parents
set_add (n->edges, node->number);
set_union (n->edges, node->parents);
dagnode_set_reachable (dag, n);
}
l->live = 0; // remove live forcing on assignment
l->dagnode = n;
set_add (n->identifiers, l->number);
dag_kill_aliases (l);
if (n->label->op) {
dag_live_aliases (n->label->op);
}
return 1;
}
static int
dag_tempop_alias_live (tempop_t *tempop, void *_live_vars)
{
set_t *live_vars = (set_t *) _live_vars;
if (!tempop->flowvar)
return 0;
return set_is_member (live_vars, tempop->flowvar->number);
}
static int
dag_def_alias_live (def_t *def, void *_live_vars)
{
set_t *live_vars = (set_t *) _live_vars;
if (!def->flowvar)
return 0;
return set_is_member (live_vars, def->flowvar->number);
}
static void
dag_remove_dead_vars (dag_t *dag, set_t *live_vars)
{
int i;
for (i = 0; i < dag->num_labels; i++) {
daglabel_t *l = dag->labels[i];
flowvar_t *var;
if (!l->op || !l->dagnode)
continue;
if (l->live) // label forced live (probably via an alias)
continue;
var = flow_get_var (l->op);
if (!var)
continue;
if (set_is_member (dag->flownode->global_vars, var->number))
continue;
if (l->op->op_type == op_def
&& def_visit_all (l->op->def, 1, dag_def_alias_live, live_vars))
continue;
if (l->op->op_type == op_temp
&& tempop_visit_all (&l->op->tempop, 1, dag_tempop_alias_live,
live_vars))
continue;
if (!set_is_member (live_vars, var->number))
set_remove (l->dagnode->identifiers, l->number);
}
}
static void
dag_sort_visit (dag_t *dag, set_t *visited, int node_index, int *topo)
{
set_iter_t *node_iter;
dagnode_t *node;
if (set_is_member (visited, node_index))
return;
set_add (visited, node_index);
node = dag->nodes[node_index];
for (node_iter = set_first (node->edges); node_iter;
node_iter = set_next (node_iter))
dag_sort_visit (dag, visited, node_iter->element, topo);
node->topo = *topo;
dag->topo[(*topo)++] = node_index;
}
static void
dag_sort_nodes (dag_t *dag)
{
set_iter_t *root_iter;
set_t *visited = set_new ();
int topo = 0;
int *tmp_topo;
if (dag->topo)
free (dag->topo);
dag->topo = alloca (dag->num_nodes * sizeof (int));
for (root_iter = set_first (dag->roots); root_iter;
root_iter = set_next (root_iter))
dag_sort_visit (dag, visited, root_iter->element, &topo);
set_delete (visited);
tmp_topo = malloc (topo * sizeof (int));
memcpy (tmp_topo, dag->topo, topo * sizeof (int));
dag->topo = tmp_topo;
dag->num_topo = topo;
}
static void
dag_kill_nodes (dag_t *dag, dagnode_t *n)
{
int i;
dagnode_t *node;
for (i = 0; i < dag->num_nodes; i++) {
node = dag->nodes[i];
if (node->killed) {
//the node is already killed
continue;
}
if (node == n->children[1]) {
// assume the pointer does not point to itself. This should be
// reasonable because without casting, only a void pointer can
// point to itself (the required type is recursive).
continue;
}
if (op_is_constant (node->label->op)) {
// While constants in the Quake VM can be changed via a pointer,
// doing so would cause much more fun than a simple
// mis-optimization would, so consider them safe from pointer
// operations.
continue;
}
if (op_is_temp (node->label->op)) {
// Assume that the pointer cannot point to a temporary variable.
// This is reasonable as there is no programmer access to temps.
continue;
}
node->killed = n;
}
n->killed = 0;
}
dag_t *
dag_create (flownode_t *flownode)
{
dag_t *dag;
sblock_t *block = flownode->sblock;
statement_t *s;
dagnode_t **nodes;
daglabel_t **labels;
int num_statements = 0;
int num_use = 0;
int num_alias = 0;
int num_nodes;
int num_lables;
set_t *live_vars = set_new ();
flush_daglabels ();
// count the number of statements so the number of nodes and labels can be
// guessed
for (s = block->statements; s; s = s->next) {
num_statements++;
for (operand_t *use = s->use; use; use = use->next) {
if (use->op_type == op_pseudo) {
continue;
}
num_use++;
}
num_alias += op_is_alias (s->opa);
num_alias += op_is_alias (s->opb);
num_alias += op_is_alias (s->opc);
}
set_assign (live_vars, flownode->live_vars.out);
dag = new_dag ();
dag->flownode = flownode;
// at most FLOW_OPERANDS per statement + use + alias
num_nodes = num_statements * FLOW_OPERANDS + num_use + num_alias;
dag->nodes = alloca (num_nodes * sizeof (dagnode_t));
// at most FLOW_OPERANDS per statement, + return + params + use + alias
num_lables = num_statements * (FLOW_OPERANDS + 1 + 8) + num_use + num_alias;
dag->labels = alloca (num_lables * sizeof (daglabel_t));
dag->roots = set_new ();
// do a first pass to ensure all operands have an "x_0" leaf node
// prior do actual dag creation
for (s = block->statements; s; s = s->next) {
operand_t *operands[FLOW_OPERANDS];
dag_make_leafs (dag, s, operands);
// make sure any auxiliary operands are given nodes, too
for (operand_t *use = s->use; use; use = use->next) {
if (use->op_type == op_pseudo) {
continue;
}
if (!dag_node (use)) {
leaf_node (dag, use, s->expr);
}
}
}
// actual dag creation
for (s = block->statements; s; s = s->next) {
operand_t *operands[FLOW_OPERANDS];
dagnode_t *n = 0, *children[3] = {0, 0, 0};
daglabel_t *op, *lx;
int i;
dag_make_children (dag, s, operands, children);
if (s->type == st_flow || s->type == st_func) {
for (i = 0; i < 3; i++) {
if (children[i]) {
dag_make_var_live (live_vars, operands[i + 1]);
}
}
}
if (operands[4]) {
// a movep instruction knew what it was reading, so mark that
// as live
dag_make_var_live (live_vars, operands[4]);
}
op = opcode_label (dag, s->opcode, s->expr);
n = children[0];
if (s->type != st_assign) {
dagnode_t search = {
.label = op,
.children = { children[0], children[1], children[2] },
};
if (!(n = dagnode_search (dag, &search))) {
n = new_node (dag);
n->type = s->type;
n->label = op;
dagnode_add_children (dag, n, operands, children);
dagnode_set_edges (dag, n, s);
dagnode_set_reachable (dag, n);
}
}
lx = operand_label (dag, operands[0]);
if (lx && lx->dagnode != n) {
lx->expr = s->expr;
if (!dagnode_attach_label (dag, n, lx)) {
// attempting to attach the label to the node would create
// a dependency cycle in the dag, so a new node needs to be
// created for the source operand
if (s->type == st_assign) {
n = leaf_node (dag, operands[1], s->expr);
dagnode_attach_label (dag, n, lx);
} else {
internal_error (s->expr, "unexpected failure to attach"
" label to node");
}
}
}
if (n->type == st_ptrassign) {
dag_kill_nodes (dag, n);
}
}
nodes = malloc (dag->num_nodes * sizeof (dagnode_t *));
memcpy (nodes, dag->nodes, dag->num_nodes * sizeof (dagnode_t *));
dag->nodes = nodes;
labels = malloc (dag->num_labels * sizeof (daglabel_t *));
memcpy (labels, dag->labels, dag->num_labels * sizeof (daglabel_t *));
dag->labels = labels;
#if 0
if (options.block_dot.dags) {
flownode->dag = dag;
dump_dot ("raw-dags", flownode->graph, dump_dot_flow_dags);
}
#endif
dag_remove_dead_vars (dag, live_vars);
dag_sort_nodes (dag);
set_delete (live_vars);
return dag;
}
static statement_t *
build_statement (const char *opcode, operand_t **operands, expr_t *expr)
{
int i;
operand_t *op;
statement_t *st = new_statement (st_none, opcode, expr);
for (i = 0; i < 3; i++) {
if ((op = operands[i])) {
while (op->op_type == op_alias)
op = op->alias;
if (op->op_type == op_temp) {
while (op->tempop.alias)
op = op->tempop.alias;
op->tempop.users++;
}
}
}
st->opa = operands[0];
st->opb = operands[1];
st->opc = operands[2];
return st;
}
#if 0
static void
dag_calc_node_costs (dagnode_t *dagnode)
{
int i;
for (i = 0; i < 3; i++)
if (dagnode->children[i])
dag_calc_node_costs (dagnode->children[i]);
// if dagnode->a is null, then this is a leaf (as b and c are guaranted to
// be null)
if (!dagnode->children[0]) {
// Because qc vm statements don't mix source and destination operands,
// leaves never need temporary variables.
dagnode->cost = 0;
} else {
int different = 0;
// a non-leaf is guaranteed to have a valid first child
dagnode->cost = dagnode->children[0]->cost;
for (i = 1; i < 3; i++) {
if (dagnode->children[i]
&& dagnode->children[i]->cost != dagnode->cost) {
dagnode->cost = max (dagnode->cost,
dagnode->children[i]->cost);
different = 1;
}
}
if (!different)
dagnode->cost += 1;
}
}
#endif
static operand_t *
fix_op_type (operand_t *op, type_t *type)
{
if (op && op->op_type != op_label && op->type != type)
op = alias_operand (type, op, op->expr);
return op;
}
static operand_t *
make_operand (dag_t *dag, sblock_t *block, const dagnode_t *dagnode, int index)
{
operand_t *op;
op = dagnode->children[index]->value;
op = fix_op_type (op, dagnode->types[index]);
return op;
}
static operand_t *
generate_moves (dag_t *dag, sblock_t *block, dagnode_t *dagnode)
{
set_iter_t *var_iter;
daglabel_t *var;
operand_t *operands[3] = {0, 0, 0};
statement_t *st;
operand_t *dst;
operands[0] = make_operand (dag, block, dagnode, 0);
operands[1] = make_operand (dag, block, dagnode, 1);
dst = operands[0];
for (var_iter = set_first (dagnode->identifiers); var_iter;
var_iter = set_next (var_iter)) {
var = dag->labels[var_iter->element];
operands[2] = var->op;
dst = operands[2];
st = build_statement ("move", operands, var->expr);
sblock_add_statement (block, st);
}
return dst;
}
static operand_t *
generate_moveps (dag_t *dag, sblock_t *block, dagnode_t *dagnode)
{
set_iter_t *var_iter;
daglabel_t *var;
operand_t *operands[3] = {0, 0, 0};
statement_t *st;
operand_t *dst = 0;
type_t *type;
int offset = 0;
def_t *dstDef;
operands[0] = make_operand (dag, block, dagnode, 0);
operands[1] = make_operand (dag, block, dagnode, 1);
if (dagnode->children[2]) {
operands[2] = make_operand (dag, block, dagnode, 2);
st = build_statement ("movep", operands, dagnode->label->expr);
sblock_add_statement (block, st);
if ((var_iter = set_first (dagnode->identifiers))) {
var = dag->labels[var_iter->element];
dst = var->op;
set_del_iter (var_iter);
}
} else {
for (var_iter = set_first (dagnode->identifiers); var_iter;
var_iter = set_next (var_iter)) {
var = dag->labels[var_iter->element];
dst = var->op;
type = dst->def->type;
dstDef = dst->def;
if (dstDef->alias) {
offset = dstDef->offset;
dstDef = dstDef->alias;
}
operands[2] = value_operand (new_pointer_val (offset, type, dstDef, 0),
operands[1]->expr);
st = build_statement ("movep", operands, var->expr);
sblock_add_statement (block, st);
}
}
return dst;
}
static operand_t *
generate_memsets (dag_t *dag, sblock_t *block, dagnode_t *dagnode)
{
set_iter_t *var_iter;
daglabel_t *var;
operand_t *operands[3] = {0, 0, 0};
statement_t *st;
operand_t *dst;
operands[0] = make_operand (dag, block, dagnode, 0);
operands[1] = make_operand (dag, block, dagnode, 1);
dst = operands[0];
for (var_iter = set_first (dagnode->identifiers); var_iter;
var_iter = set_next (var_iter)) {
var = dag->labels[var_iter->element];
operands[2] = var->op;
dst = operands[2];
st = build_statement ("memset", operands, var->expr);
sblock_add_statement (block, st);
}
return dst;
}
static operand_t *
generate_memsetps (dag_t *dag, sblock_t *block, dagnode_t *dagnode)
{
set_iter_t *var_iter;
daglabel_t *var;
operand_t *operands[3] = {0, 0, 0};
statement_t *st;
operand_t *dst = 0;
type_t *type;
int offset = 0;
def_t *dstDef;
operands[0] = make_operand (dag, block, dagnode, 0);
operands[1] = make_operand (dag, block, dagnode, 1);
if (dagnode->children[2]) {
operands[2] = make_operand (dag, block, dagnode, 2);
st = build_statement ("memsetp", operands, dagnode->label->expr);
sblock_add_statement (block, st);
} else {
for (var_iter = set_first (dagnode->identifiers); var_iter;
var_iter = set_next (var_iter)) {
var = dag->labels[var_iter->element];
dst = var->op;
type = dst->def->type;
dstDef = dst->def;
if (dstDef->alias) {
offset = dstDef->offset;
dstDef = dstDef->alias;
}
operands[2] = value_operand (new_pointer_val (offset, type, dstDef, 0),
operands[1]->expr);
st = build_statement ("memsetp", operands, var->expr);
sblock_add_statement (block, st);
}
}
return dst;
}
static operand_t *
generate_call (dag_t *dag, sblock_t *block, dagnode_t *dagnode)
{
set_iter_t *var_iter;
daglabel_t *var = 0;
operand_t *operands[3] = {0, 0, 0};
statement_t *st;
operand_t *dst;
operands[0] = make_operand (dag, block, dagnode, 0);
if (dagnode->children[1]) {
operands[1] = make_operand (dag, block, dagnode, 1);
}
dst = operands[0];
for (var_iter = set_first (dagnode->identifiers); var_iter;
var_iter = set_next (var_iter)) {
if (var) {
internal_error (var->expr, "more than one return value for call");
}
var = dag->labels[var_iter->element];
operands[2] = var->op;
dst = operands[2];
st = build_statement ("call", operands, var->expr);
sblock_add_statement (block, st);
}
if (var_iter) {
set_del_iter (var_iter);
}
if (!var) {
// void call or return value ignored, still have to call
operands[2] = make_operand (dag, block, dagnode, 2);
st = build_statement ("call", operands, dagnode->label->expr);
sblock_add_statement (block, st);
}
return dst;
}
static operand_t *
generate_assignments (dag_t *dag, sblock_t *block, operand_t *src,
set_iter_t *var_iter, type_t *type)
{
statement_t *st;
operand_t *dst = 0;
operand_t *operands[3] = {0, 0, 0};
daglabel_t *var;
operands[2] = fix_op_type (src, type);
for ( ; var_iter; var_iter = set_next (var_iter)) {
var = dag->labels[var_iter->element];
operands[0] = fix_op_type (var->op, type);
if (!dst)
dst = operands[0];
st = build_statement ("assign", operands, var->expr);
sblock_add_statement (block, st);
}
return dst;
}
static void
dag_gencode (dag_t *dag, sblock_t *block, dagnode_t *dagnode)
{
operand_t *operands[3] = {0, 0, 0};
operand_t *dst = 0;
statement_t *st;
set_iter_t *var_iter;
int i;
type_t *type;
switch (dagnode->type) {
case st_none:
if (!dagnode->label->op)
internal_error (dagnode->label->expr,
"non-leaf label in leaf node");
dst = dagnode->label->op;
if ((var_iter = set_first (dagnode->identifiers))) {
type = dst->type;
dst = generate_assignments (dag, block, dst, var_iter, type);
}
break;
case st_alias:
if (!dagnode->children[0] || !dagnode->children[0]->value
|| !dagnode->types[0]
|| dagnode->children[1] || dagnode->children[2]) {
internal_error (dagnode->label->expr, "invalid alias node");
}
dst = offset_alias_operand (dagnode->types[0], dagnode->offset,
dagnode->children[0]->value,
dagnode->label->expr);
if ((var_iter = set_first (dagnode->identifiers))) {
type = dst->type;
dst = generate_assignments (dag, block, dst, var_iter, type);
}
break;
case st_address:
case st_expr:
operands[0] = make_operand (dag, block, dagnode, 0);
if (dagnode->children[1])
operands[1] = make_operand (dag, block, dagnode, 1);
type = get_type (dagnode->label->expr);
if (!(var_iter = set_first (dagnode->identifiers))) {
operands[2] = temp_operand (get_type (dagnode->label->expr),
dagnode->label->expr);
} else {
daglabel_t *var = dag->labels[var_iter->element];
operands[2] = fix_op_type (var->op, type);
var_iter = set_next (var_iter);
}
dst = operands[2];
st = build_statement (dagnode->label->opcode, operands,
dagnode->label->expr);
sblock_add_statement (block, st);
generate_assignments (dag, block, operands[2], var_iter, type);
break;
case st_assign:
internal_error (dagnode->label->expr, "unexpected assignment node");
case st_ptrassign:
operands[2] = make_operand (dag, block, dagnode, 0);
operands[0] = make_operand (dag, block, dagnode, 2);
if (dagnode->children[1])
operands[1] = make_operand (dag, block, dagnode, 1);
st = build_statement (dagnode->label->opcode, operands,
dagnode->label->expr);
sblock_add_statement (block, st);
// the source location is suitable for use in other nodes
dst = operands[2];
break;
case st_move:
dst = generate_moves (dag, block, dagnode);
break;
case st_ptrmove:
dst = generate_moveps (dag, block, dagnode);
break;
case st_memset:
dst = generate_memsets (dag, block, dagnode);
break;
case st_ptrmemset:
dst = generate_memsetps (dag, block, dagnode);
break;
case st_func:
if (!strcmp (dagnode->label->opcode, "call")) {
dst = generate_call (dag, block, dagnode);
break;
}
// fallthrough
case st_state:
for (i = 0; i < 3; i++)
if (dagnode->children[i])
operands[i] = make_operand (dag, block, dagnode, i);
st = build_statement (dagnode->label->opcode, operands,
dagnode->label->expr);
sblock_add_statement (block, st);
break;
case st_flow:
operands[0] = make_operand (dag, block, dagnode, 0);
if (dagnode->children[1])
operands[1] = make_operand (dag, block, dagnode, 1);
if (dagnode->children[2])
operands[2] = make_operand (dag, block, dagnode, 2);
st = build_statement (dagnode->label->opcode, operands,
dagnode->label->expr);
sblock_add_statement (block, st);
break;
}
dagnode->value = dst;
}
void
dag_remove_dead_nodes (dag_t *dag)
{
int added_root;
set_iter_t *root_i, *child_i;
dagnode_t *node, *child;
do {
added_root = 0;
for (root_i = set_first (dag->roots); root_i;
root_i = set_next (root_i)) {
node = dag->nodes[root_i->element];
// only st_none (leaf nodes), st_expr and st_move can become
// dead nodes (no live vars attached).
if (node->type != st_none && node->type != st_expr
&& node->type != st_move)
continue;
if (!set_is_empty (node->identifiers))
continue;
// MOVEP with a variable destination pointer is never dead
if (node->type == st_move && node->children[2])
continue;
set_remove (dag->roots, node->number);
for (child_i = set_first (node->edges); child_i;
child_i = set_next (child_i)) {
child = dag->nodes[child_i->element];
if (!set_is_member (child->parents, node->number))
continue; // not really a child (dependency edge)
set_remove (child->parents, node->number);
if (set_is_empty (child->parents)) {
set_add (dag->roots, child->number);
added_root = 1;
}
}
}
} while (added_root);
// clean up any stray edges that point to removed nodes
for (int i = 0; i < dag->num_nodes; i++) {
node = dag->nodes[i];
for (child_i = set_first (node->edges); child_i;
child_i = set_next (child_i)) {
child = dag->nodes[child_i->element];
if (!set_is_member (dag->roots, child->number)
&& set_is_empty (child->parents)) {
set_remove (node->edges, child->number);
}
}
}
dag_sort_nodes (dag);
}
void
dag_generate (dag_t *dag, sblock_t *block)
{
int i;
for (i = 0; i < dag->num_topo; i++)
dag_gencode (dag, block, dag->nodes[dag->topo[i]]);
}