/** A scc. */
typedef struct scc {
- ir_node *head; /**< the head of the list */
+ ir_node *head; /**< the head of the list */
+ tarval *init; /**< the init value iff only one exists. */
+ tarval *incr; /**< the induction variable increment if only a single const exists. */
+ unsigned code; /**< == iro_Add if +incr, iro_Sub if -incr, 0 if not analysed, iro_Bad else */
} scc;
/** A node entry */
return e;
}
+/**
+ * Gets the scc from an IV.
+ */
+static scc *get_iv_scc(ir_node *iv, iv_env *env) {
+ node_entry *e = get_irn_ne(iv, env);
+ return e->pscc;
+}
+
/**
* Check if irn is an IV.
*
return result;
}
+/**
+ * Update the scc for a newly created IV.
+ */
+static void update_scc(ir_node *iv, node_entry *e, iv_env *env) {
+ scc *pscc = e->pscc;
+ ir_node *header = e->header;
+ waitq *wq = new_waitq();
+
+ pscc->head = NULL;
+ waitq_put(wq, iv);
+ do {
+ ir_node *irn = waitq_get(wq);
+ node_entry *ne = get_irn_ne(irn, env);
+ int i;
+
+ ne->pscc = pscc;
+ ne->next = pscc->head;
+ pscc->head = irn;
+
+ for (i = get_irn_arity(irn) - 1; i >= 0; --i) {
+ ir_node *pred = get_irn_n(irn, i);
+ node_entry *pe = get_irn_ne(pred, env);
+
+ if (pe->header == header && pe->pscc == NULL)
+ waitq_put(wq, pred);
+ }
+ } while (! waitq_empty(wq));
+ del_waitq(wq);
+}
+
/**
* The Replace operation.
*
result = reduce(irn, iv, rc, env);
if (result != irn) {
- node_entry *e, *iv_e;
+ node_entry *e;
hook_strength_red(current_ir_graph, irn);
exchange(irn, result);
e = get_irn_ne(result, env);
- iv_e = get_irn_ne(iv, env);
- e->header = iv_e->header;
+ if (e->pscc == NULL) {
+ e->pscc = obstack_alloc(&env->obst, sizeof(*e->pscc));
+ memset(e->pscc, 0, sizeof(*e->pscc));
+ update_scc(result, e, env);
+ }
++env->replaced;
return 1;
}
return 0;
}
+/**
+ * Check if an IV represents a counter with constant limits.
+ */
+static int is_counter_iv(ir_node *iv, iv_env *env) {
+ node_entry *e = get_irn_ne(iv, env);
+ scc *pscc = e->pscc;
+ ir_node *have_init = NULL;
+ ir_node *have_incr = NULL;
+ ir_opcode code = iro_Bad;
+ ir_node *irn;
+
+ if (pscc->code != 0) {
+ /* already analysed */
+ return pscc->code != iro_Bad;
+ }
+
+ pscc->code = iro_Bad;
+ for (irn = pscc->head; irn != NULL; irn = e->next) {
+ if (is_Add(irn)) {
+ if (have_incr != NULL)
+ return 0;
+
+ have_incr = get_Add_right(irn);
+ if (! is_Const(have_incr)) {
+ have_incr = get_Add_left(irn);
+ if (! is_Const(have_incr))
+ return 0;
+ }
+ code = iro_Add;
+ } else if (is_Sub(irn)) {
+ if (have_incr != NULL)
+ return 0;
+
+ have_incr = get_Sub_right(irn);
+ if (! is_Const(have_incr))
+ return 0;
+ code = iro_Sub;
+ } else if (is_Phi(irn)) {
+ int i;
+
+ for (i = get_Phi_n_preds(irn) - 1; i >= 0; --i) {
+ ir_node *pred = get_Phi_pred(irn, i);
+ node_entry *ne = get_irn_ne(pred, env);
+
+ if (ne->header == e->header)
+ continue;
+ if (have_init != NULL)
+ return 0;
+ have_init = pred;
+ if (! is_Const(pred))
+ return 0;
+ }
+ } else
+ return 0;
+ e = get_irn_ne(irn, env);
+ }
+ pscc->init = get_Const_tarval(have_init);
+ pscc->incr = get_Const_tarval(have_incr);
+ pscc->code = code;
+ return code != iro_Bad;
+}
+
/**
* Check the users of an induction variable for register pressure.
*/
static int check_users_for_reg_pressure(ir_node *iv, iv_env *env) {
ir_node *irn, *header;
- node_entry *e;
ir_node *have_user = NULL;
ir_node *have_cmp = NULL;
- waitq *wq = new_waitq();
+ node_entry *e = get_irn_ne(iv, env);
+ scc *pscc = e->pscc;
- e = get_irn_ne(iv, env);
header = e->header;
- waitq_put(wq, iv);
-
- do {
+ for (irn = pscc->head; irn != NULL; irn = e->next) {
const ir_edge_t *edge;
- irn = waitq_get(wq);
foreach_out_edge(irn, edge) {
ir_node *user = get_edge_src_irn(edge);
node_entry *ne = get_irn_ne(user, env);
if (e->header == ne->header) {
/* found user from the same IV */
- if (user != iv)
- waitq_put(wq, user);
continue;
}
if (is_Cmp(user)) {
if (have_cmp != NULL) {
/* more than one cmp, for now end here */
- goto fail;
+ return 0;
}
have_cmp = user;
} else {
/* user is a real user of the IV */
if (have_user != NULL) {
/* found the second user */
- goto fail;
+ return 0;
}
have_user = user;
}
}
- } while (! waitq_empty(wq));
- del_waitq(wq);
+ e = get_irn_ne(irn, env);
+ }
if (have_user == NULL) {
/* no user, ignore */
/*
* We found one user AND at least one cmp.
* We should check here if we can transform the Cmp.
- * For now do nothing ...
+ *
+ * For now our capabilities for doing linear function test
+ * are limited, so check if the iv has the right form: Only ONE
+ * phi, only one Add/Sub with a Const
+ */
+ if (! is_counter_iv(iv, env))
+ return 0;
+
+ /*
+ * Ok, we have only one increment AND it is a Const, we might be able
+ * to do a linear function test replacement, so go on.
*/
return 1;
-fail:
- del_waitq(wq);
- return 0;
}
/**
scc *pscc = obstack_alloc(&env->obst, sizeof(*pscc));
ir_node *x;
- pscc->head = NULL;
+ memset(pscc, 0, sizeof(*pscc));
do {
node_entry *e;
* Return NULL if the transformation cannot be done safely without
* an Overflow.
*
- * @param rc the IV node that should be translated
+ * @param iv the induction variable
+ * @param rc the constant that should be translated
* @param e the LFTR edge
* @param env the IV environment
*
* In the current implementation only the last edge is stored, so
* only one chain exists. That's why we might miss some opportunities.
*/
-static ir_node *applyOneEdge(ir_node *rc, LFTR_edge *e, iv_env *env) {
+static ir_node *applyOneEdge(ir_node *iv, ir_node *rc, LFTR_edge *e, iv_env *env) {
if (env->flags & osr_flag_lftr_with_ov_check) {
- tarval *tv_l, *tv_r, *tv;
+ tarval *tv_l, *tv_r, *tv, *tv_init, *tv_incr;
tarval_int_overflow_mode_t ovmode;
+ scc *pscc;
+
+ if (! is_counter_iv(iv, env)) {
+ DB((dbg, LEVEL_4, " not counter IV"));
+ return NULL;
+ }
/* overflow can only be decided for Consts */
if (! is_Const(e->rc)) {
ovmode = tarval_get_integer_overflow_mode();
tarval_set_integer_overflow_mode(TV_OVERFLOW_BAD);
+ pscc = get_iv_scc(iv, env);
+ tv_incr = pscc->incr;
+ tv_init = pscc->init;
+
+ /*
+ * Check that no overflow occurs:
+ * init must be transformed without overflow
+ * the new rc must be transformed without overflow
+ * rc +/- incr must be possible without overflow
+ */
switch (e->code) {
case iro_Mul:
- tv = tarval_mul(tv_l, tv_r);
+ tv = tarval_mul(tv_l, tv_r);
+ tv_init = tarval_mul(tv_init, tv_r);
+ tv_incr = tarval_mul(tv_incr, tv_r);
DB((dbg, LEVEL_4, " * %+F", tv_r));
break;
case iro_Add:
- tv = tarval_add(tv_l, tv_r);
+ tv = tarval_add(tv_l, tv_r);
+ tv_init = tarval_add(tv_init, tv_r);
DB((dbg, LEVEL_4, " + %+F", tv_r));
break;
case iro_Sub:
- tv = tarval_sub(tv_l, tv_r);
+ tv = tarval_sub(tv_l, tv_r);
+ tv_init = tarval_sub(tv_init, tv_r);
DB((dbg, LEVEL_4, " - %+F", tv_r));
break;
default:
assert(0);
tv = tarval_bad;
}
+
+ if (pscc->code == iro_Add) {
+ tv = tarval_add(tv, tv_incr);
+ } else {
+ assert(pscc->code == iro_Sub);
+ tv = tarval_sub(tv, tv_incr);
+ }
+
tarval_set_integer_overflow_mode(ovmode);
- if (tv == tarval_bad) {
+ if (tv == tarval_bad || tv_init == tarval_bad) {
DB((dbg, LEVEL_4, " = OVERFLOW"));
return NULL;
}
* if the translation was not possible
*/
static ir_node *applyEdges(ir_node *iv, ir_node *rc, iv_env *env) {
- ir_node *irn = iv;
-
if (env->flags & osr_flag_lftr_with_ov_check) {
/* overflow can only be decided for Consts */
+ if (! is_counter_iv(iv, env)) {
+ DB((dbg, LEVEL_4, "not counter IV\n", rc));
+ return NULL;
+ }
if (! is_Const(rc)) {
DB((dbg, LEVEL_4, " = UNKNOWN (%+F)\n", rc));
return NULL;
DB((dbg, LEVEL_4, "%+F", get_Const_tarval(rc)));
}
- for (irn = iv; rc;) {
- LFTR_edge *e = LFTR_find(irn, env);
+ for (; rc;) {
+ LFTR_edge *e = LFTR_find(iv, env);
if (e) {
- rc = applyOneEdge(rc, e, env);
- irn = e->dst;
+ rc = applyOneEdge(iv, rc, e, env);
+ iv = e->dst;
}
else
break;
* @param env the IV environment
*/
static void lftr(ir_graph *irg, iv_env *env) {
+ if ((env->flags & osr_flag_lftr_with_ov_check) &&
+ get_opt_overflow_unsafe_transform()) {
+ /*
+ * If overflow unsafe transformation are allowed, we cannot perform
+ * linear function test replacement with overflow checks.
+ */
+ return;
+ }
irg_walk_graph(irg, NULL, do_lftr, env);
}
projects / libfirm / blobdiff