+++ /dev/null
-/*
- * Project: libFIRM
- * File name: ir/opt/cfopt.c
- * Purpose: control flow optimizations
- * Author:
- * Created:
- * CVS-ID: $Id$
- * Copyright: (c) 1998-2004 Universität Karlsruhe
- * Licence: This file protected by GPL - GNU GENERAL PUBLIC LICENSE.
- */
-
-#ifdef HAVE_CONFIG_H
-# include <config.h>
-#endif
-
-#include <assert.h>
-
-#include "irnode_t.h"
-#include "irgraph_t.h"
-#include "irprog_t.h"
-
-#include "ircons.h"
-#include "iropt_t.h"
-#include "irgwalk.h"
-#include "irvrfy.h"
-
-#include "array.h"
-
-#include "irouts.h"
-#include "irbackedge_t.h"
-
-#include "irflag_t.h"
-#include "firmstat.h"
-
-#include "cfopt.h"
-
-/*------------------------------------------------------------------*/
-/* Control flow optimization. */
-/* Removes Bad control flow predecessors and empty blocks. A block */
-/* is empty if it contains only a Jmp node. */
-/* Blocks can only be removed if they are not needed for the */
-/* semantics of Phi nodes. */
-/*------------------------------------------------------------------*/
-
-/**
- * Removes Tuples from Block control flow predecessors.
- * Optimizes blocks with equivalent_node(). This is tricky,
- * as we want to avoid nodes that have as block predecessor Bads.
- * Therefore we also optimize at control flow operations, depending
- * how we first reach the Block.
- */
-static void merge_blocks(ir_node *n, void *env) {
- int i;
- ir_node *new_block;
-
- set_irn_link(n, NULL);
-
- if (get_irn_op(n) == op_Block) {
- /* Remove Tuples */
- for (i = 0; i < get_Block_n_cfgpreds(n); i++) {
- /* GL @@@ : is this possible? if (get_opt_normalize()) -- added, all tests go through.
- A different order of optimizations might cause problems. */
- if (get_opt_normalize())
- set_Block_cfgpred(n, i, skip_Tuple(get_Block_cfgpred(n, i)));
- }
- new_block = equivalent_node(n);
- if (new_block != n)
- exchange (n, new_block);
-
- } else if (get_opt_optimize() && (get_irn_mode(n) == mode_X)) {
- /* We will soon visit a block. Optimize it before visiting! */
- ir_node *b = get_nodes_block(n);
-
- if (!is_Bad(b)) {
- new_block = equivalent_node(b);
-
- while (irn_not_visited(b) && (!is_Bad(new_block)) && (new_block != b)) {
- /* We would have to run gigo if new is bad, so we
- promote it directly below. Nevertheless, we somtimes reach a block
- the first time through a dataflow node. In this case we optimized the
- block as such and have to promote the Bad here. */
- assert(((b == new_block) ||
- get_opt_control_flow_straightening() ||
- get_opt_control_flow_weak_simplification()) &&
- ("strange flag setting"));
- exchange (b, new_block);
- b = new_block;
- new_block = equivalent_node(b);
- }
- b = new_block;
- }
-
- /*
- * BEWARE: do not kill floating notes here as they might be needed in
- * valid blocks because of global CSE.
- */
- if (is_Bad(b) && get_opt_normalize() &&
- get_op_pinned(get_irn_op(n)) == op_pin_state_pinned)
- exchange(n, new_Bad());
- }
-}
-
-/**
- * Collects all Phi nodes in link list of Block.
- * Marks all blocks "block_visited" if they contain a node other
- * than Jmp.
- * Replaces n by Bad if n is unreachable control flow. We do that
- * in the post walker, so we catch all blocks.
- */
-static void collect_nodes(ir_node *n, void *env) {
- irg_dom_state *dom_state = env;
-
- if (is_no_Block(n)) {
- ir_node *b = get_nodes_block(n);
-
- /*
- * BEWARE: do not kill floating notes here as they might be needed in
- * valid blocks because of global CSE.
- */
- if (is_Bad(b) &&
- get_op_pinned(get_irn_op(n)) == op_pin_state_pinned) {
- /* previous merge_blocks() may have killed dead blocks */
- exchange(n, new_Bad());
- }
- else if ((get_irn_op(n) == op_Phi)) {
- /* Collect Phi nodes to compact ins along with block's ins. */
- set_irn_link(n, get_irn_link(b));
- set_irn_link(b, n);
- } else if ((get_irn_op(n) != op_Jmp) && !is_Bad(b)) { /* Check for non empty block. */
- mark_Block_block_visited(b);
- }
- }
- else {
- /* delete dead blocks: if we have dominator information, this can easily be detected
- * BEWARE: don't kill the end block */
- if (*dom_state == dom_consistent &&
- n != get_irg_end_block(current_ir_graph) &&
- get_Block_dom_depth(n) == -1 &&
- get_opt_unreachable_code()) {
- exchange (n, new_Bad());
- }
- }
-}
-
-/** Returns true if pred is predecessor of block. */
-static int is_pred_of(ir_node *pred, ir_node *b) {
- int i;
- for (i = 0; i < get_Block_n_cfgpreds(b); i++) {
- ir_node *b_pred = get_nodes_block(get_Block_cfgpred(b, i));
- if (b_pred == pred) return 1;
- }
- return 0;
-}
-
-
-static int test_whether_dispensable(ir_node *b, int pos) {
- int i, j, n_preds = 1;
- int dispensable = 1;
- ir_node *cfop = get_Block_cfgpred(b, pos);
- ir_node *pred = get_nodes_block(cfop);
-
- if (get_Block_block_visited(pred) + 1
- < get_irg_block_visited(current_ir_graph)) {
- if (!get_opt_optimize() || !get_opt_control_flow_strong_simplification()) {
- /* Mark block so that is will not be removed. */
- set_Block_block_visited(pred, get_irg_block_visited(current_ir_graph)-1);
- return 1;
- }
- /* Seems to be empty. */
- if (!get_irn_link(b)) {
- /* There are no Phi nodes ==> dispensable. */
- n_preds = get_Block_n_cfgpreds(pred);
- } else {
- /* b's pred blocks and pred's pred blocks must be pairwise disjunct.
- Work preds < pos as if they were already removed. */
- for (i = 0; i < pos; i++) {
- ir_node *b_pred = get_nodes_block(get_Block_cfgpred(b, i));
- if (get_Block_block_visited(b_pred) + 1
- < get_irg_block_visited(current_ir_graph)) {
- for (j = 0; j < get_Block_n_cfgpreds(b_pred); j++) {
- ir_node *b_pred_pred = get_nodes_block(get_Block_cfgpred(b_pred, j));
- if (is_pred_of(b_pred_pred, pred)) dispensable = 0;
- }
- } else {
- if (is_pred_of(b_pred, pred)) dispensable = 0;
- }
- }
- for (i = pos +1; i < get_Block_n_cfgpreds(b); i++) {
- ir_node *b_pred = get_nodes_block(get_Block_cfgpred(b, i));
- if (is_pred_of(b_pred, pred)) dispensable = 0;
- }
- if (!dispensable) {
- set_Block_block_visited(pred, get_irg_block_visited(current_ir_graph)-1);
- n_preds = 1;
- } else {
- n_preds = get_Block_n_cfgpreds(pred);
- }
- }
- }
-
- return n_preds;
-}
-
-static void optimize_blocks(ir_node *b, void *env) {
- int i, j, k, max_preds, n_preds;
- ir_node *pred, *phi;
- ir_node **in;
-
- /* Count the number of predecessor if this block is merged with pred blocks
- that are empty. */
- max_preds = 0;
- for (i = 0; i < get_Block_n_cfgpreds(b); i++) {
- max_preds += test_whether_dispensable(b, i);
- }
- in = (ir_node **) malloc(max_preds * sizeof(ir_node *));
-
-/*-
- printf(" working on "); DDMN(b);
- for (i = 0; i < get_Block_n_cfgpreds(b); i++) {
- pred = get_nodes_block(get_Block_cfgpred(b, i));
- if (is_Bad(get_Block_cfgpred(b, i))) {
- printf(" removing Bad %i\n ", i);
- } else if (get_Block_block_visited(pred) +1
- < get_irg_block_visited(current_ir_graph)) {
- printf(" removing pred %i ", i); DDMN(pred);
- } else { printf(" Nothing to do for "); DDMN(pred); }
- }
- * end Debug output -*/
-
- /*- Fix the Phi nodes -*/
- phi = get_irn_link(b);
- while (phi) {
- assert(get_irn_op(phi) == op_Phi);
- /* Find the new predecessors for the Phi */
- n_preds = 0;
- for (i = 0; i < get_Block_n_cfgpreds(b); i++) {
- pred = get_nodes_block(get_Block_cfgpred(b, i));
- if (is_Bad(get_Block_cfgpred(b, i))) {
- /* Do nothing */
- } else if (get_Block_block_visited(pred) + 1
- < get_irg_block_visited(current_ir_graph)) {
- /* It's an empty block and not yet visited. */
- ir_node *phi_pred = get_Phi_pred(phi, i);
-
- for (j = 0; j < get_Block_n_cfgpreds(pred); j++) {
- if (get_nodes_block(phi_pred) == pred) {
- assert(get_irn_op(phi_pred) == op_Phi); /* Block is empty!! */
- in[n_preds] = get_Phi_pred(phi_pred, j);
- } else {
- in[n_preds] = phi_pred;
- }
- n_preds++;
- }
- /* The Phi_pred node is replaced now if it is a Phi.
- In Schleifen kann offenbar der entfernte Phi Knoten legal verwendet werden.
- Daher muss der Phiknoten durch den neuen ersetzt werden.
- Weiter muss der alte Phiknoten entfernt werden (durch ersetzen oder
- durch einen Bad) damit er aus den keep_alive verschwinden kann.
- Man sollte also, falls keine Schleife vorliegt, exchange mit new_Bad
- aufrufen. */
- if (get_nodes_block(phi_pred) == pred) {
- /* remove the Phi as it might be kept alive. Further there
- might be other users. */
- exchange(phi_pred, phi); /* geht, ist aber doch semantisch falsch! Warum?? */
- }
- } else {
- in[n_preds] = get_Phi_pred(phi, i);
- n_preds ++;
- }
- }
- /* Fix the node */
- if (n_preds == 1)
- exchange(phi, in[0]);
- else
- set_irn_in(phi, n_preds, in);
-
- phi = get_irn_link(phi);
- }
-
- /*- This happens only if merge between loop backedge and single loop entry. -*/
- for (k = 0; k < get_Block_n_cfgpreds(b); k++) {
- pred = get_nodes_block(get_Block_cfgpred(b, k));
- if (get_Block_block_visited(pred)+1 < get_irg_block_visited(current_ir_graph)) {
- phi = get_irn_link(pred);
- while (phi) {
- if (get_irn_op(phi) == op_Phi) {
- set_nodes_block(phi, b);
-
- n_preds = 0;
- for (i = 0; i < k; i++) {
- pred = get_nodes_block(get_Block_cfgpred(b, i));
- if (is_Bad(get_Block_cfgpred(b, i))) {
- /* Do nothing */
- } else if (get_Block_block_visited(pred) +1
- < get_irg_block_visited(current_ir_graph)) {
- /* It's an empty block and not yet visited. */
- for (j = 0; j < get_Block_n_cfgpreds(pred); j++) {
- /* @@@ Hier brauche ich Schleifeninformation!!! Kontrollflusskante
- muss Rueckwaertskante sein! (An allen vier in[n_preds] = phi
- Anweisungen.) Trotzdem tuts bisher!! */
- in[n_preds] = phi;
- n_preds++;
- }
- } else {
- in[n_preds] = phi;
- n_preds++;
- }
- }
- for (i = 0; i < get_Phi_n_preds(phi); i++) {
- in[n_preds] = get_Phi_pred(phi, i);
- n_preds++;
- }
- for (i = k+1; i < get_Block_n_cfgpreds(b); i++) {
- pred = get_nodes_block(get_Block_cfgpred(b, i));
- if (is_Bad(get_Block_cfgpred(b, i))) {
- /* Do nothing */
- } else if (get_Block_block_visited(pred) +1
- < get_irg_block_visited(current_ir_graph)) {
- /* It's an empty block and not yet visited. */
- for (j = 0; j < get_Block_n_cfgpreds(pred); j++) {
- in[n_preds] = phi;
- n_preds++;
- }
- } else {
- in[n_preds] = phi;
- n_preds++;
- }
- }
- if (n_preds == 1)
- exchange(phi, in[0]);
- else
- set_irn_in(phi, n_preds, in);
- }
- phi = get_irn_link(phi);
- }
- }
- }
-
- /*- Fix the block -*/
- n_preds = 0;
- for (i = 0; i < get_Block_n_cfgpreds(b); i++) {
- pred = get_nodes_block(get_Block_cfgpred(b, i));
- if (is_Bad(get_Block_cfgpred(b, i))) {
- /* Do nothing */
- } else if (get_Block_block_visited(pred) +1
- < get_irg_block_visited(current_ir_graph)) {
- /* It's an empty block and not yet visited. */
- assert(get_Block_n_cfgpreds(b) > 1);
- /* Else it should be optimized by equivalent_node. */
- for (j = 0; j < get_Block_n_cfgpreds(pred); j++) {
- in[n_preds] = get_Block_cfgpred(pred, j);
- n_preds++;
- }
- /* Remove block as it might be kept alive. */
- exchange(pred, b/*new_Bad()*/);
- } else {
- in[n_preds] = get_Block_cfgpred(b, i);
- n_preds ++;
- }
- }
- set_irn_in(b, n_preds, in);
- free(in);
-}
-
-void optimize_cf(ir_graph *irg) {
- int i;
- ir_node **in;
- ir_node *end = get_irg_end(irg);
- ir_graph *rem = current_ir_graph;
- irg_dom_state dom_state = get_irg_dom_state(current_ir_graph);
- current_ir_graph = irg;
-
- /* Handle graph state */
- assert(get_irg_phase_state(irg) != phase_building);
- if (get_irg_outs_state(current_ir_graph) == outs_consistent)
- set_irg_outs_inconsistent(current_ir_graph);
- if (get_irg_dom_state(current_ir_graph) == dom_consistent)
- set_irg_dom_inconsistent(current_ir_graph);
-
- /* Use block visited flag to mark non-empty blocks. */
- inc_irg_block_visited(irg);
- irg_walk(end, merge_blocks, collect_nodes, &dom_state);
-
- /* Optimize the standard code. */
- irg_block_walk(get_irg_end_block(irg), optimize_blocks, NULL, NULL);
-
- /* Walk all keep alives, optimize them if block, add to new in-array
- for end if useful. */
- in = NEW_ARR_F (ir_node *, 1);
- in[0] = get_nodes_block(end);
- inc_irg_visited(current_ir_graph);
- for(i = 0; i < get_End_n_keepalives(end); i++) {
- ir_node *ka = get_End_keepalive(end, i);
- if (irn_not_visited(ka)) {
- if ((get_irn_op(ka) == op_Block) && Block_not_block_visited(ka)) {
- set_irg_block_visited(current_ir_graph, /* Don't walk all the way to Start. */
- get_irg_block_visited(current_ir_graph)-1);
- irg_block_walk(ka, optimize_blocks, NULL, NULL);
- mark_irn_visited(ka);
- ARR_APP1 (ir_node *, in, ka);
- } else if (get_irn_op(ka) == op_Phi) {
- mark_irn_visited(ka);
- ARR_APP1 (ir_node *, in, ka);
- }
- }
- }
- /* DEL_ARR_F(end->in); GL @@@ tut nicht ! */
- end->in = in;
-
- /* after optimize_cf(), only Bad data flow may remain. */
- if (irg_vrfy_bads(irg, BAD_DF | BAD_BLOCK | TUPLE)) {
- dump_ir_block_graph(irg, "-vrfy-cf");
- dump_ir_graph(irg, "-vrfy-cf");
- fprintf(stderr, "VRFY_BAD in optimize_cf()\n");
- }
-
- current_ir_graph = rem;
-}
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