/* * This file is part of libFirm. * Copyright (C) 2012 University of Karlsruhe. */ /** * @file * @brief Operator Strength Reduction. * @date 12.5.2006 * @author Michael Beck * @brief * Implementation of the Operator Strength Reduction algorithm * by Keith D. Cooper, L. Taylor Simpson, Christopher A. Vick. * Extended version. */ #include "array.h" #include "debug.h" #include "hashptr.h" #include "ircons.h" #include "irdom.h" #include "iredges_t.h" #include "irflag_t.h" #include "irgmod.h" #include "irgwalk.h" #include "irhooks.h" #include "irloop_t.h" #include "irop_t.h" #include "iroptimize.h" #include "irouts.h" #include "irtools.h" #include "obst.h" #include "panic.h" #include "pdeq.h" #include "set.h" #include "tv.h" #include "util.h" #include /** The debug handle. */ DEBUG_ONLY(static firm_dbg_module_t *dbg;) /** A scc. */ typedef struct scc { ir_node *head; /**< the head of the list */ ir_tarval *init; /**< the init value iff only one exists. */ ir_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 analyzed, iro_Bad else */ } scc; /** A node entry */ typedef struct node_entry { unsigned DFSnum; /**< the DFS number of this node */ unsigned low; /**< the low number of this node */ ir_node *header; /**< the header of this node */ bool in_stack; /**< flag, set if the node is on the stack */ ir_node *next; /**< link to the next node the same SCC */ scc *pscc; /**< the SCC of this node */ unsigned POnum; /**< the post order number for blocks */ } node_entry; /** The environment. */ typedef struct iv_env { struct obstack obst; /**< an obstack for allocations */ ir_node **stack; /**< the node stack */ size_t tos; /**< tos index */ unsigned nextDFSnum; /**< the current DFS number */ unsigned POnum; /**< current post order number */ set *quad_map; /**< a map from (op, iv, rc) to node */ set *lftr_edges; /**< the set of lftr edges */ unsigned replaced; /**< number of replaced ops */ unsigned lftr_replaced; /**< number of applied linear function test replacements */ unsigned osr_flags; /**< additional flags steering the transformation */ bool need_postpass; /**< set, if a post pass is needed to fix Add and Sub nodes */ /** Function called to process a SCC. */ void (*process_scc)(scc *pscc, struct iv_env *env); } iv_env; /** * An entry in the (op, node, node) -> node map. */ typedef struct quadruple_t { unsigned code; /**< the opcode of the reduced operation */ ir_node *op1; /**< the first operand the reduced operation */ ir_node *op2; /**< the second operand of the reduced operation */ ir_node *res; /**< the reduced operation */ } quadruple_t; /** * A LFTR edge. */ typedef struct ldtr_edge_t { ir_node *src; /**< the source node */ ir_node *dst; /**< the destination node */ unsigned code; /**< the opcode that must be applied */ ir_node *rc; /**< the region const that must be applied */ } ldtr_edge_t; /* forward */ static ir_node *reduce(ir_node *orig, ir_node *iv, ir_node *rc, iv_env *env); /** * Compare two LFTR edges. */ static int lftr_cmp(const void *e1, const void *e2, size_t size) { (void)size; const ldtr_edge_t *l1 = (const ldtr_edge_t*)e1; const ldtr_edge_t *l2 = (const ldtr_edge_t*)e2; return l1->src != l2->src; } /** * Find a LFTR edge. * * @param src the source node of the transition */ static ldtr_edge_t *lftr_find(ir_node *src, iv_env *env) { ldtr_edge_t key = { .src = src }; return set_find(ldtr_edge_t, env->lftr_edges, &key, sizeof(key), hash_ptr(src)); } /** * Add a LFTR edge. * * @param src the source node of the edge * @param dst the destination node of the edge * @param code the opcode of the transformed transition * @param rc the region const used in the transition * @param env the environment */ static void lftr_add(ir_node *src, ir_node *dst, unsigned code, ir_node *rc, iv_env *env) { ldtr_edge_t key = { .src = src, .dst = dst, .code = code, .rc = rc }; /* * There might be more than one edge here. This is rather bad * because we currently store only one. */ (void)set_insert(ldtr_edge_t, env->lftr_edges, &key, sizeof(key), hash_ptr(src)); } /** * Gets the node_entry of a node. * * @param irn the node * @param env the environment */ static node_entry *get_irn_ne(ir_node *irn, iv_env *env) { node_entry *e = (node_entry*)get_irn_link(irn); if (e == NULL) { e = OALLOCZ(&env->obst, node_entry); set_irn_link(irn, e); } return e; } /** * Gets the SCC from an induction variable. * * @param iv any node of the induction variable * @param env the environment */ 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. * * @param irn the node to check * @param env the environment * * @returns the header if it is one, NULL else */ static ir_node *is_iv(ir_node *irn, iv_env *env) { return get_irn_ne(irn, env)->header; } /** * Check if irn is a region constant. * The block or irn must strictly dominate the header block. * * @param irn the node to check * @param header_block the header block of the induction variable */ static bool is_rc(ir_node *irn, ir_node *header_block) { ir_node *block = get_nodes_block(irn); return (block != header_block) && block_dominates(block, header_block); } /** * Set compare function for the quad set. */ static int quad_cmp(const void *e1, const void *e2, size_t size) { (void)size; const quadruple_t *c1 = (const quadruple_t*)e1; const quadruple_t *c2 = (const quadruple_t*)e2; return c1->code != c2->code || c1->op1 != c2->op1 || c1->op2 != c2->op2; } /** * Check if an reduced operation was already calculated. * * @param code the opcode of the operation * @param op1 the first operand of the operation * @param op2 the second operand of the operation * @param env the environment * * @return the already reduced node or NULL if this operation is not yet reduced */ static ir_node *search(unsigned code, ir_node *op1, ir_node *op2, iv_env *env) { quadruple_t key = { .code = code, .op1 = op1, .op2 = op2 }; unsigned hash = (code*9) ^ hash_ptr(op1) ^ hash_ptr(op2); quadruple_t *entry = set_find(quadruple_t, env->quad_map, &key, sizeof(key), hash); if (entry != NULL) return entry->res; return NULL; } /** * Add an reduced operation. * * @param code the opcode of the operation * @param op1 the first operand of the operation * @param op2 the second operand of the operation * @param result the result of the reduced operation * @param env the environment */ static void add(unsigned code, ir_node *op1, ir_node *op2, ir_node *result, iv_env *env) { quadruple_t key = { .code = code, .op1 = op1, .op2 = op2, .res = result }; unsigned hash = (code*9) ^ hash_ptr(op1) ^ hash_ptr(op2); (void)set_insert(quadruple_t, env->quad_map, &key, sizeof(key), hash); } /** * Find a location where to place a bin-op whose operands are in * block1 and block2. * * @param block1 the block of the first operand * @param block2 the block of the second operand * * Note that we know here that such a place must exists. Moreover, this means * that either block1 dominates block2 or vice versa. So, just return * the "smaller" one. */ static ir_node *find_location(ir_node *block1, ir_node *block2) { if (block_dominates(block1, block2)) return block2; assert(block_dominates(block2, block1)); return block1; } /** * Create a node that executes an op1 code op1 operation. * * @param code the opcode to execute * @param db debug info to add to the new node * @param op1 the first operand * @param op2 the second operand * * @return the newly created node */ static ir_node *do_apply(unsigned code, dbg_info *db, ir_node *op1, ir_node *op2) { ir_node *block = find_location(get_nodes_block(op1), get_nodes_block(op2)); switch (code) { case iro_Mul: return new_rd_Mul(db, block, op1, op2); case iro_Add: return new_rd_Add(db, block, op1, op2); case iro_Sub: return new_rd_Sub(db, block, op1, op2); default: panic("unsupported opcode"); } } /** * The Apply operation. * * @param orig the node that represent the original operation and determines * the opcode, debug-info and mode of a newly created one * @param op1 the first operand * @param op2 the second operand * @param env the environment * * @return the newly created node */ static ir_node *apply(ir_node *header, ir_node *orig, ir_node *op1, ir_node *op2, iv_env *env) { unsigned code = get_irn_opcode(orig); ir_node *result = search(code, op1, op2, env); if (result == NULL) { dbg_info *db = get_irn_dbg_info(orig); ir_node *op1_header = get_irn_ne(op1, env)->header; ir_node *op2_header = get_irn_ne(op2, env)->header; if (op1_header == header && is_rc(op2, op1_header)) { result = reduce(orig, op1, op2, env); } else if (op2_header == header && is_rc(op1, op2_header)) { result = reduce(orig, op2, op1, env); } else { result = do_apply(code, db, op1, op2); get_irn_ne(result, env)->header = NULL; } } return result; } /** * The Reduce operation. * * @param orig the node that represent the original operation and determines * the opcode, debug-info and mode of a newly created one * @param iv the induction variable * @param rc the region constant * @param env the environment * * @return the reduced node */ static ir_node *reduce(ir_node *orig, ir_node *iv, ir_node *rc, iv_env *env) { unsigned code = get_irn_opcode(orig); ir_node *result = search(code, iv, rc, env); /* check if we have already done this operation on the iv */ if (result == NULL) { result = exact_copy(iv); ir_mode *mode = get_irn_mode(orig); if (get_irn_mode(result) != mode) { /* * Beware: we must always create a new induction variable with the * same mode as the node we are replacing. Especially this means * the mode might be changed from P to I and back. This is always * possible, because we have only Phi, Add and Sub nodes. * However, this might lead to AddIs(Iu,Is) which we must fix. The * best way to do this seems to be a post-pass, or we might end * with useless Conv's. */ set_irn_mode(result, mode); env->need_postpass = true; } add(code, iv, rc, result, env); DB((dbg, LEVEL_3, " Created new %+F for %+F (%s %+F)\n", result, iv, get_irn_opname(orig), rc)); node_entry *iv_e = get_irn_ne(iv, env); node_entry *e = get_irn_ne(result, env); e->header = iv_e->header; /* create the LFTR edge */ lftr_add(iv, result, code, rc, env); foreach_irn_in_r(result, i, pred) { ir_node *o = pred; e = get_irn_ne(o, env); if (e->header == iv_e->header) o = reduce(orig, o, rc, env); else if (is_Phi(result) || code == iro_Mul) o = apply(iv_e->header, orig, o, rc, env); set_irn_n(result, i, o); } } else { DB((dbg, LEVEL_3, " Already Created %+F for %+F (%s %+F)\n", result, iv, get_irn_opname(orig), rc)); } return result; } /** * Update the SCC for a newly created IV. */ static void update_scc(ir_node *iv, node_entry *e, iv_env *env) { DB((dbg, LEVEL_2, " Creating SCC for new an induction variable:\n ")); scc *pscc = e->pscc; ir_node *header = e->header; pscc->head = NULL; deq_t wq; deq_init(&wq); deq_push_pointer_right(&wq, iv); do { ir_node *irn = deq_pop_pointer_left(ir_node, &wq); node_entry *ne = get_irn_ne(irn, env); ne->pscc = pscc; ne->next = pscc->head; pscc->head = irn; DB((dbg, LEVEL_2, " %+F,", irn)); foreach_irn_in_r(irn, i, pred) { node_entry *const pe = get_irn_ne(pred, env); if (pe->header == header && pe->pscc == NULL) { /* set the pscc here to ensure that the node is NOT enqueued another time */ pe->pscc = pscc; deq_push_pointer_right(&wq, pred); } } } while (!deq_empty(&wq)); deq_free(&wq); DB((dbg, LEVEL_2, "\n")); } /** * The Replace operation. We found a node representing iv (+,-,*) rc * that can be removed by replacing the induction variable iv by a new * one that 'applies' the operation 'irn'. * * @param irn the node that will be replaced * @param iv the induction variable * @param rc the region constant * @param env the environment */ static bool replace(ir_node *irn, ir_node *iv, ir_node *rc, iv_env *env) { DB((dbg, LEVEL_2, " Replacing %+F\n", irn)); ir_node *result = reduce(irn, iv, rc, env); if (result != irn) { exchange(irn, result); node_entry *e = get_irn_ne(result, env); if (e->pscc == NULL) { e->pscc = OALLOCZ(&env->obst, scc); update_scc(result, e, env); } ++env->replaced; return true; } return false; } /** * Check if an IV represents a counter with constant limits. * * @param iv any node of the induction variable * @param env the environment */ static bool is_counter_iv(ir_node *iv, iv_env *env) { node_entry *e = get_irn_ne(iv, env); scc *pscc = e->pscc; if (pscc->code != 0) { /* already analyzed */ return pscc->code != iro_Bad; } ir_node *have_init = NULL; ir_node *have_incr = NULL; ir_opcode code = iro_Bad; pscc->code = iro_Bad; for (ir_node *irn = pscc->head; irn != NULL; irn = e->next) { if (is_Add(irn) || is_Sub(irn)) { if (have_incr != NULL) return false; have_incr = get_binop_right(irn); if (!is_Const(have_incr)) { return false; } code = get_irn_opcode(irn); } else if (is_Phi(irn)) { for (int 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 false; have_init = pred; if (!is_Const(pred)) return false; } } else { return false; } 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. * * @param iv any node of the induction variable * @param env the environment * * @return non-zero if the register pressure is estimated * to not increase, zero else */ static bool check_users_for_reg_pressure(ir_node *iv, iv_env *env) { ir_node *have_user = NULL; ir_node *have_cmp = NULL; node_entry *e = get_irn_ne(iv, env); scc *pscc = e->pscc; for (ir_node *irn = pscc->head; irn != NULL; irn = e->next) { 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 */ continue; } if (is_Cmp(user)) { if (have_cmp != NULL) { /* more than one cmp, for now end here */ return false; } have_cmp = user; } else { /* user is a real user of the IV */ if (have_user != NULL) { /* found the second user */ return false; } have_user = user; } } e = get_irn_ne(irn, env); } if (have_user == NULL) { /* no user, ignore */ return true; } if (have_cmp == NULL) { /* fine, only one user, try to reduce */ return true; } /* * We found one user AND at least one cmp. * We should check here if we can transform the Cmp. * * 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. */ return is_counter_iv(iv, env); } /** * Check if a node can be replaced (+, -, *). * * @param irn the node to check * @param env the environment * * @return non-zero if irn should be replaced */ static bool check_replace(ir_node *irn, iv_env *env) { ir_op *op = get_irn_op(irn); unsigned code = get_op_code(op); switch (code) { case iro_Mul: case iro_Add: case iro_Sub: { ir_node *left = get_binop_left(irn); ir_node *right = get_binop_right(irn); ir_node *liv = is_iv(left, env); ir_node *riv = is_iv(right, env); ir_node *iv = NULL; ir_node *rc = NULL; if (liv && is_rc(right, liv)) { iv = left; rc = right; } else if (riv && is_op_commutative(op) && is_rc(left, riv)) { iv = right; rc = left; } else { return false; } if (env->osr_flags & osr_flag_keep_reg_pressure && !check_users_for_reg_pressure(iv, env)) return false; return replace(irn, iv, rc, env); } default: return false; } } /** * Check which SCC's are induction variables. * * @param pscc a SCC * @param env the environment */ static void classify_iv(scc *pscc, iv_env *env) { /* find the header block for this SCC */ ir_node *header = NULL; node_entry *h = NULL; for (ir_node *irn = pscc->head, *next; irn != NULL; irn = next) { node_entry *e = (node_entry*)get_irn_link(irn); ir_node *block = get_nodes_block(irn); next = e->next; node_entry *b = get_irn_ne(block, env); if (header) { if (h->POnum < b->POnum) { header = block; h = b; } } else { header = block; h = b; } } /* check if this SCC contains only Phi, Add or Sub nodes */ bool only_phi = true; unsigned num_outside = 0; ir_node *out_rc = NULL; for (ir_node *irn = pscc->head, *next; irn != NULL; irn = next) { node_entry *e = get_irn_ne(irn, env); next = e->next; switch (get_irn_opcode(irn)) { case iro_Sub: { only_phi = false; ir_node *left = get_Sub_left(irn); node_entry *left_entry = get_irn_ne(left, env); ir_node *right = get_Sub_right(irn); node_entry *right_entry = get_irn_ne(right, env); if (left_entry->pscc != e->pscc || (right_entry->pscc != e->pscc && !is_rc(right, header))) { /* * Not an induction variable. * Region constant are only allowed on right hand side. */ goto fail; } break; } case iro_Add: only_phi = false; /* fall through */ case iro_Phi: foreach_irn_in_r(irn, i, pred) { node_entry *pe = get_irn_ne(pred, env); if (pe->pscc != e->pscc) { /* not in the same SCC, must be a region const */ if (!is_rc(pred, header)) { /* not an induction variable */ goto fail; } if (!out_rc) { out_rc = pred; ++num_outside; } else if (out_rc != pred) { ++num_outside; } } } break; default: /* not an induction variable */ goto fail; } } /* found an induction variable */ DB((dbg, LEVEL_2, " Found an induction variable:\n ")); if (only_phi && num_outside == 1 && get_irn_mode(pscc->head) != mode_M) { /* a phi cycle with only one real predecessor can be collapsed */ DB((dbg, LEVEL_2, " Found an USELESS Phi cycle:\n ")); for (ir_node *irn = pscc->head, *next; irn != NULL; irn = next) { node_entry *e = get_irn_ne(irn, env); next = e->next; e->header = NULL; exchange(irn, out_rc); } ++env->replaced; return; } /* set the header for every node in this SCC */ for (ir_node *irn = pscc->head, *next; irn != NULL; irn = next) { node_entry *e = get_irn_ne(irn, env); e->header = header; next = e->next; DB((dbg, LEVEL_2, " %+F,", irn)); } DB((dbg, LEVEL_2, "\n")); return; fail: for (ir_node *irn = pscc->head, *next; irn != NULL; irn = next) { node_entry *e = get_irn_ne(irn, env); next = e->next; e->header = NULL; } } /** * Process an SCC for the operator strength reduction. * * @param pscc the SCC * @param env the environment */ static void process_scc(scc *pscc, iv_env *env) { ir_node *head = pscc->head; node_entry *e = (node_entry*)get_irn_link(head); #ifdef DEBUG_libfirm DB((dbg, LEVEL_4, " SCC at %p:\n ", pscc)); for (ir_node *irn = pscc->head, *next; irn != NULL; irn = next) { node_entry *e = (node_entry*)get_irn_link(irn); next = e->next; DB((dbg, LEVEL_4, " %+F,", irn)); } DB((dbg, LEVEL_4, "\n")); #endif if (e->next == NULL) { /* this SCC has only a single member */ check_replace(head, env); } else { classify_iv(pscc, env); } } /** * If an SCC is a Phi only cycle, remove it. * * @param pscc an SCC that consists of Phi nodes only * @param env the environment */ static void remove_phi_cycle(scc *pscc, iv_env *env) { /* check if this SCC contains only Phi nodes */ ir_node *out_rc = NULL; for (ir_node *irn = pscc->head, *next; irn; irn = next) { node_entry *e = get_irn_ne(irn, env); next = e->next; if (!is_Phi(irn)) return; foreach_irn_in_r(irn, i, pred) { node_entry *pe = get_irn_ne(pred, env); if (pe->pscc != e->pscc) { /* not in the same SCC, must be the only input */ if (!out_rc) { out_rc = pred; } else if (out_rc != pred) { return; } } } } /* found a Phi cycle */ DB((dbg, LEVEL_2, " Found an USELESS Phi cycle:\n ")); for (ir_node *irn = pscc->head, *next; irn != NULL; irn = next) { node_entry *e = get_irn_ne(irn, env); next = e->next; e->header = NULL; exchange(irn, out_rc); } ++env->replaced; } /** * Process a SCC for the Phi cycle remove. * * @param pscc the SCC * @param env the environment */ static void process_phi_only_scc(scc *pscc, iv_env *env) { ir_node *head = pscc->head; node_entry *e = (node_entry*)get_irn_link(head); #ifdef DEBUG_libfirm DB((dbg, LEVEL_4, " SCC at %p:\n ", pscc)); for (ir_node *irn = pscc->head, *next; irn; irn = next) { node_entry *e = (node_entry*)get_irn_link(irn); next = e->next; DB((dbg, LEVEL_4, " %+F,", irn)); } DB((dbg, LEVEL_4, "\n")); #endif if (e->next != NULL) remove_phi_cycle(pscc, env); } /** * Push a node onto the stack. * * @param env the environment * @param n the node to push */ static void push(iv_env *env, ir_node *n) { if (env->tos == ARR_LEN(env->stack)) { size_t nlen = ARR_LEN(env->stack) * 2; ARR_RESIZE(ir_node *, env->stack, nlen); } env->stack[env->tos++] = n; node_entry *e = get_irn_ne(n, env); e->in_stack = true; } /** * Pop a node from the stack. * * @param env the environment * * @return The topmost node */ static ir_node *pop(iv_env *env) { ir_node *n = env->stack[--env->tos]; node_entry *e = get_irn_ne(n, env); e->in_stack = false; return n; } /** * Do Tarjan's SCC algorithm and drive OSR. * * @param irn start at this node * @param env the environment */ static void dfs(ir_node *irn, iv_env *env) { node_entry *node = get_irn_ne(irn, env); mark_irn_visited(irn); /* do not put blocks into the scc */ if (is_Block(irn)) { foreach_irn_in(irn, i, pred) { if (!irn_visited(pred)) dfs(pred, env); } } else { ir_node *block = get_nodes_block(irn); node->DFSnum = env->nextDFSnum++; node->low = node->DFSnum; push(env, irn); /* handle the block */ if (!irn_visited(block)) dfs(block, env); foreach_irn_in(irn, i, pred) { node_entry *o = get_irn_ne(pred, env); if (!irn_visited(pred)) { dfs(pred, env); node->low = MIN(node->low, o->low); } if (o->DFSnum < node->DFSnum && o->in_stack) node->low = MIN(o->DFSnum, node->low); } if (node->low == node->DFSnum) { scc *pscc = OALLOCZ(&env->obst, scc); ir_node *x; do { x = pop(env); node_entry *e = get_irn_ne(x, env); e->pscc = pscc; e->next = pscc->head; pscc->head = x; } while (x != irn); env->process_scc(pscc, env); } } } /** * Do the DFS by starting at the End node of a graph. * * @param irg the graph to process * @param env the environment */ static void do_dfs(ir_graph *irg, iv_env *env) { ir_node *end = get_irg_end(irg); ir_reserve_resources(irg, IR_RESOURCE_IRN_VISITED); inc_irg_visited(irg); /* visit all visible nodes */ dfs(end, env); /* visit the keep-alives */ for (int i = get_End_n_keepalives(end); i-- > 0; ) { ir_node *ka = get_End_keepalive(end, i); if (!irn_visited(ka)) dfs(ka, env); } ir_free_resources(irg, IR_RESOURCE_IRN_VISITED); } /** * Post-block-walker: assign the post-order number. */ static void assign_po(ir_node *block, void *ctx) { iv_env *env = (iv_env*)ctx; node_entry *e = get_irn_ne(block, env); e->POnum = env->POnum++; } /** * Apply one LFTR edge operation. * Return NULL if the transformation cannot be done safely without * an Overflow. * * @param iv the induction variable * @param rc the constant that should be translated * @param e the LFTR edge * @param env the IV environment * * @return the translated region constant or NULL * if the translation was not possible * * @note * 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 *apply_one_edge(ir_node *iv, ir_node *rc, ldtr_edge_t *e, iv_env *env) { if (env->osr_flags & osr_flag_lftr_with_ov_check) { 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)) { if (e->code == iro_Add && mode_is_reference(get_irn_mode(e->rc))) { /* However we allow ONE Pointer Add, as pointer arithmetic with * wrap around is undefined anyway */ return do_apply(e->code, NULL, rc, e->rc); } DB((dbg, LEVEL_4, " = UNKNOWN (%+F)", e->rc)); return NULL; } ir_tarval *tv_l = get_Const_tarval(rc); ir_tarval *tv_r = get_Const_tarval(e->rc); int old_wrap_on_overflow = tarval_get_wrap_on_overflow(); tarval_set_wrap_on_overflow(false); scc *pscc = get_iv_scc(iv, env); ir_tarval *tv_incr = pscc->incr; ir_tarval *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 */ ir_tarval *tv; switch (e->code) { case iro_Mul: 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_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_init = tarval_sub(tv_init, tv_r); DB((dbg, LEVEL_4, " - %+F", tv_r)); break; default: panic("unsupported opcode"); } if (tv == tarval_bad || tv_init == tarval_bad) { tarval_set_wrap_on_overflow(old_wrap_on_overflow); DB((dbg, LEVEL_4, " = OVERFLOW")); return NULL; } /* backwards counting in unsigned modes easily leads to overflow * in the increment. TODO: improve this situation */ if (tv_incr == tarval_bad) { tarval_set_wrap_on_overflow(old_wrap_on_overflow); DB((dbg, LEVEL_4, " = OVERFLOW (incr)")); return NULL; } ir_tarval *tv_end; if (pscc->code == iro_Add) { tv_end = tarval_add(tv, tv_incr); } else { assert(pscc->code == iro_Sub); tv_end = tarval_sub(tv, tv_incr); } tarval_set_wrap_on_overflow(old_wrap_on_overflow); if (tv_end == tarval_bad) { DB((dbg, LEVEL_4, " = OVERFLOW")); return NULL; } ir_graph *irg = get_irn_irg(iv); return new_r_Const(irg, tv); } return do_apply(e->code, NULL, rc, e->rc); } /** * Applies the operations represented by the LFTR edges to a * region constant and returns the value. * Return NULL if the transformation cannot be done safely without * an Overflow. * * @param pIV points to the IV node that starts the LFTR edge chain * after translation points to the new IV * @param rc the region constant that should be translated * @param env the IV environment * * @return the translated region constant or NULL * if the translation was not possible */ static ir_node *apply_edges(ir_node **pIV, ir_node *rc, iv_env *env) { ir_node *iv = *pIV; if (env->osr_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))); } while (rc != NULL) { ldtr_edge_t *e = lftr_find(iv, env); if (e != NULL) { rc = apply_one_edge(iv, rc, e, env); iv = e->dst; } else break; } DB((dbg, LEVEL_3, "\n")); *pIV = iv; return rc; } /** * Walker, finds Cmp(iv, rc) or Cmp(rc, iv) * and tries to optimize them. */ static void do_lftr(ir_node *cmp, void *ctx) { if (!is_Cmp(cmp)) return; iv_env *env = (iv_env*)ctx; ir_node *left = get_Cmp_left(cmp); ir_node *right = get_Cmp_right(cmp); ir_node *liv = is_iv(left, env); ir_node *riv = is_iv(right, env); ir_node *nleft = NULL; ir_node *nright = NULL; ir_node *iv; if (liv != NULL && is_rc(right, liv)) { iv = left; ir_node *rc = right; nright = apply_edges(&iv, rc, env); nleft = iv; } else if (riv != NULL && is_rc(left, riv)) { iv = right; ir_node *rc = left; nleft = apply_edges(&iv, rc, env); nright = iv; } if (nleft && nright) { if (is_counter_iv(iv, env)) { scc *pscc = get_iv_scc(iv, env); ir_tarval *tv_incr = pscc->incr; ir_mode *mode = get_tarval_mode(tv_incr); ir_tarval *zero = get_mode_null(mode); ir_relation incr_relation = tarval_cmp(tv_incr, zero); ir_relation relation = get_Cmp_relation(cmp); switch (relation) { case ir_relation_less: case ir_relation_less_equal: if (incr_relation == ir_relation_less) /* Prevent: for (i = 42; i <= 42; i--) -> for (i = 43; i >= 43; i--) */ return; /* FALLTHROUGH */ case ir_relation_greater: case ir_relation_greater_equal: if (incr_relation == ir_relation_greater) /* Prevent: for (i = 42; i >= 42; i++) -> for (i = 41; i >= 41; i++) */ return; default: break; } } DB((dbg, LEVEL_2, " LFTR for %+F\n", cmp)); set_Cmp_left(cmp, nleft); set_Cmp_right(cmp, nright); ++env->lftr_replaced; } } /** * do linear function test replacement. * * @param irg the graph that should be optimized * @param env the IV environment */ static void lftr(ir_graph *irg, iv_env *env) { irg_walk_graph(irg, NULL, do_lftr, env); } /* Remove any Phi cycles with only one real input. */ void remove_phi_cycles(ir_graph *irg) { assure_irg_properties(irg, IR_GRAPH_PROPERTY_CONSISTENT_DOMINANCE | IR_GRAPH_PROPERTY_CONSISTENT_OUTS | IR_GRAPH_PROPERTY_CONSISTENT_OUT_EDGES); FIRM_DBG_REGISTER(dbg, "firm.opt.remove_phi"); DB((dbg, LEVEL_1, "Doing Phi cycle removement for %+F\n", irg)); iv_env env; obstack_init(&env.obst); env.stack = NEW_ARR_F(ir_node *, 128); env.tos = 0; env.nextDFSnum = 0; env.POnum = 0; env.quad_map = NULL; env.lftr_edges = NULL; env.replaced = 0; env.lftr_replaced = 0; env.osr_flags = 0; env.need_postpass = false; env.process_scc = process_phi_only_scc; /* Clear all links and move Proj nodes into the * the same block as their predecessors. * This can improve the placement of new nodes. */ ir_reserve_resources(irg, IR_RESOURCE_IRN_LINK); irg_walk_graph(irg, NULL, firm_clear_link, NULL); /* calculate the post order number for blocks. */ irg_out_block_walk(get_irg_start_block(irg), NULL, assign_po, &env); /* calculate the SCC's and drive OSR. */ do_dfs(irg, &env); ir_free_resources(irg, IR_RESOURCE_IRN_LINK); if (env.replaced) { DB((dbg, LEVEL_1, "remove_phi_cycles: %u Cycles removed\n\n", env.replaced)); } DEL_ARR_F(env.stack); obstack_free(&env.obst, NULL); confirm_irg_properties(irg, IR_GRAPH_PROPERTIES_CONTROL_FLOW); } /** * Post-walker: fix Add and Sub nodes that where results of I<->P conversions. */ static void fix_adds_and_subs(ir_node *irn, void *ctx) { (void)ctx; if (is_Add(irn)) { ir_mode *mode = get_irn_mode(irn); if (mode_is_int(mode)) { ir_node *pred = get_Add_left(irn); if (get_irn_mode(pred) != mode) { ir_node *block = get_nodes_block(pred); pred = new_r_Conv(block, pred, mode); set_Add_left(irn, pred); } pred = get_Add_right(irn); if (get_irn_mode(pred) != mode) { ir_node *block = get_nodes_block(pred); pred = new_r_Conv(block, pred, mode); set_Add_right(irn, pred); } } } else if (is_Sub(irn)) { ir_mode *mode = get_irn_mode(irn); if (mode_is_int(mode)) { ir_node *left = get_Sub_left(irn); ir_node *right = get_Sub_right(irn); ir_mode *l_mode = get_irn_mode(left); ir_mode *r_mode = get_irn_mode(right); if (mode_is_int(l_mode) && mode_is_int(r_mode)) { if (l_mode != mode) { ir_node *block = get_nodes_block(left); left = new_r_Conv(block, left, mode); set_Sub_left(irn, left); } if (r_mode != mode) { ir_node *block = get_nodes_block(right); right = new_r_Conv(block, right, mode); set_Sub_right(irn, right); } } } else if (mode_is_reference(mode)) { ir_node *left = get_Sub_left(irn); ir_node *right = get_Sub_right(irn); ir_mode *l_mode = get_irn_mode(left); ir_mode *r_mode = get_irn_mode(right); if (mode_is_int(l_mode)) { /* Usually, Sub(I*,P) is an error, hence the verifier rejects it. * However, it is correct in this case, so add Conv to make verifier happy. */ ir_node *block = get_nodes_block(right); ir_node *lconv = new_r_Conv(block, left, r_mode); assert(mode_is_reference(r_mode)); set_Sub_left(irn, lconv); } } } } /* Performs Operator Strength Reduction for the passed graph. */ void opt_osr(ir_graph *irg, unsigned flags) { FIRM_DBG_REGISTER(dbg, "firm.opt.osr"); assure_irg_properties(irg, IR_GRAPH_PROPERTY_CONSISTENT_DOMINANCE | IR_GRAPH_PROPERTY_CONSISTENT_OUTS | IR_GRAPH_PROPERTY_CONSISTENT_OUT_EDGES); DB((dbg, LEVEL_1, "Doing Operator Strength Reduction for %+F\n", irg)); iv_env env; obstack_init(&env.obst); env.stack = NEW_ARR_F(ir_node *, 128); env.tos = 0; env.nextDFSnum = 0; env.POnum = 0; env.quad_map = new_set(quad_cmp, 64); env.lftr_edges = new_set(lftr_cmp, 64); env.replaced = 0; env.lftr_replaced = 0; env.osr_flags = flags; env.need_postpass = false; env.process_scc = process_scc; /* Clear all links and move Proj nodes into the * the same block as its predecessors. * This can improve the placement of new nodes. */ ir_reserve_resources(irg, IR_RESOURCE_IRN_LINK); irg_walk_graph(irg, NULL, firm_clear_link, NULL); irg_block_edges_walk(get_irg_start_block(irg), NULL, assign_po, &env); /* calculate the SCC's and drive OSR. */ do_dfs(irg, &env); if (env.replaced) { if (env.need_postpass) irg_walk_graph(irg, NULL, fix_adds_and_subs, &env); /* try linear function test replacements */ lftr(irg, &env); (void)lftr; DB((dbg, LEVEL_1, "Replacements: %u + %u (lftr)\n\n", env.replaced, env.lftr_replaced)); } ir_free_resources(irg, IR_RESOURCE_IRN_LINK); del_set(env.lftr_edges); del_set(env.quad_map); DEL_ARR_F(env.stack); obstack_free(&env.obst, NULL); confirm_irg_properties(irg, IR_GRAPH_PROPERTIES_NONE); }