X-Git-Url: http://nsz.repo.hu/git/?a=blobdiff_plain;f=ir%2Fopt%2Fopt_osr.c;h=101fb54c3f21210487d59b31ef6c2a9db82de842;hb=d16d39df6772995a29ecdc8de1904ccb2e523599;hp=26b130841c74902a8f0392ab4ca82d5035fe6004;hpb=754f75ba7836c706b5360afbb30e84cd14d59317;p=libfirm diff --git a/ir/opt/opt_osr.c b/ir/opt/opt_osr.c index 26b130841..101fb54c3 100644 --- a/ir/opt/opt_osr.c +++ b/ir/opt/opt_osr.c @@ -1,7 +1,7 @@ /** * Project: libFIRM - * File name: ir/opt/opt_osr. - * Purpose: Operator Strength Reduction, + * File name: ir/opt/opt_osr.c + * Purpose: Operator Strength Reduction, based on * Keith D. Cooper, L. Taylor Simpson, Christopher A. Vick * Author: Michael Beck * Modified by: @@ -14,13 +14,6 @@ #include "config.h" #endif -#ifdef HAVE_MALLOC_H -#include -#endif -#ifdef HAVE_ALLOCA_H -#include -#endif - #include "opt_osr.h" #include "irgraph.h" #include "ircons.h" @@ -30,13 +23,17 @@ #include "irgmod.h" #include "irflag_t.h" #include "irgwalk.h" +#include "irouts.h" #include "debug.h" #include "obst.h" #include "set.h" #include "tv.h" #include "hashptr.h" #include "irtools.h" +#include "irloop_t.h" #include "array.h" +#include "firmstat.h" +#include "xmalloc.h" /** The debug handle. */ DEBUG_ONLY(static firm_dbg_module_t *dbg;) @@ -69,27 +66,29 @@ typedef struct iv_env { unsigned replaced; /**< number of replaced ops */ unsigned lftr_replaced; /**< number of applied linear function test replacements */ unsigned flags; /**< additional flags */ + /** 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 quad_t { - opcode 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 */ +typedef struct quadruple_t { + ir_opcode 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 */ -} quad_t; + ir_node *res; /**< the reduced operation */ +} quadruple_t; /** * A LFTR edge. */ typedef struct LFTR_edge { - ir_node *src; /**< the source node */ - ir_node *dst; /**< the destination node */ - opcode code; /**< the opcode that must be applied */ - ir_node *rc; /**< the region const that must be applied */ + ir_node *src; /**< the source node */ + ir_node *dst; /**< the destination node */ + ir_opcode code; /**< the opcode that must be applied */ + ir_node *rc; /**< the region const that must be applied */ } LFTR_edge; /* forward */ @@ -105,6 +104,7 @@ static int LFTR_cmp(const void *e1, const void *e2, size_t size) { return l1->src != l2->src; } +#if 0 /** * Find a LFTR edge. */ @@ -115,11 +115,12 @@ static LFTR_edge *LFTR_find(ir_node *src, iv_env *env) { return set_find(env->lftr_edges, &key, sizeof(key), HASH_PTR(src)); } +#endif /** * Add a LFTR edge. */ -static void LFTR_add(ir_node *src, ir_node *dst, opcode code, ir_node *rc, iv_env *env) { +static void LFTR_add(ir_node *src, ir_node *dst, ir_opcode code, ir_node *rc, iv_env *env) { LFTR_edge key; key.src = src; @@ -127,7 +128,11 @@ static void LFTR_add(ir_node *src, ir_node *dst, opcode code, ir_node *rc, iv_en key.code = code; key.rc = rc; - assert(LFTR_find(src, env) == NULL); + /* + * There might be more than one edge here. This is rather bad + * because we currently store only one. + */ +// assert(LFTR_find(src, env) == NULL); set_insert(env->lftr_edges, &key, sizeof(key), HASH_PTR(src)); } @@ -148,6 +153,9 @@ static node_entry *get_irn_ne(ir_node *irn, iv_env *env) { /** * 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) { @@ -156,31 +164,42 @@ static ir_node *is_iv(ir_node *irn, iv_env *env) { /** * 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 int is_rc(ir_node *irn, ir_node *header_block) { ir_node *block = get_nodes_block(irn); - return block_dominates(block, header_block); + 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) { - const quad_t *c1 = e1; - const quad_t *c2 = e2; + const quadruple_t *c1 = e1; + const quadruple_t *c2 = 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(opcode code, ir_node *op1, ir_node *op2, iv_env *env) { - quad_t key, *entry; +static ir_node *search(ir_opcode code, ir_node *op1, ir_node *op2, iv_env *env) { + quadruple_t key, *entry; key.code = code; - key.op1 = op2; + key.op1 = op1; key.op2 = op2; entry = set_find(env->quad_map, &key, sizeof(key), @@ -191,13 +210,19 @@ static ir_node *search(opcode code, ir_node *op1, ir_node *op2, iv_env *env) { } /** - * Add an reduced operation was already calculated. + * 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(opcode code, ir_node *op1, ir_node *op2, ir_node *result, iv_env *env) { - quad_t key; +static void add(ir_opcode code, ir_node *op1, ir_node *op2, ir_node *result, iv_env *env) { + quadruple_t key; key.code = code; - key.op1 = op2; + key.op1 = op1; key.op2 = op2; key.res = result; @@ -209,21 +234,32 @@ static void add(opcode code, ir_node *op1, ir_node *op2, ir_node *result, iv_env * 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 block1; + return block2; assert(block_dominates(block2, block1)); - return block2; + return block1; } /** - * create an op1 code op1 operation. + * 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 + * @param mode the mode of the new operation + * + * @return the newly created node */ -static ir_node *do_apply(opcode code, dbg_info *db, ir_node *op1, ir_node *op2, ir_mode *mode) { +static ir_node *do_apply(ir_opcode code, dbg_info *db, ir_node *op1, ir_node *op2, ir_mode *mode) { ir_graph *irg = current_ir_graph; ir_node *result; ir_node *block = find_location(get_nodes_block(op1), get_nodes_block(op2)); @@ -247,9 +283,17 @@ static ir_node *do_apply(opcode code, dbg_info *db, ir_node *op1, ir_node *op2, /** * 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 *orig, ir_node *op1, ir_node *op2, iv_env *env) { - opcode code = get_irn_opcode(orig); + ir_opcode code = get_irn_opcode(orig); ir_node *result = search(code, op1, op2, env); if (! result) { @@ -265,17 +309,24 @@ static ir_node *apply(ir_node *orig, ir_node *op1, ir_node *op2, iv_env *env) { } else { result = do_apply(code, db, op1, op2, get_irn_mode(orig)); - get_irn_ne(result, env)->header = NULL; - } + 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) { - opcode code = get_irn_opcode(orig); + ir_opcode code = get_irn_opcode(orig); ir_node *result = search(code, iv, rc, env); if (! result) { @@ -284,11 +335,12 @@ static ir_node *reduce(ir_node *orig, ir_node *iv, ir_node *rc, iv_env *env) { ir_mode *mode = get_irn_mode(orig); result = exact_copy(iv); - if (mode_is_reference(mode)) { - /* bad case: we replace a reference mode calculation. - assure that the new IV will be a reference one */ - set_irn_mode(result, mode); - } + + /* Beware: we must always create a new nduction variable with the same mode + as the node we are replacing. Espicially 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. */ + set_irn_mode(result, mode); 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)); @@ -310,50 +362,64 @@ static ir_node *reduce(ir_node *orig, ir_node *iv, ir_node *rc, iv_env *env) { else if (is_Phi(result)) o = apply(orig, o, rc, env); else { - switch (code) { - case iro_Mul: + if (code == iro_Mul) o = apply(orig, o, rc, env); - break; - } } 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; } /** - * Do the replacement operation. + * The Replace operation. * * @param irn the node that will be replaced * @param iv the induction variable * @param rc the region constant * @param env the environment */ -static void replace(ir_node *irn, ir_node *iv, ir_node *rc, iv_env *env) { +static int replace(ir_node *irn, ir_node *iv, ir_node *rc, iv_env *env) { ir_node *result; - - DB((dbg, LEVEL_2, " Replacing %+F\n", irn)); - - result = reduce(irn, iv, rc, env); - if (result && result != irn) { - node_entry *e, *iv_e; - - exchange(irn, result); - e = get_irn_ne(result, env); - iv_e = get_irn_ne(iv, env); - e->header = iv_e->header; + ir_loop *iv_loop = get_irn_loop(get_nodes_block(iv)); + ir_loop *irn_loop = get_irn_loop(get_nodes_block(irn)); + + /* only replace nodes that are in the same (or deeper loops) */ + if (get_loop_depth(irn_loop) >= get_loop_depth(iv_loop)) { + DB((dbg, LEVEL_2, " Replacing %+F\n", irn)); + + result = reduce(irn, iv, rc, env); + if (result != irn) { + node_entry *e, *iv_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; + } + return 1; } + return 0; } /** - * check if a node can be replaced. + * Check if a node can be replaced (+, -, *). + * + * @param irn the node to check + * @param env the environment + * + * @return non-zero if irn should be Replace'd */ static int check_replace(ir_node *irn, iv_env *env) { - ir_node *left, *right, *iv, *rc; - ir_op *op = get_irn_op(irn); - opcode code = get_op_code(op); - ir_node *liv, *riv; + ir_node *left, *right, *iv, *rc; + ir_op *op = get_irn_op(irn); + ir_opcode code = get_op_code(op); + ir_node *liv, *riv; switch (code) { case iro_Mul: @@ -369,28 +435,47 @@ static int check_replace(ir_node *irn, iv_env *env) { if (liv && is_rc(right, liv)) { iv = left; rc = right; } - else if (is_op_commutative(op) && - riv && is_rc(left, riv)) { + else if (riv && is_op_commutative(op) && + is_rc(left, riv)) { iv = right; rc = left; } if (iv) { - replace(irn, iv, rc, env); - ++env->replaced; - return 1; + if (code == iro_Mul && env->flags & osr_flag_ignore_x86_shift) { + if (is_Const(rc)) { + tarval *tv = get_Const_tarval(rc); + + if (tarval_is_long(tv)) { + long value = get_tarval_long(tv); + + if (value == 2 || value == 4 || value == 8) { + /* do not reduce multiplications by 2, 4, 8 */ + break; + } + } + } + } + + return replace(irn, iv, rc, env); } break; + default: + break; } return 0; } /** - * check which SCC's are induction variables + * Check which SCC's are induction variables. + * + * @param pscc a SCC + * @param env the environment */ static void classify_iv(scc *pscc, iv_env *env) { ir_node *irn, *next, *header = NULL; - node_entry *h, *b; - int j; + node_entry *b, *h = NULL; + int j, only_phi, num_outside; + ir_node *out_rc; /* find the header block for this scc */ for (irn = pscc->head; irn; irn = next) { @@ -413,6 +498,9 @@ static void classify_iv(scc *pscc, iv_env *env) { } /* check if this scc contains only Phi, Add or Sub nodes */ + only_phi = 1; + num_outside = 0; + out_rc = NULL; for (irn = pscc->head; irn; irn = next) { node_entry *e = get_irn_ne(irn, env); @@ -420,6 +508,8 @@ static void classify_iv(scc *pscc, iv_env *env) { switch (get_irn_opcode(irn)) { case iro_Add: case iro_Sub: + only_phi = 0; + /* fall through */ case iro_Phi: for (j = get_irn_arity(irn) - 1; j >= 0; --j) { ir_node *pred = get_irn_n(irn, j); @@ -431,6 +521,12 @@ static void classify_iv(scc *pscc, iv_env *env) { /* not an induction variable */ goto fail; } + if (! out_rc) { + out_rc = pred; + ++num_outside; + } else if (out_rc != pred) { + ++num_outside; + } } } break; @@ -440,14 +536,29 @@ static void classify_iv(scc *pscc, iv_env *env) { } } /* found an induction variable */ - DB((dbg, LEVEL_2, " Found an induction variable in %+F\n", pscc->head)); + DB((dbg, LEVEL_2, " Found an induction variable:\n ")); + if (only_phi && num_outside == 1) { + /* a phi cycle with only one real predecessor can be collapsed */ + DB((dbg, LEVEL_2, " Found an USELESS Phi cycle:\n ")); + + for (irn = pscc->head; irn; 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 (irn = pscc->head; irn; 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: @@ -461,7 +572,10 @@ fail: } /** - * Process a SCC given as a list. + * Process a 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; @@ -486,14 +600,90 @@ static void process_scc(scc *pscc, iv_env *env) { if (e->next == NULL) { /* this SCC has only a single member */ check_replace(head, env); - } - else { + } else { classify_iv(pscc, env); } } +/** + * If an SCC is a Phi only cycle, remove it. + */ +static void remove_phi_cycle(scc *pscc, iv_env *env) { + ir_node *irn, *next; + int j; + ir_node *out_rc; + + /* check if this scc contains only Phi, Add or Sub nodes */ + out_rc = NULL; + for (irn = pscc->head; irn; irn = next) { + node_entry *e = get_irn_ne(irn, env); + + next = e->next; + if (! is_Phi(irn)) + return; + + for (j = get_irn_arity(irn) - 1; j >= 0; --j) { + ir_node *pred = get_irn_n(irn, j); + 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 (irn = pscc->head; irn; 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 removement. + * + * @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 = get_irn_link(head); + +#ifdef DEBUG_libfirm + { + ir_node *irn, *next; + + DB((dbg, LEVEL_4, " SCC at %p:\n ", pscc)); + for (irn = pscc->head; irn; irn = next) { + node_entry *e = 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) { node_entry *e; @@ -510,19 +700,21 @@ static void push(iv_env *env, ir_node *n) { /** * 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); + ir_node *n = env->stack[--env->tos]; + node_entry *e = get_irn_ne(n, env); - e->in_stack = 0; - return n; + e->in_stack = 0; + return n; } /** - * Do Tarjan's SCC algorithm and drive OSR + * Do Tarjan's SCC algorithm and drive OSR. * * @param irn start at this node * @param env the environment @@ -582,13 +774,16 @@ static void dfs(ir_node *irn, iv_env *env) pscc->head = x; } while (x != irn); - process_scc(pscc, env); + env->process_scc(pscc, env); } } } /** - * Do the DFS by starting end the End node + * 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_graph *rem = current_ir_graph; @@ -623,11 +818,16 @@ static void assign_po(ir_node *block, void *ctx) { e->POnum = env->POnum++; } +#if 0 /** - * follows the LFTR edges and return the last node in the chain. + * Follows the LFTR edges and return the last node in the chain. * * @param irn the node that should be followed * @param env the IV environment + * + * @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 *followEdges(ir_node *irn, iv_env *env) { for (;;) { @@ -647,6 +847,13 @@ static ir_node *followEdges(ir_node *irn, iv_env *env) { * @param rc the IV node 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 *applyOneEdge(ir_node *rc, LFTR_edge *e, iv_env *env) { if (env->flags & osr_flag_lftr_with_ov_check) { @@ -702,6 +909,9 @@ static ir_node *applyOneEdge(ir_node *rc, LFTR_edge *e, iv_env *env) { * @param iv the IV node that starts the LFTR edge chain * @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 *applyEdges(ir_node *iv, ir_node *rc, iv_env *env) { ir_node *irn = iv; @@ -729,7 +939,8 @@ static ir_node *applyEdges(ir_node *iv, ir_node *rc, iv_env *env) { } /** - * Walker; find Cmp(iv, rc) or Cmp(rc, iv) + * Walker, finds Cmp(iv, rc) or Cmp(rc, iv) + * and tries to optimize them. */ static void do_lftr(ir_node *cmp, void *ctx) { iv_env *env = ctx; @@ -749,7 +960,7 @@ static void do_lftr(ir_node *cmp, void *ctx) { iv = left; rc = right; nright = applyEdges(iv, rc, env); - if (nright) { + if (nright && nright != rc) { nleft = followEdges(iv, env); } } @@ -757,7 +968,7 @@ static void do_lftr(ir_node *cmp, void *ctx) { iv = right; rc = left; nleft = applyEdges(iv, rc, env); - if (nleft) { + if (nleft && nleft != rc) { nright = followEdges(iv, env); } } @@ -772,23 +983,44 @@ static void do_lftr(ir_node *cmp, void *ctx) { /** * 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); } +#endif + +/** + * Pre-walker: set all node links to NULL and fix the + * block of Proj nodes. + */ +static void clear_and_fix(ir_node *irn, void *env) +{ + set_irn_link(irn, NULL); + + if (is_Proj(irn)) { + ir_node *pred = get_Proj_pred(irn); + set_irn_n(irn, -1, get_irn_n(pred, -1)); + } +} /* Performs Operator Strength Reduction for the passed graph. */ void opt_osr(ir_graph *irg, unsigned flags) { - iv_env env; + iv_env env; + ir_graph *rem; - if (! get_opt_strength_red()) + if (! get_opt_strength_red()) { + /* only kill Phi cycles */ + remove_phi_cycles(irg); return; + } - FIRM_DBG_REGISTER(dbg, "firm.opt.osr"); -// firm_dbg_set_mask(dbg, SET_LEVEL_3); + rem = current_ir_graph; + current_ir_graph = irg; - /* and dominance as well */ - assure_doms(irg); + FIRM_DBG_REGISTER(dbg, "firm.opt.osr"); DB((dbg, LEVEL_1, "Doing Operator Strength Reduction for %+F\n", irg)); @@ -802,27 +1034,86 @@ void opt_osr(ir_graph *irg, unsigned flags) { env.replaced = 0; env.lftr_replaced = 0; env.flags = flags; + env.process_scc = process_scc; - /* clear all links */ - irg_walk_graph(irg, NULL, firm_clear_link, NULL); + /* Clear all links and move Proj nodes into the + the same block as it's predecessors. + This can improve the placement of new nodes. + */ + irg_walk_graph(irg, NULL, clear_and_fix, NULL); + + /* we need dominance */ + assure_doms(irg); + assure_irg_outs(irg); - /* calculate the post order number */ - irg_block_walk_graph(irg, NULL, assign_po, &env); + /* 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 */ + /* calculate the SCC's and drive OSR. */ do_dfs(irg, &env); if (env.replaced) { /* try linear function test replacements */ - lftr(irg, &env); + //lftr(irg, &env); set_irg_outs_inconsistent(irg); - set_irg_loopinfo_inconsistent(irg); + DB((dbg, LEVEL_1, "Replacements: %u + %u (lftr)\n\n", env.replaced, env.lftr_replaced)); } - DB((dbg, LEVEL_1, "Replacements: %u + %u (lftr)\n\n", env.replaced, env.lftr_replaced)); del_set(env.lftr_edges); del_set(env.quad_map); DEL_ARR_F(env.stack); obstack_free(&env.obst, NULL); + + current_ir_graph = rem; +} + +/* Remove any Phi cycles with only one real input. */ +void remove_phi_cycles(ir_graph *irg) { + iv_env env; + ir_graph *rem; + + rem = current_ir_graph; + current_ir_graph = irg; + + FIRM_DBG_REGISTER(dbg, "firm.opt.remove_phi"); + + DB((dbg, LEVEL_1, "Doing Phi cycle removement for %+F\n", irg)); + + 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.flags = 0; + env.process_scc = process_phi_only_scc; + + /* Clear all links and move Proj nodes into the + the same block as it's predecessors. + This can improve the placement of new nodes. + */ + irg_walk_graph(irg, NULL, clear_and_fix, NULL); + + /* we need dominance */ + assure_irg_outs(irg); + + /* 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); + + if (env.replaced) { + set_irg_outs_inconsistent(irg); + DB((dbg, LEVEL_1, "remove_phi_cycles: %u Cycles removed\n\n", env.replaced)); + } + + DEL_ARR_F(env.stack); + obstack_free(&env.obst, NULL); + + current_ir_graph = rem; }