X-Git-Url: http://git.sourceforge.jp/view?a=blobdiff_plain;f=gcc%2Ftree-ssa-loop-manip.c;h=22e5847b2f32abcf0780ad782dd98ac230510ee9;hb=4fb5e5ca92a88d6176b9d2a9282735bdb989a6b2;hp=43499560e5495cfaa05fb7bb5e0c7e72d9b3e00c;hpb=7218e5a93faa86e9a4f24e84d60e9b19fa49053b;p=pf3gnuchains%2Fgcc-fork.git diff --git a/gcc/tree-ssa-loop-manip.c b/gcc/tree-ssa-loop-manip.c index 43499560e54..22e5847b2f3 100644 --- a/gcc/tree-ssa-loop-manip.c +++ b/gcc/tree-ssa-loop-manip.c @@ -1,5 +1,5 @@ /* High-level loop manipulation functions. - Copyright (C) 2004 Free Software Foundation, Inc. + Copyright (C) 2004, 2005 Free Software Foundation, Inc. This file is part of GCC. @@ -15,8 +15,8 @@ for more details. You should have received a copy of the GNU General Public License along with GCC; see the file COPYING. If not, write to the Free -Software Foundation, 59 Temple Place - Suite 330, Boston, MA -02111-1307, USA. */ +Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA +02110-1301, USA. */ #include "config.h" #include "system.h" @@ -36,12 +36,14 @@ Software Foundation, 59 Temple Place - Suite 330, Boston, MA #include "tree-pass.h" #include "cfglayout.h" #include "tree-scalar-evolution.h" +#include "params.h" /* Creates an induction variable with value BASE + STEP * iteration in LOOP. It is expected that neither BASE nor STEP are shared with other expressions (unless the sharing rules allow this). Use VAR as a base var_decl for it (if NULL, a new temporary will be created). The increment will occur at - INCR_POS (after it if AFTER is true, before it otherwise). The ssa versions + INCR_POS (after it if AFTER is true, before it otherwise). INCR_POS and + AFTER can be computed using standard_iv_increment_position. The ssa versions of the variable before and after increment will be stored in VAR_BEFORE and VAR_AFTER (unless they are NULL). */ @@ -53,11 +55,12 @@ create_iv (tree base, tree step, tree var, struct loop *loop, tree stmt, initial, step1, stmts; tree vb, va; enum tree_code incr_op = PLUS_EXPR; + edge pe = loop_preheader_edge (loop); if (!var) { var = create_tmp_var (TREE_TYPE (base), "ivtmp"); - add_referenced_tmp_var (var); + add_referenced_var (var); } vb = make_ssa_name (var, NULL_TREE); @@ -73,7 +76,7 @@ create_iv (tree base, tree step, tree var, struct loop *loop, { if (TYPE_UNSIGNED (TREE_TYPE (step))) { - step1 = fold (build1 (NEGATE_EXPR, TREE_TYPE (step), step)); + step1 = fold_build1 (NEGATE_EXPR, TREE_TYPE (step), step); if (tree_int_cst_lt (step1, step)) { incr_op = MINUS_EXPR; @@ -86,14 +89,19 @@ create_iv (tree base, tree step, tree var, struct loop *loop, && may_negate_without_overflow_p (step)) { incr_op = MINUS_EXPR; - step = fold (build1 (NEGATE_EXPR, TREE_TYPE (step), step)); + step = fold_build1 (NEGATE_EXPR, TREE_TYPE (step), step); } } } - stmt = build2 (MODIFY_EXPR, void_type_node, va, - build2 (incr_op, TREE_TYPE (base), - vb, step)); + /* Gimplify the step if necessary. We put the computations in front of the + loop (i.e. the step should be loop invariant). */ + step = force_gimple_operand (step, &stmts, true, var); + if (stmts) + bsi_insert_on_edge_immediate (pe, stmts); + + stmt = build2_gimple (GIMPLE_MODIFY_STMT, va, + build2 (incr_op, TREE_TYPE (base), vb, step)); SSA_NAME_DEF_STMT (va) = stmt; if (after) bsi_insert_after (incr_pos, stmt, BSI_NEW_STMT); @@ -102,16 +110,12 @@ create_iv (tree base, tree step, tree var, struct loop *loop, initial = force_gimple_operand (base, &stmts, true, var); if (stmts) - { - edge pe = loop_preheader_edge (loop); - - bsi_insert_on_edge_immediate_loop (pe, stmts); - } + bsi_insert_on_edge_immediate (pe, stmts); stmt = create_phi_node (vb, loop->header); SSA_NAME_DEF_STMT (vb) = stmt; - add_phi_arg (&stmt, initial, loop_preheader_edge (loop)); - add_phi_arg (&stmt, va, loop_latch_edge (loop)); + add_phi_arg (stmt, initial, loop_preheader_edge (loop)); + add_phi_arg (stmt, va, loop_latch_edge (loop)); } /* Add exit phis for the USE on EXIT. */ @@ -138,11 +142,9 @@ add_exit_phis_edge (basic_block exit, tree use) return; phi = create_phi_node (use, exit); - + create_new_def_for (PHI_RESULT (phi), phi, PHI_RESULT_PTR (phi)); FOR_EACH_EDGE (e, ei, exit->preds) - add_phi_arg (&phi, use, e); - - SSA_NAME_DEF_STMT (use) = def_stmt; + add_phi_arg (phi, use, e); } /* Add exit phis for VAR that is used in LIVEIN. @@ -156,12 +158,15 @@ add_exit_phis_var (tree var, bitmap livein, bitmap exits) basic_block def_bb = bb_for_stmt (SSA_NAME_DEF_STMT (var)); bitmap_iterator bi; - bitmap_clear_bit (livein, def_bb->index); + if (is_gimple_reg (var)) + bitmap_clear_bit (livein, def_bb->index); + else + bitmap_set_bit (livein, def_bb->index); - def = BITMAP_XMALLOC (); + def = BITMAP_ALLOC (NULL); bitmap_set_bit (def, def_bb->index); compute_global_livein (livein, def); - BITMAP_XFREE (def); + BITMAP_FREE (def); EXECUTE_IF_AND_IN_BITMAP (exits, livein, 0, index, bi) { @@ -190,7 +195,7 @@ add_exit_phis (bitmap names_to_rename, bitmap *use_blocks, bitmap loop_exits) static bitmap get_loops_exits (void) { - bitmap exits = BITMAP_XMALLOC (); + bitmap exits = BITMAP_ALLOC (NULL); basic_block bb; edge e; edge_iterator ei; @@ -211,10 +216,11 @@ get_loops_exits (void) /* For USE in BB, if it is used outside of the loop it is defined in, mark it for rewrite. Record basic block BB where it is used - to USE_BLOCKS. */ + to USE_BLOCKS. Record the ssa name index to NEED_PHIS bitmap. */ static void -find_uses_to_rename_use (basic_block bb, tree use, bitmap *use_blocks) +find_uses_to_rename_use (basic_block bb, tree use, bitmap *use_blocks, + bitmap need_phis) { unsigned ver; basic_block def_bb; @@ -223,6 +229,10 @@ find_uses_to_rename_use (basic_block bb, tree use, bitmap *use_blocks) if (TREE_CODE (use) != SSA_NAME) return; + /* We don't need to keep virtual operands in loop-closed form. */ + if (!is_gimple_reg (use)) + return; + ver = SSA_NAME_VERSION (use); def_bb = bb_for_stmt (SSA_NAME_DEF_STMT (use)); if (!def_bb) @@ -234,51 +244,75 @@ find_uses_to_rename_use (basic_block bb, tree use, bitmap *use_blocks) return; if (!use_blocks[ver]) - use_blocks[ver] = BITMAP_XMALLOC (); + use_blocks[ver] = BITMAP_ALLOC (NULL); bitmap_set_bit (use_blocks[ver], bb->index); - if (!flow_bb_inside_loop_p (def_loop, bb)) - mark_for_rewrite (use); + bitmap_set_bit (need_phis, ver); } /* For uses in STMT, mark names that are used outside of the loop they are defined to rewrite. Record the set of blocks in that the ssa - names are defined to USE_BLOCKS. */ + names are defined to USE_BLOCKS and the ssa names themselves to + NEED_PHIS. */ static void -find_uses_to_rename_stmt (tree stmt, bitmap *use_blocks) +find_uses_to_rename_stmt (tree stmt, bitmap *use_blocks, bitmap need_phis) { ssa_op_iter iter; tree var; basic_block bb = bb_for_stmt (stmt); - get_stmt_operands (stmt); - - FOR_EACH_SSA_TREE_OPERAND (var, stmt, iter, SSA_OP_ALL_USES | SSA_OP_ALL_KILLS) - find_uses_to_rename_use (bb, var, use_blocks); + FOR_EACH_SSA_TREE_OPERAND (var, stmt, iter, SSA_OP_ALL_USES) + find_uses_to_rename_use (bb, var, use_blocks, need_phis); } +/* Marks names that are used in BB and outside of the loop they are + defined in for rewrite. Records the set of blocks in that the ssa + names are defined to USE_BLOCKS. Record the SSA names that will + need exit PHIs in NEED_PHIS. */ + +static void +find_uses_to_rename_bb (basic_block bb, bitmap *use_blocks, bitmap need_phis) +{ + block_stmt_iterator bsi; + edge e; + edge_iterator ei; + tree phi; + + FOR_EACH_EDGE (e, ei, bb->succs) + for (phi = phi_nodes (e->dest); phi; phi = PHI_CHAIN (phi)) + find_uses_to_rename_use (bb, PHI_ARG_DEF_FROM_EDGE (phi, e), + use_blocks, need_phis); + + for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi)) + find_uses_to_rename_stmt (bsi_stmt (bsi), use_blocks, need_phis); +} + /* Marks names that are used outside of the loop they are defined in for rewrite. Records the set of blocks in that the ssa - names are defined to USE_BLOCKS. */ + names are defined to USE_BLOCKS. If CHANGED_BBS is not NULL, + scan only blocks in this set. */ static void -find_uses_to_rename (bitmap *use_blocks) +find_uses_to_rename (bitmap changed_bbs, bitmap *use_blocks, bitmap need_phis) { basic_block bb; - block_stmt_iterator bsi; - tree phi; - unsigned i; + unsigned index; + bitmap_iterator bi; - FOR_EACH_BB (bb) + if (changed_bbs && !bitmap_empty_p (changed_bbs)) { - for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi)) - for (i = 0; i < (unsigned) PHI_NUM_ARGS (phi); i++) - find_uses_to_rename_use (PHI_ARG_EDGE (phi, i)->src, - PHI_ARG_DEF (phi, i), use_blocks); - - for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi)) - find_uses_to_rename_stmt (bsi_stmt (bsi), use_blocks); + EXECUTE_IF_SET_IN_BITMAP (changed_bbs, 0, index, bi) + { + find_uses_to_rename_bb (BASIC_BLOCK (index), use_blocks, need_phis); + } + } + else + { + FOR_EACH_BB (bb) + { + find_uses_to_rename_bb (bb, use_blocks, need_phis); + } } } @@ -306,36 +340,45 @@ find_uses_to_rename (bitmap *use_blocks) Looking from the outer loop with the normal SSA form, the first use of k is not well-behaved, while the second one is an induction variable with - base 99 and step 1. */ + base 99 and step 1. + + If CHANGED_BBS is not NULL, we look for uses outside loops only in + the basic blocks in this set. + + UPDATE_FLAG is used in the call to update_ssa. See + TODO_update_ssa* for documentation. */ void -rewrite_into_loop_closed_ssa (void) +rewrite_into_loop_closed_ssa (bitmap changed_bbs, unsigned update_flag) { bitmap loop_exits = get_loops_exits (); bitmap *use_blocks; - unsigned i; - bitmap names_to_rename; + unsigned i, old_num_ssa_names; + bitmap names_to_rename = BITMAP_ALLOC (NULL); - gcc_assert (!any_marked_for_rewrite_p ()); + /* If the pass has caused the SSA form to be out-of-date, update it + now. */ + update_ssa (update_flag); - use_blocks = xcalloc (num_ssa_names, sizeof (bitmap)); + old_num_ssa_names = num_ssa_names; + use_blocks = XCNEWVEC (bitmap, old_num_ssa_names); /* Find the uses outside loops. */ - find_uses_to_rename (use_blocks); + find_uses_to_rename (changed_bbs, use_blocks, names_to_rename); - /* Add the phi nodes on exits of the loops for the names we need to + /* Add the PHI nodes on exits of the loops for the names we need to rewrite. */ - names_to_rename = marked_ssa_names (); add_exit_phis (names_to_rename, use_blocks, loop_exits); - for (i = 0; i < num_ssa_names; i++) - BITMAP_XFREE (use_blocks[i]); + for (i = 0; i < old_num_ssa_names; i++) + BITMAP_FREE (use_blocks[i]); free (use_blocks); - BITMAP_XFREE (loop_exits); - BITMAP_XFREE (names_to_rename); + BITMAP_FREE (loop_exits); + BITMAP_FREE (names_to_rename); - /* Do the rewriting. */ - rewrite_ssa_into_ssa (); + /* Fix up all the names found to be used outside their original + loops. */ + update_ssa (TODO_update_ssa); } /* Check invariants of the loop closed ssa form for the USE in BB. */ @@ -346,7 +389,7 @@ check_loop_closed_ssa_use (basic_block bb, tree use) tree def; basic_block def_bb; - if (TREE_CODE (use) != SSA_NAME) + if (TREE_CODE (use) != SSA_NAME || !is_gimple_reg (use)) return; def = SSA_NAME_DEF_STMT (use); @@ -363,8 +406,6 @@ check_loop_closed_ssa_stmt (basic_block bb, tree stmt) ssa_op_iter iter; tree var; - get_stmt_operands (stmt); - FOR_EACH_SSA_TREE_OPERAND (var, stmt, iter, SSA_OP_ALL_USES) check_loop_closed_ssa_use (bb, var); } @@ -379,7 +420,10 @@ verify_loop_closed_ssa (void) tree phi; unsigned i; - verify_ssa (); + if (current_loops == NULL) + return; + + verify_ssa (false); FOR_EACH_BB (bb) { @@ -400,57 +444,31 @@ void split_loop_exit_edge (edge exit) { basic_block dest = exit->dest; - basic_block bb = loop_split_edge_with (exit, NULL); + basic_block bb = split_edge (exit); tree phi, new_phi, new_name, name; use_operand_p op_p; for (phi = phi_nodes (dest); phi; phi = PHI_CHAIN (phi)) { - op_p = PHI_ARG_DEF_PTR_FROM_EDGE (phi, EDGE_SUCC (bb, 0)); + op_p = PHI_ARG_DEF_PTR_FROM_EDGE (phi, single_succ_edge (bb)); name = USE_FROM_PTR (op_p); - /* If the argument of the phi node is a constant, we do not need + /* If the argument of the PHI node is a constant, we do not need to keep it inside loop. */ if (TREE_CODE (name) != SSA_NAME) continue; /* Otherwise create an auxiliary phi node that will copy the value - of the ssa name out of the loop. */ + of the SSA name out of the loop. */ new_name = duplicate_ssa_name (name, NULL); new_phi = create_phi_node (new_name, bb); SSA_NAME_DEF_STMT (new_name) = new_phi; - add_phi_arg (&new_phi, name, exit); + add_phi_arg (new_phi, name, exit); SET_USE (op_p, new_name); } } -/* Insert statement STMT to the edge E and update the loop structures. - Returns the newly created block (if any). */ - -basic_block -bsi_insert_on_edge_immediate_loop (edge e, tree stmt) -{ - basic_block src, dest, new_bb; - struct loop *loop_c; - - src = e->src; - dest = e->dest; - - loop_c = find_common_loop (src->loop_father, dest->loop_father); - - new_bb = bsi_insert_on_edge_immediate (e, stmt); - - if (!new_bb) - return NULL; - - add_bb_to_loop (new_bb, loop_c); - if (dest->loop_father->latch == src) - dest->loop_father->latch = new_bb; - - return new_bb; -} - /* Returns the basic block in that statements should be emitted for induction variables incremented at the end of the LOOP. */ @@ -470,10 +488,10 @@ ip_normal_pos (struct loop *loop) basic_block bb; edge exit; - if (EDGE_COUNT (loop->latch->preds) > 1) + if (!single_pred_p (loop->latch)) return NULL; - bb = EDGE_PRED (loop->latch, 0)->src; + bb = single_pred (loop->latch); last = last_stmt (bb); if (TREE_CODE (last) != COND_EXPR) return NULL; @@ -522,88 +540,44 @@ copy_phi_node_args (unsigned first_new_block) unsigned i; for (i = first_new_block; i < (unsigned) last_basic_block; i++) - BASIC_BLOCK (i)->rbi->duplicated = 1; + BASIC_BLOCK (i)->flags |= BB_DUPLICATED; for (i = first_new_block; i < (unsigned) last_basic_block; i++) add_phi_args_after_copy_bb (BASIC_BLOCK (i)); for (i = first_new_block; i < (unsigned) last_basic_block; i++) - BASIC_BLOCK (i)->rbi->duplicated = 0; + BASIC_BLOCK (i)->flags &= ~BB_DUPLICATED; } -/* Renames variables in the area copied by tree_duplicate_loop_to_header_edge. - FIRST_NEW_BLOCK is the first block in the copied area. DEFINITIONS is - a bitmap of all ssa names defined inside the loop. */ - -static void -rename_variables (unsigned first_new_block, bitmap definitions) -{ - unsigned i, copy_number = 0; - basic_block bb; - htab_t ssa_name_map = NULL; - - for (i = first_new_block; i < (unsigned) last_basic_block; i++) - { - bb = BASIC_BLOCK (i); - - /* We assume that first come all blocks from the first copy, then all - blocks from the second copy, etc. */ - if (copy_number != (unsigned) bb->rbi->copy_number) - { - allocate_ssa_names (definitions, &ssa_name_map); - copy_number = bb->rbi->copy_number; - } - - rewrite_to_new_ssa_names_bb (bb, ssa_name_map); - } - - htab_delete (ssa_name_map); -} - -/* Sets SSA_NAME_DEF_STMT for results of all phi nodes in BB. */ - -static void -set_phi_def_stmts (basic_block bb) -{ - tree phi; - for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi)) - SSA_NAME_DEF_STMT (PHI_RESULT (phi)) = phi; -} +/* The same as cfgloopmanip.c:duplicate_loop_to_header_edge, but also + updates the PHI nodes at start of the copied region. In order to + achieve this, only loops whose exits all lead to the same location + are handled. -/* The same as cfgloopmanip.c:duplicate_loop_to_header_edge, but also updates - ssa. In order to achieve this, only loops whose exits all lead to the same - location are handled. - - FIXME: we create some degenerate phi nodes that could be avoided by copy - propagating them instead. Unfortunately this is not completely - straightforward due to problems with constant folding. */ + Notice that we do not completely update the SSA web after + duplication. The caller is responsible for calling update_ssa + after the loop has been duplicated. */ bool tree_duplicate_loop_to_header_edge (struct loop *loop, edge e, - struct loops *loops, unsigned int ndupl, sbitmap wont_exit, edge orig, edge *to_remove, unsigned int *n_to_remove, int flags) { unsigned first_new_block; - basic_block bb; - unsigned i; - bitmap definitions; - if (!(loops->state & LOOPS_HAVE_SIMPLE_LATCHES)) + if (!(current_loops->state & LOOPS_HAVE_SIMPLE_LATCHES)) return false; - if (!(loops->state & LOOPS_HAVE_PREHEADERS)) + if (!(current_loops->state & LOOPS_HAVE_PREHEADERS)) return false; #ifdef ENABLE_CHECKING verify_loop_closed_ssa (); #endif - gcc_assert (!any_marked_for_rewrite_p ()); - first_new_block = last_basic_block; - if (!duplicate_loop_to_header_edge (loop, e, loops, ndupl, wont_exit, + if (!duplicate_loop_to_header_edge (loop, e, ndupl, wont_exit, orig, to_remove, n_to_remove, flags)) return false; @@ -613,209 +587,343 @@ tree_duplicate_loop_to_header_edge (struct loop *loop, edge e, /* Copy the phi node arguments. */ copy_phi_node_args (first_new_block); - /* Rename the variables. */ - definitions = marked_ssa_names (); - rename_variables (first_new_block, definitions); - unmark_all_for_rewrite (); - BITMAP_XFREE (definitions); - - /* For some time we have the identical ssa names as results in multiple phi - nodes. When phi node is resized, it sets SSA_NAME_DEF_STMT of its result - to the new copy. This means that we cannot easily ensure that the ssa - names defined in those phis are pointing to the right one -- so just - recompute SSA_NAME_DEF_STMT for them. */ - - for (i = first_new_block; i < (unsigned) last_basic_block; i++) - { - bb = BASIC_BLOCK (i); - set_phi_def_stmts (bb); - if (bb->rbi->copy_number == 1) - set_phi_def_stmts (bb->rbi->original); - } - scev_reset (); -#ifdef ENABLE_CHECKING - verify_loop_closed_ssa (); -#endif return true; } -/*--------------------------------------------------------------------------- - Loop versioning - ---------------------------------------------------------------------------*/ - -/* Adjust phi nodes for 'first' basic block. 'second' basic block is a copy - of 'first'. Both of them are dominated by 'new_head' basic block. When - 'new_head' was created by 'second's incoming edge it received phi arguments - on the edge by split_edge(). Later, additional edge 'e' was created to - connect 'new_head' and 'first'. Now this routine adds phi args on this - additional edge 'e' that new_head to second edge received as part of edge - splitting. -*/ +/* Build if (COND) goto THEN_LABEL; else goto ELSE_LABEL; */ -static void -lv_adjust_loop_header_phi (basic_block first, basic_block second, - basic_block new_head, edge e) +static tree +build_if_stmt (tree cond, tree then_label, tree else_label) { - tree phi1, phi2; + return build3 (COND_EXPR, void_type_node, + cond, + build1 (GOTO_EXPR, void_type_node, then_label), + build1 (GOTO_EXPR, void_type_node, else_label)); +} - /* Browse all 'second' basic block phi nodes and add phi args to - edge 'e' for 'first' head. PHI args are always in correct order. */ +/* Returns true if we can unroll LOOP FACTOR times. Number + of iterations of the loop is returned in NITER. */ - for (phi2 = phi_nodes (second), phi1 = phi_nodes (first); - phi2 && phi1; - phi2 = PHI_CHAIN (phi2), phi1 = PHI_CHAIN (phi1)) - { - int i; - for (i = 0; i < PHI_NUM_ARGS (phi2); i++) - { - if (PHI_ARG_EDGE (phi2, i)->src == new_head) - { - tree def = PHI_ARG_DEF (phi2, i); - add_phi_arg (&phi1, def, e); - } - } - } -} +bool +can_unroll_loop_p (struct loop *loop, unsigned factor, + struct tree_niter_desc *niter) +{ + edge exit; -/* Adjust entry edge for lv. - - e is an incoming edge. + /* Check whether unrolling is possible. We only want to unroll loops + for that we are able to determine number of iterations. We also + want to split the extra iterations of the loop from its end, + therefore we require that the loop has precisely one + exit. */ - --- edge e ---- > [second_head] + exit = single_dom_exit (loop); + if (!exit) + return false; - Split it and insert new conditional expression and adjust edges. - - --- edge e ---> [cond expr] ---> [first_head] - | - +---------> [second_head] + if (!number_of_iterations_exit (loop, exit, niter, false) + || niter->cmp == ERROR_MARK + /* Scalar evolutions analysis might have copy propagated + the abnormal ssa names into these expressions, hence + emitting the computations based on them during loop + unrolling might create overlapping life ranges for + them, and failures in out-of-ssa. */ + || contains_abnormal_ssa_name_p (niter->may_be_zero) + || contains_abnormal_ssa_name_p (niter->control.base) + || contains_abnormal_ssa_name_p (niter->control.step) + || contains_abnormal_ssa_name_p (niter->bound)) + return false; -*/ - -static basic_block -lv_adjust_loop_entry_edge (basic_block first_head, - basic_block second_head, - edge e, - tree cond_expr) -{ - block_stmt_iterator bsi; - basic_block new_head = NULL; - tree goto1 = NULL_TREE; - tree goto2 = NULL_TREE; - tree new_cond_expr = NULL_TREE; - edge e0, e1; - - gcc_assert (e->dest == second_head); - - /* Split edge 'e'. This will create a new basic block, where we can - insert conditional expr. */ - new_head = split_edge (e); - - /* Build new conditional expr */ - goto1 = build1 (GOTO_EXPR, void_type_node, tree_block_label (first_head)); - goto2 = build1 (GOTO_EXPR, void_type_node, tree_block_label (second_head)); - new_cond_expr = build3 (COND_EXPR, void_type_node, cond_expr, goto1, goto2); - - /* Add new cond. in new head. */ - bsi = bsi_start (new_head); - bsi_insert_after (&bsi, new_cond_expr, BSI_NEW_STMT); - - /* Adjust edges appropriately to connect new head with first head - as well as second head. */ - e0 = EDGE_SUCC (new_head, 0); - e0->flags &= ~EDGE_FALLTHRU; - e0->flags |= EDGE_FALSE_VALUE; - e1 = make_edge (new_head, first_head, EDGE_TRUE_VALUE); - set_immediate_dominator (CDI_DOMINATORS, first_head, new_head); - set_immediate_dominator (CDI_DOMINATORS, second_head, new_head); - - /* Adjust loop header phi nodes. */ - lv_adjust_loop_header_phi (first_head, second_head, new_head, e1); - - return new_head; -} + /* And of course, we must be able to duplicate the loop. */ + if (!can_duplicate_loop_p (loop)) + return false; -/* Main entry point for Loop Versioning transformation. - -This transformation given a condition and a loop, creates --if (condition) { loop_copy1 } else { loop_copy2 }, -where loop_copy1 is the loop transformed in one way, and loop_copy2 -is the loop transformed in another way (or unchanged). 'condition' -may be a run time test for things that were not resolved by static -analysis (overlapping ranges (anti-aliasing), alignment, etc.). */ - -struct loop * -tree_ssa_loop_version (struct loops *loops, struct loop * loop, - tree cond_expr, basic_block *condition_bb) -{ - edge entry, latch_edge, exit, true_edge, false_edge; - basic_block first_head, second_head; - int irred_flag; - struct loop *nloop; + /* The final loop should be small enough. */ + if (tree_num_loop_insns (loop) * factor + > (unsigned) PARAM_VALUE (PARAM_MAX_UNROLLED_INSNS)) + return false; - /* CHECKME: Loop versioning does not handle nested loop at this point. */ - if (loop->inner) - return NULL; + return true; +} - /* Record entry and latch edges for the loop */ - entry = loop_preheader_edge (loop); +/* Determines the conditions that control execution of LOOP unrolled FACTOR + times. DESC is number of iterations of LOOP. ENTER_COND is set to + condition that must be true if the main loop can be entered. + EXIT_BASE, EXIT_STEP, EXIT_CMP and EXIT_BOUND are set to values describing + how the exit from the unrolled loop should be controlled. */ - /* Note down head of loop as first_head. */ - first_head = entry->dest; +static void +determine_exit_conditions (struct loop *loop, struct tree_niter_desc *desc, + unsigned factor, tree *enter_cond, + tree *exit_base, tree *exit_step, + enum tree_code *exit_cmp, tree *exit_bound) +{ + tree stmts; + tree base = desc->control.base; + tree step = desc->control.step; + tree bound = desc->bound; + tree type = TREE_TYPE (base); + tree bigstep, delta; + tree min = lower_bound_in_type (type, type); + tree max = upper_bound_in_type (type, type); + enum tree_code cmp = desc->cmp; + tree cond = boolean_true_node, assum; + + *enter_cond = boolean_false_node; + *exit_base = NULL_TREE; + *exit_step = NULL_TREE; + *exit_cmp = ERROR_MARK; + *exit_bound = NULL_TREE; + gcc_assert (cmp != ERROR_MARK); + + /* We only need to be correct when we answer question + "Do at least FACTOR more iterations remain?" in the unrolled loop. + Thus, transforming BASE + STEP * i <> BOUND to + BASE + STEP * i < BOUND is ok. */ + if (cmp == NE_EXPR) + { + if (tree_int_cst_sign_bit (step)) + cmp = GT_EXPR; + else + cmp = LT_EXPR; + } + else if (cmp == LT_EXPR) + { + gcc_assert (!tree_int_cst_sign_bit (step)); + } + else if (cmp == GT_EXPR) + { + gcc_assert (tree_int_cst_sign_bit (step)); + } + else + gcc_unreachable (); + + /* The main body of the loop may be entered iff: + + 1) desc->may_be_zero is false. + 2) it is possible to check that there are at least FACTOR iterations + of the loop, i.e., BOUND - step * FACTOR does not overflow. + 3) # of iterations is at least FACTOR */ + + if (!zero_p (desc->may_be_zero)) + cond = fold_build2 (TRUTH_AND_EXPR, boolean_type_node, + invert_truthvalue (desc->may_be_zero), + cond); + + bigstep = fold_build2 (MULT_EXPR, type, step, + build_int_cst_type (type, factor)); + delta = fold_build2 (MINUS_EXPR, type, bigstep, step); + if (cmp == LT_EXPR) + assum = fold_build2 (GE_EXPR, boolean_type_node, + bound, + fold_build2 (PLUS_EXPR, type, min, delta)); + else + assum = fold_build2 (LE_EXPR, boolean_type_node, + bound, + fold_build2 (PLUS_EXPR, type, max, delta)); + cond = fold_build2 (TRUTH_AND_EXPR, boolean_type_node, assum, cond); - /* Duplicate loop. */ - irred_flag = entry->flags & EDGE_IRREDUCIBLE_LOOP; - entry->flags &= ~EDGE_IRREDUCIBLE_LOOP; - if (!tree_duplicate_loop_to_header_edge (loop, entry, loops, 1, - NULL, NULL, NULL, NULL, 0)) + bound = fold_build2 (MINUS_EXPR, type, bound, delta); + assum = fold_build2 (cmp, boolean_type_node, base, bound); + cond = fold_build2 (TRUTH_AND_EXPR, boolean_type_node, assum, cond); + + cond = force_gimple_operand (unshare_expr (cond), &stmts, false, NULL_TREE); + if (stmts) + bsi_insert_on_edge_immediate (loop_preheader_edge (loop), stmts); + /* cond now may be a gimple comparison, which would be OK, but also any + other gimple rhs (say a && b). In this case we need to force it to + operand. */ + if (!is_gimple_condexpr (cond)) { - entry->flags |= irred_flag; - return NULL; + cond = force_gimple_operand (cond, &stmts, true, NULL_TREE); + if (stmts) + bsi_insert_on_edge_immediate (loop_preheader_edge (loop), stmts); } + *enter_cond = cond; - /* After duplication entry edge now points to new loop head block. - Note down new head as second_head. */ - second_head = entry->dest; + base = force_gimple_operand (unshare_expr (base), &stmts, true, NULL_TREE); + if (stmts) + bsi_insert_on_edge_immediate (loop_preheader_edge (loop), stmts); + bound = force_gimple_operand (unshare_expr (bound), &stmts, true, NULL_TREE); + if (stmts) + bsi_insert_on_edge_immediate (loop_preheader_edge (loop), stmts); - /* Split loop entry edge and insert new block with cond expr. */ - *condition_bb = lv_adjust_loop_entry_edge (first_head, second_head, entry, - cond_expr); + *exit_base = base; + *exit_step = bigstep; + *exit_cmp = cmp; + *exit_bound = bound; +} - latch_edge = EDGE_SUCC (loop->latch->rbi->copy, 0); - - extract_true_false_edges_from_block (*condition_bb, &true_edge, &false_edge); - nloop = loopify (loops, - latch_edge, - EDGE_PRED (loop->header->rbi->copy, 0), - *condition_bb, true_edge, false_edge, - false /* Do not redirect all edges. */); - - exit = loop->single_exit; - if (exit) - nloop->single_exit = find_edge (exit->src->rbi->copy, exit->dest); - - /* loopify redirected latch_edge. Update its PENDING_STMTS. */ - flush_pending_stmts (latch_edge); - - /* loopify redirected condition_bb's succ edge. Update its PENDING_STMTS. */ - extract_true_false_edges_from_block (*condition_bb, &true_edge, &false_edge); - flush_pending_stmts (false_edge); - - /* Adjust irreducible flag. */ - if (irred_flag) +/* Unroll LOOP FACTOR times. DESC describes number of iterations of LOOP. + EXIT is the exit of the loop to that DESC corresponds. + + If N is number of iterations of the loop and MAY_BE_ZERO is the condition + under that loop exits in the first iteration even if N != 0, + + while (1) + { + x = phi (init, next); + + pre; + if (st) + break; + post; + } + + becomes (with possibly the exit conditions formulated a bit differently, + avoiding the need to create a new iv): + + if (MAY_BE_ZERO || N < FACTOR) + goto rest; + + do + { + x = phi (init, next); + + pre; + post; + pre; + post; + ... + pre; + post; + N -= FACTOR; + + } while (N >= FACTOR); + + rest: + init' = phi (init, x); + + while (1) + { + x = phi (init', next); + + pre; + if (st) + break; + post; + } */ + +void +tree_unroll_loop (struct loop *loop, unsigned factor, + edge exit, struct tree_niter_desc *desc) +{ + tree dont_exit, exit_if, ctr_before, ctr_after; + tree enter_main_cond, exit_base, exit_step, exit_bound; + enum tree_code exit_cmp; + tree phi_old_loop, phi_new_loop, phi_rest, init, next, new_init, var; + struct loop *new_loop; + basic_block rest, exit_bb; + edge old_entry, new_entry, old_latch, precond_edge, new_exit; + edge nonexit, new_nonexit; + block_stmt_iterator bsi; + use_operand_p op; + bool ok; + unsigned est_niter; + unsigned irr = loop_preheader_edge (loop)->flags & EDGE_IRREDUCIBLE_LOOP; + sbitmap wont_exit; + + est_niter = expected_loop_iterations (loop); + determine_exit_conditions (loop, desc, factor, + &enter_main_cond, &exit_base, &exit_step, + &exit_cmp, &exit_bound); + + new_loop = loop_version (loop, enter_main_cond, NULL, true); + gcc_assert (new_loop != NULL); + update_ssa (TODO_update_ssa); + + /* Unroll the loop and remove the old exits. */ + dont_exit = ((exit->flags & EDGE_TRUE_VALUE) + ? boolean_false_node + : boolean_true_node); + if (exit == EDGE_SUCC (exit->src, 0)) + nonexit = EDGE_SUCC (exit->src, 1); + else + nonexit = EDGE_SUCC (exit->src, 0); + nonexit->probability = REG_BR_PROB_BASE; + exit->probability = 0; + nonexit->count += exit->count; + exit->count = 0; + exit_if = last_stmt (exit->src); + COND_EXPR_COND (exit_if) = dont_exit; + update_stmt (exit_if); + + wont_exit = sbitmap_alloc (factor); + sbitmap_ones (wont_exit); + ok = tree_duplicate_loop_to_header_edge + (loop, loop_latch_edge (loop), factor - 1, + wont_exit, NULL, NULL, NULL, DLTHE_FLAG_UPDATE_FREQ); + free (wont_exit); + gcc_assert (ok); + update_ssa (TODO_update_ssa); + + /* Prepare the cfg and update the phi nodes. */ + rest = loop_preheader_edge (new_loop)->src; + precond_edge = single_pred_edge (rest); + split_edge (loop_latch_edge (loop)); + exit_bb = single_pred (loop->latch); + + new_exit = make_edge (exit_bb, rest, EDGE_FALSE_VALUE | irr); + new_exit->count = loop_preheader_edge (loop)->count; + est_niter = est_niter / factor + 1; + new_exit->probability = REG_BR_PROB_BASE / est_niter; + + new_nonexit = single_pred_edge (loop->latch); + new_nonexit->flags = EDGE_TRUE_VALUE; + new_nonexit->probability = REG_BR_PROB_BASE - new_exit->probability; + + old_entry = loop_preheader_edge (loop); + new_entry = loop_preheader_edge (new_loop); + old_latch = loop_latch_edge (loop); + for (phi_old_loop = phi_nodes (loop->header), + phi_new_loop = phi_nodes (new_loop->header); + phi_old_loop; + phi_old_loop = PHI_CHAIN (phi_old_loop), + phi_new_loop = PHI_CHAIN (phi_new_loop)) { - (*condition_bb)->flags |= BB_IRREDUCIBLE_LOOP; - loop_preheader_edge (loop)->flags |= EDGE_IRREDUCIBLE_LOOP; - loop_preheader_edge (nloop)->flags |= EDGE_IRREDUCIBLE_LOOP; - EDGE_PRED ((*condition_bb), 0)->flags |= EDGE_IRREDUCIBLE_LOOP; + init = PHI_ARG_DEF_FROM_EDGE (phi_old_loop, old_entry); + op = PHI_ARG_DEF_PTR_FROM_EDGE (phi_new_loop, new_entry); + gcc_assert (operand_equal_for_phi_arg_p (init, USE_FROM_PTR (op))); + next = PHI_ARG_DEF_FROM_EDGE (phi_old_loop, old_latch); + + /* Prefer using original variable as a base for the new ssa name. + This is necessary for virtual ops, and useful in order to avoid + losing debug info for real ops. */ + if (TREE_CODE (next) == SSA_NAME) + var = SSA_NAME_VAR (next); + else if (TREE_CODE (init) == SSA_NAME) + var = SSA_NAME_VAR (init); + else + { + var = create_tmp_var (TREE_TYPE (init), "unrinittmp"); + add_referenced_var (var); + } + + new_init = make_ssa_name (var, NULL_TREE); + phi_rest = create_phi_node (new_init, rest); + SSA_NAME_DEF_STMT (new_init) = phi_rest; + + add_phi_arg (phi_rest, init, precond_edge); + add_phi_arg (phi_rest, next, new_exit); + SET_USE (op, new_init); } - /* At this point condition_bb is loop predheader with two successors, - first_head and second_head. Make sure that loop predheader has only - one successor. */ - loop_split_edge_with (loop_preheader_edge (loop), NULL); - loop_split_edge_with (loop_preheader_edge (nloop), NULL); + /* Finally create the new counter for number of iterations and add the new + exit instruction. */ + bsi = bsi_last (exit_bb); + create_iv (exit_base, exit_step, NULL_TREE, loop, + &bsi, true, &ctr_before, &ctr_after); + exit_if = build_if_stmt (build2 (exit_cmp, boolean_type_node, ctr_after, + exit_bound), + tree_block_label (loop->latch), + tree_block_label (rest)); + bsi_insert_after (&bsi, exit_if, BSI_NEW_STMT); - return nloop; +#ifdef ENABLE_CHECKING + verify_flow_info (); + verify_dominators (CDI_DOMINATORS); + verify_loop_structure (); + verify_loop_closed_ssa (); +#endif }