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Diffstat (limited to 'gcc-4.8/gcc/tree-ssa-loop-manip.c')
| -rw-r--r-- | gcc-4.8/gcc/tree-ssa-loop-manip.c | 1398 |
1 files changed, 0 insertions, 1398 deletions
diff --git a/gcc-4.8/gcc/tree-ssa-loop-manip.c b/gcc-4.8/gcc/tree-ssa-loop-manip.c deleted file mode 100644 index 4645588..0000000 --- a/gcc-4.8/gcc/tree-ssa-loop-manip.c +++ /dev/null @@ -1,1398 +0,0 @@ -/* High-level loop manipulation functions. - Copyright (C) 2004-2013 Free Software Foundation, Inc. - -This file is part of GCC. - -GCC is free software; you can redistribute it and/or modify it -under the terms of the GNU General Public License as published by the -Free Software Foundation; either version 3, or (at your option) any -later version. - -GCC is distributed in the hope that it will be useful, but WITHOUT -ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or -FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License -for more details. - -You should have received a copy of the GNU General Public License -along with GCC; see the file COPYING3. If not see -<http://www.gnu.org/licenses/>. */ - -#include "config.h" -#include "system.h" -#include "coretypes.h" -#include "tm.h" -#include "tree.h" -#include "tm_p.h" -#include "basic-block.h" -#include "tree-flow.h" -#include "dumpfile.h" -#include "gimple-pretty-print.h" -#include "cfgloop.h" -#include "tree-pass.h" /* ??? for TODO_update_ssa but this isn't a pass. */ -#include "tree-scalar-evolution.h" -#include "params.h" -#include "tree-inline.h" -#include "langhooks.h" - -/* All bitmaps for rewriting into loop-closed SSA go on this obstack, - so that we can free them all at once. */ -static bitmap_obstack loop_renamer_obstack; - -/* 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). 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). */ - -void -create_iv (tree base, tree step, tree var, struct loop *loop, - gimple_stmt_iterator *incr_pos, bool after, - tree *var_before, tree *var_after) -{ - gimple stmt; - tree initial, step1; - gimple_seq stmts; - tree vb, va; - enum tree_code incr_op = PLUS_EXPR; - edge pe = loop_preheader_edge (loop); - - if (var != NULL_TREE) - { - vb = make_ssa_name (var, NULL); - va = make_ssa_name (var, NULL); - } - else - { - vb = make_temp_ssa_name (TREE_TYPE (base), NULL, "ivtmp"); - va = make_temp_ssa_name (TREE_TYPE (base), NULL, "ivtmp"); - } - if (var_before) - *var_before = vb; - if (var_after) - *var_after = va; - - /* For easier readability of the created code, produce MINUS_EXPRs - when suitable. */ - if (TREE_CODE (step) == INTEGER_CST) - { - if (TYPE_UNSIGNED (TREE_TYPE (step))) - { - step1 = fold_build1 (NEGATE_EXPR, TREE_TYPE (step), step); - if (tree_int_cst_lt (step1, step)) - { - incr_op = MINUS_EXPR; - step = step1; - } - } - else - { - bool ovf; - - if (!tree_expr_nonnegative_warnv_p (step, &ovf) - && may_negate_without_overflow_p (step)) - { - incr_op = MINUS_EXPR; - step = fold_build1 (NEGATE_EXPR, TREE_TYPE (step), step); - } - } - } - if (POINTER_TYPE_P (TREE_TYPE (base))) - { - if (TREE_CODE (base) == ADDR_EXPR) - mark_addressable (TREE_OPERAND (base, 0)); - step = convert_to_ptrofftype (step); - if (incr_op == MINUS_EXPR) - step = fold_build1 (NEGATE_EXPR, TREE_TYPE (step), step); - incr_op = POINTER_PLUS_EXPR; - } - /* 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, NULL_TREE); - if (stmts) - gsi_insert_seq_on_edge_immediate (pe, stmts); - - stmt = gimple_build_assign_with_ops (incr_op, va, vb, step); - if (after) - gsi_insert_after (incr_pos, stmt, GSI_NEW_STMT); - else - gsi_insert_before (incr_pos, stmt, GSI_NEW_STMT); - - initial = force_gimple_operand (base, &stmts, true, var); - if (stmts) - gsi_insert_seq_on_edge_immediate (pe, stmts); - - stmt = create_phi_node (vb, loop->header); - add_phi_arg (stmt, initial, loop_preheader_edge (loop), UNKNOWN_LOCATION); - add_phi_arg (stmt, va, loop_latch_edge (loop), UNKNOWN_LOCATION); -} - -/* Return the innermost superloop LOOP of USE_LOOP that is a superloop of - both DEF_LOOP and USE_LOOP. */ - -static inline struct loop * -find_sibling_superloop (struct loop *use_loop, struct loop *def_loop) -{ - unsigned ud = loop_depth (use_loop); - unsigned dd = loop_depth (def_loop); - gcc_assert (ud > 0 && dd > 0); - if (ud > dd) - use_loop = superloop_at_depth (use_loop, dd); - if (ud < dd) - def_loop = superloop_at_depth (def_loop, ud); - while (loop_outer (use_loop) != loop_outer (def_loop)) - { - use_loop = loop_outer (use_loop); - def_loop = loop_outer (def_loop); - gcc_assert (use_loop && def_loop); - } - return use_loop; -} - -/* DEF_BB is a basic block containing a DEF that needs rewriting into - loop-closed SSA form. USE_BLOCKS is the set of basic blocks containing - uses of DEF that "escape" from the loop containing DEF_BB (i.e. blocks in - USE_BLOCKS are dominated by DEF_BB but not in the loop father of DEF_B). - ALL_EXITS[I] is the set of all basic blocks that exit loop I. - - Compute the subset of LOOP_EXITS that exit the loop containing DEF_BB - or one of its loop fathers, in which DEF is live. This set is returned - in the bitmap LIVE_EXITS. - - Instead of computing the complete livein set of the def, we use the loop - nesting tree as a form of poor man's structure analysis. This greatly - speeds up the analysis, which is important because this function may be - called on all SSA names that need rewriting, one at a time. */ - -static void -compute_live_loop_exits (bitmap live_exits, bitmap use_blocks, - bitmap *loop_exits, basic_block def_bb) -{ - unsigned i; - bitmap_iterator bi; - vec<basic_block> worklist; - struct loop *def_loop = def_bb->loop_father; - unsigned def_loop_depth = loop_depth (def_loop); - bitmap def_loop_exits; - - /* Normally the work list size is bounded by the number of basic - blocks in the largest loop. We don't know this number, but we - can be fairly sure that it will be relatively small. */ - worklist.create (MAX (8, n_basic_blocks / 128)); - - EXECUTE_IF_SET_IN_BITMAP (use_blocks, 0, i, bi) - { - basic_block use_bb = BASIC_BLOCK (i); - struct loop *use_loop = use_bb->loop_father; - gcc_checking_assert (def_loop != use_loop - && ! flow_loop_nested_p (def_loop, use_loop)); - if (! flow_loop_nested_p (use_loop, def_loop)) - use_bb = find_sibling_superloop (use_loop, def_loop)->header; - if (bitmap_set_bit (live_exits, use_bb->index)) - worklist.safe_push (use_bb); - } - - /* Iterate until the worklist is empty. */ - while (! worklist.is_empty ()) - { - edge e; - edge_iterator ei; - - /* Pull a block off the worklist. */ - basic_block bb = worklist.pop (); - - /* Make sure we have at least enough room in the work list - for all predecessors of this block. */ - worklist.reserve (EDGE_COUNT (bb->preds)); - - /* For each predecessor block. */ - FOR_EACH_EDGE (e, ei, bb->preds) - { - basic_block pred = e->src; - struct loop *pred_loop = pred->loop_father; - unsigned pred_loop_depth = loop_depth (pred_loop); - bool pred_visited; - - /* We should have met DEF_BB along the way. */ - gcc_assert (pred != ENTRY_BLOCK_PTR); - - if (pred_loop_depth >= def_loop_depth) - { - if (pred_loop_depth > def_loop_depth) - pred_loop = superloop_at_depth (pred_loop, def_loop_depth); - /* If we've reached DEF_LOOP, our train ends here. */ - if (pred_loop == def_loop) - continue; - } - else if (! flow_loop_nested_p (pred_loop, def_loop)) - pred = find_sibling_superloop (pred_loop, def_loop)->header; - - /* Add PRED to the LIVEIN set. PRED_VISITED is true if - we had already added PRED to LIVEIN before. */ - pred_visited = !bitmap_set_bit (live_exits, pred->index); - - /* If we have visited PRED before, don't add it to the worklist. - If BB dominates PRED, then we're probably looking at a loop. - We're only interested in looking up in the dominance tree - because DEF_BB dominates all the uses. */ - if (pred_visited || dominated_by_p (CDI_DOMINATORS, pred, bb)) - continue; - - worklist.quick_push (pred); - } - } - worklist.release (); - - def_loop_exits = BITMAP_ALLOC (&loop_renamer_obstack); - for (struct loop *loop = def_loop; - loop != current_loops->tree_root; - loop = loop_outer (loop)) - bitmap_ior_into (def_loop_exits, loop_exits[loop->num]); - bitmap_and_into (live_exits, def_loop_exits); - BITMAP_FREE (def_loop_exits); -} - -/* Add a loop-closing PHI for VAR in basic block EXIT. */ - -static void -add_exit_phi (basic_block exit, tree var) -{ - gimple phi; - edge e; - edge_iterator ei; - -#ifdef ENABLE_CHECKING - /* Check that at least one of the edges entering the EXIT block exits - the loop, or a superloop of that loop, that VAR is defined in. */ - gimple def_stmt = SSA_NAME_DEF_STMT (var); - basic_block def_bb = gimple_bb (def_stmt); - FOR_EACH_EDGE (e, ei, exit->preds) - { - struct loop *aloop = find_common_loop (def_bb->loop_father, - e->src->loop_father); - if (!flow_bb_inside_loop_p (aloop, e->dest)) - break; - } - - gcc_checking_assert (e); -#endif - - phi = create_phi_node (NULL_TREE, exit); - create_new_def_for (var, phi, gimple_phi_result_ptr (phi)); - FOR_EACH_EDGE (e, ei, exit->preds) - add_phi_arg (phi, var, e, UNKNOWN_LOCATION); - - if (dump_file && (dump_flags & TDF_DETAILS)) - { - fprintf (dump_file, ";; Created LCSSA PHI: "); - print_gimple_stmt (dump_file, phi, 0, dump_flags); - } -} - -/* Add exit phis for VAR that is used in LIVEIN. - Exits of the loops are stored in LOOP_EXITS. */ - -static void -add_exit_phis_var (tree var, bitmap use_blocks, bitmap *loop_exits) -{ - unsigned index; - bitmap_iterator bi; - basic_block def_bb = gimple_bb (SSA_NAME_DEF_STMT (var)); - bitmap live_exits = BITMAP_ALLOC (&loop_renamer_obstack); - - gcc_checking_assert (! bitmap_bit_p (use_blocks, def_bb->index)); - - compute_live_loop_exits (live_exits, use_blocks, loop_exits, def_bb); - - EXECUTE_IF_SET_IN_BITMAP (live_exits, 0, index, bi) - { - add_exit_phi (BASIC_BLOCK (index), var); - } - - BITMAP_FREE (live_exits); -} - -/* Add exit phis for the names marked in NAMES_TO_RENAME. - Exits of the loops are stored in EXITS. Sets of blocks where the ssa - names are used are stored in USE_BLOCKS. */ - -static void -add_exit_phis (bitmap names_to_rename, bitmap *use_blocks, bitmap *loop_exits) -{ - unsigned i; - bitmap_iterator bi; - - EXECUTE_IF_SET_IN_BITMAP (names_to_rename, 0, i, bi) - { - add_exit_phis_var (ssa_name (i), use_blocks[i], loop_exits); - } -} - -/* Fill the array of bitmaps LOOP_EXITS with all loop exit edge targets. */ - -static void -get_loops_exits (bitmap *loop_exits) -{ - loop_iterator li; - struct loop *loop; - unsigned j; - edge e; - - FOR_EACH_LOOP (li, loop, 0) - { - vec<edge> exit_edges = get_loop_exit_edges (loop); - loop_exits[loop->num] = BITMAP_ALLOC (&loop_renamer_obstack); - FOR_EACH_VEC_ELT (exit_edges, j, e) - bitmap_set_bit (loop_exits[loop->num], e->dest->index); - exit_edges.release (); - } -} - -/* 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. Record the ssa name index to NEED_PHIS bitmap. */ - -static void -find_uses_to_rename_use (basic_block bb, tree use, bitmap *use_blocks, - bitmap need_phis) -{ - unsigned ver; - basic_block def_bb; - struct loop *def_loop; - - if (TREE_CODE (use) != SSA_NAME) - return; - - ver = SSA_NAME_VERSION (use); - def_bb = gimple_bb (SSA_NAME_DEF_STMT (use)); - if (!def_bb) - return; - def_loop = def_bb->loop_father; - - /* If the definition is not inside a loop, it is not interesting. */ - if (!loop_outer (def_loop)) - return; - - /* If the use is not outside of the loop it is defined in, it is not - interesting. */ - if (flow_bb_inside_loop_p (def_loop, bb)) - return; - - /* If we're seeing VER for the first time, we still have to allocate - a bitmap for its uses. */ - if (bitmap_set_bit (need_phis, ver)) - use_blocks[ver] = BITMAP_ALLOC (&loop_renamer_obstack); - bitmap_set_bit (use_blocks[ver], bb->index); -} - -/* 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 and the ssa names themselves to - NEED_PHIS. */ - -static void -find_uses_to_rename_stmt (gimple stmt, bitmap *use_blocks, bitmap need_phis) -{ - ssa_op_iter iter; - tree var; - basic_block bb = gimple_bb (stmt); - - if (is_gimple_debug (stmt)) - return; - - FOR_EACH_SSA_TREE_OPERAND (var, stmt, iter, SSA_OP_USE) - 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) -{ - gimple_stmt_iterator bsi; - edge e; - edge_iterator ei; - - FOR_EACH_EDGE (e, ei, bb->succs) - for (bsi = gsi_start_phis (e->dest); !gsi_end_p (bsi); gsi_next (&bsi)) - { - gimple phi = gsi_stmt (bsi); - if (! virtual_operand_p (gimple_phi_result (phi))) - find_uses_to_rename_use (bb, PHI_ARG_DEF_FROM_EDGE (phi, e), - use_blocks, need_phis); - } - - for (bsi = gsi_start_bb (bb); !gsi_end_p (bsi); gsi_next (&bsi)) - find_uses_to_rename_stmt (gsi_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. If CHANGED_BBS is not NULL, - scan only blocks in this set. */ - -static void -find_uses_to_rename (bitmap changed_bbs, bitmap *use_blocks, bitmap need_phis) -{ - basic_block bb; - unsigned index; - bitmap_iterator bi; - - /* ??? If CHANGED_BBS is empty we rewrite the whole function -- why? */ - if (changed_bbs && !bitmap_empty_p (changed_bbs)) - { - 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); - } - } -} - -/* Rewrites the program into a loop closed ssa form -- i.e. inserts extra - phi nodes to ensure that no variable is used outside the loop it is - defined in. - - This strengthening of the basic ssa form has several advantages: - - 1) Updating it during unrolling/peeling/versioning is trivial, since - we do not need to care about the uses outside of the loop. - The same applies to virtual operands which are also rewritten into - loop closed SSA form. Note that virtual operands are always live - until function exit. - 2) The behavior of all uses of an induction variable is the same. - Without this, you need to distinguish the case when the variable - is used outside of the loop it is defined in, for example - - for (i = 0; i < 100; i++) - { - for (j = 0; j < 100; j++) - { - k = i + j; - use1 (k); - } - use2 (k); - } - - 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. - - 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 (bitmap changed_bbs, unsigned update_flag) -{ - bitmap *loop_exits; - bitmap *use_blocks; - bitmap names_to_rename; - - loops_state_set (LOOP_CLOSED_SSA); - if (number_of_loops () <= 1) - return; - - /* If the pass has caused the SSA form to be out-of-date, update it - now. */ - update_ssa (update_flag); - - bitmap_obstack_initialize (&loop_renamer_obstack); - - names_to_rename = BITMAP_ALLOC (&loop_renamer_obstack); - - /* An array of bitmaps where LOOP_EXITS[I] is the set of basic blocks - that are the destination of an edge exiting loop number I. */ - loop_exits = XNEWVEC (bitmap, number_of_loops ()); - get_loops_exits (loop_exits); - - /* Uses of names to rename. We don't have to initialize this array, - because we know that we will only have entries for the SSA names - in NAMES_TO_RENAME. */ - use_blocks = XNEWVEC (bitmap, num_ssa_names); - - /* Find the uses outside loops. */ - 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 - rewrite. */ - add_exit_phis (names_to_rename, use_blocks, loop_exits); - - bitmap_obstack_release (&loop_renamer_obstack); - free (use_blocks); - free (loop_exits); - - /* 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. */ - -static void -check_loop_closed_ssa_use (basic_block bb, tree use) -{ - gimple def; - basic_block def_bb; - - if (TREE_CODE (use) != SSA_NAME || virtual_operand_p (use)) - return; - - def = SSA_NAME_DEF_STMT (use); - def_bb = gimple_bb (def); - gcc_assert (!def_bb - || flow_bb_inside_loop_p (def_bb->loop_father, bb)); -} - -/* Checks invariants of loop closed ssa form in statement STMT in BB. */ - -static void -check_loop_closed_ssa_stmt (basic_block bb, gimple stmt) -{ - ssa_op_iter iter; - tree var; - - if (is_gimple_debug (stmt)) - return; - - FOR_EACH_SSA_TREE_OPERAND (var, stmt, iter, SSA_OP_USE) - check_loop_closed_ssa_use (bb, var); -} - -/* Checks that invariants of the loop closed ssa form are preserved. - Call verify_ssa when VERIFY_SSA_P is true. */ - -DEBUG_FUNCTION void -verify_loop_closed_ssa (bool verify_ssa_p) -{ - basic_block bb; - gimple_stmt_iterator bsi; - gimple phi; - edge e; - edge_iterator ei; - - if (number_of_loops () <= 1) - return; - - if (verify_ssa_p) - verify_ssa (false); - - timevar_push (TV_VERIFY_LOOP_CLOSED); - - FOR_EACH_BB (bb) - { - for (bsi = gsi_start_phis (bb); !gsi_end_p (bsi); gsi_next (&bsi)) - { - phi = gsi_stmt (bsi); - FOR_EACH_EDGE (e, ei, bb->preds) - check_loop_closed_ssa_use (e->src, - PHI_ARG_DEF_FROM_EDGE (phi, e)); - } - - for (bsi = gsi_start_bb (bb); !gsi_end_p (bsi); gsi_next (&bsi)) - check_loop_closed_ssa_stmt (bb, gsi_stmt (bsi)); - } - - timevar_pop (TV_VERIFY_LOOP_CLOSED); -} - -/* Split loop exit edge EXIT. The things are a bit complicated by a need to - preserve the loop closed ssa form. The newly created block is returned. */ - -basic_block -split_loop_exit_edge (edge exit) -{ - basic_block dest = exit->dest; - basic_block bb = split_edge (exit); - gimple phi, new_phi; - tree new_name, name; - use_operand_p op_p; - gimple_stmt_iterator psi; - source_location locus; - - for (psi = gsi_start_phis (dest); !gsi_end_p (psi); gsi_next (&psi)) - { - phi = gsi_stmt (psi); - op_p = PHI_ARG_DEF_PTR_FROM_EDGE (phi, single_succ_edge (bb)); - locus = gimple_phi_arg_location_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 - 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. */ - new_name = duplicate_ssa_name (name, NULL); - new_phi = create_phi_node (new_name, bb); - add_phi_arg (new_phi, name, exit, locus); - SET_USE (op_p, new_name); - } - - return bb; -} - -/* Returns the basic block in that statements should be emitted for induction - variables incremented at the end of the LOOP. */ - -basic_block -ip_end_pos (struct loop *loop) -{ - return loop->latch; -} - -/* Returns the basic block in that statements should be emitted for induction - variables incremented just before exit condition of a LOOP. */ - -basic_block -ip_normal_pos (struct loop *loop) -{ - gimple last; - basic_block bb; - edge exit; - - if (!single_pred_p (loop->latch)) - return NULL; - - bb = single_pred (loop->latch); - last = last_stmt (bb); - if (!last - || gimple_code (last) != GIMPLE_COND) - return NULL; - - exit = EDGE_SUCC (bb, 0); - if (exit->dest == loop->latch) - exit = EDGE_SUCC (bb, 1); - - if (flow_bb_inside_loop_p (loop, exit->dest)) - return NULL; - - return bb; -} - -/* Stores the standard position for induction variable increment in LOOP - (just before the exit condition if it is available and latch block is empty, - end of the latch block otherwise) to BSI. INSERT_AFTER is set to true if - the increment should be inserted after *BSI. */ - -void -standard_iv_increment_position (struct loop *loop, gimple_stmt_iterator *bsi, - bool *insert_after) -{ - basic_block bb = ip_normal_pos (loop), latch = ip_end_pos (loop); - gimple last = last_stmt (latch); - - if (!bb - || (last && gimple_code (last) != GIMPLE_LABEL)) - { - *bsi = gsi_last_bb (latch); - *insert_after = true; - } - else - { - *bsi = gsi_last_bb (bb); - *insert_after = false; - } -} - -/* Copies phi node arguments for duplicated blocks. The index of the first - duplicated block is FIRST_NEW_BLOCK. */ - -static void -copy_phi_node_args (unsigned first_new_block) -{ - unsigned i; - - for (i = first_new_block; i < (unsigned) last_basic_block; i++) - 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)->flags &= ~BB_DUPLICATED; -} - - -/* 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. - - 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 -gimple_duplicate_loop_to_header_edge (struct loop *loop, edge e, - unsigned int ndupl, sbitmap wont_exit, - edge orig, vec<edge> *to_remove, - int flags) -{ - unsigned first_new_block; - - if (!loops_state_satisfies_p (LOOPS_HAVE_SIMPLE_LATCHES)) - return false; - if (!loops_state_satisfies_p (LOOPS_HAVE_PREHEADERS)) - return false; - -#ifdef ENABLE_CHECKING - /* ??? This forces needless update_ssa calls after processing each - loop instead of just once after processing all loops. We should - instead verify that loop-closed SSA form is up-to-date for LOOP - only (and possibly SSA form). For now just skip verifying if - there are to-be renamed variables. */ - if (!need_ssa_update_p (cfun) - && loops_state_satisfies_p (LOOP_CLOSED_SSA)) - verify_loop_closed_ssa (true); -#endif - - first_new_block = last_basic_block; - if (!duplicate_loop_to_header_edge (loop, e, ndupl, wont_exit, - orig, to_remove, flags)) - return false; - - /* Readd the removed phi args for e. */ - flush_pending_stmts (e); - - /* Copy the phi node arguments. */ - copy_phi_node_args (first_new_block); - - scev_reset (); - - return true; -} - -/* Returns true if we can unroll LOOP FACTOR times. Number - of iterations of the loop is returned in NITER. */ - -bool -can_unroll_loop_p (struct loop *loop, unsigned factor, - struct tree_niter_desc *niter) -{ - edge exit; - - /* 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. */ - - exit = single_dom_exit (loop); - if (!exit) - return false; - - 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; - - /* And of course, we must be able to duplicate the loop. */ - if (!can_duplicate_loop_p (loop)) - return false; - - /* The final loop should be small enough. */ - if (tree_num_loop_insns (loop, &eni_size_weights) * factor - > (unsigned) PARAM_VALUE (PARAM_MAX_UNROLLED_INSNS)) - return false; - - return true; -} - -/* 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. */ - -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) -{ - gimple_seq stmts; - tree base = desc->control.base; - tree step = desc->control.step; - tree bound = desc->bound; - tree type = TREE_TYPE (step); - 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; - - /* For pointers, do the arithmetics in the type of step. */ - base = fold_convert (type, base); - bound = fold_convert (type, bound); - - *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 (!integer_zerop (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); - - 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) - gsi_insert_seq_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)) - { - cond = force_gimple_operand (cond, &stmts, true, NULL_TREE); - if (stmts) - gsi_insert_seq_on_edge_immediate (loop_preheader_edge (loop), stmts); - } - *enter_cond = cond; - - base = force_gimple_operand (unshare_expr (base), &stmts, true, NULL_TREE); - if (stmts) - gsi_insert_seq_on_edge_immediate (loop_preheader_edge (loop), stmts); - bound = force_gimple_operand (unshare_expr (bound), &stmts, true, NULL_TREE); - if (stmts) - gsi_insert_seq_on_edge_immediate (loop_preheader_edge (loop), stmts); - - *exit_base = base; - *exit_step = bigstep; - *exit_cmp = cmp; - *exit_bound = bound; -} - -/* Scales the frequencies of all basic blocks in LOOP that are strictly - dominated by BB by NUM/DEN. */ - -static void -scale_dominated_blocks_in_loop (struct loop *loop, basic_block bb, - int num, int den) -{ - basic_block son; - - if (den == 0) - return; - - for (son = first_dom_son (CDI_DOMINATORS, bb); - son; - son = next_dom_son (CDI_DOMINATORS, son)) - { - if (!flow_bb_inside_loop_p (loop, son)) - continue; - scale_bbs_frequencies_int (&son, 1, num, den); - scale_dominated_blocks_in_loop (loop, son, num, den); - } -} - -/* 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; - } - - Before the loop is unrolled, TRANSFORM is called for it (only for the - unrolled loop, but not for its versioned copy). DATA is passed to - TRANSFORM. */ - -/* Probability in % that the unrolled loop is entered. Just a guess. */ -#define PROB_UNROLLED_LOOP_ENTERED 90 - -void -tree_transform_and_unroll_loop (struct loop *loop, unsigned factor, - edge exit, struct tree_niter_desc *desc, - transform_callback transform, - void *data) -{ - gimple exit_if; - tree ctr_before, ctr_after; - tree enter_main_cond, exit_base, exit_step, exit_bound; - enum tree_code exit_cmp; - gimple phi_old_loop, phi_new_loop, phi_rest; - gimple_stmt_iterator psi_old_loop, psi_new_loop; - tree init, next, new_init; - struct loop *new_loop; - basic_block rest, exit_bb; - edge old_entry, new_entry, old_latch, precond_edge, new_exit; - edge new_nonexit, e; - gimple_stmt_iterator bsi; - use_operand_p op; - bool ok; - unsigned est_niter, prob_entry, scale_unrolled, scale_rest, freq_e, freq_h; - unsigned new_est_niter, i, prob; - unsigned irr = loop_preheader_edge (loop)->flags & EDGE_IRREDUCIBLE_LOOP; - sbitmap wont_exit; - vec<edge> to_remove = vNULL; - - est_niter = expected_loop_iterations (loop); - determine_exit_conditions (loop, desc, factor, - &enter_main_cond, &exit_base, &exit_step, - &exit_cmp, &exit_bound); - - /* Let us assume that the unrolled loop is quite likely to be entered. */ - if (integer_nonzerop (enter_main_cond)) - prob_entry = REG_BR_PROB_BASE; - else - prob_entry = PROB_UNROLLED_LOOP_ENTERED * REG_BR_PROB_BASE / 100; - - /* The values for scales should keep profile consistent, and somewhat close - to correct. - - TODO: The current value of SCALE_REST makes it appear that the loop that - is created by splitting the remaining iterations of the unrolled loop is - executed the same number of times as the original loop, and with the same - frequencies, which is obviously wrong. This does not appear to cause - problems, so we do not bother with fixing it for now. To make the profile - correct, we would need to change the probability of the exit edge of the - loop, and recompute the distribution of frequencies in its body because - of this change (scale the frequencies of blocks before and after the exit - by appropriate factors). */ - scale_unrolled = prob_entry; - scale_rest = REG_BR_PROB_BASE; - - new_loop = loop_version (loop, enter_main_cond, NULL, - prob_entry, scale_unrolled, scale_rest, true); - gcc_assert (new_loop != NULL); - update_ssa (TODO_update_ssa); - - /* Determine the probability of the exit edge of the unrolled loop. */ - new_est_niter = est_niter / factor; - - /* Without profile feedback, loops for that we do not know a better estimate - are assumed to roll 10 times. When we unroll such loop, it appears to - roll too little, and it may even seem to be cold. To avoid this, we - ensure that the created loop appears to roll at least 5 times (but at - most as many times as before unrolling). */ - if (new_est_niter < 5) - { - if (est_niter < 5) - new_est_niter = est_niter; - else - new_est_niter = 5; - } - - /* Prepare the cfg and update the phi nodes. Move the loop exit to the - loop latch (and make its condition dummy, for the moment). */ - 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); - - /* Since the exit edge will be removed, the frequency of all the blocks - in the loop that are dominated by it must be scaled by - 1 / (1 - exit->probability). */ - scale_dominated_blocks_in_loop (loop, exit->src, - REG_BR_PROB_BASE, - REG_BR_PROB_BASE - exit->probability); - - bsi = gsi_last_bb (exit_bb); - exit_if = gimple_build_cond (EQ_EXPR, integer_zero_node, - integer_zero_node, - NULL_TREE, NULL_TREE); - - gsi_insert_after (&bsi, exit_if, GSI_NEW_STMT); - new_exit = make_edge (exit_bb, rest, EDGE_FALSE_VALUE | irr); - rescan_loop_exit (new_exit, true, false); - - /* Set the probability of new exit to the same of the old one. Fix - the frequency of the latch block, by scaling it back by - 1 - exit->probability. */ - new_exit->count = exit->count; - new_exit->probability = exit->probability; - new_nonexit = single_pred_edge (loop->latch); - new_nonexit->probability = REG_BR_PROB_BASE - exit->probability; - new_nonexit->flags = EDGE_TRUE_VALUE; - new_nonexit->count -= exit->count; - if (new_nonexit->count < 0) - new_nonexit->count = 0; - scale_bbs_frequencies_int (&loop->latch, 1, new_nonexit->probability, - REG_BR_PROB_BASE); - - old_entry = loop_preheader_edge (loop); - new_entry = loop_preheader_edge (new_loop); - old_latch = loop_latch_edge (loop); - for (psi_old_loop = gsi_start_phis (loop->header), - psi_new_loop = gsi_start_phis (new_loop->header); - !gsi_end_p (psi_old_loop); - gsi_next (&psi_old_loop), gsi_next (&psi_new_loop)) - { - phi_old_loop = gsi_stmt (psi_old_loop); - phi_new_loop = gsi_stmt (psi_new_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 - && useless_type_conversion_p (TREE_TYPE (next), - TREE_TYPE (init))) - new_init = copy_ssa_name (next, NULL); - else if (TREE_CODE (init) == SSA_NAME - && useless_type_conversion_p (TREE_TYPE (init), - TREE_TYPE (next))) - new_init = copy_ssa_name (init, NULL); - else if (useless_type_conversion_p (TREE_TYPE (next), TREE_TYPE (init))) - new_init = make_temp_ssa_name (TREE_TYPE (next), NULL, "unrinittmp"); - else - new_init = make_temp_ssa_name (TREE_TYPE (init), NULL, "unrinittmp"); - - phi_rest = create_phi_node (new_init, rest); - - add_phi_arg (phi_rest, init, precond_edge, UNKNOWN_LOCATION); - add_phi_arg (phi_rest, next, new_exit, UNKNOWN_LOCATION); - SET_USE (op, new_init); - } - - remove_path (exit); - - /* Transform the loop. */ - if (transform) - (*transform) (loop, data); - - /* Unroll the loop and remove the exits in all iterations except for the - last one. */ - wont_exit = sbitmap_alloc (factor); - bitmap_ones (wont_exit); - bitmap_clear_bit (wont_exit, factor - 1); - - ok = gimple_duplicate_loop_to_header_edge - (loop, loop_latch_edge (loop), factor - 1, - wont_exit, new_exit, &to_remove, DLTHE_FLAG_UPDATE_FREQ); - free (wont_exit); - gcc_assert (ok); - - FOR_EACH_VEC_ELT (to_remove, i, e) - { - ok = remove_path (e); - gcc_assert (ok); - } - to_remove.release (); - update_ssa (TODO_update_ssa); - - /* Ensure that the frequencies in the loop match the new estimated - number of iterations, and change the probability of the new - exit edge. */ - freq_h = loop->header->frequency; - freq_e = EDGE_FREQUENCY (loop_preheader_edge (loop)); - if (freq_h != 0) - scale_loop_frequencies (loop, freq_e * (new_est_niter + 1), freq_h); - - exit_bb = single_pred (loop->latch); - new_exit = find_edge (exit_bb, rest); - new_exit->count = loop_preheader_edge (loop)->count; - new_exit->probability = REG_BR_PROB_BASE / (new_est_niter + 1); - - rest->count += new_exit->count; - rest->frequency += EDGE_FREQUENCY (new_exit); - - new_nonexit = single_pred_edge (loop->latch); - prob = new_nonexit->probability; - new_nonexit->probability = REG_BR_PROB_BASE - new_exit->probability; - new_nonexit->count = exit_bb->count - new_exit->count; - if (new_nonexit->count < 0) - new_nonexit->count = 0; - if (prob > 0) - scale_bbs_frequencies_int (&loop->latch, 1, new_nonexit->probability, - prob); - - /* Finally create the new counter for number of iterations and add the new - exit instruction. */ - bsi = gsi_last_nondebug_bb (exit_bb); - exit_if = gsi_stmt (bsi); - create_iv (exit_base, exit_step, NULL_TREE, loop, - &bsi, false, &ctr_before, &ctr_after); - gimple_cond_set_code (exit_if, exit_cmp); - gimple_cond_set_lhs (exit_if, ctr_after); - gimple_cond_set_rhs (exit_if, exit_bound); - update_stmt (exit_if); - -#ifdef ENABLE_CHECKING - verify_flow_info (); - verify_loop_structure (); - verify_loop_closed_ssa (true); -#endif -} - -/* Wrapper over tree_transform_and_unroll_loop for case we do not - want to transform the loop before unrolling. The meaning - of the arguments is the same as for tree_transform_and_unroll_loop. */ - -void -tree_unroll_loop (struct loop *loop, unsigned factor, - edge exit, struct tree_niter_desc *desc) -{ - tree_transform_and_unroll_loop (loop, factor, exit, desc, - NULL, NULL); -} - -/* Rewrite the phi node at position PSI in function of the main - induction variable MAIN_IV and insert the generated code at GSI. */ - -static void -rewrite_phi_with_iv (loop_p loop, - gimple_stmt_iterator *psi, - gimple_stmt_iterator *gsi, - tree main_iv) -{ - affine_iv iv; - gimple stmt, phi = gsi_stmt (*psi); - tree atype, mtype, val, res = PHI_RESULT (phi); - - if (virtual_operand_p (res) || res == main_iv) - { - gsi_next (psi); - return; - } - - if (!simple_iv (loop, loop, res, &iv, true)) - { - gsi_next (psi); - return; - } - - remove_phi_node (psi, false); - - atype = TREE_TYPE (res); - mtype = POINTER_TYPE_P (atype) ? sizetype : atype; - val = fold_build2 (MULT_EXPR, mtype, unshare_expr (iv.step), - fold_convert (mtype, main_iv)); - val = fold_build2 (POINTER_TYPE_P (atype) - ? POINTER_PLUS_EXPR : PLUS_EXPR, - atype, unshare_expr (iv.base), val); - val = force_gimple_operand_gsi (gsi, val, false, NULL_TREE, true, - GSI_SAME_STMT); - stmt = gimple_build_assign (res, val); - gsi_insert_before (gsi, stmt, GSI_SAME_STMT); - SSA_NAME_DEF_STMT (res) = stmt; -} - -/* Rewrite all the phi nodes of LOOP in function of the main induction - variable MAIN_IV. */ - -static void -rewrite_all_phi_nodes_with_iv (loop_p loop, tree main_iv) -{ - unsigned i; - basic_block *bbs = get_loop_body_in_dom_order (loop); - gimple_stmt_iterator psi; - - for (i = 0; i < loop->num_nodes; i++) - { - basic_block bb = bbs[i]; - gimple_stmt_iterator gsi = gsi_after_labels (bb); - - if (bb->loop_father != loop) - continue; - - for (psi = gsi_start_phis (bb); !gsi_end_p (psi); ) - rewrite_phi_with_iv (loop, &psi, &gsi, main_iv); - } - - free (bbs); -} - -/* Bases all the induction variables in LOOP on a single induction - variable (unsigned with base 0 and step 1), whose final value is - compared with *NIT. When the IV type precision has to be larger - than *NIT type precision, *NIT is converted to the larger type, the - conversion code is inserted before the loop, and *NIT is updated to - the new definition. When BUMP_IN_LATCH is true, the induction - variable is incremented in the loop latch, otherwise it is - incremented in the loop header. Return the induction variable that - was created. */ - -tree -canonicalize_loop_ivs (struct loop *loop, tree *nit, bool bump_in_latch) -{ - unsigned precision = TYPE_PRECISION (TREE_TYPE (*nit)); - unsigned original_precision = precision; - tree type, var_before; - gimple_stmt_iterator gsi, psi; - gimple stmt; - edge exit = single_dom_exit (loop); - gimple_seq stmts; - enum machine_mode mode; - bool unsigned_p = false; - - for (psi = gsi_start_phis (loop->header); - !gsi_end_p (psi); gsi_next (&psi)) - { - gimple phi = gsi_stmt (psi); - tree res = PHI_RESULT (phi); - bool uns; - - type = TREE_TYPE (res); - if (virtual_operand_p (res) - || (!INTEGRAL_TYPE_P (type) - && !POINTER_TYPE_P (type)) - || TYPE_PRECISION (type) < precision) - continue; - - uns = POINTER_TYPE_P (type) | TYPE_UNSIGNED (type); - - if (TYPE_PRECISION (type) > precision) - unsigned_p = uns; - else - unsigned_p |= uns; - - precision = TYPE_PRECISION (type); - } - - mode = smallest_mode_for_size (precision, MODE_INT); - precision = GET_MODE_PRECISION (mode); - type = build_nonstandard_integer_type (precision, unsigned_p); - - if (original_precision != precision) - { - *nit = fold_convert (type, *nit); - *nit = force_gimple_operand (*nit, &stmts, true, NULL_TREE); - if (stmts) - gsi_insert_seq_on_edge_immediate (loop_preheader_edge (loop), stmts); - } - - if (bump_in_latch) - gsi = gsi_last_bb (loop->latch); - else - gsi = gsi_last_nondebug_bb (loop->header); - create_iv (build_int_cst_type (type, 0), build_int_cst (type, 1), NULL_TREE, - loop, &gsi, bump_in_latch, &var_before, NULL); - - rewrite_all_phi_nodes_with_iv (loop, var_before); - - stmt = last_stmt (exit->src); - /* Make the loop exit if the control condition is not satisfied. */ - if (exit->flags & EDGE_TRUE_VALUE) - { - edge te, fe; - - extract_true_false_edges_from_block (exit->src, &te, &fe); - te->flags = EDGE_FALSE_VALUE; - fe->flags = EDGE_TRUE_VALUE; - } - gimple_cond_set_code (stmt, LT_EXPR); - gimple_cond_set_lhs (stmt, var_before); - gimple_cond_set_rhs (stmt, *nit); - update_stmt (stmt); - - return var_before; -} |