/* CFG cleanup for trees.
- Copyright (C) 2001, 2002, 2003, 2004, 2005 Free Software Foundation, Inc.
+ Copyright (C) 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010
+ 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 2, or (at your option)
+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,
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 COPYING. If not, write to
-the Free Software Foundation, 59 Temple Place - Suite 330,
-Boston, MA 02111-1307, USA. */
+along with GCC; see the file COPYING3. If not see
+<http://www.gnu.org/licenses/>. */
#include "config.h"
#include "system.h"
#include "hard-reg-set.h"
#include "basic-block.h"
#include "output.h"
-#include "errors.h"
+#include "toplev.h"
#include "flags.h"
#include "function.h"
#include "expr.h"
#include "cfglayout.h"
#include "hashtab.h"
#include "tree-ssa-propagate.h"
+#include "tree-scalar-evolution.h"
+
+/* The set of blocks in that at least one of the following changes happened:
+ -- the statement at the end of the block was changed
+ -- the block was newly created
+ -- the set of the predecessors of the block changed
+ -- the set of the successors of the block changed
+ ??? Maybe we could track these changes separately, since they determine
+ what cleanups it makes sense to try on the block. */
+bitmap cfgcleanup_altered_bbs;
/* Remove any fallthru edge from EV. Return true if an edge was removed. */
FOR_EACH_EDGE (e, ei, ev)
if ((e->flags & EDGE_FALLTHRU) != 0)
{
- remove_edge (e);
+ remove_edge_and_dominated_blocks (e);
return true;
}
return false;
}
+
/* Disconnect an unreachable block in the control expression starting
at block BB. */
static bool
-cleanup_control_expr_graph (basic_block bb, block_stmt_iterator bsi)
+cleanup_control_expr_graph (basic_block bb, gimple_stmt_iterator gsi)
{
edge taken_edge;
bool retval = false;
- tree expr = bsi_stmt (bsi), val;
+ gimple stmt = gsi_stmt (gsi);
+ tree val;
if (!single_succ_p (bb))
{
edge e;
edge_iterator ei;
+ bool warned;
+ location_t loc;
- switch (TREE_CODE (expr))
+ fold_defer_overflow_warnings ();
+ loc = gimple_location (stmt);
+ switch (gimple_code (stmt))
{
- case COND_EXPR:
- val = COND_EXPR_COND (expr);
- break;
-
- case SWITCH_EXPR:
- val = SWITCH_COND (expr);
- if (TREE_CODE (val) != INTEGER_CST)
- return false;
+ case GIMPLE_COND:
+ {
+ tree lhs = gimple_cond_lhs (stmt);
+ tree rhs = gimple_cond_rhs (stmt);
+ /* For conditions try harder and lookup single-argument
+ PHI nodes. Only do so from the same basic-block though
+ as other basic-blocks may be dead already. */
+ if (TREE_CODE (lhs) == SSA_NAME
+ && !name_registered_for_update_p (lhs))
+ {
+ gimple def_stmt = SSA_NAME_DEF_STMT (lhs);
+ if (gimple_code (def_stmt) == GIMPLE_PHI
+ && gimple_phi_num_args (def_stmt) == 1
+ && gimple_bb (def_stmt) == gimple_bb (stmt)
+ && (TREE_CODE (PHI_ARG_DEF (def_stmt, 0)) != SSA_NAME
+ || !name_registered_for_update_p (PHI_ARG_DEF (def_stmt,
+ 0))))
+ lhs = PHI_ARG_DEF (def_stmt, 0);
+ }
+ if (TREE_CODE (rhs) == SSA_NAME
+ && !name_registered_for_update_p (rhs))
+ {
+ gimple def_stmt = SSA_NAME_DEF_STMT (rhs);
+ if (gimple_code (def_stmt) == GIMPLE_PHI
+ && gimple_phi_num_args (def_stmt) == 1
+ && gimple_bb (def_stmt) == gimple_bb (stmt)
+ && (TREE_CODE (PHI_ARG_DEF (def_stmt, 0)) != SSA_NAME
+ || !name_registered_for_update_p (PHI_ARG_DEF (def_stmt,
+ 0))))
+ rhs = PHI_ARG_DEF (def_stmt, 0);
+ }
+ val = fold_binary_loc (loc, gimple_cond_code (stmt),
+ boolean_type_node, lhs, rhs);
+ break;
+ }
+
+ case GIMPLE_SWITCH:
+ val = gimple_switch_index (stmt);
break;
default:
- gcc_unreachable ();
+ val = NULL_TREE;
}
-
taken_edge = find_taken_edge (bb, val);
if (!taken_edge)
- return false;
+ {
+ fold_undefer_and_ignore_overflow_warnings ();
+ return false;
+ }
/* Remove all the edges except the one that is always executed. */
+ warned = false;
for (ei = ei_start (bb->succs); (e = ei_safe_edge (ei)); )
{
if (e != taken_edge)
{
+ if (!warned)
+ {
+ fold_undefer_overflow_warnings
+ (true, stmt, WARN_STRICT_OVERFLOW_CONDITIONAL);
+ warned = true;
+ }
+
taken_edge->probability += e->probability;
taken_edge->count += e->count;
- remove_edge (e);
+ remove_edge_and_dominated_blocks (e);
retval = true;
}
else
ei_next (&ei);
}
+ if (!warned)
+ fold_undefer_and_ignore_overflow_warnings ();
if (taken_edge->probability > REG_BR_PROB_BASE)
taken_edge->probability = REG_BR_PROB_BASE;
}
else
taken_edge = single_succ_edge (bb);
- bsi_remove (&bsi);
+ bitmap_set_bit (cfgcleanup_altered_bbs, bb->index);
+ gsi_remove (&gsi, true);
taken_edge->flags = EDGE_FALLTHRU;
- /* We removed some paths from the cfg. */
- free_dominance_info (CDI_DOMINATORS);
-
return retval;
}
-/* A list of all the noreturn calls passed to modify_stmt.
- cleanup_control_flow uses it to detect cases where a mid-block
- indirect call has been turned into a noreturn call. When this
- happens, all the instructions after the call are no longer
- reachable and must be deleted as dead. */
-
-VEC(tree,gc) *modified_noreturn_calls;
-
-/* Try to remove superfluous control structures. */
+/* Try to remove superfluous control structures in basic block BB. Returns
+ true if anything changes. */
static bool
-cleanup_control_flow (void)
+cleanup_control_flow_bb (basic_block bb)
{
- basic_block bb;
- block_stmt_iterator bsi;
+ gimple_stmt_iterator gsi;
bool retval = false;
- tree stmt;
+ gimple stmt;
- /* Detect cases where a mid-block call is now known not to return. */
- while (VEC_length (tree, modified_noreturn_calls))
- {
- stmt = VEC_pop (tree, modified_noreturn_calls);
- bb = bb_for_stmt (stmt);
- if (bb != NULL && last_stmt (bb) != stmt && noreturn_call_p (stmt))
- split_block (bb, stmt);
- }
+ /* If the last statement of the block could throw and now cannot,
+ we need to prune cfg. */
+ retval |= gimple_purge_dead_eh_edges (bb);
- FOR_EACH_BB (bb)
- {
- bsi = bsi_last (bb);
-
- if (bsi_end_p (bsi))
- continue;
+ gsi = gsi_last_bb (bb);
+ if (gsi_end_p (gsi))
+ return retval;
- stmt = bsi_stmt (bsi);
- if (TREE_CODE (stmt) == COND_EXPR
- || TREE_CODE (stmt) == SWITCH_EXPR)
- retval |= cleanup_control_expr_graph (bb, bsi);
+ stmt = gsi_stmt (gsi);
+ if (gimple_code (stmt) == GIMPLE_COND
+ || gimple_code (stmt) == GIMPLE_SWITCH)
+ retval |= cleanup_control_expr_graph (bb, gsi);
+ else if (gimple_code (stmt) == GIMPLE_GOTO
+ && TREE_CODE (gimple_goto_dest (stmt)) == ADDR_EXPR
+ && (TREE_CODE (TREE_OPERAND (gimple_goto_dest (stmt), 0))
+ == LABEL_DECL))
+ {
/* If we had a computed goto which has a compile-time determinable
destination, then we can eliminate the goto. */
- if (TREE_CODE (stmt) == GOTO_EXPR
- && TREE_CODE (GOTO_DESTINATION (stmt)) == ADDR_EXPR
- && TREE_CODE (TREE_OPERAND (GOTO_DESTINATION (stmt), 0)) == LABEL_DECL)
+ edge e;
+ tree label;
+ edge_iterator ei;
+ basic_block target_block;
+
+ /* First look at all the outgoing edges. Delete any outgoing
+ edges which do not go to the right block. For the one
+ edge which goes to the right block, fix up its flags. */
+ label = TREE_OPERAND (gimple_goto_dest (stmt), 0);
+ target_block = label_to_block (label);
+ for (ei = ei_start (bb->succs); (e = ei_safe_edge (ei)); )
{
- edge e;
- tree label;
- edge_iterator ei;
- basic_block target_block;
- bool removed_edge = false;
-
- /* First look at all the outgoing edges. Delete any outgoing
- edges which do not go to the right block. For the one
- edge which goes to the right block, fix up its flags. */
- label = TREE_OPERAND (GOTO_DESTINATION (stmt), 0);
- target_block = label_to_block (label);
- for (ei = ei_start (bb->succs); (e = ei_safe_edge (ei)); )
+ if (e->dest != target_block)
+ remove_edge_and_dominated_blocks (e);
+ else
{
- if (e->dest != target_block)
- {
- removed_edge = true;
- remove_edge (e);
- }
- else
- {
- /* Turn off the EDGE_ABNORMAL flag. */
- e->flags &= ~EDGE_ABNORMAL;
-
- /* And set EDGE_FALLTHRU. */
- e->flags |= EDGE_FALLTHRU;
- ei_next (&ei);
- }
- }
+ /* Turn off the EDGE_ABNORMAL flag. */
+ e->flags &= ~EDGE_ABNORMAL;
- /* If we removed one or more edges, then we will need to fix the
- dominators. It may be possible to incrementally update them. */
- if (removed_edge)
- free_dominance_info (CDI_DOMINATORS);
-
- /* Remove the GOTO_EXPR as it is not needed. The CFG has all the
- relevant information we need. */
- bsi_remove (&bsi);
- retval = true;
+ /* And set EDGE_FALLTHRU. */
+ e->flags |= EDGE_FALLTHRU;
+ ei_next (&ei);
+ }
}
- /* Check for indirect calls that have been turned into
- noreturn calls. */
- if (noreturn_call_p (stmt) && remove_fallthru_edge (bb->succs))
- {
- free_dominance_info (CDI_DOMINATORS);
- retval = true;
- }
+ bitmap_set_bit (cfgcleanup_altered_bbs, bb->index);
+ bitmap_set_bit (cfgcleanup_altered_bbs, target_block->index);
+
+ /* Remove the GOTO_EXPR as it is not needed. The CFG has all the
+ relevant information we need. */
+ gsi_remove (&gsi, true);
+ retval = true;
}
+
+ /* Check for indirect calls that have been turned into
+ noreturn calls. */
+ else if (is_gimple_call (stmt)
+ && gimple_call_noreturn_p (stmt)
+ && remove_fallthru_edge (bb->succs))
+ retval = true;
+
return retval;
}
static bool
tree_forwarder_block_p (basic_block bb, bool phi_wanted)
{
- block_stmt_iterator bsi;
+ gimple_stmt_iterator gsi;
/* BB must have a single outgoing edge. */
if (single_succ_p (bb) != 1
/* If PHI_WANTED is false, BB must not have any PHI nodes.
Otherwise, BB must have PHI nodes. */
- || (phi_nodes (bb) != NULL_TREE) != phi_wanted
+ || gimple_seq_empty_p (phi_nodes (bb)) == phi_wanted
/* BB may not be a predecessor of EXIT_BLOCK_PTR. */
|| single_succ (bb) == EXIT_BLOCK_PTR
/* Nor should this be an infinite loop. */
gcc_assert (bb != ENTRY_BLOCK_PTR);
#endif
+ /* There should not be an edge coming from entry, or an EH edge. */
+ {
+ edge_iterator ei;
+ edge e;
+
+ FOR_EACH_EDGE (e, ei, bb->preds)
+ if (e->src == ENTRY_BLOCK_PTR || (e->flags & EDGE_EH))
+ return false;
+ }
+
/* Now walk through the statements backward. We can ignore labels,
anything else means this is not a forwarder block. */
- for (bsi = bsi_last (bb); !bsi_end_p (bsi); bsi_prev (&bsi))
+ for (gsi = gsi_last_bb (bb); !gsi_end_p (gsi); gsi_prev (&gsi))
{
- tree stmt = bsi_stmt (bsi);
+ gimple stmt = gsi_stmt (gsi);
- switch (TREE_CODE (stmt))
+ switch (gimple_code (stmt))
{
- case LABEL_EXPR:
- if (DECL_NONLOCAL (LABEL_EXPR_LABEL (stmt)))
+ case GIMPLE_LABEL:
+ if (DECL_NONLOCAL (gimple_label_label (stmt)))
return false;
break;
+ /* ??? For now, hope there's a corresponding debug
+ assignment at the destination. */
+ case GIMPLE_DEBUG:
+ break;
+
default:
return false;
}
}
- if (find_edge (ENTRY_BLOCK_PTR, bb))
- return false;
-
if (current_loops)
{
basic_block dest;
if (dest->loop_father->header == dest)
return false;
}
-
return true;
}
{
int n1 = e1->dest_idx;
int n2 = e2->dest_idx;
- tree phi;
+ gimple_stmt_iterator gsi;
- for (phi = phi_nodes (dest); phi; phi = PHI_CHAIN (phi))
+ for (gsi = gsi_start_phis (dest); !gsi_end_p (gsi); gsi_next (&gsi))
{
- tree val1 = PHI_ARG_DEF (phi, n1);
- tree val2 = PHI_ARG_DEF (phi, n2);
+ gimple phi = gsi_stmt (gsi);
+ tree val1 = gimple_phi_arg_def (phi, n1);
+ tree val2 = gimple_phi_arg_def (phi, n2);
gcc_assert (val1 != NULL_TREE);
gcc_assert (val2 != NULL_TREE);
return true;
}
-/* Removes forwarder block BB. Returns false if this failed. If a new
- forwarder block is created due to redirection of edges, it is
- stored to worklist. */
+/* Removes forwarder block BB. Returns false if this failed. */
static bool
-remove_forwarder_block (basic_block bb, basic_block **worklist)
+remove_forwarder_block (basic_block bb)
{
edge succ = single_succ_edge (bb), e, s;
basic_block dest = succ->dest;
- tree label;
- tree phi;
+ gimple label;
edge_iterator ei;
- block_stmt_iterator bsi, bsi_to;
- bool seen_abnormal_edge = false;
+ gimple_stmt_iterator gsi, gsi_to;
+ bool can_move_debug_stmts;
/* We check for infinite loops already in tree_forwarder_block_p.
However it may happen that the infinite loop is created
if (dest == bb)
return false;
- /* If the destination block consists of a nonlocal label, do not merge
- it. */
+ /* If the destination block consists of a nonlocal label or is a
+ EH landing pad, do not merge it. */
label = first_stmt (dest);
if (label
- && TREE_CODE (label) == LABEL_EXPR
- && DECL_NONLOCAL (LABEL_EXPR_LABEL (label)))
+ && gimple_code (label) == GIMPLE_LABEL
+ && (DECL_NONLOCAL (gimple_label_label (label))
+ || EH_LANDING_PAD_NR (gimple_label_label (label)) != 0))
return false;
/* If there is an abnormal edge to basic block BB, but not into
So if there is an abnormal edge to BB, proceed only if there is
no abnormal edge to DEST and there are no phi nodes in DEST. */
- if (has_abnormal_incoming_edge_p (bb))
- {
- seen_abnormal_edge = true;
-
- if (has_abnormal_incoming_edge_p (dest)
- || phi_nodes (dest) != NULL_TREE)
- return false;
- }
+ if (has_abnormal_incoming_edge_p (bb)
+ && (has_abnormal_incoming_edge_p (dest)
+ || !gimple_seq_empty_p (phi_nodes (dest))))
+ return false;
/* If there are phi nodes in DEST, and some of the blocks that are
predecessors of BB are also predecessors of DEST, check that the
phi node arguments match. */
- if (phi_nodes (dest))
+ if (!gimple_seq_empty_p (phi_nodes (dest)))
{
FOR_EACH_EDGE (e, ei, bb->preds)
{
}
}
+ can_move_debug_stmts = single_pred_p (dest);
+
/* Redirect the edges. */
for (ei = ei_start (bb->preds); (e = ei_safe_edge (ei)); )
{
+ bitmap_set_bit (cfgcleanup_altered_bbs, e->src->index);
+
if (e->flags & EDGE_ABNORMAL)
{
/* If there is an abnormal edge, redirect it anyway, and
{
/* Create arguments for the phi nodes, since the edge was not
here before. */
- for (phi = phi_nodes (dest); phi; phi = PHI_CHAIN (phi))
- add_phi_arg (phi, PHI_ARG_DEF (phi, succ->dest_idx), s);
+ for (gsi = gsi_start_phis (dest);
+ !gsi_end_p (gsi);
+ gsi_next (&gsi))
+ {
+ gimple phi = gsi_stmt (gsi);
+ source_location l = gimple_phi_arg_location_from_edge (phi, succ);
+ add_phi_arg (phi, gimple_phi_arg_def (phi, succ->dest_idx), s, l);
+ }
}
- else
+ }
+
+ /* Move nonlocal labels and computed goto targets as well as user
+ defined labels and labels with an EH landing pad number to the
+ new block, so that the redirection of the abnormal edges works,
+ jump targets end up in a sane place and debug information for
+ labels is retained. */
+ gsi_to = gsi_start_bb (dest);
+ for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); )
+ {
+ tree decl;
+ label = gsi_stmt (gsi);
+ if (is_gimple_debug (label))
+ break;
+ decl = gimple_label_label (label);
+ if (EH_LANDING_PAD_NR (decl) != 0
+ || DECL_NONLOCAL (decl)
+ || FORCED_LABEL (decl)
+ || !DECL_ARTIFICIAL (decl))
{
- /* The source basic block might become a forwarder. We know
- that it was not a forwarder before, since it used to have
- at least two outgoing edges, so we may just add it to
- worklist. */
- if (tree_forwarder_block_p (s->src, false))
- *(*worklist)++ = s->src;
+ gsi_remove (&gsi, false);
+ gsi_insert_before (&gsi_to, label, GSI_SAME_STMT);
}
+ else
+ gsi_next (&gsi);
}
- if (seen_abnormal_edge)
+ /* Move debug statements if the destination has just a single
+ predecessor. */
+ if (can_move_debug_stmts)
{
- /* Move the labels to the new block, so that the redirection of
- the abnormal edges works. */
-
- bsi_to = bsi_start (dest);
- for (bsi = bsi_start (bb); !bsi_end_p (bsi); )
+ gsi_to = gsi_after_labels (dest);
+ for (gsi = gsi_after_labels (bb); !gsi_end_p (gsi); )
{
- label = bsi_stmt (bsi);
- gcc_assert (TREE_CODE (label) == LABEL_EXPR);
- bsi_remove (&bsi);
- bsi_insert_before (&bsi_to, label, BSI_CONTINUE_LINKING);
+ gimple debug = gsi_stmt (gsi);
+ if (!is_gimple_debug (debug))
+ break;
+ gsi_remove (&gsi, false);
+ gsi_insert_before (&gsi_to, debug, GSI_SAME_STMT);
}
}
+ bitmap_set_bit (cfgcleanup_altered_bbs, dest->index);
+
/* Update the dominators. */
if (dom_info_available_p (CDI_DOMINATORS))
{
return true;
}
-/* Removes forwarder blocks. */
+/* Split basic blocks on calls in the middle of a basic block that are now
+ known not to return, and remove the unreachable code. */
static bool
-cleanup_forwarder_blocks (void)
+split_bbs_on_noreturn_calls (void)
{
- basic_block bb;
bool changed = false;
- basic_block *worklist = xmalloc (sizeof (basic_block) * n_basic_blocks);
- basic_block *current = worklist;
+ gimple stmt;
+ basic_block bb;
- FOR_EACH_BB (bb)
- {
- if (tree_forwarder_block_p (bb, false))
- *current++ = bb;
- }
+ /* Detect cases where a mid-block call is now known not to return. */
+ if (cfun->gimple_df)
+ while (VEC_length (gimple, MODIFIED_NORETURN_CALLS (cfun)))
+ {
+ stmt = VEC_pop (gimple, MODIFIED_NORETURN_CALLS (cfun));
+ bb = gimple_bb (stmt);
+ /* BB might be deleted at this point, so verify first
+ BB is present in the cfg. */
+ if (bb == NULL
+ || bb->index < NUM_FIXED_BLOCKS
+ || bb->index >= n_basic_blocks
+ || BASIC_BLOCK (bb->index) != bb
+ || last_stmt (bb) == stmt
+ || !gimple_call_noreturn_p (stmt))
+ continue;
+
+ changed = true;
+ split_block (bb, stmt);
+ remove_fallthru_edge (bb->succs);
+ }
- while (current != worklist)
+ return changed;
+}
+
+/* If GIMPLE_OMP_RETURN in basic block BB is unreachable, remove it. */
+
+static bool
+cleanup_omp_return (basic_block bb)
+{
+ gimple stmt = last_stmt (bb);
+ basic_block control_bb;
+
+ if (stmt == NULL
+ || gimple_code (stmt) != GIMPLE_OMP_RETURN
+ || !single_pred_p (bb))
+ return false;
+
+ control_bb = single_pred (bb);
+ stmt = last_stmt (control_bb);
+
+ if (stmt == NULL || gimple_code (stmt) != GIMPLE_OMP_SECTIONS_SWITCH)
+ return false;
+
+ /* The block with the control statement normally has two entry edges -- one
+ from entry, one from continue. If continue is removed, return is
+ unreachable, so we remove it here as well. */
+ if (EDGE_COUNT (control_bb->preds) == 2)
+ return false;
+
+ gcc_assert (EDGE_COUNT (control_bb->preds) == 1);
+ remove_edge_and_dominated_blocks (single_pred_edge (bb));
+ return true;
+}
+
+/* Tries to cleanup cfg in basic block BB. Returns true if anything
+ changes. */
+
+static bool
+cleanup_tree_cfg_bb (basic_block bb)
+{
+ bool retval = false;
+
+ if (cleanup_omp_return (bb))
+ return true;
+
+ retval = cleanup_control_flow_bb (bb);
+
+ /* Forwarder blocks can carry line number information which is
+ useful when debugging, so we only clean them up when
+ optimizing. */
+ if (optimize > 0
+ && tree_forwarder_block_p (bb, false)
+ && remove_forwarder_block (bb))
+ return true;
+
+ /* Merging the blocks may create new opportunities for folding
+ conditional branches (due to the elimination of single-valued PHI
+ nodes). */
+ if (single_succ_p (bb)
+ && can_merge_blocks_p (bb, single_succ (bb)))
{
- bb = *--current;
- changed |= remove_forwarder_block (bb, ¤t);
+ merge_blocks (bb, single_succ (bb));
+ return true;
}
- free (worklist);
- return changed;
+ return retval;
}
-/* Remove unreachable blocks and other miscellaneous clean up work. */
+/* Iterate the cfg cleanups, while anything changes. */
-bool
-cleanup_tree_cfg (void)
+static bool
+cleanup_tree_cfg_1 (void)
{
bool retval = false;
+ basic_block bb;
+ unsigned i, n;
- timevar_push (TV_TREE_CLEANUP_CFG);
+ retval |= split_bbs_on_noreturn_calls ();
- retval = cleanup_control_flow ();
- retval |= delete_unreachable_blocks ();
+ /* Prepare the worklists of altered blocks. */
+ cfgcleanup_altered_bbs = BITMAP_ALLOC (NULL);
- /* cleanup_forwarder_blocks can redirect edges out of SWITCH_EXPRs,
- which can get expensive. So we want to enable recording of edge
- to CASE_LABEL_EXPR mappings around the call to
- cleanup_forwarder_blocks. */
+ /* During forwarder block cleanup, we may redirect edges out of
+ SWITCH_EXPRs, which can get expensive. So we want to enable
+ recording of edge to CASE_LABEL_EXPR. */
start_recording_case_labels ();
- retval |= cleanup_forwarder_blocks ();
+
+ /* Start by iterating over all basic blocks. We cannot use FOR_EACH_BB,
+ since the basic blocks may get removed. */
+ n = last_basic_block;
+ for (i = NUM_FIXED_BLOCKS; i < n; i++)
+ {
+ bb = BASIC_BLOCK (i);
+ if (bb)
+ retval |= cleanup_tree_cfg_bb (bb);
+ }
+
+ /* Now process the altered blocks, as long as any are available. */
+ while (!bitmap_empty_p (cfgcleanup_altered_bbs))
+ {
+ i = bitmap_first_set_bit (cfgcleanup_altered_bbs);
+ bitmap_clear_bit (cfgcleanup_altered_bbs, i);
+ if (i < NUM_FIXED_BLOCKS)
+ continue;
+
+ bb = BASIC_BLOCK (i);
+ if (!bb)
+ continue;
+
+ retval |= cleanup_tree_cfg_bb (bb);
+
+ /* Rerun split_bbs_on_noreturn_calls, in case we have altered any noreturn
+ calls. */
+ retval |= split_bbs_on_noreturn_calls ();
+ }
+
end_recording_case_labels ();
+ BITMAP_FREE (cfgcleanup_altered_bbs);
+ return retval;
+}
-#ifdef ENABLE_CHECKING
- if (retval)
+
+/* Remove unreachable blocks and other miscellaneous clean up work.
+ Return true if the flowgraph was modified, false otherwise. */
+
+static bool
+cleanup_tree_cfg_noloop (void)
+{
+ bool changed;
+
+ timevar_push (TV_TREE_CLEANUP_CFG);
+
+ /* Iterate until there are no more cleanups left to do. If any
+ iteration changed the flowgraph, set CHANGED to true.
+
+ If dominance information is available, there cannot be any unreachable
+ blocks. */
+ if (!dom_info_available_p (CDI_DOMINATORS))
{
- gcc_assert (!cleanup_control_flow ());
- gcc_assert (!delete_unreachable_blocks ());
- gcc_assert (!cleanup_forwarder_blocks ());
+ changed = delete_unreachable_blocks ();
+ calculate_dominance_info (CDI_DOMINATORS);
}
+ else
+ {
+#ifdef ENABLE_CHECKING
+ verify_dominators (CDI_DOMINATORS);
#endif
+ changed = false;
+ }
- /* Merging the blocks creates no new opportunities for the other
- optimizations, so do it here. */
- retval |= merge_seq_blocks ();
+ changed |= cleanup_tree_cfg_1 ();
+ gcc_assert (dom_info_available_p (CDI_DOMINATORS));
compact_blocks ();
#ifdef ENABLE_CHECKING
verify_flow_info ();
#endif
+
timevar_pop (TV_TREE_CLEANUP_CFG);
- return retval;
+
+ if (changed && current_loops)
+ loops_state_set (LOOPS_NEED_FIXUP);
+
+ return changed;
}
-/* Cleanup cfg and repair loop structures. */
+/* Repairs loop structures. */
-void
-cleanup_tree_cfg_loop (void)
+static void
+repair_loop_structures (void)
{
bitmap changed_bbs = BITMAP_ALLOC (NULL);
-
- cleanup_tree_cfg ();
-
- fix_loop_structure (current_loops, changed_bbs);
- calculate_dominance_info (CDI_DOMINATORS);
+ fix_loop_structure (changed_bbs);
/* This usually does nothing. But sometimes parts of cfg that originally
were inside a loop get out of it due to edge removal (since they
become unreachable by back edges from latch). */
- rewrite_into_loop_closed_ssa (changed_bbs, TODO_update_ssa);
+ if (loops_state_satisfies_p (LOOP_CLOSED_SSA))
+ rewrite_into_loop_closed_ssa (changed_bbs, TODO_update_ssa);
BITMAP_FREE (changed_bbs);
#ifdef ENABLE_CHECKING
- verify_loop_structure (current_loops);
+ verify_loop_structure ();
#endif
+ scev_reset ();
+
+ loops_state_clear (LOOPS_NEED_FIXUP);
+}
+
+/* Cleanup cfg and repair loop structures. */
+
+bool
+cleanup_tree_cfg (void)
+{
+ bool changed = cleanup_tree_cfg_noloop ();
+
+ if (current_loops != NULL
+ && loops_state_satisfies_p (LOOPS_NEED_FIXUP))
+ repair_loop_structures ();
+
+ return changed;
}
/* Merge the PHI nodes at BB into those at BB's sole successor. */
{
edge succ = single_succ_edge (bb);
basic_block dest = succ->dest;
- tree label;
+ gimple label;
basic_block dombb, domdest, dom;
/* We check for infinite loops already in tree_forwarder_block_p.
merge it. */
label = first_stmt (dest);
if (label
- && TREE_CODE (label) == LABEL_EXPR
- && DECL_NONLOCAL (LABEL_EXPR_LABEL (label)))
+ && gimple_code (label) == GIMPLE_LABEL
+ && DECL_NONLOCAL (gimple_label_label (label)))
return;
/* Redirect each incoming edge to BB to DEST. */
while (EDGE_COUNT (bb->preds) > 0)
{
edge e = EDGE_PRED (bb, 0), s;
- tree phi;
+ gimple_stmt_iterator gsi;
s = find_edge (e->src, dest);
if (s)
if (phi_alternatives_equal (dest, s, succ))
{
e = redirect_edge_and_branch (e, dest);
- PENDING_STMT (e) = NULL_TREE;
+ redirect_edge_var_map_clear (e);
continue;
}
/* Add to the PHI nodes at DEST each PHI argument removed at the
destination of E. */
- for (phi = phi_nodes (dest); phi; phi = PHI_CHAIN (phi))
+ for (gsi = gsi_start_phis (dest);
+ !gsi_end_p (gsi);
+ gsi_next (&gsi))
{
- tree def = PHI_ARG_DEF (phi, succ->dest_idx);
+ gimple phi = gsi_stmt (gsi);
+ tree def = gimple_phi_arg_def (phi, succ->dest_idx);
+ source_location locus = gimple_phi_arg_location_from_edge (phi, succ);
if (TREE_CODE (def) == SSA_NAME)
{
- tree var;
+ edge_var_map_vector head;
+ edge_var_map *vm;
+ size_t i;
/* If DEF is one of the results of PHI nodes removed during
redirection, replace it with the PHI argument that used
to be on E. */
- for (var = PENDING_STMT (e); var; var = TREE_CHAIN (var))
+ head = redirect_edge_var_map_vector (e);
+ for (i = 0; VEC_iterate (edge_var_map, head, i, vm); ++i)
{
- tree old_arg = TREE_PURPOSE (var);
- tree new_arg = TREE_VALUE (var);
+ tree old_arg = redirect_edge_var_map_result (vm);
+ tree new_arg = redirect_edge_var_map_def (vm);
if (def == old_arg)
{
def = new_arg;
+ locus = redirect_edge_var_map_location (vm);
break;
}
}
}
- add_phi_arg (phi, def, s);
+ add_phi_arg (phi, def, s, locus);
}
- PENDING_STMT (e) = NULL;
+ redirect_edge_var_map_clear (e);
}
/* Update the dominators. */
<L10>:;
*/
-static void
+static unsigned int
merge_phi_nodes (void)
{
- basic_block *worklist = xmalloc (sizeof (basic_block) * n_basic_blocks);
+ basic_block *worklist = XNEWVEC (basic_block, n_basic_blocks);
basic_block *current = worklist;
basic_block bb;
/* We have to feed into another basic block with PHI
nodes. */
- if (!phi_nodes (dest)
+ if (gimple_seq_empty_p (phi_nodes (dest))
/* We don't want to deal with a basic block with
abnormal edges. */
|| has_abnormal_incoming_edge_p (bb))
nodes at BB. */
*current++ = bb;
}
+ else
+ {
+ gimple_stmt_iterator gsi;
+ unsigned int dest_idx = single_succ_edge (bb)->dest_idx;
+
+ /* BB dominates DEST. There may be many users of the PHI
+ nodes in BB. However, there is still a trivial case we
+ can handle. If the result of every PHI in BB is used
+ only by a PHI in DEST, then we can trivially merge the
+ PHI nodes from BB into DEST. */
+ for (gsi = gsi_start_phis (bb); !gsi_end_p (gsi);
+ gsi_next (&gsi))
+ {
+ gimple phi = gsi_stmt (gsi);
+ tree result = gimple_phi_result (phi);
+ use_operand_p imm_use;
+ gimple use_stmt;
+
+ /* If the PHI's result is never used, then we can just
+ ignore it. */
+ if (has_zero_uses (result))
+ continue;
+
+ /* Get the single use of the result of this PHI node. */
+ if (!single_imm_use (result, &imm_use, &use_stmt)
+ || gimple_code (use_stmt) != GIMPLE_PHI
+ || gimple_bb (use_stmt) != dest
+ || gimple_phi_arg_def (use_stmt, dest_idx) != result)
+ break;
+ }
+
+ /* If the loop above iterated through all the PHI nodes
+ in BB, then we can merge the PHIs from BB into DEST. */
+ if (gsi_end_p (gsi))
+ *current++ = bb;
+ }
}
/* Now let's drain WORKLIST. */
}
free (worklist);
+ return 0;
}
static bool
return 1;
}
-struct tree_opt_pass pass_merge_phi = {
+struct gimple_opt_pass pass_merge_phi =
+{
+ {
+ GIMPLE_PASS,
"mergephi", /* name */
gate_merge_phi, /* gate */
merge_phi_nodes, /* execute */
0, /* properties_destroyed */
0, /* todo_flags_start */
TODO_dump_func | TODO_ggc_collect /* todo_flags_finish */
- | TODO_verify_ssa,
- 0 /* letter */
+ | TODO_verify_ssa
+ }
};
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