fprintf (dump_file, " Threaded jump %d --> %d to %d\n",
e->src->index, e->dest->index, rd->dup_blocks[0]->index);
- /* If we redirect a loop latch edge cancel its loop. */
- if (e->src == e->src->loop_father->latch)
- mark_loop_for_removal (e->src->loop_father);
-
/* Redirect the incoming edge (possibly to the joiner block) to the
appropriate duplicate block. */
e2 = redirect_edge_and_branch (e, rd->dup_blocks[0]);
return retval;
}
-
-/* Threads edge E through E->dest to the edge THREAD_TARGET (E). Returns the
- copy of E->dest created during threading, or E->dest if it was not necessary
- to copy it (E is its single predecessor). */
-
-static basic_block
-thread_single_edge (edge e)
-{
- basic_block bb = e->dest;
- struct redirection_data rd;
- vec<jump_thread_edge *> *path = THREAD_PATH (e);
- edge eto = (*path)[1]->e;
-
- delete_jump_thread_path (path);
- e->aux = NULL;
-
- thread_stats.num_threaded_edges++;
-
- if (single_pred_p (bb))
- {
- /* If BB has just a single predecessor, we should only remove the
- control statements at its end, and successors except for ETO. */
- remove_ctrl_stmt_and_useless_edges (bb, eto->dest);
-
- /* And fixup the flags on the single remaining edge. */
- eto->flags &= ~(EDGE_TRUE_VALUE | EDGE_FALSE_VALUE | EDGE_ABNORMAL);
- eto->flags |= EDGE_FALLTHRU;
-
- return bb;
- }
-
- /* Otherwise, we need to create a copy. */
- if (e->dest == eto->src)
- update_bb_profile_for_threading (bb, EDGE_FREQUENCY (e), e->count, eto);
-
- vec<jump_thread_edge *> *npath = new vec<jump_thread_edge *> ();
- jump_thread_edge *x = new jump_thread_edge (e, EDGE_START_JUMP_THREAD);
- npath->safe_push (x);
-
- x = new jump_thread_edge (eto, EDGE_COPY_SRC_BLOCK);
- npath->safe_push (x);
- rd.path = npath;
-
- create_block_for_threading (bb, &rd, 0, NULL);
- remove_ctrl_stmt_and_useless_edges (rd.dup_blocks[0], NULL);
- create_edge_and_update_destination_phis (&rd, rd.dup_blocks[0], 0);
-
- if (dump_file && (dump_flags & TDF_DETAILS))
- fprintf (dump_file, " Threaded jump %d --> %d to %d\n",
- e->src->index, e->dest->index, rd.dup_blocks[0]->index);
-
- rd.dup_blocks[0]->count = e->count;
- rd.dup_blocks[0]->frequency = EDGE_FREQUENCY (e);
- single_succ_edge (rd.dup_blocks[0])->count = e->count;
- redirect_edge_and_branch (e, rd.dup_blocks[0]);
- flush_pending_stmts (e);
-
- delete_jump_thread_path (npath);
- return rd.dup_blocks[0];
-}
-
/* Callback for dfs_enumerate_from. Returns true if BB is different
from STOP and DBDS_CE_STOP. */
return (bb_reachable ? DOMST_DOMINATING : DOMST_LOOP_BROKEN);
}
-/* Return true if BB is part of the new pre-header that is created
- when threading the latch to DATA. */
-
-static bool
-def_split_header_continue_p (const_basic_block bb, const void *data)
-{
- const_basic_block new_header = (const_basic_block) data;
- const struct loop *l;
-
- if (bb == new_header
- || loop_depth (bb->loop_father) < loop_depth (new_header->loop_father))
- return false;
- for (l = bb->loop_father; l; l = loop_outer (l))
- if (l == new_header->loop_father)
- return true;
- return false;
-}
-
/* Thread jumps through the header of LOOP. Returns true if cfg changes.
If MAY_PEEL_LOOP_HEADERS is false, we avoid threading from entry edges
to the inside of the loop. */
if (single_succ_p (header))
goto fail;
- /* If we threaded the latch using a joiner block, we cancel the
- threading opportunity out of an abundance of caution. However,
- still allow threading from outside to inside the loop. */
- if (latch->aux)
- {
- vec<jump_thread_edge *> *path = THREAD_PATH (latch);
- if ((*path)[1]->type == EDGE_COPY_SRC_JOINER_BLOCK)
- {
- delete_jump_thread_path (path);
- latch->aux = NULL;
- }
- }
-
- if (latch->aux)
- {
- vec<jump_thread_edge *> *path = THREAD_PATH (latch);
- tgt_edge = (*path)[1]->e;
- tgt_bb = tgt_edge->dest;
- }
- else if (!may_peel_loop_headers
- && !redirection_block_p (loop->header))
+ if (!may_peel_loop_headers && !redirection_block_p (loop->header))
goto fail;
else
{
tgt_bb = split_edge (tgt_edge);
}
- if (latch->aux)
- {
- basic_block *bblocks;
- unsigned nblocks, i;
-
- /* First handle the case latch edge is redirected. We are copying
- the loop header but not creating a multiple entry loop. Make the
- cfg manipulation code aware of that fact. */
- set_loop_copy (loop, loop);
- loop->latch = thread_single_edge (latch);
- set_loop_copy (loop, NULL);
- gcc_assert (single_succ (loop->latch) == tgt_bb);
- loop->header = tgt_bb;
-
- /* Remove the new pre-header blocks from our loop. */
- bblocks = XCNEWVEC (basic_block, loop->num_nodes);
- nblocks = dfs_enumerate_from (header, 0, def_split_header_continue_p,
- bblocks, loop->num_nodes, tgt_bb);
- for (i = 0; i < nblocks; i++)
- if (bblocks[i]->loop_father == loop)
- {
- remove_bb_from_loops (bblocks[i]);
- add_bb_to_loop (bblocks[i], loop_outer (loop));
- }
- free (bblocks);
-
- /* If the new header has multiple latches mark it so. */
- FOR_EACH_EDGE (e, ei, loop->header->preds)
- if (e->src->loop_father == loop
- && e->src != loop->latch)
- {
- loop->latch = NULL;
- loops_state_set (LOOPS_MAY_HAVE_MULTIPLE_LATCHES);
- }
-
- /* Cancel remaining threading requests that would make the
- loop a multiple entry loop. */
- FOR_EACH_EDGE (e, ei, header->preds)
- {
- edge e2;
-
- if (e->aux == NULL)
- continue;
+ basic_block new_preheader;
- vec<jump_thread_edge *> *path = THREAD_PATH (e);
- e2 = path->last ()->e;
-
- if (e->src->loop_father != e2->dest->loop_father
- && e2->dest != loop->header)
- {
- delete_jump_thread_path (path);
- e->aux = NULL;
- }
- }
-
- /* Thread the remaining edges through the former header. */
- thread_block (header, false);
- }
- else
+ /* Now consider the case entry edges are redirected to the new entry
+ block. Remember one entry edge, so that we can find the new
+ preheader (its destination after threading). */
+ FOR_EACH_EDGE (e, ei, header->preds)
{
- basic_block new_preheader;
+ if (e->aux)
+ break;
+ }
- /* Now consider the case entry edges are redirected to the new entry
- block. Remember one entry edge, so that we can find the new
- preheader (its destination after threading). */
- FOR_EACH_EDGE (e, ei, header->preds)
- {
- if (e->aux)
- break;
- }
+ /* The duplicate of the header is the new preheader of the loop. Ensure
+ that it is placed correctly in the loop hierarchy. */
+ set_loop_copy (loop, loop_outer (loop));
- /* The duplicate of the header is the new preheader of the loop. Ensure
- that it is placed correctly in the loop hierarchy. */
- set_loop_copy (loop, loop_outer (loop));
-
- thread_block (header, false);
- set_loop_copy (loop, NULL);
- new_preheader = e->dest;
-
- /* Create the new latch block. This is always necessary, as the latch
- must have only a single successor, but the original header had at
- least two successors. */
- loop->latch = NULL;
- mfb_kj_edge = single_succ_edge (new_preheader);
- loop->header = mfb_kj_edge->dest;
- latch = make_forwarder_block (tgt_bb, mfb_keep_just, NULL);
- loop->header = latch->dest;
- loop->latch = latch->src;
- }
+ thread_block (header, false);
+ set_loop_copy (loop, NULL);
+ new_preheader = e->dest;
+ /* Create the new latch block. This is always necessary, as the latch
+ must have only a single successor, but the original header had at
+ least two successors. */
+ loop->latch = NULL;
+ mfb_kj_edge = single_succ_edge (new_preheader);
+ loop->header = mfb_kj_edge->dest;
+ latch = make_forwarder_block (tgt_bb, mfb_keep_just, NULL);
+ loop->header = latch->dest;
+ loop->latch = latch->src;
return true;
fail:
}
-/* Return TRUE if BB ends with a switch statement or a computed goto.
- Otherwise return false. */
-static bool
-bb_ends_with_multiway_branch (basic_block bb ATTRIBUTE_UNUSED)
-{
- gimple *stmt = last_stmt (bb);
- if (stmt && gimple_code (stmt) == GIMPLE_SWITCH)
- return true;
- if (stmt && gimple_code (stmt) == GIMPLE_GOTO
- && TREE_CODE (gimple_goto_dest (stmt)) == SSA_NAME)
- return true;
- return false;
-}
-
/* Verify that the REGION is a valid jump thread. A jump thread is a special
case of SEME Single Entry Multiple Exits region in which all nodes in the
REGION have exactly one incoming edge. The only exception is the first block
e->aux = NULL;
ei_next (&ei);
}
- else if (bb_ends_with_multiway_branch (path->last ()->e->src))
- {
- /* The code to thread through loop headers may have
- split a block with jump threads attached to it.
-
- We can identify this with a disjoint jump threading
- path. If found, just remove it. */
- for (unsigned int i = 0; i < path->length () - 1; i++)
- if ((*path)[i]->e->dest != (*path)[i + 1]->e->src)
- {
- delete_jump_thread_path (path);
- e->aux = NULL;
- ei_next (&ei);
- break;
- }
-
- /* Our path is still valid, thread it. */
- if (e->aux)
- {
- if (thread_block ((*path)[0]->e->dest, false))
- e->aux = NULL;
- else
- {
- delete_jump_thread_path (path);
- e->aux = NULL;
- ei_next (&ei);
- }
- }
- }
- else
+ else
{
delete_jump_thread_path (path);
e->aux = NULL;
/* First make sure there are no NULL outgoing edges on the jump threading
path. That can happen for jumping to a constant address. */
for (unsigned int i = 0; i < path->length (); i++)
- if ((*path)[i]->e == NULL)
- {
- if (dump_file && (dump_flags & TDF_DETAILS))
- {
- fprintf (dump_file,
- "Found NULL edge in jump threading path. Cancelling jump thread:\n");
- dump_jump_thread_path (dump_file, *path, false);
- }
+ {
+ if ((*path)[i]->e == NULL)
+ {
+ if (dump_file && (dump_flags & TDF_DETAILS))
+ {
+ fprintf (dump_file,
+ "Found NULL edge in jump threading path. Cancelling jump thread:\n");
+ dump_jump_thread_path (dump_file, *path, false);
+ }
- delete_jump_thread_path (path);
- return;
- }
+ delete_jump_thread_path (path);
+ return;
+ }
+
+ /* Only the FSM threader is allowed to thread across
+ backedges in the CFG. */
+ if (flag_checking
+ && (*path)[0]->type != EDGE_FSM_THREAD)
+ gcc_assert (((*path)[i]->e->flags & EDGE_DFS_BACK) == 0);
+ }
if (dump_file && (dump_flags & TDF_DETAILS))
dump_jump_thread_path (dump_file, *path, true);
projects / gcc.git / commitdiff