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tree-cfg.c (thread_jumps): Use a do-while loop instead of a loop with goto.
* tree-cfg.c (thread_jumps): Use a do-while loop instead of a loop with goto. From-SVN: r89276
This commit is contained in:
Kazu Hirata
Kazu Hirata
parent
e836a5a26a
commit
e61d7b781e
@ -1,3 +1,8 @@
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2004-10-19 Kazu Hirata <kazu@cs.umass.edu>
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* tree-cfg.c (thread_jumps): Use a do-while loop instead of a
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loop with goto.
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2004-10-19 Kazu Hirata <kazu@cs.umass.edu>
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* expr.c (expand_assignment): Remove the last argument.
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284
gcc/tree-cfg.c
284
gcc/tree-cfg.c
@ -3781,173 +3781,179 @@ thread_jumps (void)
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FOR_EACH_BB (bb)
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bb_ann (bb)->forwardable = tree_forwarder_block_p (bb);
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restart:
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rerun = false;
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FOR_EACH_BB (bb)
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do
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{
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edge_iterator ei;
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bool this_jump_threaded = false;
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/* Don't waste time on forwarders. */
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if (bb_ann (bb)->forwardable)
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continue;
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/* Examine each of our block's successors to see if it is
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forwardable. */
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for (ei = ei_start (bb->succs); (e = ei_safe_edge (ei)); )
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rerun = false;
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FOR_EACH_BB (bb)
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{
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int freq;
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gcov_type count;
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edge_iterator ei;
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bool this_jump_threaded = false;
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/* If the edge is abnormal or its destination is not
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forwardable, then there's nothing to do. */
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if ((e->flags & EDGE_ABNORMAL)
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|| !bb_ann (e->dest)->forwardable)
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/* Don't waste time on forwarders. */
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if (bb_ann (bb)->forwardable)
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continue;
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/* Examine each of our block's successors to see if it is
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forwardable. */
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for (ei = ei_start (bb->succs); (e = ei_safe_edge (ei)); )
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{
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ei_next (&ei);
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continue;
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}
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int freq;
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gcov_type count;
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count = e->count;
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freq = EDGE_FREQUENCY (e);
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/* If the edge is abnormal or its destination is not
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forwardable, then there's nothing to do. */
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if ((e->flags & EDGE_ABNORMAL)
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|| !bb_ann (e->dest)->forwardable)
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{
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ei_next (&ei);
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continue;
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}
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/* Now walk through as many forwarder blocks as possible to
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find the ultimate destination we want to thread our jump
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to. */
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last = EDGE_SUCC (e->dest, 0);
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bb_ann (e->dest)->forwardable = 0;
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for (dest = EDGE_SUCC (e->dest, 0)->dest;
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bb_ann (dest)->forwardable;
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last = EDGE_SUCC (dest, 0),
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dest = EDGE_SUCC (dest, 0)->dest)
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bb_ann (dest)->forwardable = 0;
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count = e->count;
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freq = EDGE_FREQUENCY (e);
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/* Reset the forwardable marks to 1. */
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for (tmp = e->dest;
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tmp != dest;
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tmp = EDGE_SUCC (tmp, 0)->dest)
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bb_ann (tmp)->forwardable = 1;
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/* Now walk through as many forwarder blocks as possible to
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find the ultimate destination we want to thread our jump
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to. */
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last = EDGE_SUCC (e->dest, 0);
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bb_ann (e->dest)->forwardable = 0;
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for (dest = EDGE_SUCC (e->dest, 0)->dest;
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bb_ann (dest)->forwardable;
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last = EDGE_SUCC (dest, 0),
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dest = EDGE_SUCC (dest, 0)->dest)
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bb_ann (dest)->forwardable = 0;
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if (dest == e->dest)
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{
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ei_next (&ei);
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continue;
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}
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/* Reset the forwardable marks to 1. */
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for (tmp = e->dest;
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tmp != dest;
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tmp = EDGE_SUCC (tmp, 0)->dest)
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bb_ann (tmp)->forwardable = 1;
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if (dest == e->dest)
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{
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ei_next (&ei);
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continue;
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}
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old = find_edge (bb, dest);
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if (old)
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{
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/* If there already is an edge, check whether the values
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in phi nodes differ. */
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if (!phi_alternatives_equal (dest, last, old))
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old = find_edge (bb, dest);
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if (old)
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{
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/* The previous block is forwarder. Redirect our jump
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to that target instead since we know it has no PHI
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nodes that will need updating. */
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dest = last->src;
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/* That might mean that no forwarding at all is possible. */
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if (dest == e->dest)
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/* If there already is an edge, check whether the values
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in phi nodes differ. */
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if (!phi_alternatives_equal (dest, last, old))
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{
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ei_next (&ei);
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continue;
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/* The previous block is forwarder. Redirect our jump
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to that target instead since we know it has no PHI
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nodes that will need updating. */
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dest = last->src;
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/* That might mean that no forwarding at all is
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possible. */
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if (dest == e->dest)
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{
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ei_next (&ei);
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continue;
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}
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old = find_edge (bb, dest);
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}
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old = find_edge (bb, dest);
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}
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}
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/* Perform the redirection. */
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retval = this_jump_threaded = true;
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old_dest = e->dest;
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e = redirect_edge_and_branch (e, dest);
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/* Perform the redirection. */
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retval = this_jump_threaded = true;
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old_dest = e->dest;
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e = redirect_edge_and_branch (e, dest);
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/* Update the profile. */
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if (profile_status != PROFILE_ABSENT)
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for (curr = old_dest; curr != dest; curr = EDGE_SUCC (curr, 0)->dest)
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{
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curr->frequency -= freq;
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if (curr->frequency < 0)
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curr->frequency = 0;
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curr->count -= count;
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if (curr->count < 0)
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curr->count = 0;
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EDGE_SUCC (curr, 0)->count -= count;
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if (EDGE_SUCC (curr, 0)->count < 0)
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EDGE_SUCC (curr, 0)->count = 0;
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}
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/* Update the profile. */
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if (profile_status != PROFILE_ABSENT)
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for (curr = old_dest;
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curr != dest;
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curr = EDGE_SUCC (curr, 0)->dest)
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{
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curr->frequency -= freq;
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if (curr->frequency < 0)
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curr->frequency = 0;
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curr->count -= count;
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if (curr->count < 0)
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curr->count = 0;
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EDGE_SUCC (curr, 0)->count -= count;
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if (EDGE_SUCC (curr, 0)->count < 0)
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EDGE_SUCC (curr, 0)->count = 0;
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}
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if (!old)
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{
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/* Update PHI nodes. We know that the new argument should
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have the same value as the argument associated with LAST.
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Otherwise we would have changed our target block above. */
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for (phi = phi_nodes (dest); phi; phi = PHI_CHAIN (phi))
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if (!old)
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{
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arg = phi_arg_from_edge (phi, last);
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gcc_assert (arg >= 0);
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add_phi_arg (&phi, PHI_ARG_DEF (phi, arg), e);
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/* Update PHI nodes. We know that the new argument
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should have the same value as the argument
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associated with LAST. Otherwise we would have
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changed our target block above. */
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for (phi = phi_nodes (dest); phi; phi = PHI_CHAIN (phi))
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{
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arg = phi_arg_from_edge (phi, last);
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gcc_assert (arg >= 0);
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add_phi_arg (&phi, PHI_ARG_DEF (phi, arg), e);
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}
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}
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}
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/* Remove the unreachable blocks (observe that if all blocks
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were reachable before, only those in the path we threaded
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over and did not have any predecessor outside of the path
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become unreachable). */
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for (; old_dest != dest; old_dest = tmp)
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{
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tmp = EDGE_SUCC (old_dest, 0)->dest;
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if (EDGE_COUNT (old_dest->preds) > 0)
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break;
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delete_basic_block (old_dest);
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}
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/* Update the dominators. */
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if (dom_info_available_p (CDI_DOMINATORS))
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{
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/* If the dominator of the destination was in the path, set its
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dominator to the start of the redirected edge. */
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if (get_immediate_dominator (CDI_DOMINATORS, old_dest) == NULL)
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set_immediate_dominator (CDI_DOMINATORS, old_dest, bb);
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/* Now proceed like if we forwarded just over one edge at a time.
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Algorithm for forwarding edge S --> A over edge A --> B then
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is
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if (idom (B) == A
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&& !dominated_by (S, B))
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idom (B) = idom (A);
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recount_idom (A); */
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/* Remove the unreachable blocks (observe that if all blocks
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were reachable before, only those in the path we threaded
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over and did not have any predecessor outside of the path
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become unreachable). */
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for (; old_dest != dest; old_dest = tmp)
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{
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tmp = EDGE_SUCC (old_dest, 0)->dest;
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if (get_immediate_dominator (CDI_DOMINATORS, tmp) == old_dest
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&& !dominated_by_p (CDI_DOMINATORS, bb, tmp))
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{
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dom = get_immediate_dominator (CDI_DOMINATORS, old_dest);
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set_immediate_dominator (CDI_DOMINATORS, tmp, dom);
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}
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if (EDGE_COUNT (old_dest->preds) > 0)
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break;
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dom = recount_dominator (CDI_DOMINATORS, old_dest);
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set_immediate_dominator (CDI_DOMINATORS, old_dest, dom);
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delete_basic_block (old_dest);
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}
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/* Update the dominators. */
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if (dom_info_available_p (CDI_DOMINATORS))
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{
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/* If the dominator of the destination was in the
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path, set its dominator to the start of the
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redirected edge. */
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if (get_immediate_dominator (CDI_DOMINATORS, old_dest) == NULL)
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set_immediate_dominator (CDI_DOMINATORS, old_dest, bb);
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/* Now proceed like if we forwarded just over one
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edge at a time. Algorithm for forwarding edge
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S --> A over edge A --> B then is
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if (idom (B) == A
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&& !dominated_by (S, B))
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idom (B) = idom (A);
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recount_idom (A); */
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for (; old_dest != dest; old_dest = tmp)
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{
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tmp = EDGE_SUCC (old_dest, 0)->dest;
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if (get_immediate_dominator (CDI_DOMINATORS, tmp) == old_dest
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&& !dominated_by_p (CDI_DOMINATORS, bb, tmp))
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{
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dom = get_immediate_dominator (CDI_DOMINATORS, old_dest);
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set_immediate_dominator (CDI_DOMINATORS, tmp, dom);
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}
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dom = recount_dominator (CDI_DOMINATORS, old_dest);
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set_immediate_dominator (CDI_DOMINATORS, old_dest, dom);
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}
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}
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}
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}
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/* If we succeeded in threading a jump at BB, update the
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forwardable mark as BB may have become a new forwarder block.
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This could happen if we have a useless "if" statement whose
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two arms eventually merge without any intervening
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statements. */
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if (this_jump_threaded && tree_forwarder_block_p (bb))
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bb_ann (bb)->forwardable = rerun = true;
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/* If we succeeded in threading a jump at BB, update the
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forwardable mark as BB may have become a new forwarder
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block. This could happen if we have a useless "if"
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statement whose two arms eventually merge without any
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intervening statements. */
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if (this_jump_threaded && tree_forwarder_block_p (bb))
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bb_ann (bb)->forwardable = rerun = true;
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}
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}
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if (rerun)
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goto restart;
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while (rerun);
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return retval;
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}
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