--- a/hotspot/src/share/vm/opto/block.cpp Thu Oct 30 17:08:48 2008 -0700
+++ b/hotspot/src/share/vm/opto/block.cpp Thu Nov 06 14:59:10 2008 -0800
@@ -57,6 +57,14 @@
_blocks[i] = b;
}
+#ifndef PRODUCT
+void Block_List::print() {
+ for (uint i=0; i < size(); i++) {
+ tty->print("B%d ", _blocks[i]->_pre_order);
+ }
+ tty->print("size = %d\n", size());
+}
+#endif
//=============================================================================
@@ -66,6 +74,12 @@
// Check for Start block
if( _pre_order == 1 ) return InteriorEntryAlignment;
// Check for loop alignment
+ if (has_loop_alignment()) return loop_alignment();
+
+ return 1; // no particular alignment
+}
+
+uint Block::compute_loop_alignment() {
Node *h = head();
if( h->is_Loop() && h->as_Loop()->is_inner_loop() ) {
// Pre- and post-loops have low trip count so do not bother with
@@ -83,13 +97,15 @@
}
return OptoLoopAlignment; // Otherwise align loop head
}
+
return 1; // no particular alignment
}
//-----------------------------------------------------------------------------
// Compute the size of first 'inst_cnt' instructions in this block.
// Return the number of instructions left to compute if the block has
-// less then 'inst_cnt' instructions.
+// less then 'inst_cnt' instructions. Stop, and return 0 if sum_size
+// exceeds OptoLoopAlignment.
uint Block::compute_first_inst_size(uint& sum_size, uint inst_cnt,
PhaseRegAlloc* ra) {
uint last_inst = _nodes.size();
@@ -307,6 +323,8 @@
tty->print("\tLoop: B%d-B%d ", bhead->_pre_order, bx->_pre_order);
// Dump any loop-specific bits, especially for CountedLoops.
loop->dump_spec(tty);
+ } else if (has_loop_alignment()) {
+ tty->print(" top-of-loop");
}
tty->print(" Freq: %g",_freq);
if( Verbose || WizardMode ) {
@@ -509,9 +527,11 @@
int branch_idx = b->_nodes.size() - b->_num_succs-1;
if( branch_idx < 1 ) return false;
Node *bra = b->_nodes[branch_idx];
- if( bra->is_Catch() ) return true;
+ if( bra->is_Catch() )
+ return true;
if( bra->is_Mach() ) {
- if( bra->is_MachNullCheck() ) return true;
+ if( bra->is_MachNullCheck() )
+ return true;
int iop = bra->as_Mach()->ideal_Opcode();
if( iop == Op_FastLock || iop == Op_FastUnlock )
return true;
@@ -557,10 +577,10 @@
dead->_nodes[k]->del_req(j);
}
-//------------------------------MoveToNext-------------------------------------
+//------------------------------move_to_next-----------------------------------
// Helper function to move block bx to the slot following b_index. Return
// true if the move is successful, otherwise false
-bool PhaseCFG::MoveToNext(Block* bx, uint b_index) {
+bool PhaseCFG::move_to_next(Block* bx, uint b_index) {
if (bx == NULL) return false;
// Return false if bx is already scheduled.
@@ -591,9 +611,9 @@
return true;
}
-//------------------------------MoveToEnd--------------------------------------
+//------------------------------move_to_end------------------------------------
// Move empty and uncommon blocks to the end.
-void PhaseCFG::MoveToEnd(Block *b, uint i) {
+void PhaseCFG::move_to_end(Block *b, uint i) {
int e = b->is_Empty();
if (e != Block::not_empty) {
if (e == Block::empty_with_goto) {
@@ -609,15 +629,31 @@
_blocks.push(b);
}
-//------------------------------RemoveEmpty------------------------------------
-// Remove empty basic blocks and useless branches.
-void PhaseCFG::RemoveEmpty() {
+//---------------------------set_loop_alignment--------------------------------
+// Set loop alignment for every block
+void PhaseCFG::set_loop_alignment() {
+ uint last = _num_blocks;
+ assert( _blocks[0] == _broot, "" );
+
+ for (uint i = 1; i < last; i++ ) {
+ Block *b = _blocks[i];
+ if (b->head()->is_Loop()) {
+ b->set_loop_alignment(b);
+ }
+ }
+}
+
+//-----------------------------remove_empty------------------------------------
+// Make empty basic blocks to be "connector" blocks, Move uncommon blocks
+// to the end.
+void PhaseCFG::remove_empty() {
// Move uncommon blocks to the end
uint last = _num_blocks;
- uint i;
assert( _blocks[0] == _broot, "" );
- for( i = 1; i < last; i++ ) {
+
+ for (uint i = 1; i < last; i++) {
Block *b = _blocks[i];
+ if (b->is_connector()) break;
// Check for NeverBranch at block end. This needs to become a GOTO to the
// true target. NeverBranch are treated as a conditional branch that
@@ -629,37 +665,40 @@
convert_NeverBranch_to_Goto(b);
// Look for uncommon blocks and move to end.
- if( b->is_uncommon(_bbs) ) {
- MoveToEnd(b, i);
- last--; // No longer check for being uncommon!
- if( no_flip_branch(b) ) { // Fall-thru case must follow?
- b = _blocks[i]; // Find the fall-thru block
- MoveToEnd(b, i);
- last--;
+ if (!C->do_freq_based_layout()) {
+ if( b->is_uncommon(_bbs) ) {
+ move_to_end(b, i);
+ last--; // No longer check for being uncommon!
+ if( no_flip_branch(b) ) { // Fall-thru case must follow?
+ b = _blocks[i]; // Find the fall-thru block
+ move_to_end(b, i);
+ last--;
+ }
+ i--; // backup block counter post-increment
}
- i--; // backup block counter post-increment
}
}
- // Remove empty blocks
- uint j1;
+ // Move empty blocks to the end
last = _num_blocks;
- for( i=0; i < last; i++ ) {
+ for (uint i = 1; i < last; i++) {
Block *b = _blocks[i];
- if (i > 0) {
- if (b->is_Empty() != Block::not_empty) {
- MoveToEnd(b, i);
- last--;
- i--;
- }
+ if (b->is_Empty() != Block::not_empty) {
+ move_to_end(b, i);
+ last--;
+ i--;
}
} // End of for all blocks
+}
+//-----------------------------fixup_flow--------------------------------------
+// Fix up the final control flow for basic blocks.
+void PhaseCFG::fixup_flow() {
// Fixup final control flow for the blocks. Remove jump-to-next
// block. If neither arm of a IF follows the conditional branch, we
// have to add a second jump after the conditional. We place the
// TRUE branch target in succs[0] for both GOTOs and IFs.
- for( i=0; i < _num_blocks; i++ ) {
+ for (uint i=0; i < _num_blocks; i++) {
Block *b = _blocks[i];
b->_pre_order = i; // turn pre-order into block-index
@@ -700,7 +739,7 @@
}
}
// Remove all CatchProjs
- for (j1 = 0; j1 < b->_num_succs; j1++) b->_nodes.pop();
+ for (uint j1 = 0; j1 < b->_num_succs; j1++) b->_nodes.pop();
} else if (b->_num_succs == 1) {
// Block ends in a Goto?
@@ -730,8 +769,7 @@
// successors after the current one, provided that the
// successor was previously unscheduled, but moveable
// (i.e., all paths to it involve a branch).
- if( bnext != bs0 && bnext != bs1 ) {
-
+ if( !C->do_freq_based_layout() && bnext != bs0 && bnext != bs1 ) {
// Choose the more common successor based on the probability
// of the conditional branch.
Block *bx = bs0;
@@ -751,9 +789,9 @@
}
// Attempt the more common successor first
- if (MoveToNext(bx, i)) {
+ if (move_to_next(bx, i)) {
bnext = bx;
- } else if (MoveToNext(by, i)) {
+ } else if (move_to_next(by, i)) {
bnext = by;
}
}
@@ -774,10 +812,8 @@
// Flip projection for each target
{ ProjNode *tmp = proj0; proj0 = proj1; proj1 = tmp; }
- } else if( bnext == bs1 ) { // Fall-thru is already in succs[1]
-
- } else { // Else need a double-branch
-
+ } else if( bnext != bs1 ) {
+ // Need a double-branch
// The existing conditional branch need not change.
// Add a unconditional branch to the false target.
// Alas, it must appear in its own block and adding a
@@ -786,8 +822,9 @@
}
// Make sure we TRUE branch to the target
- if( proj0->Opcode() == Op_IfFalse )
+ if( proj0->Opcode() == Op_IfFalse ) {
iff->negate();
+ }
b->_nodes.pop(); // Remove IfFalse & IfTrue projections
b->_nodes.pop();
@@ -796,9 +833,7 @@
// Multi-exit block, e.g. a switch statement
// But we don't need to do anything here
}
-
} // End of for all blocks
-
}
@@ -905,7 +940,7 @@
// Force the Union-Find mapping to be at least this large
extend(max,0);
// Initialize to be the ID mapping.
- for( uint i=0; i<_max; i++ ) map(i,i);
+ for( uint i=0; i<max; i++ ) map(i,i);
}
//------------------------------Find_compress----------------------------------
@@ -937,7 +972,6 @@
if( idx >= _max ) return idx;
uint next = lookup(idx);
while( next != idx ) { // Scan chain of equivalences
- assert( next < idx, "always union smaller" );
idx = next; // until find a fixed-point
next = lookup(idx);
}
@@ -956,3 +990,491 @@
assert( src < dst, "always union smaller" );
map(dst,src);
}
+
+#ifndef PRODUCT
+static void edge_dump(GrowableArray<CFGEdge *> *edges) {
+ tty->print_cr("---- Edges ----");
+ for (int i = 0; i < edges->length(); i++) {
+ CFGEdge *e = edges->at(i);
+ if (e != NULL) {
+ edges->at(i)->dump();
+ }
+ }
+}
+
+static void trace_dump(Trace *traces[], int count) {
+ tty->print_cr("---- Traces ----");
+ for (int i = 0; i < count; i++) {
+ Trace *tr = traces[i];
+ if (tr != NULL) {
+ tr->dump();
+ }
+ }
+}
+
+void Trace::dump( ) const {
+ tty->print_cr("Trace (freq %f)", first_block()->_freq);
+ for (Block *b = first_block(); b != NULL; b = next(b)) {
+ tty->print(" B%d", b->_pre_order);
+ if (b->head()->is_Loop()) {
+ tty->print(" (L%d)", b->compute_loop_alignment());
+ }
+ if (b->has_loop_alignment()) {
+ tty->print(" (T%d)", b->code_alignment());
+ }
+ }
+ tty->cr();
+}
+
+void CFGEdge::dump( ) const {
+ tty->print(" B%d --> B%d Freq: %f out:%3d%% in:%3d%% State: ",
+ from()->_pre_order, to()->_pre_order, freq(), _from_pct, _to_pct);
+ switch(state()) {
+ case connected:
+ tty->print("connected");
+ break;
+ case open:
+ tty->print("open");
+ break;
+ case interior:
+ tty->print("interior");
+ break;
+ }
+ if (infrequent()) {
+ tty->print(" infrequent");
+ }
+ tty->cr();
+}
+#endif
+
+//=============================================================================
+
+//------------------------------edge_order-------------------------------------
+// Comparison function for edges
+static int edge_order(CFGEdge **e0, CFGEdge **e1) {
+ float freq0 = (*e0)->freq();
+ float freq1 = (*e1)->freq();
+ if (freq0 != freq1) {
+ return freq0 > freq1 ? -1 : 1;
+ }
+
+ int dist0 = (*e0)->to()->_rpo - (*e0)->from()->_rpo;
+ int dist1 = (*e1)->to()->_rpo - (*e1)->from()->_rpo;
+
+ return dist1 - dist0;
+}
+
+//------------------------------trace_frequency_order--------------------------
+// Comparison function for edges
+static int trace_frequency_order(const void *p0, const void *p1) {
+ Trace *tr0 = *(Trace **) p0;
+ Trace *tr1 = *(Trace **) p1;
+ Block *b0 = tr0->first_block();
+ Block *b1 = tr1->first_block();
+
+ // The trace of connector blocks goes at the end;
+ // we only expect one such trace
+ if (b0->is_connector() != b1->is_connector()) {
+ return b1->is_connector() ? -1 : 1;
+ }
+
+ // Pull more frequently executed blocks to the beginning
+ float freq0 = b0->_freq;
+ float freq1 = b1->_freq;
+ if (freq0 != freq1) {
+ return freq0 > freq1 ? -1 : 1;
+ }
+
+ int diff = tr0->first_block()->_rpo - tr1->first_block()->_rpo;
+
+ return diff;
+}
+
+//------------------------------find_edges-------------------------------------
+// Find edges of interest, i.e, those which can fall through. Presumes that
+// edges which don't fall through are of low frequency and can be generally
+// ignored. Initialize the list of traces.
+void PhaseBlockLayout::find_edges()
+{
+ // Walk the blocks, creating edges and Traces
+ uint i;
+ Trace *tr = NULL;
+ for (i = 0; i < _cfg._num_blocks; i++) {
+ Block *b = _cfg._blocks[i];
+ tr = new Trace(b, next, prev);
+ traces[tr->id()] = tr;
+
+ // All connector blocks should be at the end of the list
+ if (b->is_connector()) break;
+
+ // If this block and the next one have a one-to-one successor
+ // predecessor relationship, simply append the next block
+ int nfallthru = b->num_fall_throughs();
+ while (nfallthru == 1 &&
+ b->succ_fall_through(0)) {
+ Block *n = b->_succs[0];
+
+ // Skip over single-entry connector blocks, we don't want to
+ // add them to the trace.
+ while (n->is_connector() && n->num_preds() == 1) {
+ n = n->_succs[0];
+ }
+
+ // We see a merge point, so stop search for the next block
+ if (n->num_preds() != 1) break;
+
+ i++;
+ assert(n = _cfg._blocks[i], "expecting next block");
+ tr->append(n);
+ uf->map(n->_pre_order, tr->id());
+ traces[n->_pre_order] = NULL;
+ nfallthru = b->num_fall_throughs();
+ b = n;
+ }
+
+ if (nfallthru > 0) {
+ // Create a CFGEdge for each outgoing
+ // edge that could be a fall-through.
+ for (uint j = 0; j < b->_num_succs; j++ ) {
+ if (b->succ_fall_through(j)) {
+ Block *target = b->non_connector_successor(j);
+ float freq = b->_freq * b->succ_prob(j);
+ int from_pct = (int) ((100 * freq) / b->_freq);
+ int to_pct = (int) ((100 * freq) / target->_freq);
+ edges->append(new CFGEdge(b, target, freq, from_pct, to_pct));
+ }
+ }
+ }
+ }
+
+ // Group connector blocks into one trace
+ for (i++; i < _cfg._num_blocks; i++) {
+ Block *b = _cfg._blocks[i];
+ assert(b->is_connector(), "connector blocks at the end");
+ tr->append(b);
+ uf->map(b->_pre_order, tr->id());
+ traces[b->_pre_order] = NULL;
+ }
+}
+
+//------------------------------union_traces----------------------------------
+// Union two traces together in uf, and null out the trace in the list
+void PhaseBlockLayout::union_traces(Trace* updated_trace, Trace* old_trace)
+{
+ uint old_id = old_trace->id();
+ uint updated_id = updated_trace->id();
+
+ uint lo_id = updated_id;
+ uint hi_id = old_id;
+
+ // If from is greater than to, swap values to meet
+ // UnionFind guarantee.
+ if (updated_id > old_id) {
+ lo_id = old_id;
+ hi_id = updated_id;
+
+ // Fix up the trace ids
+ traces[lo_id] = traces[updated_id];
+ updated_trace->set_id(lo_id);
+ }
+
+ // Union the lower with the higher and remove the pointer
+ // to the higher.
+ uf->Union(lo_id, hi_id);
+ traces[hi_id] = NULL;
+}
+
+//------------------------------grow_traces-------------------------------------
+// Append traces together via the most frequently executed edges
+void PhaseBlockLayout::grow_traces()
+{
+ // Order the edges, and drive the growth of Traces via the most
+ // frequently executed edges.
+ edges->sort(edge_order);
+ for (int i = 0; i < edges->length(); i++) {
+ CFGEdge *e = edges->at(i);
+
+ if (e->state() != CFGEdge::open) continue;
+
+ Block *src_block = e->from();
+ Block *targ_block = e->to();
+
+ // Don't grow traces along backedges?
+ if (!BlockLayoutRotateLoops) {
+ if (targ_block->_rpo <= src_block->_rpo) {
+ targ_block->set_loop_alignment(targ_block);
+ continue;
+ }
+ }
+
+ Trace *src_trace = trace(src_block);
+ Trace *targ_trace = trace(targ_block);
+
+ // If the edge in question can join two traces at their ends,
+ // append one trace to the other.
+ if (src_trace->last_block() == src_block) {
+ if (src_trace == targ_trace) {
+ e->set_state(CFGEdge::interior);
+ if (targ_trace->backedge(e)) {
+ // Reset i to catch any newly eligible edge
+ // (Or we could remember the first "open" edge, and reset there)
+ i = 0;
+ }
+ } else if (targ_trace->first_block() == targ_block) {
+ e->set_state(CFGEdge::connected);
+ src_trace->append(targ_trace);
+ union_traces(src_trace, targ_trace);
+ }
+ }
+ }
+}
+
+//------------------------------merge_traces-----------------------------------
+// Embed one trace into another, if the fork or join points are sufficiently
+// balanced.
+void PhaseBlockLayout::merge_traces(bool fall_thru_only)
+{
+ // Walk the edge list a another time, looking at unprocessed edges.
+ // Fold in diamonds
+ for (int i = 0; i < edges->length(); i++) {
+ CFGEdge *e = edges->at(i);
+
+ if (e->state() != CFGEdge::open) continue;
+ if (fall_thru_only) {
+ if (e->infrequent()) continue;
+ }
+
+ Block *src_block = e->from();
+ Trace *src_trace = trace(src_block);
+ bool src_at_tail = src_trace->last_block() == src_block;
+
+ Block *targ_block = e->to();
+ Trace *targ_trace = trace(targ_block);
+ bool targ_at_start = targ_trace->first_block() == targ_block;
+
+ if (src_trace == targ_trace) {
+ // This may be a loop, but we can't do much about it.
+ e->set_state(CFGEdge::interior);
+ continue;
+ }
+
+ if (fall_thru_only) {
+ // If the edge links the middle of two traces, we can't do anything.
+ // Mark the edge and continue.
+ if (!src_at_tail & !targ_at_start) {
+ continue;
+ }
+
+ // Don't grow traces along backedges?
+ if (!BlockLayoutRotateLoops && (targ_block->_rpo <= src_block->_rpo)) {
+ continue;
+ }
+
+ // If both ends of the edge are available, why didn't we handle it earlier?
+ assert(src_at_tail ^ targ_at_start, "Should have caught this edge earlier.");
+
+ if (targ_at_start) {
+ // Insert the "targ" trace in the "src" trace if the insertion point
+ // is a two way branch.
+ // Better profitability check possible, but may not be worth it.
+ // Someday, see if the this "fork" has an associated "join";
+ // then make a policy on merging this trace at the fork or join.
+ // For example, other things being equal, it may be better to place this
+ // trace at the join point if the "src" trace ends in a two-way, but
+ // the insertion point is one-way.
+ assert(src_block->num_fall_throughs() == 2, "unexpected diamond");
+ e->set_state(CFGEdge::connected);
+ src_trace->insert_after(src_block, targ_trace);
+ union_traces(src_trace, targ_trace);
+ } else if (src_at_tail) {
+ if (src_trace != trace(_cfg._broot)) {
+ e->set_state(CFGEdge::connected);
+ targ_trace->insert_before(targ_block, src_trace);
+ union_traces(targ_trace, src_trace);
+ }
+ }
+ } else if (e->state() == CFGEdge::open) {
+ // Append traces, even without a fall-thru connection.
+ // But leave root entry at the begining of the block list.
+ if (targ_trace != trace(_cfg._broot)) {
+ e->set_state(CFGEdge::connected);
+ src_trace->append(targ_trace);
+ union_traces(src_trace, targ_trace);
+ }
+ }
+ }
+}
+
+//----------------------------reorder_traces-----------------------------------
+// Order the sequence of the traces in some desirable way, and fixup the
+// jumps at the end of each block.
+void PhaseBlockLayout::reorder_traces(int count)
+{
+ ResourceArea *area = Thread::current()->resource_area();
+ Trace ** new_traces = NEW_ARENA_ARRAY(area, Trace *, count);
+ Block_List worklist;
+ int new_count = 0;
+
+ // Compact the traces.
+ for (int i = 0; i < count; i++) {
+ Trace *tr = traces[i];
+ if (tr != NULL) {
+ new_traces[new_count++] = tr;
+ }
+ }
+
+ // The entry block should be first on the new trace list.
+ Trace *tr = trace(_cfg._broot);
+ assert(tr == new_traces[0], "entry trace misplaced");
+
+ // Sort the new trace list by frequency
+ qsort(new_traces + 1, new_count - 1, sizeof(new_traces[0]), trace_frequency_order);
+
+ // Patch up the successor blocks
+ _cfg._blocks.reset();
+ _cfg._num_blocks = 0;
+ for (int i = 0; i < new_count; i++) {
+ Trace *tr = new_traces[i];
+ if (tr != NULL) {
+ tr->fixup_blocks(_cfg);
+ }
+ }
+}
+
+//------------------------------PhaseBlockLayout-------------------------------
+// Order basic blocks based on frequency
+PhaseBlockLayout::PhaseBlockLayout(PhaseCFG &cfg) :
+ Phase(BlockLayout),
+ _cfg(cfg)
+{
+ ResourceMark rm;
+ ResourceArea *area = Thread::current()->resource_area();
+
+ // List of traces
+ int size = _cfg._num_blocks + 1;
+ traces = NEW_ARENA_ARRAY(area, Trace *, size);
+ memset(traces, 0, size*sizeof(Trace*));
+ next = NEW_ARENA_ARRAY(area, Block *, size);
+ memset(next, 0, size*sizeof(Block *));
+ prev = NEW_ARENA_ARRAY(area, Block *, size);
+ memset(prev , 0, size*sizeof(Block *));
+
+ // List of edges
+ edges = new GrowableArray<CFGEdge*>;
+
+ // Mapping block index --> block_trace
+ uf = new UnionFind(size);
+ uf->reset(size);
+
+ // Find edges and create traces.
+ find_edges();
+
+ // Grow traces at their ends via most frequent edges.
+ grow_traces();
+
+ // Merge one trace into another, but only at fall-through points.
+ // This may make diamonds and other related shapes in a trace.
+ merge_traces(true);
+
+ // Run merge again, allowing two traces to be catenated, even if
+ // one does not fall through into the other. This appends loosely
+ // related traces to be near each other.
+ merge_traces(false);
+
+ // Re-order all the remaining traces by frequency
+ reorder_traces(size);
+
+ assert(_cfg._num_blocks >= (uint) (size - 1), "number of blocks can not shrink");
+}
+
+
+//------------------------------backedge---------------------------------------
+// Edge e completes a loop in a trace. If the target block is head of the
+// loop, rotate the loop block so that the loop ends in a conditional branch.
+bool Trace::backedge(CFGEdge *e) {
+ bool loop_rotated = false;
+ Block *src_block = e->from();
+ Block *targ_block = e->to();
+
+ assert(last_block() == src_block, "loop discovery at back branch");
+ if (first_block() == targ_block) {
+ if (BlockLayoutRotateLoops && last_block()->num_fall_throughs() < 2) {
+ // Find the last block in the trace that has a conditional
+ // branch.
+ Block *b;
+ for (b = last_block(); b != NULL; b = prev(b)) {
+ if (b->num_fall_throughs() == 2) {
+ break;
+ }
+ }
+
+ if (b != last_block() && b != NULL) {
+ loop_rotated = true;
+
+ // Rotate the loop by doing two-part linked-list surgery.
+ append(first_block());
+ break_loop_after(b);
+ }
+ }
+
+ // Backbranch to the top of a trace
+ // Scroll foward through the trace from the targ_block. If we find
+ // a loop head before another loop top, use the the loop head alignment.
+ for (Block *b = targ_block; b != NULL; b = next(b)) {
+ if (b->has_loop_alignment()) {
+ break;
+ }
+ if (b->head()->is_Loop()) {
+ targ_block = b;
+ break;
+ }
+ }
+
+ first_block()->set_loop_alignment(targ_block);
+
+ } else {
+ // Backbranch into the middle of a trace
+ targ_block->set_loop_alignment(targ_block);
+ }
+
+ return loop_rotated;
+}
+
+//------------------------------fixup_blocks-----------------------------------
+// push blocks onto the CFG list
+// ensure that blocks have the correct two-way branch sense
+void Trace::fixup_blocks(PhaseCFG &cfg) {
+ Block *last = last_block();
+ for (Block *b = first_block(); b != NULL; b = next(b)) {
+ cfg._blocks.push(b);
+ cfg._num_blocks++;
+ if (!b->is_connector()) {
+ int nfallthru = b->num_fall_throughs();
+ if (b != last) {
+ if (nfallthru == 2) {
+ // Ensure that the sense of the branch is correct
+ Block *bnext = next(b);
+ Block *bs0 = b->non_connector_successor(0);
+
+ MachNode *iff = b->_nodes[b->_nodes.size()-3]->as_Mach();
+ ProjNode *proj0 = b->_nodes[b->_nodes.size()-2]->as_Proj();
+ ProjNode *proj1 = b->_nodes[b->_nodes.size()-1]->as_Proj();
+
+ if (bnext == bs0) {
+ // Fall-thru case in succs[0], should be in succs[1]
+
+ // Flip targets in _succs map
+ Block *tbs0 = b->_succs[0];
+ Block *tbs1 = b->_succs[1];
+ b->_succs.map( 0, tbs1 );
+ b->_succs.map( 1, tbs0 );
+
+ // Flip projections to match targets
+ b->_nodes.map(b->_nodes.size()-2, proj1);
+ b->_nodes.map(b->_nodes.size()-1, proj0);
+ }
+ }
+ }
+ }
+ }
+}