196 Block* pop() { Block* b = _stack_top->block; _stack_top--; return b; }
197 bool is_nonempty() { return (_stack_top >= _stack); }
198 bool last_successor() { return (_stack_top->index == _stack_top->freq_idx); }
199 Block* next_successor() {
200 int i = _stack_top->index;
201 i++;
202 if (i == _stack_top->freq_idx) i++;
203 if (i >= (int)(_stack_top->block->_num_succs)) {
204 i = _stack_top->freq_idx; // process most frequent successor last
205 }
206 _stack_top->index = i;
207 return _stack_top->block->_succs[ i ];
208 }
209 };
210
211 // Find the index into the b->succs[] array of the most frequent successor.
212 uint Block_Stack::most_frequent_successor( Block *b ) {
213 uint freq_idx = 0;
214 int eidx = b->end_idx();
215 Node *n = b->get_node(eidx);
216 int op = n->is_Mach() ? n->as_Mach()->ideal_Opcode() : n->Opcode();
217 switch( op ) {
218 case Op_CountedLoopEnd:
219 case Op_If: { // Split frequency amongst children
220 float prob = n->as_MachIf()->_prob;
221 // Is succ[0] the TRUE branch or the FALSE branch?
222 if( b->get_node(eidx+1)->Opcode() == Op_IfFalse )
223 prob = 1.0f - prob;
224 freq_idx = prob < PROB_FAIR; // freq=1 for succ[0] < 0.5 prob
225 break;
226 }
227 case Op_Catch: // Split frequency amongst children
228 for( freq_idx = 0; freq_idx < b->_num_succs; freq_idx++ )
229 if( b->get_node(eidx+1+freq_idx)->as_CatchProj()->_con == CatchProjNode::fall_through_index )
230 break;
231 // Handle case of no fall-thru (e.g., check-cast MUST throw an exception)
232 if( freq_idx == b->_num_succs ) freq_idx = 0;
233 break;
234 // Currently there is no support for finding out the most
235 // frequent successor for jumps, so lets just make it the first one
236 case Op_Jump:
237 case Op_Root:
238 case Op_Goto:
239 case Op_NeverBranch:
240 freq_idx = 0; // fall thru
241 break;
242 case Op_TailCall:
243 case Op_TailJump:
244 case Op_Return:
245 case Op_Halt:
246 case Op_Rethrow:
247 break;
248 default:
249 ShouldNotReachHere();
250 }
251 return freq_idx;
252 }
253
254 // Perform DFS search. Setup 'vertex' as DFS to vertex mapping. Setup
255 // 'semi' as vertex to DFS mapping. Set 'parent' to DFS parent.
256 uint PhaseCFG::do_DFS(Tarjan *tarjan, uint rpo_counter) {
257 Block* root_block = get_root_block();
258 uint pre_order = 1;
259 // Allocate stack of size number_of_blocks() + 1 to avoid frequent realloc
260 Block_Stack bstack(tarjan, number_of_blocks() + 1);
261
262 // Push on stack the state for the first block
263 bstack.push(pre_order, root_block);
264 ++pre_order;
265
266 while (bstack.is_nonempty()) {
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196 Block* pop() { Block* b = _stack_top->block; _stack_top--; return b; }
197 bool is_nonempty() { return (_stack_top >= _stack); }
198 bool last_successor() { return (_stack_top->index == _stack_top->freq_idx); }
199 Block* next_successor() {
200 int i = _stack_top->index;
201 i++;
202 if (i == _stack_top->freq_idx) i++;
203 if (i >= (int)(_stack_top->block->_num_succs)) {
204 i = _stack_top->freq_idx; // process most frequent successor last
205 }
206 _stack_top->index = i;
207 return _stack_top->block->_succs[ i ];
208 }
209 };
210
211 // Find the index into the b->succs[] array of the most frequent successor.
212 uint Block_Stack::most_frequent_successor( Block *b ) {
213 uint freq_idx = 0;
214 int eidx = b->end_idx();
215 Node *n = b->get_node(eidx);
216 Opcodes op = n->is_Mach() ? n->as_Mach()->ideal_Opcode() : n->Opcode();
217 switch( op ) {
218 case Opcodes::Op_CountedLoopEnd:
219 case Opcodes::Op_If: { // Split frequency amongst children
220 float prob = n->as_MachIf()->_prob;
221 // Is succ[0] the TRUE branch or the FALSE branch?
222 if( b->get_node(eidx+1)->Opcode() == Opcodes::Op_IfFalse )
223 prob = 1.0f - prob;
224 freq_idx = prob < PROB_FAIR; // freq=1 for succ[0] < 0.5 prob
225 break;
226 }
227 case Opcodes::Op_Catch: // Split frequency amongst children
228 for( freq_idx = 0; freq_idx < b->_num_succs; freq_idx++ )
229 if( b->get_node(eidx+1+freq_idx)->as_CatchProj()->_con == CatchProjNode::fall_through_index )
230 break;
231 // Handle case of no fall-thru (e.g., check-cast MUST throw an exception)
232 if( freq_idx == b->_num_succs ) freq_idx = 0;
233 break;
234 // Currently there is no support for finding out the most
235 // frequent successor for jumps, so lets just make it the first one
236 case Opcodes::Op_Jump:
237 case Opcodes::Op_Root:
238 case Opcodes::Op_Goto:
239 case Opcodes::Op_NeverBranch:
240 freq_idx = 0; // fall thru
241 break;
242 case Opcodes::Op_TailCall:
243 case Opcodes::Op_TailJump:
244 case Opcodes::Op_Return:
245 case Opcodes::Op_Halt:
246 case Opcodes::Op_Rethrow:
247 break;
248 default:
249 ShouldNotReachHere();
250 }
251 return freq_idx;
252 }
253
254 // Perform DFS search. Setup 'vertex' as DFS to vertex mapping. Setup
255 // 'semi' as vertex to DFS mapping. Set 'parent' to DFS parent.
256 uint PhaseCFG::do_DFS(Tarjan *tarjan, uint rpo_counter) {
257 Block* root_block = get_root_block();
258 uint pre_order = 1;
259 // Allocate stack of size number_of_blocks() + 1 to avoid frequent realloc
260 Block_Stack bstack(tarjan, number_of_blocks() + 1);
261
262 // Push on stack the state for the first block
263 bstack.push(pre_order, root_block);
264 ++pre_order;
265
266 while (bstack.is_nonempty()) {
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