diff -r e1b7673b2435 -r 6bcf9255d470 hotspot/src/share/vm/c1/c1_Optimizer.cpp --- a/hotspot/src/share/vm/c1/c1_Optimizer.cpp Wed Oct 13 15:38:14 2010 -0700 +++ b/hotspot/src/share/vm/c1/c1_Optimizer.cpp Fri Oct 15 09:38:20 2010 +0200 @@ -38,18 +38,20 @@ private: IR* _hir; int _cee_count; // the number of CEs successfully eliminated + int _ifop_count; // the number of IfOps successfully simplified int _has_substitution; public: - CE_Eliminator(IR* hir) : _cee_count(0), _hir(hir) { + CE_Eliminator(IR* hir) : _cee_count(0), _ifop_count(0), _hir(hir) { _has_substitution = false; _hir->iterate_preorder(this); if (_has_substitution) { - // substituted some phis so resolve the substitution + // substituted some ifops/phis, so resolve the substitution SubstitutionResolver sr(_hir); } } int cee_count() const { return _cee_count; } + int ifop_count() const { return _ifop_count; } void adjust_exception_edges(BlockBegin* block, BlockBegin* sux) { int e = sux->number_of_exception_handlers(); @@ -68,156 +70,214 @@ } } - virtual void block_do(BlockBegin* block) { - // 1) find conditional expression - // check if block ends with an If - If* if_ = block->end()->as_If(); - if (if_ == NULL) return; + virtual void block_do(BlockBegin* block); + + private: + Value make_ifop(Value x, Instruction::Condition cond, Value y, Value tval, Value fval); +}; - // check if If works on int or object types - // (we cannot handle If's working on long, float or doubles yet, - // since IfOp doesn't support them - these If's show up if cmp - // operations followed by If's are eliminated) - ValueType* if_type = if_->x()->type(); - if (!if_type->is_int() && !if_type->is_object()) return; +void CE_Eliminator::block_do(BlockBegin* block) { + // 1) find conditional expression + // check if block ends with an If + If* if_ = block->end()->as_If(); + if (if_ == NULL) return; - BlockBegin* t_block = if_->tsux(); - BlockBegin* f_block = if_->fsux(); - Instruction* t_cur = t_block->next(); - Instruction* f_cur = f_block->next(); + // check if If works on int or object types + // (we cannot handle If's working on long, float or doubles yet, + // since IfOp doesn't support them - these If's show up if cmp + // operations followed by If's are eliminated) + ValueType* if_type = if_->x()->type(); + if (!if_type->is_int() && !if_type->is_object()) return; - // one Constant may be present between BlockBegin and BlockEnd - Value t_const = NULL; - Value f_const = NULL; - if (t_cur->as_Constant() != NULL && !t_cur->can_trap()) { - t_const = t_cur; - t_cur = t_cur->next(); - } - if (f_cur->as_Constant() != NULL && !f_cur->can_trap()) { - f_const = f_cur; - f_cur = f_cur->next(); - } + BlockBegin* t_block = if_->tsux(); + BlockBegin* f_block = if_->fsux(); + Instruction* t_cur = t_block->next(); + Instruction* f_cur = f_block->next(); - // check if both branches end with a goto - Goto* t_goto = t_cur->as_Goto(); - if (t_goto == NULL) return; - Goto* f_goto = f_cur->as_Goto(); - if (f_goto == NULL) return; + // one Constant may be present between BlockBegin and BlockEnd + Value t_const = NULL; + Value f_const = NULL; + if (t_cur->as_Constant() != NULL && !t_cur->can_trap()) { + t_const = t_cur; + t_cur = t_cur->next(); + } + if (f_cur->as_Constant() != NULL && !f_cur->can_trap()) { + f_const = f_cur; + f_cur = f_cur->next(); + } - // check if both gotos merge into the same block - BlockBegin* sux = t_goto->default_sux(); - if (sux != f_goto->default_sux()) return; + // check if both branches end with a goto + Goto* t_goto = t_cur->as_Goto(); + if (t_goto == NULL) return; + Goto* f_goto = f_cur->as_Goto(); + if (f_goto == NULL) return; - // check if at least one word was pushed on sux_state - ValueStack* sux_state = sux->state(); - if (sux_state->stack_size() <= if_->state()->stack_size()) return; + // check if both gotos merge into the same block + BlockBegin* sux = t_goto->default_sux(); + if (sux != f_goto->default_sux()) return; - // check if phi function is present at end of successor stack and that - // only this phi was pushed on the stack - Value sux_phi = sux_state->stack_at(if_->state()->stack_size()); - if (sux_phi == NULL || sux_phi->as_Phi() == NULL || sux_phi->as_Phi()->block() != sux) return; - if (sux_phi->type()->size() != sux_state->stack_size() - if_->state()->stack_size()) return; - - // get the values that were pushed in the true- and false-branch - Value t_value = t_goto->state()->stack_at(if_->state()->stack_size()); - Value f_value = f_goto->state()->stack_at(if_->state()->stack_size()); + // check if at least one word was pushed on sux_state + ValueStack* sux_state = sux->state(); + if (sux_state->stack_size() <= if_->state()->stack_size()) return; - // backend does not support floats - assert(t_value->type()->base() == f_value->type()->base(), "incompatible types"); - if (t_value->type()->is_float_kind()) return; + // check if phi function is present at end of successor stack and that + // only this phi was pushed on the stack + Value sux_phi = sux_state->stack_at(if_->state()->stack_size()); + if (sux_phi == NULL || sux_phi->as_Phi() == NULL || sux_phi->as_Phi()->block() != sux) return; + if (sux_phi->type()->size() != sux_state->stack_size() - if_->state()->stack_size()) return; - // check that successor has no other phi functions but sux_phi - // this can happen when t_block or f_block contained additonal stores to local variables - // that are no longer represented by explicit instructions - for_each_phi_fun(sux, phi, - if (phi != sux_phi) return; - ); - // true and false blocks can't have phis - for_each_phi_fun(t_block, phi, return; ); - for_each_phi_fun(f_block, phi, return; ); + // get the values that were pushed in the true- and false-branch + Value t_value = t_goto->state()->stack_at(if_->state()->stack_size()); + Value f_value = f_goto->state()->stack_at(if_->state()->stack_size()); + + // backend does not support floats + assert(t_value->type()->base() == f_value->type()->base(), "incompatible types"); + if (t_value->type()->is_float_kind()) return; - // 2) substitute conditional expression - // with an IfOp followed by a Goto - // cut if_ away and get node before - Instruction* cur_end = if_->prev(block); + // check that successor has no other phi functions but sux_phi + // this can happen when t_block or f_block contained additonal stores to local variables + // that are no longer represented by explicit instructions + for_each_phi_fun(sux, phi, + if (phi != sux_phi) return; + ); + // true and false blocks can't have phis + for_each_phi_fun(t_block, phi, return; ); + for_each_phi_fun(f_block, phi, return; ); + + // 2) substitute conditional expression + // with an IfOp followed by a Goto + // cut if_ away and get node before + Instruction* cur_end = if_->prev(block); - // append constants of true- and false-block if necessary - // clone constants because original block must not be destroyed - assert((t_value != f_const && f_value != t_const) || t_const == f_const, "mismatch"); - if (t_value == t_const) { - t_value = new Constant(t_const->type()); - NOT_PRODUCT(t_value->set_printable_bci(if_->printable_bci())); - cur_end = cur_end->set_next(t_value); - } - if (f_value == f_const) { - f_value = new Constant(f_const->type()); - NOT_PRODUCT(f_value->set_printable_bci(if_->printable_bci())); - cur_end = cur_end->set_next(f_value); - } + // append constants of true- and false-block if necessary + // clone constants because original block must not be destroyed + assert((t_value != f_const && f_value != t_const) || t_const == f_const, "mismatch"); + if (t_value == t_const) { + t_value = new Constant(t_const->type()); + NOT_PRODUCT(t_value->set_printable_bci(if_->printable_bci())); + cur_end = cur_end->set_next(t_value); + } + if (f_value == f_const) { + f_value = new Constant(f_const->type()); + NOT_PRODUCT(f_value->set_printable_bci(if_->printable_bci())); + cur_end = cur_end->set_next(f_value); + } - // it is very unlikely that the condition can be statically decided - // (this was checked previously by the Canonicalizer), so always - // append IfOp - Value result = new IfOp(if_->x(), if_->cond(), if_->y(), t_value, f_value); + Value result = make_ifop(if_->x(), if_->cond(), if_->y(), t_value, f_value); + assert(result != NULL, "make_ifop must return a non-null instruction"); + if (!result->is_linked() && result->can_be_linked()) { NOT_PRODUCT(result->set_printable_bci(if_->printable_bci())); cur_end = cur_end->set_next(result); + } - // append Goto to successor - ValueStack* state_before = if_->is_safepoint() ? if_->state_before() : NULL; - Goto* goto_ = new Goto(sux, state_before, if_->is_safepoint() || t_goto->is_safepoint() || f_goto->is_safepoint()); + // append Goto to successor + ValueStack* state_before = if_->is_safepoint() ? if_->state_before() : NULL; + Goto* goto_ = new Goto(sux, state_before, if_->is_safepoint() || t_goto->is_safepoint() || f_goto->is_safepoint()); + + // prepare state for Goto + ValueStack* goto_state = if_->state(); + while (sux_state->scope() != goto_state->scope()) { + goto_state = goto_state->caller_state(); + assert(goto_state != NULL, "states do not match up"); + } + goto_state = goto_state->copy(ValueStack::StateAfter, goto_state->bci()); + goto_state->push(result->type(), result); + assert(goto_state->is_same(sux_state), "states must match now"); + goto_->set_state(goto_state); + + cur_end = cur_end->set_next(goto_, goto_state->bci()); + + // Adjust control flow graph + BlockBegin::disconnect_edge(block, t_block); + BlockBegin::disconnect_edge(block, f_block); + if (t_block->number_of_preds() == 0) { + BlockBegin::disconnect_edge(t_block, sux); + } + adjust_exception_edges(block, t_block); + if (f_block->number_of_preds() == 0) { + BlockBegin::disconnect_edge(f_block, sux); + } + adjust_exception_edges(block, f_block); + + // update block end + block->set_end(goto_); + + // substitute the phi if possible + if (sux_phi->as_Phi()->operand_count() == 1) { + assert(sux_phi->as_Phi()->operand_at(0) == result, "screwed up phi"); + sux_phi->set_subst(result); + _has_substitution = true; + } + + // 3) successfully eliminated a conditional expression + _cee_count++; + if (PrintCEE) { + tty->print_cr("%d. CEE in B%d (B%d B%d)", cee_count(), block->block_id(), t_block->block_id(), f_block->block_id()); + tty->print_cr("%d. IfOp in B%d", ifop_count(), block->block_id()); + } - // prepare state for Goto - ValueStack* goto_state = if_->state(); - while (sux_state->scope() != goto_state->scope()) { - goto_state = goto_state->caller_state(); - assert(goto_state != NULL, "states do not match up"); - } - goto_state = goto_state->copy(ValueStack::StateAfter, goto_state->bci()); - goto_state->push(result->type(), result); - assert(goto_state->is_same(sux_state), "states must match now"); - goto_->set_state(goto_state); + _hir->verify(); +} + +Value CE_Eliminator::make_ifop(Value x, Instruction::Condition cond, Value y, Value tval, Value fval) { + if (!OptimizeIfOps) { + return new IfOp(x, cond, y, tval, fval); + } + + tval = tval->subst(); + fval = fval->subst(); + if (tval == fval) { + _ifop_count++; + return tval; + } + + x = x->subst(); + y = y->subst(); + + Constant* y_const = y->as_Constant(); + if (y_const != NULL) { + IfOp* x_ifop = x->as_IfOp(); + if (x_ifop != NULL) { // x is an ifop, y is a constant + Constant* x_tval_const = x_ifop->tval()->subst()->as_Constant(); + Constant* x_fval_const = x_ifop->fval()->subst()->as_Constant(); - cur_end = cur_end->set_next(goto_, goto_state->bci()); + if (x_tval_const != NULL && x_fval_const != NULL) { + Instruction::Condition x_ifop_cond = x_ifop->cond(); + + Constant::CompareResult t_compare_res = x_tval_const->compare(cond, y_const); + Constant::CompareResult f_compare_res = x_fval_const->compare(cond, y_const); + + guarantee(t_compare_res != Constant::not_comparable && f_compare_res != Constant::not_comparable, "incomparable constants in IfOp"); + + Value new_tval = t_compare_res == Constant::cond_true ? tval : fval; + Value new_fval = f_compare_res == Constant::cond_true ? tval : fval; - // Adjust control flow graph - BlockBegin::disconnect_edge(block, t_block); - BlockBegin::disconnect_edge(block, f_block); - if (t_block->number_of_preds() == 0) { - BlockBegin::disconnect_edge(t_block, sux); + _ifop_count++; + if (new_tval == new_fval) { + return new_tval; + } else { + return new IfOp(x_ifop->x(), x_ifop_cond, x_ifop->y(), new_tval, new_fval); + } + } + } else { + Constant* x_const = x->as_Constant(); + if (x_const != NULL) { // x and y are constants + Constant::CompareResult x_compare_res = x_const->compare(cond, y_const); + guarantee(x_compare_res != Constant::not_comparable, "incomparable constants in IfOp"); + + _ifop_count++; + return x_compare_res == Constant::cond_true ? tval : fval; + } } - adjust_exception_edges(block, t_block); - if (f_block->number_of_preds() == 0) { - BlockBegin::disconnect_edge(f_block, sux); - } - adjust_exception_edges(block, f_block); - - // update block end - block->set_end(goto_); - - // substitute the phi if possible - if (sux_phi->as_Phi()->operand_count() == 1) { - assert(sux_phi->as_Phi()->operand_at(0) == result, "screwed up phi"); - sux_phi->set_subst(result); - _has_substitution = true; - } - - // 3) successfully eliminated a conditional expression - _cee_count++; - if (PrintCEE) { - tty->print_cr("%d. CEE in B%d (B%d B%d)", cee_count(), block->block_id(), t_block->block_id(), f_block->block_id()); - } - - _hir->verify(); } -}; - + return new IfOp(x, cond, y, tval, fval); +} void Optimizer::eliminate_conditional_expressions() { // find conditional expressions & replace them with IfOps CE_Eliminator ce(ir()); } - class BlockMerger: public BlockClosure { private: IR* _hir;