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src/hotspot/share/opto/loopopts.cpp

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*** 44,54 **** #include "utilities/macros.hpp" //============================================================================= //------------------------------split_thru_phi--------------------------------- // Split Node 'n' through merge point if there is enough win. ! Node *PhaseIdealLoop::split_thru_phi( Node *n, Node *region, int policy ) { if (n->Opcode() == Op_ConvI2L && n->bottom_type() != TypeLong::LONG) { // ConvI2L may have type information on it which is unsafe to push up // so disable this for now return NULL; } --- 44,54 ---- #include "utilities/macros.hpp" //============================================================================= //------------------------------split_thru_phi--------------------------------- // Split Node 'n' through merge point if there is enough win. ! Node* PhaseIdealLoop::split_thru_phi(Node* n, Node* region, int policy) { if (n->Opcode() == Op_ConvI2L && n->bottom_type() != TypeLong::LONG) { // ConvI2L may have type information on it which is unsafe to push up // so disable this for now return NULL; }
*** 59,103 **** if (n->Opcode() == Op_CastII && n->as_CastII()->has_range_check() && region->is_CountedLoop() && n->in(1) == region->as_CountedLoop()->phi()) { return NULL; } int wins = 0; assert(!n->is_CFG(), ""); assert(region->is_Region(), ""); const Type* type = n->bottom_type(); ! const TypeOopPtr *t_oop = _igvn.type(n)->isa_oopptr(); ! Node *phi; if (t_oop != NULL && t_oop->is_known_instance_field()) { int iid = t_oop->instance_id(); int index = C->get_alias_index(t_oop); int offset = t_oop->offset(); phi = new PhiNode(region, type, NULL, iid, index, offset); } else { phi = PhiNode::make_blank(region, n); } uint old_unique = C->unique(); for (uint i = 1; i < region->req(); i++) { ! Node *x; Node* the_clone = NULL; if (region->in(i) == C->top()) { x = C->top(); // Dead path? Use a dead data op } else { x = n->clone(); // Else clone up the data op the_clone = x; // Remember for possible deletion. // Alter data node to use pre-phi inputs if (n->in(0) == region) x->set_req( 0, region->in(i) ); for (uint j = 1; j < n->req(); j++) { ! Node *in = n->in(j); if (in->is_Phi() && in->in(0) == region) ! x->set_req( j, in->in(i) ); // Use pre-Phi input for the clone } } // Check for a 'win' on some paths ! const Type *t = x->Value(&_igvn); bool singleton = t->singleton(); // A TOP singleton indicates that there are no possible values incoming // along a particular edge. In most cases, this is OK, and the Phi will --- 59,130 ---- if (n->Opcode() == Op_CastII && n->as_CastII()->has_range_check() && region->is_CountedLoop() && n->in(1) == region->as_CountedLoop()->phi()) { return NULL; } + // Bail out if 'n' is a Div or Mod node whose zero check was removed earlier (i.e. control is NULL) and its divisor is a phi node d_phi whose + // inputs could be zero (include zero in their type range). This can only happen if d_phi is an induction variable of a trip-counted (integer) + // loop. d_phi could have a more precise type range that does not necessarily include all values of its inputs. Since each of these inputs will + // be a divisor of the newly cloned nodes of 'n', we need to bail out of one of these divisors could be zero (zero in its type range). + if ((n->Opcode() == Op_DivI || n->Opcode() == Op_ModI) && n->in(0) == NULL + && region->is_CountedLoop() && n->in(2) == region->as_CountedLoop()->phi()) { + Node* phi = region->as_CountedLoop()->phi(); + for (uint i = 1; i < phi->req(); i++) { + if (_igvn.type(phi->in(i))->filter_speculative(TypeInt::ZERO) != Type::TOP) { + // Zero could be a possible value but we already removed the zero check. Bail out to avoid a possible division by zero at a later point. + return NULL; + } + } + } + + #ifdef ASSERT + // A phi only has a more precise type than its inputs if it is an induction variable of a trip-counted integer loop. Verify that this is the + // case and we are not about to split a Mod or Div node without zero check that could end up with a new divisor that can be zero. + // A split of a division by a floating point zero, on the other hand, is not a problem since the result would just be INFINITY as floating point + // representation and does not result in an exception. + if ((n->Opcode() == Op_DivI || n->Opcode() == Op_ModI)) { + check_divide_by_zero(n, TypeInt::ZERO); + } else if ((n->Opcode() == Op_DivL || n->Opcode() == Op_ModL)) { + check_divide_by_zero(n, TypeLong::ZERO); + } + #endif + int wins = 0; assert(!n->is_CFG(), ""); assert(region->is_Region(), ""); const Type* type = n->bottom_type(); ! const TypeOopPtr* t_oop = _igvn.type(n)->isa_oopptr(); ! Node* phi; if (t_oop != NULL && t_oop->is_known_instance_field()) { int iid = t_oop->instance_id(); int index = C->get_alias_index(t_oop); int offset = t_oop->offset(); phi = new PhiNode(region, type, NULL, iid, index, offset); } else { phi = PhiNode::make_blank(region, n); } uint old_unique = C->unique(); for (uint i = 1; i < region->req(); i++) { ! Node* x; Node* the_clone = NULL; if (region->in(i) == C->top()) { x = C->top(); // Dead path? Use a dead data op } else { x = n->clone(); // Else clone up the data op the_clone = x; // Remember for possible deletion. // Alter data node to use pre-phi inputs if (n->in(0) == region) x->set_req( 0, region->in(i) ); for (uint j = 1; j < n->req(); j++) { ! Node* in = n->in(j); if (in->is_Phi() && in->in(0) == region) ! x->set_req(j, in->in(i)); // Use pre-Phi input for the clone } } // Check for a 'win' on some paths ! const Type* t = x->Value(&_igvn); bool singleton = t->singleton(); // A TOP singleton indicates that there are no possible values incoming // along a particular edge. In most cases, this is OK, and the Phi will
*** 208,217 **** --- 235,260 ---- } return phi; } + #ifdef ASSERT + void PhaseIdealLoop::check_divide_by_zero(const Node* n, const Type* zero) const { + if (n->in(0) == NULL && n->in(2)->is_Phi()) { + Node* phi = n->in(2); + for (uint i = 1; i < phi->req(); i++) { + if (_igvn.type(phi->in(i))->filter_speculative(zero) != Type::TOP) { + // Zero could be a possible value + n->dump(2); + phi->dump(2); + assert(false, "should not happen that pre-phi type includes zero as possible value but zero check was already removed"); + } + } + } + } + #endif + //------------------------------dominated_by------------------------------------ // Replace the dominated test with an obvious true or false. Place it on the // IGVN worklist for later cleanup. Move control-dependent data Nodes on the // live path up to the dominating control. void PhaseIdealLoop::dominated_by( Node *prevdom, Node *iff, bool flip, bool exclude_loop_predicate ) {
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