6667612: (Escape Analysis) disable loop cloning if it has a scalar replaceable allocation
Summary: Cloning an allocation will not allow scalar replacement since memory operations could not be associated with one allocation.
Reviewed-by: rasbold
--- a/hotspot/src/share/vm/opto/callnode.cpp Thu Mar 06 10:30:17 2008 -0800
+++ b/hotspot/src/share/vm/opto/callnode.cpp Thu Mar 06 10:53:33 2008 -0800
@@ -832,6 +832,7 @@
{
init_class_id(Class_Allocate);
init_flags(Flag_is_macro);
+ _is_scalar_replaceable = false;
Node *topnode = C->top();
init_req( TypeFunc::Control , ctrl );
--- a/hotspot/src/share/vm/opto/callnode.hpp Thu Mar 06 10:30:17 2008 -0800
+++ b/hotspot/src/share/vm/opto/callnode.hpp Thu Mar 06 10:53:33 2008 -0800
@@ -626,6 +626,8 @@
return TypeFunc::make(domain, range);
}
+ bool _is_scalar_replaceable; // Result of Escape Analysis
+
virtual uint size_of() const; // Size is bigger
AllocateNode(Compile* C, const TypeFunc *atype, Node *ctrl, Node *mem, Node *abio,
Node *size, Node *klass_node, Node *initial_test);
--- a/hotspot/src/share/vm/opto/escape.cpp Thu Mar 06 10:30:17 2008 -0800
+++ b/hotspot/src/share/vm/opto/escape.cpp Thu Mar 06 10:53:33 2008 -0800
@@ -601,6 +601,11 @@
if (es != PointsToNode::NoEscape || !ptn._unique_type) {
continue; // can't make a unique type
}
+ if (alloc->is_Allocate()) {
+ // Set the scalar_replaceable flag before the next check.
+ alloc->as_Allocate()->_is_scalar_replaceable = true;
+ }
+
set_map(alloc->_idx, n);
set_map(n->_idx, alloc);
const TypeInstPtr *t = igvn->type(n)->isa_instptr();
--- a/hotspot/src/share/vm/opto/loopTransform.cpp Thu Mar 06 10:30:17 2008 -0800
+++ b/hotspot/src/share/vm/opto/loopTransform.cpp Thu Mar 06 10:53:33 2008 -0800
@@ -1714,6 +1714,7 @@
// Gate unrolling, RCE and peeling efforts.
if( !_child && // If not an inner loop, do not split
!_irreducible &&
+ _allow_optimizations &&
!tail()->is_top() ) { // Also ignore the occasional dead backedge
if (!_has_call) {
iteration_split_impl( phase, old_new );
--- a/hotspot/src/share/vm/opto/loopnode.cpp Thu Mar 06 10:30:17 2008 -0800
+++ b/hotspot/src/share/vm/opto/loopnode.cpp Thu Mar 06 10:53:33 2008 -0800
@@ -1561,7 +1561,7 @@
// on just their loop-phi's for this pass of loop opts
if( SplitIfBlocks && do_split_ifs ) {
if (lpt->policy_range_check(this)) {
- lpt->_rce_candidate = true;
+ lpt->_rce_candidate = 1; // = true
}
}
}
@@ -2145,7 +2145,7 @@
// as well? If so, then I found another entry into the loop.
while( is_postvisited(l->_head) ) {
// found irreducible
- l->_irreducible = true;
+ l->_irreducible = 1; // = true
l = l->_parent;
_has_irreducible_loops = true;
// Check for bad CFG here to prevent crash, and bailout of compile
@@ -2199,6 +2199,12 @@
(iff->as_If()->_prob >= 0.01) )
innermost->_has_call = 1;
}
+ } else if( n->is_Allocate() && n->as_Allocate()->_is_scalar_replaceable ) {
+ // Disable loop optimizations if the loop has a scalar replaceable
+ // allocation. This disabling may cause a potential performance lost
+ // if the allocation is not eliminated for some reason.
+ innermost->_allow_optimizations = false;
+ innermost->_has_call = 1; // = true
}
}
}
--- a/hotspot/src/share/vm/opto/loopnode.hpp Thu Mar 06 10:30:17 2008 -0800
+++ b/hotspot/src/share/vm/opto/loopnode.hpp Thu Mar 06 10:53:33 2008 -0800
@@ -289,13 +289,15 @@
_has_sfpt:1, // True if has non-call safepoint
_rce_candidate:1; // True if candidate for range check elimination
- Node_List* _required_safept; // A inner loop cannot delete these safepts;
+ Node_List* _required_safept; // A inner loop cannot delete these safepts;
+ bool _allow_optimizations; // Allow loop optimizations
IdealLoopTree( PhaseIdealLoop* phase, Node *head, Node *tail )
: _parent(0), _next(0), _child(0),
_head(head), _tail(tail),
_phase(phase),
_required_safept(NULL),
+ _allow_optimizations(true),
_nest(0), _irreducible(0), _has_call(0), _has_sfpt(0), _rce_candidate(0)
{ }