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8239072: subtype check macro node causes node budget to be exhausted

Reviewed-by: vlivanov, kvn
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rwestrel committed Mar 31, 2020
1 parent 73ddea7 commit ea56776ef53128e8586fa24551880d8210014c80
Showing with 71 additions and 15 deletions.
  1. +17 −0 src/hotspot/share/opto/compile.cpp
  2. +2 −0 src/hotspot/share/opto/compile.hpp
  3. +52 −15 src/hotspot/share/opto/macro.cpp
@@ -4224,3 +4224,20 @@ void CloneMap::dump(node_idx_t key) const {
ni.dump();
}
}

// Move Allocate nodes to the start of the list
void Compile::sort_macro_nodes() {
int count = macro_count();
int allocates = 0;
for (int i = 0; i < count; i++) {
Node* n = macro_node(i);
if (n->is_Allocate()) {
if (i != allocates) {
Node* tmp = macro_node(allocates);
_macro_nodes->at_put(allocates, n);
_macro_nodes->at_put(i, tmp);
}
allocates++;
}
}
}
@@ -718,6 +718,8 @@ class Compile : public Phase {
int opaque4_count() const { return _opaque4_nodes->length(); }
void remove_opaque4_nodes(PhaseIterGVN &igvn);

void sort_macro_nodes();

// remove the opaque nodes that protect the predicates so that the unused checks and
// uncommon traps will be eliminated from the graph.
void cleanup_loop_predicates(PhaseIterGVN &igvn);
@@ -2658,12 +2658,6 @@ bool PhaseMacroExpand::expand_macro_nodes() {
// Last attempt to eliminate macro nodes.
eliminate_macro_nodes();

// Make sure expansion will not cause node limit to be exceeded.
// Worst case is a macro node gets expanded into about 200 nodes.
// Allow 50% more for optimization.
if (C->check_node_count(C->macro_count() * 300, "out of nodes before macro expansion" ) )
return true;

// Eliminate Opaque and LoopLimit nodes. Do it after all loop optimizations.
bool progress = true;
while (progress) {
@@ -2719,17 +2713,44 @@ bool PhaseMacroExpand::expand_macro_nodes() {
}
}

// Clean up the graph so we're less likely to hit the maximum node
// limit
_igvn.set_delay_transform(false);
_igvn.optimize();
if (C->failing()) return true;
_igvn.set_delay_transform(true);


// Because we run IGVN after each expansion, some macro nodes may go
// dead and be removed from the list as we iterate over it. Move
// Allocate nodes (processed in a second pass) at the beginning of
// the list and then iterate from the last element of the list until
// an Allocate node is seen. This is robust to random deletion in
// the list due to nodes going dead.
C->sort_macro_nodes();

// expand arraycopy "macro" nodes first
// For ReduceBulkZeroing, we must first process all arraycopy nodes
// before the allocate nodes are expanded.
for (int i = C->macro_count(); i > 0; i--) {
Node* n = C->macro_node(i-1);
while (C->macro_count() > 0) {
int macro_count = C->macro_count();
Node * n = C->macro_node(macro_count-1);
assert(n->is_macro(), "only macro nodes expected here");
if (_igvn.type(n) == Type::TOP || (n->in(0) != NULL && n->in(0)->is_top())) {
// node is unreachable, so don't try to expand it
C->remove_macro_node(n);
continue;
}
if (n->is_Allocate()) {
break;
}
// Make sure expansion will not cause node limit to be exceeded.
// Worst case is a macro node gets expanded into about 200 nodes.
// Allow 50% more for optimization.
if (C->check_node_count(300, "out of nodes before macro expansion")) {
return true;
}

debug_only(int old_macro_count = C->macro_count(););
switch (n->class_id()) {
case Node::Class_Lock:
@@ -2748,18 +2769,23 @@ bool PhaseMacroExpand::expand_macro_nodes() {
expand_subtypecheck_node(n->as_SubTypeCheck());
assert(C->macro_count() == (old_macro_count - 1), "expansion must have deleted one node from macro list");
break;
default:
assert(false, "unknown node type in macro list");
}
assert(C->macro_count() < macro_count, "must have deleted a node from macro list");
if (C->failing()) return true;

// Clean up the graph so we're less likely to hit the maximum node
// limit
_igvn.set_delay_transform(false);
_igvn.optimize();
if (C->failing()) return true;
_igvn.set_delay_transform(true);
}

// All nodes except Allocate nodes are expanded now. There could be
// new optimization opportunities (such as folding newly created
// load from a just allocated object). Run IGVN.
_igvn.set_delay_transform(false);
_igvn.optimize();
if (C->failing()) return true;

_igvn.set_delay_transform(true);

// expand "macro" nodes
// nodes are removed from the macro list as they are processed
@@ -2772,6 +2798,12 @@ bool PhaseMacroExpand::expand_macro_nodes() {
C->remove_macro_node(n);
continue;
}
// Make sure expansion will not cause node limit to be exceeded.
// Worst case is a macro node gets expanded into about 200 nodes.
// Allow 50% more for optimization.
if (C->check_node_count(300, "out of nodes before macro expansion")) {
return true;
}
switch (n->class_id()) {
case Node::Class_Allocate:
expand_allocate(n->as_Allocate());
@@ -2784,10 +2816,15 @@ bool PhaseMacroExpand::expand_macro_nodes() {
}
assert(C->macro_count() < macro_count, "must have deleted a node from macro list");
if (C->failing()) return true;

// Clean up the graph so we're less likely to hit the maximum node
// limit
_igvn.set_delay_transform(false);
_igvn.optimize();
if (C->failing()) return true;
_igvn.set_delay_transform(true);
}

_igvn.set_delay_transform(false);
_igvn.optimize();
if (C->failing()) return true;
return false;
}

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