8146612: C2: Precedence edges specification violated
Reviewed-by: kvn
diff --git a/hotspot/src/share/vm/opto/lcm.cpp b/hotspot/src/share/vm/opto/lcm.cpp
index 57614f7..3edfc5e 100644
--- a/hotspot/src/share/vm/opto/lcm.cpp
+++ b/hotspot/src/share/vm/opto/lcm.cpp
@@ -1,5 +1,5 @@
/*
- * Copyright (c) 1998, 2015, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1998, 2016, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
@@ -949,6 +949,13 @@
// and the edge will be lost. This is why this code should be
// executed only when Precedent (== TypeFunc::Parms) edge is present.
Node *x = n->in(TypeFunc::Parms);
+ if (x != NULL && get_block_for_node(x) == block && n->find_prec_edge(x) != -1) {
+ // Old edge to node within same block will get removed, but no precedence
+ // edge will get added because it already exists. Update ready count.
+ int cnt = ready_cnt.at(n->_idx);
+ assert(cnt > 1, "MemBar node %d must not get ready here", n->_idx);
+ ready_cnt.at_put(n->_idx, cnt-1);
+ }
n->del_req(TypeFunc::Parms);
n->add_prec(x);
}
diff --git a/hotspot/src/share/vm/opto/node.cpp b/hotspot/src/share/vm/opto/node.cpp
index ac09369..433cfaf 100644
--- a/hotspot/src/share/vm/opto/node.cpp
+++ b/hotspot/src/share/vm/opto/node.cpp
@@ -1,5 +1,5 @@
/*
- * Copyright (c) 1997, 2015, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1997, 2016, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
@@ -796,8 +796,9 @@
// First remove corresponding def-use edge
Node *n = in(idx);
if (n != NULL) n->del_out((Node *)this);
- _in[idx] = in(--_cnt); // Compact the array
- _in[_cnt] = NULL; // NULL out emptied slot
+ _in[idx] = in(--_cnt); // Compact the array
+ // Avoid spec violation: Gap in prec edges.
+ close_prec_gap_at(_cnt);
Compile::current()->record_modified_node(this);
}
@@ -810,10 +811,11 @@
// First remove corresponding def-use edge
Node *n = in(idx);
if (n != NULL) n->del_out((Node *)this);
- if (idx < _cnt - 1) { // Not last edge ?
- Copy::conjoint_words_to_lower((HeapWord*)&_in[idx+1], (HeapWord*)&_in[idx], ((_cnt-idx-1)*sizeof(Node*)));
+ if (idx < --_cnt) { // Not last edge ?
+ Copy::conjoint_words_to_lower((HeapWord*)&_in[idx+1], (HeapWord*)&_in[idx], ((_cnt-idx)*sizeof(Node*)));
}
- _in[--_cnt] = NULL; // NULL out emptied slot
+ // Avoid spec violation: Gap in prec edges.
+ close_prec_gap_at(_cnt);
Compile::current()->record_modified_node(this);
}
@@ -845,10 +847,12 @@
uint nrep = 0;
for (uint i = 0; i < len(); i++) {
if (in(i) == old) {
- if (i < req())
+ if (i < req()) {
set_req(i, neww);
- else
+ } else {
+ assert(find_prec_edge(neww) == -1, "spec violation: duplicated prec edge (node %d -> %d)", _idx, neww->_idx);
set_prec(i, neww);
+ }
nrep++;
}
}
@@ -982,24 +986,27 @@
// Find a precedence edge to move
uint i = _cnt;
- while( in(i) != NULL ) i++;
+ while( in(i) != NULL ) {
+ if (in(i) == n) return; // Avoid spec violation: duplicated prec edge.
+ i++;
+ }
_in[i] = n; // Stuff prec edge over NULL
if ( n != NULL) n->add_out((Node *)this); // Add mirror edge
+
+#ifdef ASSERT
+ while ((++i)<_max) { assert(_in[i] == NULL, "spec violation: Gap in prec edges (node %d)", _idx); }
+#endif
}
//------------------------------rm_prec----------------------------------------
// Remove a precedence input. Precedence inputs are unordered, with
// duplicates removed and NULLs packed down at the end.
void Node::rm_prec( uint j ) {
-
- // Find end of precedence list to pack NULLs
- uint i;
- for( i=j; i<_max; i++ )
- if( !_in[i] ) // Find the NULL at end of prec edge list
- break;
- if (_in[j] != NULL) _in[j]->del_out((Node *)this);
- _in[j] = _in[--i]; // Move last element over removed guy
- _in[i] = NULL; // NULL out last element
+ assert(j < _max, "oob: i=%d, _max=%d", j, _max);
+ assert(j >= _cnt, "not a precedence edge");
+ if (_in[j] == NULL) return; // Avoid spec violation: Gap in prec edges.
+ _in[j]->del_out((Node *)this);
+ close_prec_gap_at(j);
}
//------------------------------size_of----------------------------------------
diff --git a/hotspot/src/share/vm/opto/node.hpp b/hotspot/src/share/vm/opto/node.hpp
index d737f53..559a449 100644
--- a/hotspot/src/share/vm/opto/node.hpp
+++ b/hotspot/src/share/vm/opto/node.hpp
@@ -1,5 +1,5 @@
/*
- * Copyright (c) 1997, 2015, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1997, 2016, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
@@ -423,6 +423,16 @@
}
// Find first occurrence of n among my edges:
int find_edge(Node* n);
+ int find_prec_edge(Node* n) {
+ for (uint i = req(); i < len(); i++) {
+ if (_in[i] == n) return i;
+ if (_in[i] == NULL) {
+ DEBUG_ONLY( while ((++i) < len()) assert(_in[i] == NULL, "Gap in prec edges!"); )
+ break;
+ }
+ }
+ return -1;
+ }
int replace_edge(Node* old, Node* neww);
int replace_edges_in_range(Node* old, Node* neww, int start, int end);
// NULL out all inputs to eliminate incoming Def-Use edges.
@@ -476,6 +486,19 @@
debug_only(_last_del = n; ++_del_tick);
#endif
}
+ // Close gap after removing edge.
+ void close_prec_gap_at(uint gap) {
+ assert(_cnt <= gap && gap < _max, "no valid prec edge");
+ uint i = gap;
+ Node *last = NULL;
+ for (; i < _max-1; ++i) {
+ Node *next = _in[i+1];
+ if (next == NULL) break;
+ last = next;
+ }
+ _in[gap] = last; // Move last slot to empty one.
+ _in[i] = NULL; // NULL out last slot.
+ }
public:
// Globally replace this node by a given new node, updating all uses.
@@ -492,13 +515,23 @@
// Add or remove precedence edges
void add_prec( Node *n );
void rm_prec( uint i );
+
+ // Note: prec(i) will not necessarily point to n if edge already exists.
void set_prec( uint i, Node *n ) {
- assert( is_not_dead(n), "can not use dead node");
- assert( i >= _cnt, "not a precedence edge");
+ assert(i < _max, "oob: i=%d, _max=%d", i, _max);
+ assert(is_not_dead(n), "can not use dead node");
+ assert(i >= _cnt, "not a precedence edge");
+ // Avoid spec violation: duplicated prec edge.
+ if (_in[i] == n) return;
+ if (n == NULL || find_prec_edge(n) != -1) {
+ rm_prec(i);
+ return;
+ }
if (_in[i] != NULL) _in[i]->del_out((Node *)this);
_in[i] = n;
if (n != NULL) n->add_out((Node *)this);
}
+
// Set this node's index, used by cisc_version to replace current node
void set_idx(uint new_idx) {
const node_idx_t* ref = &_idx;
