--- a/hotspot/src/share/vm/opto/macro.cpp Wed Jul 15 13:37:35 2009 -0700
+++ b/hotspot/src/share/vm/opto/macro.cpp Thu Jul 16 14:10:42 2009 -0700
@@ -198,14 +198,79 @@
}
// Eliminate a card mark sequence. p2x is a ConvP2XNode
-void PhaseMacroExpand::eliminate_card_mark(Node *p2x) {
+void PhaseMacroExpand::eliminate_card_mark(Node* p2x) {
assert(p2x->Opcode() == Op_CastP2X, "ConvP2XNode required");
- Node *shift = p2x->unique_out();
- Node *addp = shift->unique_out();
- for (DUIterator_Last jmin, j = addp->last_outs(jmin); j >= jmin; --j) {
- Node *st = addp->last_out(j);
- assert(st->is_Store(), "store required");
- _igvn.replace_node(st, st->in(MemNode::Memory));
+ if (!UseG1GC) {
+ // vanilla/CMS post barrier
+ Node *shift = p2x->unique_out();
+ Node *addp = shift->unique_out();
+ for (DUIterator_Last jmin, j = addp->last_outs(jmin); j >= jmin; --j) {
+ Node *st = addp->last_out(j);
+ assert(st->is_Store(), "store required");
+ _igvn.replace_node(st, st->in(MemNode::Memory));
+ }
+ } else {
+ // G1 pre/post barriers
+ assert(p2x->outcnt() == 2, "expects 2 users: Xor and URShift nodes");
+ // It could be only one user, URShift node, in Object.clone() instrinsic
+ // but the new allocation is passed to arraycopy stub and it could not
+ // be scalar replaced. So we don't check the case.
+
+ // Remove G1 post barrier.
+
+ // Search for CastP2X->Xor->URShift->Cmp path which
+ // checks if the store done to a different from the value's region.
+ // And replace Cmp with #0 (false) to collapse G1 post barrier.
+ Node* xorx = NULL;
+ for (DUIterator_Fast imax, i = p2x->fast_outs(imax); i < imax; i++) {
+ Node* u = p2x->fast_out(i);
+ if (u->Opcode() == Op_XorX) {
+ xorx = u;
+ break;
+ }
+ }
+ assert(xorx != NULL, "missing G1 post barrier");
+ Node* shift = xorx->unique_out();
+ Node* cmpx = shift->unique_out();
+ assert(cmpx->is_Cmp() && cmpx->unique_out()->is_Bool() &&
+ cmpx->unique_out()->as_Bool()->_test._test == BoolTest::ne,
+ "missing region check in G1 post barrier");
+ _igvn.replace_node(cmpx, makecon(TypeInt::CC_EQ));
+
+ // Remove G1 pre barrier.
+
+ // Search "if (marking != 0)" check and set it to "false".
+ Node* this_region = p2x->in(0);
+ assert(this_region != NULL, "");
+ // There is no G1 pre barrier if previous stored value is NULL
+ // (for example, after initialization).
+ if (this_region->is_Region() && this_region->req() == 3) {
+ int ind = 1;
+ if (!this_region->in(ind)->is_IfFalse()) {
+ ind = 2;
+ }
+ if (this_region->in(ind)->is_IfFalse()) {
+ Node* bol = this_region->in(ind)->in(0)->in(1);
+ assert(bol->is_Bool(), "");
+ cmpx = bol->in(1);
+ if (bol->as_Bool()->_test._test == BoolTest::ne &&
+ cmpx->is_Cmp() && cmpx->in(2) == intcon(0) &&
+ cmpx->in(1)->is_Load()) {
+ Node* adr = cmpx->in(1)->as_Load()->in(MemNode::Address);
+ const int marking_offset = in_bytes(JavaThread::satb_mark_queue_offset() +
+ PtrQueue::byte_offset_of_active());
+ if (adr->is_AddP() && adr->in(AddPNode::Base) == top() &&
+ adr->in(AddPNode::Address)->Opcode() == Op_ThreadLocal &&
+ adr->in(AddPNode::Offset) == MakeConX(marking_offset)) {
+ _igvn.replace_node(cmpx, makecon(TypeInt::CC_EQ));
+ }
+ }
+ }
+ }
+ // Now CastP2X can be removed since it is used only on dead path
+ // which currently still alive until igvn optimize it.
+ assert(p2x->unique_out()->Opcode() == Op_URShiftX, "");
+ _igvn.replace_node(p2x, top());
}
}
@@ -760,14 +825,11 @@
if (n->is_Store()) {
_igvn.replace_node(n, n->in(MemNode::Memory));
} else {
- assert( n->Opcode() == Op_CastP2X, "CastP2X required");
eliminate_card_mark(n);
}
k -= (oc2 - use->outcnt());
}
} else {
- assert( !use->is_SafePoint(), "safepoint uses must have been already elimiated");
- assert( use->Opcode() == Op_CastP2X, "CastP2X required");
eliminate_card_mark(use);
}
j -= (oc1 - res->outcnt());