1.1 --- a/src/share/vm/opto/compile.cpp Fri Feb 18 10:07:34 2011 -0800
1.2 +++ b/src/share/vm/opto/compile.cpp Tue Apr 05 19:14:03 2011 -0700
1.3 @@ -2050,6 +2050,52 @@
1.4 // Note that OffsetBot and OffsetTop are very negative.
1.5 }
1.6
1.7 +// Eliminate trivially redundant StoreCMs and accumulate their
1.8 +// precedence edges.
1.9 +static void eliminate_redundant_card_marks(Node* n) {
1.10 + assert(n->Opcode() == Op_StoreCM, "expected StoreCM");
1.11 + if (n->in(MemNode::Address)->outcnt() > 1) {
1.12 + // There are multiple users of the same address so it might be
1.13 + // possible to eliminate some of the StoreCMs
1.14 + Node* mem = n->in(MemNode::Memory);
1.15 + Node* adr = n->in(MemNode::Address);
1.16 + Node* val = n->in(MemNode::ValueIn);
1.17 + Node* prev = n;
1.18 + bool done = false;
1.19 + // Walk the chain of StoreCMs eliminating ones that match. As
1.20 + // long as it's a chain of single users then the optimization is
1.21 + // safe. Eliminating partially redundant StoreCMs would require
1.22 + // cloning copies down the other paths.
1.23 + while (mem->Opcode() == Op_StoreCM && mem->outcnt() == 1 && !done) {
1.24 + if (adr == mem->in(MemNode::Address) &&
1.25 + val == mem->in(MemNode::ValueIn)) {
1.26 + // redundant StoreCM
1.27 + if (mem->req() > MemNode::OopStore) {
1.28 + // Hasn't been processed by this code yet.
1.29 + n->add_prec(mem->in(MemNode::OopStore));
1.30 + } else {
1.31 + // Already converted to precedence edge
1.32 + for (uint i = mem->req(); i < mem->len(); i++) {
1.33 + // Accumulate any precedence edges
1.34 + if (mem->in(i) != NULL) {
1.35 + n->add_prec(mem->in(i));
1.36 + }
1.37 + }
1.38 + // Everything above this point has been processed.
1.39 + done = true;
1.40 + }
1.41 + // Eliminate the previous StoreCM
1.42 + prev->set_req(MemNode::Memory, mem->in(MemNode::Memory));
1.43 + assert(mem->outcnt() == 0, "should be dead");
1.44 + mem->disconnect_inputs(NULL);
1.45 + } else {
1.46 + prev = mem;
1.47 + }
1.48 + mem = prev->in(MemNode::Memory);
1.49 + }
1.50 + }
1.51 +}
1.52 +
1.53 //------------------------------final_graph_reshaping_impl----------------------
1.54 // Implement items 1-5 from final_graph_reshaping below.
1.55 static void final_graph_reshaping_impl( Node *n, Final_Reshape_Counts &frc ) {
1.56 @@ -2176,9 +2222,19 @@
1.57 frc.inc_float_count();
1.58 goto handle_mem;
1.59
1.60 + case Op_StoreCM:
1.61 + {
1.62 + // Convert OopStore dependence into precedence edge
1.63 + Node* prec = n->in(MemNode::OopStore);
1.64 + n->del_req(MemNode::OopStore);
1.65 + n->add_prec(prec);
1.66 + eliminate_redundant_card_marks(n);
1.67 + }
1.68 +
1.69 + // fall through
1.70 +
1.71 case Op_StoreB:
1.72 case Op_StoreC:
1.73 - case Op_StoreCM:
1.74 case Op_StorePConditional:
1.75 case Op_StoreI:
1.76 case Op_StoreL:
