truffle: src/share/vm/opto/compile.cpp comparison

comparison src/share/vm/opto/compile.cpp @ 3248:e6beb62de02d

7032963: StoreCM shouldn't participate in store elimination Reviewed-by: kvn

author	never
date	Tue, 05 Apr 2011 19:14:03 -0700
parents	c7f3d0b4570f
children	e1162778c1c8

comparison

equal deleted inserted replaced

-:8f1042ff784d
+:e6beb62de02d
 // Make sure the offset goes inside the instance layout.
 return k->contains_field_offset(tp->offset());
 // Note that OffsetBot and OffsetTop are very negative.
 }
+// Eliminate trivially redundant StoreCMs and accumulate their
+// precedence edges.
+static void eliminate_redundant_card_marks(Node* n) {
+assert(n->Opcode() == Op_StoreCM, "expected StoreCM");
+if (n->in(MemNode::Address)->outcnt() > 1) {
+// There are multiple users of the same address so it might be
+// possible to eliminate some of the StoreCMs
+Node* mem = n->in(MemNode::Memory);
+Node* adr = n->in(MemNode::Address);
+Node* val = n->in(MemNode::ValueIn);
+Node* prev = n;
+bool done = false;
+// Walk the chain of StoreCMs eliminating ones that match.  As
+// long as it's a chain of single users then the optimization is
+// safe.  Eliminating partially redundant StoreCMs would require
+// cloning copies down the other paths.
+while (mem->Opcode() == Op_StoreCM && mem->outcnt() == 1 && !done) {
+if (adr == mem->in(MemNode::Address) &&
+val == mem->in(MemNode::ValueIn)) {
+// redundant StoreCM
+if (mem->req() > MemNode::OopStore) {
+// Hasn't been processed by this code yet.
+n->add_prec(mem->in(MemNode::OopStore));
+} else {
+// Already converted to precedence edge
+for (uint i = mem->req(); i < mem->len(); i++) {
+// Accumulate any precedence edges
+if (mem->in(i) != NULL) {
+n->add_prec(mem->in(i));
+}
+}
+// Everything above this point has been processed.
+done = true;
+}
+// Eliminate the previous StoreCM
+prev->set_req(MemNode::Memory, mem->in(MemNode::Memory));
+assert(mem->outcnt() == 0, "should be dead");
+mem->disconnect_inputs(NULL);
+} else {
+prev = mem;
+}
+mem = prev->in(MemNode::Memory);
+}
+}
+}
 //------------------------------final_graph_reshaping_impl----------------------
 // Implement items 1-5 from final_graph_reshaping below.
 static void final_graph_reshaping_impl( Node *n, Final_Reshape_Counts &frc ) {
 if ( n->outcnt() == 0 ) return; // dead node
 case Op_StoreF:
 case Op_LoadF:
 frc.inc_float_count();
 goto handle_mem;
+case Op_StoreCM:
+{
+// Convert OopStore dependence into precedence edge
+Node* prec = n->in(MemNode::OopStore);
+n->del_req(MemNode::OopStore);
+n->add_prec(prec);
+eliminate_redundant_card_marks(n);
+}
+// fall through
 case Op_StoreB:
 case Op_StoreC:
-case Op_StoreCM:
 case Op_StorePConditional:
 case Op_StoreI:
 case Op_StoreL:
 case Op_StoreIConditional:
 case Op_StoreLConditional:

Mercurial > hg > truffle

comparison src/share/vm/opto/compile.cpp @ 3248:e6beb62de02d