src/share/vm/opto/memnode.cpp
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@@ -670,220 +670,10 @@
#endif
return tp;
}
}
-//------------------------adr_phi_is_loop_invariant----------------------------
-// A helper function for Ideal_DU_postCCP to check if a Phi in a counted
-// loop is loop invariant. Make a quick traversal of Phi and associated
-// CastPP nodes, looking to see if they are a closed group within the loop.
-bool MemNode::adr_phi_is_loop_invariant(Node* adr_phi, Node* cast) {
- // The idea is that the phi-nest must boil down to only CastPP nodes
- // with the same data. This implies that any path into the loop already
- // includes such a CastPP, and so the original cast, whatever its input,
- // must be covered by an equivalent cast, with an earlier control input.
- ResourceMark rm;
-
- // The loop entry input of the phi should be the unique dominating
- // node for every Phi/CastPP in the loop.
- Unique_Node_List closure;
- closure.push(adr_phi->in(LoopNode::EntryControl));
-
- // Add the phi node and the cast to the worklist.
- Unique_Node_List worklist;
- worklist.push(adr_phi);
- if( cast != NULL ){
- if( !cast->is_ConstraintCast() ) return false;
- worklist.push(cast);
- }
-
- // Begin recursive walk of phi nodes.
- while( worklist.size() ){
- // Take a node off the worklist
- Node *n = worklist.pop();
- if( !closure.member(n) ){
- // Add it to the closure.
- closure.push(n);
- // Make a sanity check to ensure we don't waste too much time here.
- if( closure.size() > 20) return false;
- // This node is OK if:
- // - it is a cast of an identical value
- // - or it is a phi node (then we add its inputs to the worklist)
- // Otherwise, the node is not OK, and we presume the cast is not invariant
- if( n->is_ConstraintCast() ){
- worklist.push(n->in(1));
- } else if( n->is_Phi() ) {
- for( uint i = 1; i < n->req(); i++ ) {
- worklist.push(n->in(i));
- }
- } else {
- return false;
- }
- }
- }
-
- // Quit when the worklist is empty, and we've found no offending nodes.
- return true;
-}
-
-//------------------------------Ideal_DU_postCCP-------------------------------
-// Find any cast-away of null-ness and keep its control. Null cast-aways are
-// going away in this pass and we need to make this memory op depend on the
-// gating null check.
-Node *MemNode::Ideal_DU_postCCP( PhaseCCP *ccp ) {
- return Ideal_common_DU_postCCP(ccp, this, in(MemNode::Address));
-}
-
-// I tried to leave the CastPP's in. This makes the graph more accurate in
-// some sense; we get to keep around the knowledge that an oop is not-null
-// after some test. Alas, the CastPP's interfere with GVN (some values are
-// the regular oop, some are the CastPP of the oop, all merge at Phi's which
-// cannot collapse, etc). This cost us 10% on SpecJVM, even when I removed
-// some of the more trivial cases in the optimizer. Removing more useless
-// Phi's started allowing Loads to illegally float above null checks. I gave
-// up on this approach. CNC 10/20/2000
-// This static method may be called not from MemNode (EncodePNode calls it).
-// Only the control edge of the node 'n' might be updated.
-Node *MemNode::Ideal_common_DU_postCCP( PhaseCCP *ccp, Node* n, Node* adr ) {
- Node *skipped_cast = NULL;
- // Need a null check? Regular static accesses do not because they are
- // from constant addresses. Array ops are gated by the range check (which
- // always includes a NULL check). Just check field ops.
- if( n->in(MemNode::Control) == NULL ) {
- // Scan upwards for the highest location we can place this memory op.
- while( true ) {
- switch( adr->Opcode() ) {
-
- case Op_AddP: // No change to NULL-ness, so peek thru AddP's
- adr = adr->in(AddPNode::Base);
- continue;
-
- case Op_DecodeN: // No change to NULL-ness, so peek thru
- case Op_DecodeNKlass:
- adr = adr->in(1);
- continue;
-
- case Op_EncodeP:
- case Op_EncodePKlass:
- // EncodeP node's control edge could be set by this method
- // when EncodeP node depends on CastPP node.
- //
- // Use its control edge for memory op because EncodeP may go away
- // later when it is folded with following or preceding DecodeN node.
- if (adr->in(0) == NULL) {
- // Keep looking for cast nodes.
- adr = adr->in(1);
- continue;
- }
- ccp->hash_delete(n);
- n->set_req(MemNode::Control, adr->in(0));
- ccp->hash_insert(n);
- return n;
-
- case Op_CastPP:
- // If the CastPP is useless, just peek on through it.
- if( ccp->type(adr) == ccp->type(adr->in(1)) ) {
- // Remember the cast that we've peeked though. If we peek
- // through more than one, then we end up remembering the highest
- // one, that is, if in a loop, the one closest to the top.
- skipped_cast = adr;
- adr = adr->in(1);
- continue;
- }
- // CastPP is going away in this pass! We need this memory op to be
- // control-dependent on the test that is guarding the CastPP.
- ccp->hash_delete(n);
- n->set_req(MemNode::Control, adr->in(0));
- ccp->hash_insert(n);
- return n;
-
- case Op_Phi:
- // Attempt to float above a Phi to some dominating point.
- if (adr->in(0) != NULL && adr->in(0)->is_CountedLoop()) {
- // If we've already peeked through a Cast (which could have set the
- // control), we can't float above a Phi, because the skipped Cast
- // may not be loop invariant.
- if (adr_phi_is_loop_invariant(adr, skipped_cast)) {
- adr = adr->in(1);
- continue;
- }
- }
-
- // Intentional fallthrough!
-
- // No obvious dominating point. The mem op is pinned below the Phi
- // by the Phi itself. If the Phi goes away (no true value is merged)
- // then the mem op can float, but not indefinitely. It must be pinned
- // behind the controls leading to the Phi.
- case Op_CheckCastPP:
- // These usually stick around to change address type, however a
- // useless one can be elided and we still need to pick up a control edge
- if (adr->in(0) == NULL) {
- // This CheckCastPP node has NO control and is likely useless. But we
- // need check further up the ancestor chain for a control input to keep
- // the node in place. 4959717.
- skipped_cast = adr;
- adr = adr->in(1);
- continue;
- }
- ccp->hash_delete(n);
- n->set_req(MemNode::Control, adr->in(0));
- ccp->hash_insert(n);
- return n;
-
- // List of "safe" opcodes; those that implicitly block the memory
- // op below any null check.
- case Op_CastX2P: // no null checks on native pointers
- case Op_Parm: // 'this' pointer is not null
- case Op_LoadP: // Loading from within a klass
- case Op_LoadN: // Loading from within a klass
- case Op_LoadKlass: // Loading from within a klass
- case Op_LoadNKlass: // Loading from within a klass
- case Op_ConP: // Loading from a klass
- case Op_ConN: // Loading from a klass
- case Op_ConNKlass: // Loading from a klass
- case Op_CreateEx: // Sucking up the guts of an exception oop
- case Op_Con: // Reading from TLS
- case Op_CMoveP: // CMoveP is pinned
- case Op_CMoveN: // CMoveN is pinned
- break; // No progress
-
- case Op_Proj: // Direct call to an allocation routine
- case Op_SCMemProj: // Memory state from store conditional ops
-#ifdef ASSERT
- {
- assert(adr->as_Proj()->_con == TypeFunc::Parms, "must be return value");
- const Node* call = adr->in(0);
- if (call->is_CallJava()) {
- const CallJavaNode* call_java = call->as_CallJava();
- const TypeTuple *r = call_java->tf()->range();
- assert(r->cnt() > TypeFunc::Parms, "must return value");
- const Type* ret_type = r->field_at(TypeFunc::Parms);
- assert(ret_type && ret_type->isa_ptr(), "must return pointer");
- // We further presume that this is one of
- // new_instance_Java, new_array_Java, or
- // the like, but do not assert for this.
- } else if (call->is_Allocate()) {
- // similar case to new_instance_Java, etc.
- } else if (!call->is_CallLeaf()) {
- // Projections from fetch_oop (OSR) are allowed as well.
- ShouldNotReachHere();
- }
- }
-#endif
- break;
- default:
- ShouldNotReachHere();
- }
- break;
- }
- }
-
- return NULL; // No progress
-}
-
-
//=============================================================================
// Should LoadNode::Ideal() attempt to remove control edges?
bool LoadNode::can_remove_control() const {
return true;
}