8245955: Shenandoah: Remove LRB/is_redundant optimization
Reviewed-by: roland, shade
This commit is contained in:
Roman Kennke
parent
57388f807f
commit
6f4f6a2a59
src/hotspot/share/gc/shenandoah
@ -1096,9 +1096,6 @@ void ShenandoahBarrierC2Support::pin_and_expand(PhaseIdealLoop* phase) {
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Node_List clones;
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for (int i = state->load_reference_barriers_count() - 1; i >= 0; i--) {
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ShenandoahLoadReferenceBarrierNode* lrb = state->load_reference_barrier(i);
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if (lrb->is_redundant()) {
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continue;
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}
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Node* ctrl = phase->get_ctrl(lrb);
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Node* val = lrb->in(ShenandoahLoadReferenceBarrierNode::ValueIn);
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@ -1290,9 +1287,6 @@ void ShenandoahBarrierC2Support::pin_and_expand(PhaseIdealLoop* phase) {
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for (int i = 0; i < state->load_reference_barriers_count(); i++) {
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ShenandoahLoadReferenceBarrierNode* lrb = state->load_reference_barrier(i);
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if (lrb->is_redundant()) {
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continue;
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}
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Node* ctrl = phase->get_ctrl(lrb);
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IdealLoopTree* loop = phase->get_loop(ctrl);
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if (loop->_head->is_OuterStripMinedLoop()) {
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@ -1309,10 +1303,6 @@ void ShenandoahBarrierC2Support::pin_and_expand(PhaseIdealLoop* phase) {
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Unique_Node_List uses_to_ignore;
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for (int i = state->load_reference_barriers_count() - 1; i >= 0; i--) {
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ShenandoahLoadReferenceBarrierNode* lrb = state->load_reference_barrier(i);
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if (lrb->is_redundant()) {
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phase->igvn().replace_node(lrb, lrb->in(ShenandoahLoadReferenceBarrierNode::ValueIn));
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continue;
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}
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uint last = phase->C->unique();
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Node* ctrl = phase->get_ctrl(lrb);
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Node* val = lrb->in(ShenandoahLoadReferenceBarrierNode::ValueIn);
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@ -3026,163 +3016,3 @@ bool ShenandoahLoadReferenceBarrierNode::needs_barrier_impl(PhaseGVN* phase, Nod
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#endif
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return true;
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}
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bool ShenandoahLoadReferenceBarrierNode::is_redundant() {
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Unique_Node_List visited;
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Node_Stack stack(0);
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stack.push(this, 0);
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// Check if the barrier is actually useful: go over nodes looking for useful uses
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// (e.g. memory accesses). Stop once we detected a required use. Otherwise, walk
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// until we ran out of nodes, and then declare the barrier redundant.
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while (stack.size() > 0) {
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Node* n = stack.node();
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if (visited.member(n)) {
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stack.pop();
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continue;
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}
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visited.push(n);
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bool visit_users = false;
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switch (n->Opcode()) {
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case Op_CallStaticJava:
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case Op_CallDynamicJava:
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case Op_CallLeaf:
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case Op_CallLeafNoFP:
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case Op_CompareAndSwapL:
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case Op_CompareAndSwapI:
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case Op_CompareAndSwapB:
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case Op_CompareAndSwapS:
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case Op_CompareAndSwapN:
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case Op_CompareAndSwapP:
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case Op_CompareAndExchangeL:
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case Op_CompareAndExchangeI:
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case Op_CompareAndExchangeB:
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case Op_CompareAndExchangeS:
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case Op_CompareAndExchangeN:
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case Op_CompareAndExchangeP:
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case Op_WeakCompareAndSwapL:
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case Op_WeakCompareAndSwapI:
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case Op_WeakCompareAndSwapB:
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case Op_WeakCompareAndSwapS:
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case Op_WeakCompareAndSwapN:
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case Op_WeakCompareAndSwapP:
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case Op_ShenandoahCompareAndSwapN:
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case Op_ShenandoahCompareAndSwapP:
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case Op_ShenandoahWeakCompareAndSwapN:
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case Op_ShenandoahWeakCompareAndSwapP:
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case Op_ShenandoahCompareAndExchangeN:
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case Op_ShenandoahCompareAndExchangeP:
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case Op_GetAndSetL:
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case Op_GetAndSetI:
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case Op_GetAndSetB:
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case Op_GetAndSetS:
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case Op_GetAndSetP:
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case Op_GetAndSetN:
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case Op_GetAndAddL:
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case Op_GetAndAddI:
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case Op_GetAndAddB:
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case Op_GetAndAddS:
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case Op_ShenandoahEnqueueBarrier:
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case Op_FastLock:
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case Op_FastUnlock:
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case Op_Rethrow:
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case Op_Return:
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case Op_StoreB:
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case Op_StoreC:
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case Op_StoreD:
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case Op_StoreF:
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case Op_StoreL:
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case Op_StoreLConditional:
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case Op_StoreI:
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case Op_StoreIConditional:
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case Op_StoreN:
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case Op_StoreP:
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case Op_StoreVector:
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case Op_StrInflatedCopy:
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case Op_StrCompressedCopy:
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case Op_EncodeP:
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case Op_CastP2X:
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case Op_SafePoint:
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case Op_EncodeISOArray:
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case Op_AryEq:
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case Op_StrEquals:
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case Op_StrComp:
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case Op_StrIndexOf:
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case Op_StrIndexOfChar:
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case Op_HasNegatives:
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// Known to require barriers
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return false;
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case Op_CmpP: {
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if (n->in(1)->bottom_type()->higher_equal(TypePtr::NULL_PTR) ||
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n->in(2)->bottom_type()->higher_equal(TypePtr::NULL_PTR)) {
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// One of the sides is known null, no need for barrier.
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} else {
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return false;
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}
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break;
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}
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case Op_LoadB:
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case Op_LoadUB:
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case Op_LoadUS:
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case Op_LoadD:
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case Op_LoadF:
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case Op_LoadL:
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case Op_LoadI:
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case Op_LoadS:
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case Op_LoadN:
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case Op_LoadP:
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case Op_LoadVector: {
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const TypePtr* adr_type = n->adr_type();
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int alias_idx = Compile::current()->get_alias_index(adr_type);
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Compile::AliasType* alias_type = Compile::current()->alias_type(alias_idx);
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ciField* field = alias_type->field();
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bool is_static = field != NULL && field->is_static();
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bool is_final = field != NULL && field->is_final();
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if (ShenandoahOptimizeStaticFinals && is_static && is_final) {
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// Loading the constant does not require barriers: it should be handled
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// as part of GC roots already.
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} else {
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return false;
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}
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break;
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}
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case Op_Conv2B:
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case Op_LoadRange:
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case Op_LoadKlass:
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case Op_LoadNKlass:
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// Do not require barriers
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break;
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case Op_AddP:
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case Op_CheckCastPP:
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case Op_CastPP:
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case Op_CMoveP:
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case Op_Phi:
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case Op_ShenandoahLoadReferenceBarrier:
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// Whether or not these need the barriers depends on their users
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visit_users = true;
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break;
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default: {
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#ifdef ASSERT
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fatal("Unknown node in is_redundant: %s", NodeClassNames[n->Opcode()]);
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#else
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// Default to have excess barriers, rather than miss some.
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return false;
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#endif
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}
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}
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stack.pop();
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if (visit_users) {
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for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
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Node* user = n->fast_out(i);
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if (user != NULL) {
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stack.push(user, 0);
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}
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}
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}
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}
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// No need for barrier found.
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return true;
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}
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@ -250,8 +250,6 @@ public:
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virtual uint hash() const;
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virtual bool cmp( const Node &n ) const;
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bool is_redundant();
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private:
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bool needs_barrier(PhaseGVN* phase, Node* n);
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bool needs_barrier_impl(PhaseGVN* phase, Node* n, Unique_Node_List &visited);
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@ -351,11 +351,6 @@
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" 1 - parallel iterator;" \
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" 2 - parallel iterator with cset filters;") \
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\
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diagnostic(bool, ShenandoahOptimizeStaticFinals, true, \
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"Optimize barriers on static final fields. " \
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"Turn it off for maximum compatibility with reflection or JNI " \
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"code that manipulates final fields.") \
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\
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develop(bool, ShenandoahVerifyOptoBarriers, false, \
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"Verify no missing barriers in C2.") \
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\
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