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8202377: Modularize C2 GC barriers

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Reviewed-by: neliasso, roland
This commit is contained in:
Erik Österlund 2018-05-18 14:51:06 +02:00
parent 2aa9d028c7
commit 53ec88908c
31 changed files with 2648 additions and 1832 deletions
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112
src/hotspot/share/opto/macro.cpp
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@ -227,108 +227,9 @@ void PhaseMacroExpand::extract_call_projections(CallNode *call) {
}
// Eliminate a card mark sequence. p2x is a ConvP2XNode
void PhaseMacroExpand::eliminate_card_mark(Node* p2x) {
assert(p2x->Opcode() == Op_CastP2X, "ConvP2XNode required");
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 *mem = addp->last_out(j);
if (UseCondCardMark && mem->is_Load()) {
assert(mem->Opcode() == Op_LoadB, "unexpected code shape");
// The load is checking if the card has been written so
// replace it with zero to fold the test.
_igvn.replace_node(mem, intcon(0));
continue;
}
assert(mem->is_Store(), "store required");
_igvn.replace_node(mem, mem->in(MemNode::Memory));
}
}
#if INCLUDE_G1GC
else {
// G1 pre/post barriers
assert(p2x->outcnt() <= 2, "expects 1 or 2 users: Xor and URShift nodes");
// It could be only one user, URShift node, in Object.clone() intrinsic
// but the new allocation is passed to arraycopy stub and it could not
// be scalar replaced. So we don't check the case.
// An other case of only one user (Xor) is when the value check for NULL
// in G1 post barrier is folded after CCP so the code which used URShift
// is removed.
// Take Region node before eliminating post barrier since it also
// eliminates CastP2X node when it has only one user.
Node* this_region = p2x->in(0);
assert(this_region != NULL, "");
// 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 = p2x->find_out_with(Op_XorX);
if (xorx != NULL) {
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".
// 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() &&
this_region->in(ind)->in(0)->Opcode() == Op_If) {
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(G1ThreadLocalData::satb_mark_queue_active_offset());
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));
}
}
}
}
} else {
assert(!GraphKit::use_ReduceInitialCardMarks(), "can only happen with card marking");
// This is a G1 post barrier emitted by the Object.clone() intrinsic.
// Search for the CastP2X->URShiftX->AddP->LoadB->Cmp path which checks if the card
// is marked as young_gen and replace the Cmp with 0 (false) to collapse the barrier.
Node* shift = p2x->find_out_with(Op_URShiftX);
assert(shift != NULL, "missing G1 post barrier");
Node* addp = shift->unique_out();
Node* load = addp->find_out_with(Op_LoadB);
assert(load != NULL, "missing G1 post barrier");
Node* cmpx = load->unique_out();
assert(cmpx->is_Cmp() && cmpx->unique_out()->is_Bool() &&
cmpx->unique_out()->as_Bool()->_test._test == BoolTest::ne,
"missing card value check in G1 post barrier");
_igvn.replace_node(cmpx, makecon(TypeInt::CC_EQ));
// There is no G1 pre barrier in this case
}
// Now CastP2X can be removed since it is used only on dead path
// which currently still alive until igvn optimize it.
assert(p2x->outcnt() == 0 || p2x->unique_out()->Opcode() == Op_URShiftX, "");
_igvn.replace_node(p2x, top());
}
#endif // INCLUDE_G1GC
void PhaseMacroExpand::eliminate_gc_barrier(Node* p2x) {
BarrierSetC2 *bs = BarrierSet::barrier_set()->barrier_set_c2();
bs->eliminate_gc_barrier(this, p2x);
}
// Search for a memory operation for the specified memory slice.
@ -1029,7 +930,7 @@ void PhaseMacroExpand::process_users_of_allocation(CallNode *alloc) {
disconnect_projections(membar_after->as_MemBar(), _igvn);
}
} else {
eliminate_card_mark(n);
eliminate_gc_barrier(n);
}
k -= (oc2 - use->outcnt());
}
@ -1062,7 +963,7 @@ void PhaseMacroExpand::process_users_of_allocation(CallNode *alloc) {
_igvn._worklist.push(ac);
} else {
eliminate_card_mark(use);
eliminate_gc_barrier(use);
}
j -= (oc1 - res->outcnt());
}
@ -2801,5 +2702,6 @@ bool PhaseMacroExpand::expand_macro_nodes() {
_igvn.set_delay_transform(false);
_igvn.optimize();
if (C->failing()) return true;
return false;
BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
return bs->expand_macro_nodes(this);
}