Mercurial > hg > truffle
changeset 3282:149bb459be66
7029167: add support for conditional card marks
Reviewed-by: iveresov, kvn
author | never |
---|---|
date | Wed, 27 Apr 2011 15:40:36 -0700 |
parents | 273b56978029 |
children | 01fd6090fdd8 |
files | src/share/vm/opto/graphKit.cpp src/share/vm/opto/macro.cpp src/share/vm/runtime/globals.hpp |
diffstat | 3 files changed, 32 insertions(+), 5 deletions(-) [+] |
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--- a/src/share/vm/opto/graphKit.cpp Tue Apr 26 12:14:22 2011 -0700 +++ b/src/share/vm/opto/graphKit.cpp Wed Apr 27 15:40:36 2011 -0700 @@ -3447,9 +3447,22 @@ // Get the alias_index for raw card-mark memory int adr_type = Compile::AliasIdxRaw; + Node* zero = __ ConI(0); // Dirty card value + BasicType bt = T_BYTE; + + if (UseCondCardMark) { + // The classic GC reference write barrier is typically implemented + // as a store into the global card mark table. Unfortunately + // unconditional stores can result in false sharing and excessive + // coherence traffic as well as false transactional aborts. + // UseCondCardMark enables MP "polite" conditional card mark + // stores. In theory we could relax the load from ctrl() to + // no_ctrl, but that doesn't buy much latitude. + Node* card_val = __ load( __ ctrl(), card_adr, TypeInt::BYTE, bt, adr_type); + __ if_then(card_val, BoolTest::ne, zero); + } + // Smash zero into card - Node* zero = __ ConI(0); - BasicType bt = T_BYTE; if( !UseConcMarkSweepGC ) { __ store(__ ctrl(), card_adr, zero, bt, adr_type); } else { @@ -3457,6 +3470,10 @@ __ storeCM(__ ctrl(), card_adr, zero, oop_store, adr_idx, bt, adr_type); } + if (UseCondCardMark) { + __ end_if(); + } + // Final sync IdealKit and GraphKit. final_sync(ideal); }
--- a/src/share/vm/opto/macro.cpp Tue Apr 26 12:14:22 2011 -0700 +++ b/src/share/vm/opto/macro.cpp Wed Apr 27 15:40:36 2011 -0700 @@ -221,9 +221,16 @@ Node *shift = p2x->unique_out(); Node *addp = shift->unique_out(); for (DUIterator_Last jmin, j = addp->last_outs(jmin); j >= jmin; --j) { - Node *st = addp->last_out(j); - assert(st->is_Store(), "store required"); - _igvn.replace_node(st, st->in(MemNode::Memory)); + 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)); } } else { // G1 pre/post barriers
--- a/src/share/vm/runtime/globals.hpp Tue Apr 26 12:14:22 2011 -0700 +++ b/src/share/vm/runtime/globals.hpp Wed Apr 27 15:40:36 2011 -0700 @@ -620,6 +620,9 @@ product(bool, UseSSE42Intrinsics, false, \ "SSE4.2 versions of intrinsics") \ \ + product(bool, UseCondCardMark, false, \ + "Check for already marked card before updating card table") \ + \ develop(bool, TraceCallFixup, false, \ "traces all call fixups") \ \