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[Backport] 8225776: Optimize branch frequency of G1's write post-barrier in C2 #769

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merged 2 commits into from
Jan 8, 2024
Merged

[Backport] 8225776: Optimize branch frequency of G1's write post-barrier in C2 #769

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9bb6db9
[Backport] 8225776: Optimize branch frequency of G1's write post-barr…
lusou-zhangquan Jan 5, 2024
00cf3e2
[Backport] 8232828: AArch64: compiler/c2/aarch64/TestVolatilesG1.java…
lusou-zhangquan Jan 5, 2024
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9 changes: 5 additions & 4 deletions src/hotspot/share/gc/g1/c2/g1BarrierSetC2.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -414,7 +414,8 @@ void G1BarrierSetC2::post_barrier(GraphKit* kit,
Node* tls = __ thread(); // ThreadLocalStorage

Node* no_base = __ top();
float unlikely = PROB_UNLIKELY(0.999);
float likely = PROB_LIKELY_MAG(3);
float unlikely = PROB_UNLIKELY_MAG(3);
Node* young_card = __ ConI((jint)G1CardTable::g1_young_card_val());
Node* dirty_card = __ ConI((jint)G1CardTable::dirty_card_val());
Node* zeroX = __ ConX(0);
Expand Down Expand Up @@ -457,17 +458,17 @@ void G1BarrierSetC2::post_barrier(GraphKit* kit,
Node* xor_res = __ URShiftX ( __ XorX( cast, __ CastPX(__ ctrl(), val)), __ ConI(HeapRegion::LogOfHRGrainBytes));

// if (xor_res == 0) same region so skip
__ if_then(xor_res, BoolTest::ne, zeroX); {
__ if_then(xor_res, BoolTest::ne, zeroX, likely); {

// No barrier if we are storing a NULL
__ if_then(val, BoolTest::ne, kit->null(), unlikely); {
__ if_then(val, BoolTest::ne, kit->null(), likely); {

// Ok must mark the card if not already dirty

// load the original value of the card
Node* card_val = __ load(__ ctrl(), card_adr, TypeInt::INT, T_BYTE, Compile::AliasIdxRaw);

__ if_then(card_val, BoolTest::ne, young_card); {
__ if_then(card_val, BoolTest::ne, young_card, unlikely); {
kit->sync_kit(ideal);
kit->insert_mem_bar(Op_MemBarVolatile, oop_store);
__ sync_kit(kit);
Expand Down
84 changes: 58 additions & 26 deletions test/hotspot/jtreg/compiler/c2/aarch64/TestVolatiles.java
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Original file line number Diff line number Diff line change
Expand Up @@ -331,14 +331,18 @@ private void checkstore(OutputAnalyzer output, String testType, boolean useBarri
case "G1":
// a card mark volatile barrier should be generated
// before the card mark strb
//
// following the fix for 8225776 the G1 barrier is now
// scheduled out of line after the membar volatile and
// and subsequent return
matches = new String[] {
"membar_release \\(elided\\)",
useCompressedOops ? "stlrw?" : "stlr",
"membar_volatile \\(elided\\)",
"ret",
"membar_volatile",
"dmb ish",
"strb",
"membar_volatile \\(elided\\)",
"ret"
"strb"
};
break;
case "CMSCondMark":
Expand Down Expand Up @@ -399,16 +403,20 @@ private void checkstore(OutputAnalyzer output, String testType, boolean useBarri
case "G1":
// a card mark volatile barrier should be generated
// before the card mark strb
//
// following the fix for 8225776 the G1 barrier is now
// scheduled out of line after the membar volatile and
// and subsequent return
matches = new String[] {
"membar_release",
"dmb ish",
useCompressedOops ? "strw?" : "str",
"membar_volatile",
"dmb ish",
"strb",
"ret",
"membar_volatile",
"dmb ish",
"ret"
"strb"
};
break;
case "CMSCondMark":
Expand Down Expand Up @@ -522,14 +530,18 @@ private void checkcas(OutputAnalyzer output, String testType, boolean useBarrier
case "G1":
// a card mark volatile barrier should be generated
// before the card mark strb
//
// following the fix for 8225776 the G1 barrier is now
// scheduled out of line after the membar acquire and
// and subsequent return
matches = new String[] {
"membar_release \\(elided\\)",
useCompressedOops ? "cmpxchgw?_acq" : "cmpxchg_acq",
"membar_acquire \\(elided\\)",
"ret",
"membar_volatile",
"dmb ish",
"strb",
"membar_acquire \\(elided\\)",
"ret"
"strb"
};
break;
case "CMSCondMark":
Expand Down Expand Up @@ -589,16 +601,20 @@ private void checkcas(OutputAnalyzer output, String testType, boolean useBarrier
case "G1":
// a card mark volatile barrier should be generated
// before the card mark strb
//
// following the fix for 8225776 the G1 barrier is now
// scheduled out of line after the membar acquire and
// and subsequent return
matches = new String[] {
"membar_release",
"dmb ish",
useCompressedOops ? "cmpxchgw? " : "cmpxchg ",
"membar_volatile",
"dmb ish",
"strb",
"membar_acquire",
"dmb ish",
"ret"
"ret",
"membar_volatile",
"dmb ish",
"strb"
};
break;
case "CMSCondMark":
Expand Down Expand Up @@ -725,14 +741,18 @@ private void checkcae(OutputAnalyzer output, String testType, boolean useBarrier
case "G1":
// a card mark volatile barrier should be generated
// before the card mark strb
//
// following the fix for 8225776 the G1 barrier is now
// scheduled out of line after the membar acquire and
// and subsequent return
matches = new String[] {
"membar_release \\(elided\\)",
useCompressedOops ? "cmpxchgw?_acq" : "cmpxchg_acq",
"membar_acquire \\(elided\\)",
"ret",
"membar_volatile",
"dmb ish",
"strb",
"membar_acquire \\(elided\\)",
"ret"
"strb"
};
break;
case "CMSCondMark":
Expand Down Expand Up @@ -781,16 +801,20 @@ private void checkcae(OutputAnalyzer output, String testType, boolean useBarrier
case "G1":
// a card mark volatile barrier should be generated
// before the card mark strb
//
// following the fix for 8225776 the G1 barrier is now
// scheduled out of line after the membar acquire and
// and subsequent return
matches = new String[] {
"membar_release",
"dmb ish",
useCompressedOops ? "cmpxchgw? " : "cmpxchg ",
"membar_volatile",
"dmb ish",
"strb",
"membar_acquire",
"dmb ish",
"ret"
"ret",
"membar_volatile",
"dmb ish",
"strb"
};
break;
case "CMSCondMark":
Expand Down Expand Up @@ -899,14 +923,18 @@ private void checkgas(OutputAnalyzer output, String testType, boolean useBarrier
case "G1":
// a card mark volatile barrier should be generated
// before the card mark strb
//
// following the fix for 8225776 the G1 barrier is now
// scheduled out of line after the membar acquire and
// and subsequent return
matches = new String[] {
"membar_release \\(elided\\)",
useCompressedOops ? "atomic_xchgw?_acq" : "atomic_xchg_acq",
"membar_acquire \\(elided\\)",
"ret",
"membar_volatile",
"dmb ish",
"strb",
"membar_acquire \\(elided\\)",
"ret"
"strb"
};
break;
case "CMSCondMark":
Expand Down Expand Up @@ -955,16 +983,20 @@ private void checkgas(OutputAnalyzer output, String testType, boolean useBarrier
case "G1":
// a card mark volatile barrier should be generated
// before the card mark strb
//
// following the fix for 8225776 the G1 barrier is now
// scheduled out of line after the membar acquire and
// and subsequent return
matches = new String[] {
"membar_release",
"dmb ish",
useCompressedOops ? "atomic_xchgw? " : "atomic_xchg ",
"membar_volatile",
"dmb ish",
"strb",
"membar_acquire",
"dmb ish",
"ret"
"ret",
"membar_volatile",
"dmb ish",
"strb"
};
break;
case "CMSCondMark":
Expand Down
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