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JIT: Avoid calling GC write barrier for byrefs #105934

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JIT: Avoid calling GC write barrier for byrefs #105934

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908703b
unroll byref struct copies
markples May 26, 2023
4a9c52a
HasGCByRef and some xarch/arm consolidation
markples Jul 14, 2023
512e1d5
loongarch64/riscv64 and more arch consolidation
markples Jul 15, 2023
ecbc3cc
Jakob's change
markples Jul 18, 2023
bb426df
Use IsGCRef
markples Jul 18, 2023
56c4afd
undo whitespace change
markples Jul 18, 2023
ba03213
Merge branch 'w80086' into w80086-fix-withcq
markples Jul 18, 2023
7641a70
Remove unnecessary envvars from test
markples Jul 18, 2023
18c1008
Merge branch 'w80086' into w80086-fix-withcq
markples Jul 18, 2023
d100ad8
format
markples Jul 18, 2023
4469cc2
Remove this->
markples Jul 18, 2023
8b77d57
Merge branch 'w80086' into w80086-fix-withcq
markples Jul 18, 2023
b440357
Merge remote-tracking branch 'dotnet/main' into w80086-fix-withcq
markples Jul 18, 2023
ad29cb1
Merge remote-tracking branch 'dotnet/main' into w80086-fix-withcq
markples Jul 18, 2023
ec39662
Merge branch 'main' of github.com:dotnet/runtime into pr-89064
jakobbotsch Aug 5, 2024
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7 changes: 2 additions & 5 deletions src/coreclr/jit/codegenarm.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -857,12 +857,10 @@ void CodeGen::genCodeForCpObj(GenTreeBlk* cpObjNode)
}
else
{
unsigned gcPtrCount = layout->GetGCPtrCount();

unsigned i = 0;
while (i < slots)
{
if (!layout->IsGCPtr(i))
if (!layout->IsGCRef(i))
{
emit->emitIns_R_R_I(INS_ldr, EA_PTRSIZE, tmpReg, REG_WRITE_BARRIER_SRC_BYREF, TARGET_POINTER_SIZE,
INS_FLAGS_DONT_CARE, INS_OPTS_LDST_POST_INC);
Expand All @@ -872,11 +870,10 @@ void CodeGen::genCodeForCpObj(GenTreeBlk* cpObjNode)
else
{
genEmitHelperCall(CORINFO_HELP_ASSIGN_BYREF, 0, EA_PTRSIZE);
gcPtrCount--;
}

++i;
}
assert(gcPtrCount == 0);
}

if (cpObjNode->IsVolatile())
Expand Down
10 changes: 3 additions & 7 deletions src/coreclr/jit/codegenarm64.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -3740,8 +3740,6 @@ void CodeGen::genCodeForCpObj(GenTreeBlk* cpObjNode)
}
else
{
unsigned gcPtrCount = cpObjNode->GetLayout()->GetGCPtrCount();

// We might also need SIMD regs if we have 4 or more continuous non-gc slots
// On ARM64, SIMD loads/stores provide 8-byte atomicity guarantees when aligned to 8 bytes.
regNumber tmpSimdReg1 = REG_NA;
Expand All @@ -3755,15 +3753,15 @@ void CodeGen::genCodeForCpObj(GenTreeBlk* cpObjNode)
unsigned i = 0;
while (i < slots)
{
if (!layout->IsGCPtr(i))
if (!layout->IsGCRef(i))
{
// How many continuous non-gc slots do we have?
// How many continuous non-GC ref slots do we have?
unsigned nonGcSlots = 0;
do
{
nonGcSlots++;
i++;
} while ((i < slots) && !layout->IsGCPtr(i));
} while ((i < slots) && !layout->IsGCRef(i));

const regNumber srcReg = REG_WRITE_BARRIER_SRC_BYREF;
const regNumber dstReg = REG_WRITE_BARRIER_DST_BYREF;
Expand Down Expand Up @@ -3802,11 +3800,9 @@ void CodeGen::genCodeForCpObj(GenTreeBlk* cpObjNode)
{
// In the case of a GC-Pointer we'll call the ByRef write barrier helper
genEmitHelperCall(CORINFO_HELP_ASSIGN_BYREF, 0, EA_PTRSIZE);
gcPtrCount--;
i++;
}
}
assert(gcPtrCount == 0);
}

if (cpObjNode->IsVolatile())
Expand Down
10 changes: 3 additions & 7 deletions src/coreclr/jit/codegenloongarch64.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -2325,15 +2325,13 @@ void CodeGen::genCodeForCpObj(GenTreeBlk* cpObjNode)
}
else
{
unsigned gcPtrCount = cpObjNode->GetLayout()->GetGCPtrCount();

unsigned i = 0;
while (i < slots)
{
if (!layout->IsGCPtr(i))
if (!layout->IsGCRef(i))
{
// Check if the next slot's type is also TYP_GC_NONE and use two load/store
if ((i + 1 < slots) && !layout->IsGCPtr(i + 1))
// Check if the next slot's type is also non-ref and use two load/store
if ((i + 1 < slots) && !layout->IsGCRef(i + 1))
{
if ((i + 2) == slots)
{
Expand Down Expand Up @@ -2369,11 +2367,9 @@ void CodeGen::genCodeForCpObj(GenTreeBlk* cpObjNode)
{
// In the case of a GC-Pointer we'll call the ByRef write barrier helper
genEmitHelperCall(CORINFO_HELP_ASSIGN_BYREF, 0, EA_PTRSIZE);
gcPtrCount--;
}
++i;
}
assert(gcPtrCount == 0);
}

if (cpObjNode->IsVolatile())
Expand Down
10 changes: 3 additions & 7 deletions src/coreclr/jit/codegenriscv64.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -2247,15 +2247,13 @@ void CodeGen::genCodeForCpObj(GenTreeBlk* cpObjNode)
}
else
{
unsigned gcPtrCount = cpObjNode->GetLayout()->GetGCPtrCount();

unsigned i = 0;
while (i < slots)
{
if (!layout->IsGCPtr(i))
if (!layout->IsGCRef(i))
{
// Check if the next slot's type is also TYP_GC_NONE and use two ld/sd
if ((i + 1 < slots) && !layout->IsGCPtr(i + 1))
// Check if the next slot's type is also non-ref and use two ld/sd
if ((i + 1 < slots) && !layout->IsGCRef(i + 1))
{
if ((i + 2) == slots)
{
Expand Down Expand Up @@ -2291,11 +2289,9 @@ void CodeGen::genCodeForCpObj(GenTreeBlk* cpObjNode)
{
// In the case of a GC-Pointer we'll call the ByRef write barrier helper
genEmitHelperCall(CORINFO_HELP_ASSIGN_BYREF, 0, EA_PTRSIZE);
gcPtrCount--;
}
++i;
}
assert(gcPtrCount == 0);
}

if (cpObjNode->IsVolatile())
Expand Down
22 changes: 9 additions & 13 deletions src/coreclr/jit/codegenxarch.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -4321,32 +4321,31 @@ void CodeGen::genCodeForCpObj(GenTreeBlk* cpObjNode)
}
else
{
ClassLayout* layout = cpObjNode->GetLayout();
unsigned gcPtrCount = layout->GetGCPtrCount();
ClassLayout* layout = cpObjNode->GetLayout();

unsigned i = 0;
while (i < slots)
{
if (!layout->IsGCPtr(i))
if (!layout->IsGCRef(i))
{
// Let's see if we can use rep movsp instead of a sequence of movsp instructions
// to save cycles and code size.
unsigned nonGcSlotCount = 0;
unsigned nonRefSlotCount = 0;

do
{
nonGcSlotCount++;
nonRefSlotCount++;
i++;
} while ((i < slots) && !layout->IsGCPtr(i));
} while ((i < slots) && !layout->IsGCRef(i));

// If we have a very small contiguous non-gc region, it's better just to
// emit a sequence of movsp instructions
if (nonGcSlotCount < CPOBJ_NONGC_SLOTS_LIMIT)
if (nonRefSlotCount < CPOBJ_NONGC_SLOTS_LIMIT)
{
while (nonGcSlotCount > 0)
while (nonRefSlotCount > 0)
{
instGen(INS_movsp);
nonGcSlotCount--;
nonRefSlotCount--;
}
}
else
Expand All @@ -4355,19 +4354,16 @@ void CodeGen::genCodeForCpObj(GenTreeBlk* cpObjNode)
// rep movsp (alias for movsd/movsq for x86/x64)
assert((internalRegisters.GetAll(cpObjNode) & RBM_RCX) != 0);

GetEmitter()->emitIns_R_I(INS_mov, EA_4BYTE, REG_RCX, nonGcSlotCount);
GetEmitter()->emitIns_R_I(INS_mov, EA_4BYTE, REG_RCX, nonRefSlotCount);
instGen(INS_r_movsp);
}
}
else
{
genEmitHelperCall(CORINFO_HELP_ASSIGN_BYREF, 0, EA_PTRSIZE);
gcPtrCount--;
i++;
}
}

assert(gcPtrCount == 0);
}

// Clear the gcInfo for RSI and RDI.
Expand Down
18 changes: 9 additions & 9 deletions src/coreclr/jit/lowerxarch.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -475,37 +475,37 @@ void Lowering::LowerBlockStore(GenTreeBlk* blkNode)
// we can use REP MOVSD/Q instead of a sequence of MOVSD/Q instructions. According to the
// Intel Manual, the sweet spot for small structs is between 4 to 12 slots of size where
// the entire operation takes 20 cycles and encodes in 5 bytes (loading RCX and REP MOVSD/Q).
unsigned nonGCSlots = 0;
unsigned nonRefSlots = 0;

if (dstAddr->OperIs(GT_LCL_ADDR) || layout->IsStackOnly(comp))
{
// If the destination is on the stack then no write barriers are needed.
nonGCSlots = layout->GetSlotCount();
nonRefSlots = layout->GetSlotCount();
}
else
{
// Otherwise a write barrier is needed for every GC pointer in the layout
// so we need to check if there's a long enough sequence of non-GC slots.
// Otherwise a write barrier is needed for every TYP_REF pointer in the layout
// so we need to check if there's a long enough sequence of non-TYP_REF slots.
unsigned slots = layout->GetSlotCount();
for (unsigned i = 0; i < slots; i++)
{
if (layout->IsGCPtr(i))
if (layout->IsGCRef(i))
{
nonGCSlots = 0;
nonRefSlots = 0;
}
else
{
nonGCSlots++;
nonRefSlots++;

if (nonGCSlots >= CPOBJ_NONGC_SLOTS_LIMIT)
if (nonRefSlots >= CPOBJ_NONGC_SLOTS_LIMIT)
{
break;
}
}
}
}

if (nonGCSlots >= CPOBJ_NONGC_SLOTS_LIMIT)
if (nonRefSlots >= CPOBJ_NONGC_SLOTS_LIMIT)
{
blkNode->gtBlkOpKind = GenTreeBlk::BlkOpKindCpObjRepInstr;
}
Expand Down
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