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Unify unroll limits in a single entry point #83274

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Merged
merged 8 commits into from
Mar 13, 2023
Merged

Unify unroll limits in a single entry point #83274

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6426a70
Unify unroll limits in a single entry point
EgorBo Mar 10, 2023
6bcfedf
Fix compilation
EgorBo Mar 10, 2023
a9bb9ae
Fix comment
EgorBo Mar 10, 2023
c1e865f
Update compiler.h
EgorBo Mar 11, 2023
559957b
Merge branch 'main' of github.com:dotnet/runtime into unify-unroll-li…
EgorBo Mar 11, 2023
e0b40ec
Mitigate regressions
EgorBo Mar 11, 2023
0481c3e
Clean up
EgorBo Mar 11, 2023
0f99a42
Update compiler.h
EgorBo Mar 12, 2023
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32 changes: 22 additions & 10 deletions src/coreclr/jit/compiler.h
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Original file line number Diff line number Diff line change
Expand Up @@ -8950,22 +8950,34 @@ XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
Memcpy // Copying memory from src to dst
};

unsigned int getUnrollThreshold(UnrollKind type)
unsigned int getUnrollThreshold(UnrollKind type, bool canUseSimd = true)
{
unsigned threshold = TARGET_POINTER_SIZE;

#if defined(FEATURE_SIMD)
threshold = maxSIMDStructBytes();
if (canUseSimd)
{
threshold = maxSIMDStructBytes();
#if defined(TARGET_ARM64)
// ldp/stp instructions can load/store two 16-byte vectors at once, e.g.:
//
// ldp q0, q1, [x1]
// stp q0, q1, [x0]
//
threshold *= 2;
// ldp/stp instructions can load/store two 16-byte vectors at once, e.g.:
//
// ldp q0, q1, [x1]
// stp q0, q1, [x0]
//
threshold *= 2;
#elif defined(TARGET_XARCH)
// Ignore AVX-512 for now
threshold = max(threshold, YMM_REGSIZE_BYTES);
// Ignore AVX-512 for now
threshold = max(threshold, YMM_REGSIZE_BYTES);
#endif
}
#if defined(TARGET_XARCH)
else
{
// Compatibility with previous logic: we used to allow memset:128/memcpy:64
// on AMD64 (and 64/32 on x86) for cases where we don't use SIMD
// see https://github.com/dotnet/runtime/issues/83297
threshold *= 2;
}
#endif
#endif

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13 changes: 10 additions & 3 deletions src/coreclr/jit/lowerxarch.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -332,7 +332,6 @@ void Lowering::LowerBlockStore(GenTreeBlk* blkNode)
}
else
{
blkNode->gtBlkOpKind = GenTreeBlk::BlkOpKindUnroll;

// The fill value of an initblk is interpreted to hold a
// value of (unsigned int8) however a constant of any size
Expand All @@ -357,6 +356,10 @@ void Lowering::LowerBlockStore(GenTreeBlk* blkNode)
{
src->SetContained();
}
else if (size > comp->getUnrollThreshold(Compiler::UnrollKind::Memset, /*canUseSimd*/ false))
{
goto TOO_BIG_TO_UNROLL;
}
}
}
#ifdef TARGET_AMD64
Expand All @@ -371,13 +374,15 @@ void Lowering::LowerBlockStore(GenTreeBlk* blkNode)
fill *= 0x01010101;
}

blkNode->gtBlkOpKind = GenTreeBlk::BlkOpKindUnroll;
src->AsIntCon()->SetIconValue(fill);

ContainBlockStoreAddress(blkNode, size, dstAddr, nullptr);
}
}
else
{
TOO_BIG_TO_UNROLL:
#ifdef TARGET_AMD64
blkNode->gtBlkOpKind = GenTreeBlk::BlkOpKindHelper;
#else
Expand Down Expand Up @@ -412,7 +417,8 @@ void Lowering::LowerBlockStore(GenTreeBlk* blkNode)
blkNode->SetOper(GT_STORE_BLK);
}
#ifndef JIT32_GCENCODER
else if (dstAddr->OperIsLocalAddr() && (size <= comp->getUnrollThreshold(Compiler::UnrollKind::Memcpy)))
else if (dstAddr->OperIsLocalAddr() &&
(size <= comp->getUnrollThreshold(Compiler::UnrollKind::Memcpy, false)))
{
// If the size is small enough to unroll then we need to mark the block as non-interruptible
// to actually allow unrolling. The generated code does not report GC references loaded in the
Expand Down Expand Up @@ -472,7 +478,8 @@ void Lowering::LowerBlockStore(GenTreeBlk* blkNode)
blkNode->gtBlkOpKind = GenTreeBlk::BlkOpKindUnroll;
}
}
else if (blkNode->OperIs(GT_STORE_BLK) && (size <= comp->getUnrollThreshold(Compiler::UnrollKind::Memcpy)))
else if (blkNode->OperIs(GT_STORE_BLK) &&
(size <= comp->getUnrollThreshold(Compiler::UnrollKind::Memcpy, !blkNode->GetLayout()->HasGCPtr())))
{
blkNode->gtBlkOpKind = GenTreeBlk::BlkOpKindUnroll;

Expand Down