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JIT: use VNVisitReachingVNs in IsVNNeverNegative (#105197)
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@EgorBo
EgorBo authored Jul 25, 2024
1 parent 5377b58 commit 86cb7b9
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Showing 2 changed files with 225 additions and 104 deletions.
228 changes: 124 additions & 104 deletions src/coreclr/jit/valuenum.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -1635,7 +1635,20 @@ bool ValueNumStore::IsKnownNonNull(ValueNum vn)
}

VNFuncApp funcAttr;
return GetVNFunc(vn, &funcAttr) && (s_vnfOpAttribs[funcAttr.m_func] & VNFOA_KnownNonNull) != 0;
if (!GetVNFunc(vn, &funcAttr))
{
return false;
}

if ((s_vnfOpAttribs[funcAttr.m_func] & VNFOA_KnownNonNull) != 0)
{
return true;
}

// TODO: we can recognize more non-null idioms here, e.g.
// ADD(IsKnownNonNull(op1), smallCns), etc.

return false;
}

bool ValueNumStore::IsSharedStatic(ValueNum vn)
Expand Down Expand Up @@ -3191,81 +3204,81 @@ ValueNum ValueNumStore::VNForMapPhysicalSelect(
return result;
}

typedef JitHashTable<ValueNum, JitSmallPrimitiveKeyFuncs<ValueNum>, bool> ValueNumSet;

class SmallValueNumSet
bool ValueNumStore::SmallValueNumSet::Lookup(ValueNum vn)
{
union
// O(N) lookup for inline elements
if (m_numElements <= ArrLen(m_inlineElements))
{
ValueNum m_inlineElements[4];
ValueNumSet* m_set;
};
unsigned m_numElements = 0;

public:
unsigned Count()
{
return m_numElements;
}

template <typename Func>
void ForEach(Func func)
{
if (m_numElements <= ArrLen(m_inlineElements))
for (unsigned i = 0; i < m_numElements; i++)
{
for (unsigned i = 0; i < m_numElements; i++)
if (m_inlineElements[i] == vn)
{
func(m_inlineElements[i]);
}
}
else
{
for (ValueNum vn : ValueNumSet::KeyIteration(m_set))
{
func(vn);
return true;
}
}

// Not found
return false;
}

void Add(Compiler* comp, ValueNum vn)
return m_set->Lookup(vn);
}

// Returns false if the value already exists
bool ValueNumStore::SmallValueNumSet::Add(Compiler* comp, ValueNum vn)
{
if (m_numElements <= ArrLen(m_inlineElements))
{
if (m_numElements <= ArrLen(m_inlineElements))
for (unsigned i = 0; i < m_numElements; i++)
{
for (unsigned i = 0; i < m_numElements; i++)
if (m_inlineElements[i] == vn)
{
if (m_inlineElements[i] == vn)
{
return;
}
// Already exists
return false;
}
}

if (m_numElements < ArrLen(m_inlineElements))
if (m_numElements < ArrLen(m_inlineElements))
{
m_inlineElements[m_numElements] = vn;
m_numElements++;
}
else
{
ValueNumSet* set = new (comp, CMK_ValueNumber) ValueNumSet(comp->getAllocator(CMK_ValueNumber));
for (ValueNum oldVn : m_inlineElements)
{
m_inlineElements[m_numElements] = vn;
m_numElements++;
set->Set(oldVn, true);
}
else
{
ValueNumSet* set = new (comp, CMK_ValueNumber) ValueNumSet(comp->getAllocator(CMK_ValueNumber));
for (ValueNum oldVn : m_inlineElements)
{
set->Set(oldVn, true);
}

set->Set(vn, true);
set->Set(vn, true);

m_set = set;
m_numElements++;
assert(m_numElements == set->GetCount());
}
}
else
{
m_set->Set(vn, true, ValueNumSet::SetKind::Overwrite);
m_numElements = m_set->GetCount();
m_set = set;
m_numElements++;
assert(m_numElements == set->GetCount());
}
return true;
}
};

bool exists = m_set->Set(vn, true, ValueNumSet::SetKind::Overwrite);
m_numElements = m_set->GetCount();
return !exists;
}

//------------------------------------------------------------------------------
// VNPhiDefToVN: Extracts the VN for a specific argument of a phi definition.
//
// Arguments:
// phiDef - The phi definition
// ssaArgNum - The argument number to extract
//
// Return Value:
// The VN for the specified argument of the phi definition.
//
ValueNum ValueNumStore::VNPhiDefToVN(const VNPhiDef& phiDef, unsigned ssaArgNum)
{
return m_pComp->lvaGetDesc(phiDef.LclNum)->GetPerSsaData(phiDef.SsaArgs[ssaArgNum])->m_vnPair.Get(VNK_Conservative);
}

//------------------------------------------------------------------------------
// VNForMapSelectInner: Select value from a map and record loop memory dependencies.
Expand Down Expand Up @@ -6513,68 +6526,75 @@ bool ValueNumStore::IsVNInt32Constant(ValueNum vn)

bool ValueNumStore::IsVNNeverNegative(ValueNum vn)
{
assert(varTypeIsIntegral(TypeOfVN(vn)));

if (IsVNConstant(vn))
{
var_types vnTy = TypeOfVN(vn);
if (vnTy == TYP_INT)
auto vnVisitor = [this](ValueNum vn) -> VNVisit {
if ((vn == NoVN) || !varTypeIsIntegral(TypeOfVN(vn)))
{
return GetConstantInt32(vn) >= 0;
return VNVisit::Abort;
}
else if (vnTy == TYP_LONG)

if (IsVNConstant(vn))
{
return GetConstantInt64(vn) >= 0;
var_types vnTy = TypeOfVN(vn);
if (vnTy == TYP_INT)
{
return GetConstantInt32(vn) >= 0 ? VNVisit::Continue : VNVisit::Abort;
}
if (vnTy == TYP_LONG)
{
return GetConstantInt64(vn) >= 0 ? VNVisit::Continue : VNVisit::Abort;
}
return VNVisit::Abort;
}

return false;
}
// Array length can never be negative.
if (IsVNArrLen(vn))
{
return VNVisit::Continue;
}

// Array length can never be negative.
if (IsVNArrLen(vn))
{
return true;
}
// TODO-VN: Recognize Span.Length
// Handle more intrinsics such as Math.Max(neverNegative1, neverNegative2)

VNFuncApp funcApp;
if (GetVNFunc(vn, &funcApp))
{
switch (funcApp.m_func)
VNFuncApp funcApp;
if (GetVNFunc(vn, &funcApp))
{
case VNF_GE_UN:
case VNF_GT_UN:
case VNF_LE_UN:
case VNF_LT_UN:
case VNF_COUNT:
case VNF_ADD_UN_OVF:
case VNF_SUB_UN_OVF:
case VNF_MUL_UN_OVF:
switch (funcApp.m_func)
{
case VNF_GE_UN:
case VNF_GT_UN:
case VNF_LE_UN:
case VNF_LT_UN:
case VNF_COUNT:
case VNF_ADD_UN_OVF:
case VNF_SUB_UN_OVF:
case VNF_MUL_UN_OVF:
#ifdef FEATURE_HW_INTRINSICS
#ifdef TARGET_XARCH
case VNF_HWI_POPCNT_PopCount:
case VNF_HWI_POPCNT_X64_PopCount:
case VNF_HWI_LZCNT_LeadingZeroCount:
case VNF_HWI_LZCNT_X64_LeadingZeroCount:
case VNF_HWI_BMI1_TrailingZeroCount:
case VNF_HWI_BMI1_X64_TrailingZeroCount:
return true;
case VNF_HWI_POPCNT_PopCount:
case VNF_HWI_POPCNT_X64_PopCount:
case VNF_HWI_LZCNT_LeadingZeroCount:
case VNF_HWI_LZCNT_X64_LeadingZeroCount:
case VNF_HWI_BMI1_TrailingZeroCount:
case VNF_HWI_BMI1_X64_TrailingZeroCount:
return VNVisit::Continue;
#elif defined(TARGET_ARM64)
case VNF_HWI_AdvSimd_PopCount:
case VNF_HWI_AdvSimd_LeadingZeroCount:
case VNF_HWI_AdvSimd_LeadingSignCount:
case VNF_HWI_ArmBase_LeadingZeroCount:
case VNF_HWI_ArmBase_Arm64_LeadingZeroCount:
case VNF_HWI_ArmBase_Arm64_LeadingSignCount:
return true;
case VNF_HWI_AdvSimd_PopCount:
case VNF_HWI_AdvSimd_LeadingZeroCount:
case VNF_HWI_AdvSimd_LeadingSignCount:
case VNF_HWI_ArmBase_LeadingZeroCount:
case VNF_HWI_ArmBase_Arm64_LeadingZeroCount:
case VNF_HWI_ArmBase_Arm64_LeadingSignCount:
return VNVisit::Continue;
#endif
#endif // FEATURE_HW_INTRINSICS

default:
break;
default:
break;
}
}
}

return false;
return VNVisit::Abort;
};
return VNVisitReachingVNs(vn, vnVisitor) == VNVisit::Continue;
}

GenTreeFlags ValueNumStore::GetHandleFlags(ValueNum vn)
Expand Down
101 changes: 101 additions & 0 deletions src/coreclr/jit/valuenum.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -529,6 +529,107 @@ class ValueNumStore

void PeelOffsets(ValueNum* vn, target_ssize_t* offset);

typedef JitHashTable<ValueNum, JitSmallPrimitiveKeyFuncs<ValueNum>, bool> ValueNumSet;

class SmallValueNumSet
{
union
{
ValueNum m_inlineElements[4];
ValueNumSet* m_set;
};
unsigned m_numElements = 0;

public:
unsigned Count()
{
return m_numElements;
}

template <typename Func>
void ForEach(Func func)
{
if (m_numElements <= ArrLen(m_inlineElements))
{
for (unsigned i = 0; i < m_numElements; i++)
{
func(m_inlineElements[i]);
}
}
else
{
for (ValueNum vn : ValueNumSet::KeyIteration(m_set))
{
func(vn);
}
}
}

// Returns false if the value wasn't found
bool Lookup(ValueNum vn);

// Returns false if the value already exists
bool Add(Compiler* comp, ValueNum vn);
};

enum class VNVisit
{
Continue,
Abort,
};

ValueNum VNPhiDefToVN(const VNPhiDef& phiDef, unsigned ssaArgNum);

//--------------------------------------------------------------------------------
// VNVisitReachingVNs: given a VN, call the specified callback function on it and all the VNs that reach it
// via PHI definitions if any.
//
// Arguments:
// vn - The VN to visit all the reaching VNs for
// argVisitor - The callback function to call on the vn and its PHI arguments if any
//
// Return Value:
// VNVisit::Aborted - an argVisitor returned VNVisit::Abort, we stop the walk and return
// VNVisit::Continue - all argVisitor returned VNVisit::Continue
//
template <typename TArgVisitor>
VNVisit VNVisitReachingVNs(ValueNum vn, TArgVisitor argVisitor)
{
ArrayStack<ValueNum> toVisit(m_alloc);
toVisit.Push(vn);

SmallValueNumSet visited;
visited.Add(m_pComp, vn);
while (toVisit.Height() > 0)
{
ValueNum vnToVisit = toVisit.Pop();

// We need to handle nested (and, potentially, recursive) phi definitions.
// For now, we ignore memory phi definitions.
VNPhiDef phiDef;
if (GetPhiDef(vnToVisit, &phiDef))
{
for (unsigned ssaArgNum = 0; ssaArgNum < phiDef.NumArgs; ssaArgNum++)
{
ValueNum childVN = VNPhiDefToVN(phiDef, ssaArgNum);
if (visited.Add(m_pComp, childVN))
{
toVisit.Push(childVN);
}
}
}
else
{
if (argVisitor(vnToVisit) == VNVisit::Abort)
{
// The visitor wants to abort the walk.
return VNVisit::Abort;
}
}
}
return VNVisit::Continue;
}

// And the single constant for an object reference type.
static ValueNum VNForNull()
{
Expand Down

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