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Rewrite selection for fields (#61370)
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The issue was that VNApplySelectors uses the types
of fields when selecting, but that's not valid for
"the first field" maps.

Mirror how the stores to fields are numbered.
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@SingleAccretion
SingleAccretion committed Nov 15, 2021
1 parent a66a9d8 commit bb3bdf8
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Showing 2 changed files with 55 additions and 63 deletions.
114 changes: 54 additions & 60 deletions src/coreclr/jit/valuenum.cpp
View file
Original file line number Diff line number Diff line change
Expand Up @@ -2531,41 +2531,50 @@ ValueNum ValueNumStore::VNForMapSelectWork(
// that is used for field handle selectors.
//
// Arguments:
// fieldHnd - handle of the field in question
// pFieldType - [out] parameter for the field's type
// pStructHnd - optional [out] parameter for the struct handle,
// populated if the field is of a struct type
// fieldHnd - handle of the field in question
// pFieldType - [out] parameter for the field's type
// pStructSize - optional [out] parameter for the size of the struct,
// populated if the field in question is of a struct type,
// otherwise set to zero
//
// Return Value:
// Value number corresponding to the given field handle.
//
ValueNum ValueNumStore::VNForFieldSelector(CORINFO_FIELD_HANDLE fieldHnd,
var_types* pFieldType,
CORINFO_CLASS_HANDLE* pStructHnd)
ValueNum ValueNumStore::VNForFieldSelector(CORINFO_FIELD_HANDLE fieldHnd, var_types* pFieldType, size_t* pStructSize)
{
CORINFO_CLASS_HANDLE structHnd = NO_CLASS_HANDLE;
ValueNum fldHndVN = VNForHandle(ssize_t(fieldHnd), GTF_ICON_FIELD_HDL);
CORINFO_CLASS_HANDLE structHnd = NO_CLASS_HANDLE;
ValueNum fldHndVN = VNForHandle(ssize_t(fieldHnd), GTF_ICON_FIELD_HDL);
var_types fieldType = m_pComp->eeGetFieldType(fieldHnd, &structHnd);
size_t structSize = 0;

CorInfoType fieldCit = m_pComp->info.compCompHnd->getFieldType(fieldHnd, &structHnd);
var_types fieldType = JITtype2varType(fieldCit);
if (fieldType == TYP_STRUCT)
{
structSize = m_pComp->info.compCompHnd->getClassSize(structHnd);

// We have to normalize here since there is no CorInfoType for vectors...
if (m_pComp->structSizeMightRepresentSIMDType(structSize))
{
fieldType = m_pComp->impNormStructType(structHnd);
}
}

#ifdef DEBUG
if (m_pComp->verbose)
{
const char* modName;
const char* fldName = m_pComp->eeGetFieldName(fieldHnd, &modName);
printf(" VNForHandle(%s) is " FMT_VN ", fieldType is %s", fldName, fldHndVN, varTypeName(fieldType));
if (varTypeIsStruct(fieldType))
if (structSize != 0)
{
printf(", size = %u", m_pComp->info.compCompHnd->getClassSize(structHnd));
printf(", size = %u", structSize);
}
printf("\n");
}
#endif

if (pStructHnd != nullptr)
if (pStructSize != nullptr)
{
*pStructHnd = structHnd;
*pStructSize = structSize;
}
*pFieldType = fieldType;

Expand Down Expand Up @@ -3890,22 +3899,10 @@ ValueNum ValueNumStore::VNApplySelectors(ValueNumKind vnk,
assert(field != FieldSeqStore::NotAField());

JITDUMP(" VNApplySelectors:\n");
var_types fieldType;
CORINFO_CLASS_HANDLE structHnd;
CORINFO_FIELD_HANDLE fldHnd = field->GetFieldHandle();
ValueNum fldHndVN = VNForFieldSelector(fldHnd, &fieldType, &structHnd);
var_types fieldType;
size_t structSize;
ValueNum fldHndVN = VNForFieldSelector(field->GetFieldHandle(), &fieldType, &structSize);

size_t structSize = 0;
if (varTypeIsStruct(fieldType))
{
structSize = m_pComp->info.compCompHnd->getClassSize(structHnd);
// We do not normalize the type field accesses during importation unless they
// are used in a call, return or assignment.
if ((fieldType == TYP_STRUCT) && m_pComp->structSizeMightRepresentSIMDType(structSize))
{
fieldType = m_pComp->impNormStructType(structHnd);
}
}
if (wbFinalStructSize != nullptr)
{
*wbFinalStructSize = structSize;
Expand Down Expand Up @@ -9016,10 +9013,11 @@ void Compiler::fgValueNumberTree(GenTree* tree)
}
else if (fldSeq2 != nullptr)
{
// Get the first (instance or static) field from field seq. GcHeap[field] will yield the "field
// map".
CLANG_FORMAT_COMMENT_ANCHOR;

if (fldSeq2->IsFirstElemFieldSeq())
{
fldSeq2 = fldSeq2->m_next;
assert(fldSeq2 != nullptr);
}
#ifdef DEBUG
CORINFO_CLASS_HANDLE fldCls = info.compCompHnd->getFieldClass(fldSeq2->m_fieldHnd);
if (obj != nullptr)
Expand All @@ -9031,42 +9029,38 @@ void Compiler::fgValueNumberTree(GenTree* tree)
}
#endif // DEBUG

// Get a field sequence for just the first field in the sequence
//
FieldSeqNode* firstFieldOnly = GetFieldSeqStore()->CreateSingleton(fldSeq2->m_fieldHnd);
size_t structSize = 0;
ValueNum fldMapVN =
vnStore->VNApplySelectors(VNK_Liberal, fgCurMemoryVN[GcHeap], firstFieldOnly, &structSize);
// The size of the ultimate value we will select, if it is of a struct type.
size_t structSize = 0;

// The final field in the sequence will need to match the 'indType'
var_types indType = tree->TypeGet();
// Get the selector for the first field.
var_types firstFieldType;
ValueNum firstFieldSelectorVN =
vnStore->VNForFieldSelector(fldSeq2->GetFieldHandle(), &firstFieldType, &structSize);

// The type of the field is "struct" if there are more fields in the sequence,
// otherwise it is the type returned from VNApplySelectors above.
var_types firstFieldType = vnStore->TypeOfVN(fldMapVN);
ValueNum fldMapVN = vnStore->VNForMapSelect(VNK_Liberal, firstFieldType, fgCurMemoryVN[GcHeap],
firstFieldSelectorVN);

ValueNum valAtAddr = fldMapVN;
ValueNum firstFieldValueSelectorVN;
if (obj != nullptr)
{
// construct the ValueNumber for 'fldMap at obj'
ValueNum objNormVal = vnStore->VNLiberalNormalValue(obj->gtVNPair);
valAtAddr = vnStore->VNForMapSelect(VNK_Liberal, firstFieldType, fldMapVN, objNormVal);
firstFieldValueSelectorVN = vnStore->VNLiberalNormalValue(obj->gtVNPair);
}
else if (staticOffset != nullptr)
else
{
// construct the ValueNumber for 'fldMap at staticOffset'
ValueNum offsetNormVal = vnStore->VNLiberalNormalValue(staticOffset->gtVNPair);
valAtAddr = vnStore->VNForMapSelect(VNK_Liberal, firstFieldType, fldMapVN, offsetNormVal);
assert(staticOffset != nullptr);
firstFieldValueSelectorVN = vnStore->VNLiberalNormalValue(staticOffset->gtVNPair);
}

// Now get rid of any remaining struct field dereferences.
if (fldSeq2->m_next)
{
valAtAddr = vnStore->VNApplySelectors(VNK_Liberal, valAtAddr, fldSeq2->m_next, &structSize);
}
valAtAddr = vnStore->VNApplySelectorsTypeCheck(valAtAddr, indType, structSize);
// Construct the value number for fldMap[obj/offset].
ValueNum firstFieldValueVN =
vnStore->VNForMapSelect(VNK_Liberal, firstFieldType, fldMapVN, firstFieldValueSelectorVN);

// Finally, account for the rest of the fields in the sequence.
ValueNum valueVN =
vnStore->VNApplySelectors(VNK_Liberal, firstFieldValueVN, fldSeq2->m_next, &structSize);

tree->gtVNPair.SetLiberal(valAtAddr);
valueVN = vnStore->VNApplySelectorsTypeCheck(valueVN, tree->TypeGet(), structSize);
tree->gtVNPair.SetLiberal(valueVN);

// The conservative value is a new, unique VN.
tree->gtVNPair.SetConservative(vnStore->VNForExpr(compCurBB, tree->TypeGet()));
Expand Down
4 changes: 1 addition & 3 deletions src/coreclr/jit/valuenum.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -591,9 +591,7 @@ class ValueNumStore
// A specialized version of VNForFunc that is used for VNF_MapStore and provides some logging when verbose is set
ValueNum VNForMapStore(var_types type, ValueNum map, ValueNum index, ValueNum value);

ValueNum VNForFieldSelector(CORINFO_FIELD_HANDLE fieldHnd,
var_types* pFieldType,
CORINFO_CLASS_HANDLE* pStructHnd = nullptr);
ValueNum VNForFieldSelector(CORINFO_FIELD_HANDLE fieldHnd, var_types* pFieldType, size_t* pStructSize = nullptr);

// These functions parallel the ones above, except that they take liberal/conservative VN pairs
// as arguments, and return such a pair (the pair of the function applied to the liberal args, and
Expand Down

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