void RangeCheck::OptimizeRangeCheck(BasicBlock* block, GenTreePtr stmt, GenTreePtr treeParent)
{
// Check if we are dealing with a bounds check node.
if (treeParent->OperGet() != GT_COMMA)
{
return;
}
// If we are not looking at array bounds check, bail.
GenTreePtr tree = treeParent->gtOp.gtOp1;
if (tree->gtOper != GT_ARR_BOUNDS_CHECK)
{
return;
}
GenTreeBoundsChk* bndsChk = tree->AsBoundsChk();
m_pCurBndsChk = bndsChk;
GenTreePtr treeIndex = bndsChk->gtIndex;
// Take care of constant index first, like a[2], for example.
ValueNum idxVn = treeIndex->gtVNPair.GetConservative();
ValueNum arrLenVn = bndsChk->gtArrLen->gtVNPair.GetConservative();
int arrSize = GetArrLength(arrLenVn);
JITDUMP("ArrSize for lengthVN:%03X = %d\n", arrLenVn, arrSize);
if (m_pCompiler->vnStore->IsVNConstant(idxVn) && arrSize > 0)
{
ssize_t idxVal = -1;
unsigned iconFlags = 0;
if (!m_pCompiler->optIsTreeKnownIntValue(true, treeIndex, &idxVal, &iconFlags))
{
return;
}
JITDUMP("[RangeCheck::OptimizeRangeCheck] Is index %d in <0, arrLenVn VN%X sz:%d>.\n", idxVal, arrLenVn, arrSize);
if (arrSize > 0 && idxVal < arrSize && idxVal >= 0)
{
JITDUMP("Removing range check\n");
m_pCompiler->optRemoveRangeCheck(treeParent, stmt, true, GTF_ASG, true /* force remove */);
return;
}
}
GetRangeMap()->RemoveAll();
GetOverflowMap()->RemoveAll();
// Get the range for this index.
SearchPath* path = new (m_pCompiler->getAllocator()) SearchPath(m_pCompiler->getAllocator());
Range range = GetRange(block, stmt, treeIndex, path, false DEBUGARG(0));
// If upper or lower limit is found to be unknown (top), or it was found to
// be unknown because of over budget or a deep search, then return early.
if (range.UpperLimit().IsUnknown() || range.LowerLimit().IsUnknown())
{
// Note: If we had stack depth too deep in the GetRange call, we'd be
// too deep even in the DoesOverflow call. So return early.
return;
}
if (DoesOverflow(block, stmt, treeIndex, path))
{
JITDUMP("Method determined to overflow.\n");
return;
}
JITDUMP("Range value %s\n", range.ToString(m_pCompiler->getAllocatorDebugOnly()));
path->RemoveAll();
Widen(block, stmt, treeIndex, path, &range);
// If upper or lower limit is unknown, then return.
if (range.UpperLimit().IsUnknown() || range.LowerLimit().IsUnknown())
{
return;
}
// Is the range between the lower and upper bound values.
if (BetweenBounds(range, 0, bndsChk->gtArrLen))
{
JITDUMP("[RangeCheck::OptimizeRangeCheck] Between bounds\n");
m_pCompiler->optRemoveRangeCheck(treeParent, stmt, true, GTF_ASG, true /* force remove */);
}
return;
}
void RangeCheck::OptimizeRangeCheck(BasicBlock* block, GenTreeStmt* stmt, GenTree* treeParent)
{
// Check if we are dealing with a bounds check node.
if (treeParent->OperGet() != GT_COMMA)
{
return;
}
// If we are not looking at array bounds check, bail.
GenTree* tree = treeParent->gtOp.gtOp1;
if (!tree->OperIsBoundsCheck())
{
return;
}
GenTreeBoundsChk* bndsChk = tree->AsBoundsChk();
m_pCurBndsChk = bndsChk;
GenTree* treeIndex = bndsChk->gtIndex;
// Take care of constant index first, like a[2], for example.
ValueNum idxVn = m_pCompiler->vnStore->VNConservativeNormalValue(treeIndex->gtVNPair);
ValueNum arrLenVn = m_pCompiler->vnStore->VNConservativeNormalValue(bndsChk->gtArrLen->gtVNPair);
int arrSize = 0;
if (m_pCompiler->vnStore->IsVNConstant(arrLenVn))
{
ssize_t constVal = -1;
unsigned iconFlags = 0;
if (m_pCompiler->optIsTreeKnownIntValue(true, bndsChk->gtArrLen, &constVal, &iconFlags))
{
arrSize = (int)constVal;
}
}
else
#ifdef FEATURE_SIMD
if (tree->gtOper != GT_SIMD_CHK
#ifdef FEATURE_HW_INTRINSICS
&& tree->gtOper != GT_HW_INTRINSIC_CHK
#endif // FEATURE_HW_INTRINSICS
)
#endif // FEATURE_SIMD
{
arrSize = GetArrLength(arrLenVn);
}
JITDUMP("ArrSize for lengthVN:%03X = %d\n", arrLenVn, arrSize);
if (m_pCompiler->vnStore->IsVNConstant(idxVn) && (arrSize > 0))
{
ssize_t idxVal = -1;
unsigned iconFlags = 0;
if (!m_pCompiler->optIsTreeKnownIntValue(true, treeIndex, &idxVal, &iconFlags))
{
return;
}
JITDUMP("[RangeCheck::OptimizeRangeCheck] Is index %d in <0, arrLenVn " FMT_VN " sz:%d>.\n", idxVal, arrLenVn,
arrSize);
if ((idxVal < arrSize) && (idxVal >= 0))
{
JITDUMP("Removing range check\n");
m_pCompiler->optRemoveRangeCheck(treeParent, stmt);
return;
}
}
GetRangeMap()->RemoveAll();
GetOverflowMap()->RemoveAll();
m_pSearchPath = new (m_alloc) SearchPath(m_alloc);
// Get the range for this index.
Range range = GetRange(block, treeIndex, false DEBUGARG(0));
// If upper or lower limit is found to be unknown (top), or it was found to
// be unknown because of over budget or a deep search, then return early.
if (range.UpperLimit().IsUnknown() || range.LowerLimit().IsUnknown())
{
// Note: If we had stack depth too deep in the GetRange call, we'd be
// too deep even in the DoesOverflow call. So return early.
return;
}
if (DoesOverflow(block, treeIndex))
{
JITDUMP("Method determined to overflow.\n");
return;
}
JITDUMP("Range value %s\n", range.ToString(m_pCompiler->getAllocatorDebugOnly()));
m_pSearchPath->RemoveAll();
Widen(block, treeIndex, &range);
// If upper or lower limit is unknown, then return.
if (range.UpperLimit().IsUnknown() || range.LowerLimit().IsUnknown())
{
return;
}
// Is the range between the lower and upper bound values.
if (BetweenBounds(range, 0, bndsChk->gtArrLen))
{
JITDUMP("[RangeCheck::OptimizeRangeCheck] Between bounds\n");
m_pCompiler->optRemoveRangeCheck(treeParent, stmt);
}
return;
}