Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

JIT: Optimize range checks for a[i & C], a[i % c] and a[(i & c1)>>c2)] patterns #1644

Merged
merged 11 commits into from
Mar 4, 2020
Merged

JIT: Optimize range checks for a[i & C], a[i % c] and a[(i & c1)>>c2)] patterns #1644

Changes from 4 commits
Commits
Show all changes
11 commits
Select commit Hold shift + click to select a range
e6e02e9
Optimize range checks for array[x & c]
EgorBo Jan 12, 2020
d64eb57
Handle more cases...
EgorBo Jan 12, 2020
6bd42c9
Fix possible crash
EgorBo Jan 12, 2020
f799b41
Formatting
EgorBo Jan 12, 2020
dbb3d24
Allow only [0..31] range for RSH operator
EgorBo Jan 16, 2020
37b2baf
Address feedback
EgorBo Jan 18, 2020
ae52d3c
Merge branch 'master' of github.com:dotnet/runtime into rngchk-and
EgorBo Feb 1, 2020
e04b86a
Add tests, also handle GT_LSH
EgorBo Feb 1, 2020
e912715
Merge branch 'master' of github.com:dotnet/runtime into rngchk-and
EgorBo Feb 23, 2020
4087400
Address feedback
EgorBo Feb 23, 2020
11e8fa4
Add a comment
EgorBo Mar 4, 2020
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
46 changes: 43 additions & 3 deletions src/coreclr/src/jit/rangecheck.cpp
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -773,11 +773,46 @@ void RangeCheck::MergeAssertion(BasicBlock* block, GenTree* op, Range* pRange DE
// Compute the range for a binary operation.
Range RangeCheck::ComputeRangeForBinOp(BasicBlock* block, GenTreeOp* binop, bool monIncreasing DEBUGARG(int indent))
{
assert(binop->OperIs(GT_ADD));
assert(binop->OperIs(GT_ADD, GT_AND, GT_RSH, GT_UMOD));

GenTree* op1 = binop->gtGetOp1();
GenTree* op2 = binop->gtGetOp2();

if (binop->OperIs(GT_AND, GT_RSH, GT_UMOD))
{
if (!op2->IsIntCnsFitsInI32())
{
// only cns is supported for op2 at the moment for &,%,>> operators
EgorBo marked this conversation as resolved.
Show resolved Hide resolved
return Range(Limit::keUnknown);
}

int icon = -1;
if (binop->OperIs(GT_AND))
{
// x & cns -> [0..cns]
icon = static_cast<int>(op2->AsIntCon()->IconValue());
}
else if (binop->OperIs(GT_UMOD))
{
// x % cns -> [0..cns-1]
icon = static_cast<int>(op2->AsIntCon()->IconValue()) - 1;
}
else if (binop->OperIs(GT_RSH) && op1->OperIs(GT_AND) && op1->AsOp()->gtGetOp2()->IsIntCnsFitsInI32())
{
// (x & cns1) >> cns2 -> [0..cns1>>cns2]
icon = static_cast<int>(op1->AsOp()->gtGetOp2()->AsIntCon()->IconValue()) >>
static_cast<int>(op2->AsIntCon()->IconValue());
EgorBo marked this conversation as resolved.
Show resolved Hide resolved
}

if (icon < 0)
{
return Range(Limit::keUnknown);
}
Range range(Limit(Limit::keConstant, 0), Limit(Limit::keConstant, icon));
JITDUMP("Limit range to %s\n", range.ToString(m_pCompiler->getAllocatorDebugOnly()));
return range;
}

EgorBo marked this conversation as resolved.
Show resolved Hide resolved
Range* op1RangeCached = nullptr;
Range op1Range = Limit(Limit::keUndef);
// Check if the range value is already cached.
Expand Down Expand Up @@ -1032,6 +1067,11 @@ bool RangeCheck::ComputeDoesOverflow(BasicBlock* block, GenTree* expr)
{
overflows = DoesBinOpOverflow(block, expr->AsOp());
}
// GT_AND, GT_UMOD and GT_RSH don't overflow
else if (expr->OperIs(GT_AND, GT_RSH, GT_UMOD))
{
overflows = false;
}
// Walk through phi arguments to check if phi arguments involve arithmetic that overflows.
else if (expr->OperGet() == GT_PHI)
{
Expand Down Expand Up @@ -1117,8 +1157,8 @@ Range RangeCheck::ComputeRange(BasicBlock* block, GenTree* expr, bool monIncreas
range = ComputeRangeForLocalDef(block, expr->AsLclVarCommon(), monIncreasing DEBUGARG(indent + 1));
MergeAssertion(block, expr, &range DEBUGARG(indent + 1));
}
// If add, then compute the range for the operands and add them.
else if (expr->OperGet() == GT_ADD)
// compute the range for binary operation
else if (expr->OperIs(GT_ADD, GT_AND, GT_RSH, GT_UMOD))
{
range = ComputeRangeForBinOp(block, expr->AsOp(), monIncreasing DEBUGARG(indent + 1));
}
Expand Down