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.

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

Eliminate bound checks for "arr[index % arr.Length]" #84231

Merged
merged 7 commits into from
Apr 15, 2023
Merged
Show file tree
Hide file tree
Changes from all commits
Commits
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
14 changes: 11 additions & 3 deletions src/coreclr/jit/assertionprop.cpp
Original file line number Diff line number Diff line change
Expand Up @@ -196,7 +196,7 @@ bool IntegralRange::Contains(int64_t value) const
ForNode(node->AsQmark()->ElseNode(), compiler));

case GT_CAST:
return ForCastOutput(node->AsCast());
return ForCastOutput(node->AsCast(), compiler);

#if defined(FEATURE_HW_INTRINSICS)
case GT_HWINTRINSIC:
Expand Down Expand Up @@ -369,12 +369,13 @@ bool IntegralRange::Contains(int64_t value) const
// Unlike ForCastInput, this method supports casts from floating point types.
//
// Arguments:
// cast - the cast node for which the range will be computed
// cast - the cast node for which the range will be computed
// compiler - Compiler object
//
// Return Value:
// The range this cast produces - see description.
//
/* static */ IntegralRange IntegralRange::ForCastOutput(GenTreeCast* cast)
/* static */ IntegralRange IntegralRange::ForCastOutput(GenTreeCast* cast, Compiler* compiler)
{
var_types fromType = genActualType(cast->CastOp());
var_types toType = cast->CastToType();
Expand Down Expand Up @@ -407,6 +408,13 @@ bool IntegralRange::Contains(int64_t value) const
return ForCastInput(cast);
}

// if we're upcasting and the cast op is a known non-negative - consider
// this cast unsigned
if (!fromUnsigned && (genTypeSize(toType) >= genTypeSize(fromType)))
{
fromUnsigned = cast->CastOp()->IsNeverNegative(compiler);
}

// CAST(uint/int <- ulong/long) - [INT_MIN..INT_MAX]
// CAST(ulong/long <- uint) - [0..UINT_MAX]
// CAST(ulong/long <- int) - [INT_MIN..INT_MAX]
Expand Down
2 changes: 1 addition & 1 deletion src/coreclr/jit/compiler.h
Original file line number Diff line number Diff line change
Expand Up @@ -1355,7 +1355,7 @@ class IntegralRange

static IntegralRange ForNode(GenTree* node, Compiler* compiler);
static IntegralRange ForCastInput(GenTreeCast* cast);
static IntegralRange ForCastOutput(GenTreeCast* cast);
static IntegralRange ForCastOutput(GenTreeCast* cast, Compiler* compiler);
static IntegralRange Union(IntegralRange range1, IntegralRange range2);

#ifdef DEBUG
Expand Down
15 changes: 15 additions & 0 deletions src/coreclr/jit/rangecheck.cpp
Original file line number Diff line number Diff line change
Expand Up @@ -325,6 +325,21 @@ void RangeCheck::OptimizeRangeCheck(BasicBlock* block, Statement* stmt, GenTree*
}
}

if (m_pCompiler->vnStore->GetVNFunc(idxVn, &funcApp) && (funcApp.m_func == (VNFunc)GT_UMOD))
{
// We can always omit bound checks for Arr[X u% Arr.Length] pattern (unsigned MOD).
//
// if arr.Length is 0 we technically should keep the bounds check, but since the expression
// has to throw DividedByZeroException anyway - no special handling needed.
EgorBo marked this conversation as resolved.
Show resolved Hide resolved
if (funcApp.m_args[1] == arrLenVn)
{
JITDUMP("[RangeCheck::OptimizeRangeCheck] UMOD(X, ARR_LEN) is always between bounds\n");
m_pCompiler->optRemoveRangeCheck(bndsChk, comma, stmt);
m_updateStmt = true;
return;
}
}

// Get the range for this index.
Range range = GetRange(block, treeIndex, false DEBUGARG(0));

Expand Down
Original file line number Diff line number Diff line change
Expand Up @@ -78,7 +78,7 @@ private bool Find(TKey key, bool add, bool set, [MaybeNullWhen(false)] ref TValu
{
int hashCode = GetKeyHashCode(key);

for (int i = buckets[hashCode % buckets.Length] - 1; i >= 0; i = slots[i].next)
for (int i = buckets[(uint)hashCode % buckets.Length] - 1; i >= 0; i = slots[i].next)
{
if (slots[i].hashCode == hashCode && AreKeysEqual(slots[i].key, key))
{
Expand Down
2 changes: 1 addition & 1 deletion src/libraries/System.Linq/src/System/Linq/Lookup.cs
Original file line number Diff line number Diff line change
Expand Up @@ -196,7 +196,7 @@ private int InternalGetHashCode(TKey key)
internal Grouping<TKey, TElement>? GetGrouping(TKey key, bool create)
{
int hashCode = InternalGetHashCode(key);
for (Grouping<TKey, TElement>? g = _groupings[hashCode % _groupings.Length]; g != null; g = g._hashNext)
for (Grouping<TKey, TElement>? g = _groupings[(uint)hashCode % _groupings.Length]; g != null; g = g._hashNext)
EgorBo marked this conversation as resolved.
Show resolved Hide resolved
{
if (g._hashCode == hashCode && _comparer.Equals(g._key, key))
{
Expand Down
Original file line number Diff line number Diff line change
Expand Up @@ -1322,7 +1322,7 @@ private ref int GetBucket(uint hashCode)
#if TARGET_64BIT
return ref buckets[HashHelpers.FastMod(hashCode, (uint)buckets.Length, _fastModMultiplier)];
#else
return ref buckets[hashCode % (uint)buckets.Length];
return ref buckets[(uint)hashCode % buckets.Length];
#endif
}

Expand Down
Original file line number Diff line number Diff line change
Expand Up @@ -508,7 +508,7 @@ internal TimerQueueTimer(TimerCallback timerCallback, object? state, uint dueTim
{
_executionContext = ExecutionContext.Capture();
}
_associatedTimerQueue = TimerQueue.Instances[Thread.GetCurrentProcessorId() % TimerQueue.Instances.Length];
_associatedTimerQueue = TimerQueue.Instances[(uint)Thread.GetCurrentProcessorId() % TimerQueue.Instances.Length];

// After the following statement, the timer may fire. No more manipulation of timer state outside of
// the lock is permitted beyond this point!
Expand Down
99 changes: 99 additions & 0 deletions src/tests/JIT/opt/RangeChecks/ModLength.cs
Original file line number Diff line number Diff line change
@@ -0,0 +1,99 @@
// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.

using System;
using System.Runtime.CompilerServices;

public class ModLength
{
public static int Main()
{
Throws<DivideByZeroException>(() => Test1(new int[0], 0));
Throws<DivideByZeroException>(() => Test2(new int[0], 1));
Throws<DivideByZeroException>(() => Test3(new int[0], int.MaxValue));
Throws<DivideByZeroException>(() => Test4(new int[0], 0));
Throws<DivideByZeroException>(() => Test5(new int[0], 0));
Throws<DivideByZeroException>(() => Test6(new int[0], 0));
Throws<DivideByZeroException>(() => Test7(new int[0], 0));
Throws<DivideByZeroException>(() => Test8(new int[0], 0));
Throws<DivideByZeroException>(() => Test9(new int[0], 0));
Test1(new int[1], 1);
Test2(new int[1], 1);
Throws<IndexOutOfRangeException>(() => Test9(new int[1], 2));
Test3(new int[1], int.MaxValue);
Throws<IndexOutOfRangeException>(() => Test4(new int[1], int.MinValue));
Test5(new int[1], -1);
Test6(new int[1], 1);
Test7(new int[1], 1);
Test8(new int[1], 1);
Test1(new int[10], 10);
Test2(new int[10], 11);
Test3(new int[10], int.MaxValue);
Throws<IndexOutOfRangeException>(() => Test4(new int[10], int.MinValue));
Throws<IndexOutOfRangeException>(() => Test5(new int[10], -1));
Test6(new int[10], 0);
Test7(new int[10], 0);
Throws<DivideByZeroException>(() => Test8(new int[10], 0));
return 100;
}

static void Throws<T>(Action action, [CallerLineNumber] int line = 0)
{
try
{
action();
}
catch (Exception e)
{
if (e is T)
{
return;
}
throw new InvalidOperationException($"{typeof(T)} exception was expected, actual: {e.GetType()}");
}
throw new InvalidOperationException($"{typeof(T)} exception was expected");
}

[MethodImpl(MethodImplOptions.NoInlining)]
static int Test1(int[] arr, int index) => arr[index % arr.Length];

[MethodImpl(MethodImplOptions.NoInlining)]
static int Test2(int[] arr, int index) => arr[(int)index % (int)arr.Length];

[MethodImpl(MethodImplOptions.NoInlining)]
static int Test3(int[] arr, int index) => arr[(int)((uint)index % (uint)arr.Length)];

[MethodImpl(MethodImplOptions.NoInlining)]
static int Test4(int[] arr, int index) => arr[arr.Length % index];

[MethodImpl(MethodImplOptions.NoInlining)]
static int Test5(int[] arr, int index)
{
var span = arr.AsSpan();
return arr[index % arr.Length];
}

[MethodImpl(MethodImplOptions.NoInlining)]
static int Test6(int[] arr, int index)
{
var span = arr.AsSpan();
return span[(int)index % (int)span.Length];
}

[MethodImpl(MethodImplOptions.NoInlining)]
static int Test7(int[] arr, int index)
{
var span = arr.AsSpan();
return span[(int)((uint)index % (uint)span.Length)];
}

[MethodImpl(MethodImplOptions.NoInlining)]
static int Test8(int[] arr, int index)
{
var span = arr.AsSpan();
return span[span.Length % index];
}

[MethodImpl(MethodImplOptions.NoInlining)]
static int Test9(int[] arr, int index) => arr[index / arr.Length];
}
9 changes: 9 additions & 0 deletions src/tests/JIT/opt/RangeChecks/ModLength.csproj
Original file line number Diff line number Diff line change
@@ -0,0 +1,9 @@
<Project Sdk="Microsoft.NET.Sdk">
<PropertyGroup>
<OutputType>Exe</OutputType>
<Optimize>True</Optimize>
</PropertyGroup>
<ItemGroup>
<Compile Include="$(MSBuildProjectName).cs" />
</ItemGroup>
</Project>