Marking code as unchecked (pt 2) (#15885)

Marking code that may intentionally lead to over or underflows with
unchecked in preparation of turning on CheckForOverflowUnderflow for
all projects (issue #3140)

25 files changed, 203 insertions, 128 deletions

diff --git a/src/Common/src/System/Numerics/Hashing/HashHelpers.cs b/src/Common/src/System/Numerics/Hashing/HashHelpers.cs
index 166c49fe02..841eb04d87 100644
--- a/src/Common/src/System/Numerics/Hashing/HashHelpers.cs
+++ b/src/Common/src/System/Numerics/Hashing/HashHelpers.cs
@@ -10,11 +10,13 @@ namespace System.Numerics.Hashing
 
         public static int Combine(int h1, int h2)
         {
-            // RyuJIT optimizes this to use the ROL instruction
-            // Related GitHub pull request: dotnet/coreclr#1830
-            uint rol5 = ((uint)h1 << 5) | ((uint)h1 >> 27);
-            return ((int)rol5 + h1) ^ h2;
+            unchecked
+            {
+                // RyuJIT optimizes this to use the ROL instruction
+                // Related GitHub pull request: dotnet/coreclr#1830
+                uint rol5 = ((uint)h1 << 5) | ((uint)h1 >> 27);
+                return ((int)rol5 + h1) ^ h2;
+            }
         }
     }
-}
-
+}
\ No newline at end of file
diff --git a/src/Microsoft.CSharp/src/Microsoft/CSharp/RuntimeBinder/Syntax/NameTable.cs b/src/Microsoft.CSharp/src/Microsoft/CSharp/RuntimeBinder/Syntax/NameTable.cs
index 0018816ba3..29e844062a 100644
--- a/src/Microsoft.CSharp/src/Microsoft/CSharp/RuntimeBinder/Syntax/NameTable.cs
+++ b/src/Microsoft.CSharp/src/Microsoft/CSharp/RuntimeBinder/Syntax/NameTable.cs
@@ -75,17 +75,22 @@ namespace Microsoft.CSharp.RuntimeBinder.Syntax
 
         private int ComputeHashCode(string key)
         {
-            int len = key.Length;
-            int hashCode = len + _hashCodeRandomizer;
-            // use key.Length to eliminate the range check
-            for (int i = 0; i < key.Length; i++)
+            int hashCode, len = key.Length;
+
+            unchecked
             {
-                hashCode += (hashCode << 7) ^ key[i];
+                hashCode = len + _hashCodeRandomizer;
+                // use key.Length to eliminate the range check
+                for (int i = 0; i < key.Length; i++)
+                {
+                    hashCode += (hashCode << 7) ^ key[i];
+                }
+                // mix it a bit more
+                hashCode -= hashCode >> 17;
+                hashCode -= hashCode >> 11;
+                hashCode -= hashCode >> 5;
             }
-            // mix it a bit more
-            hashCode -= hashCode >> 17;
-            hashCode -= hashCode >> 11;
-            hashCode -= hashCode >> 5;
+
             return hashCode;
         }
 
diff --git a/src/System.Collections/src/System/Collections/BitArray.cs b/src/System.Collections/src/System/Collections/BitArray.cs
index 819bf18a2d..75bc51996e 100644
--- a/src/System.Collections/src/System/Collections/BitArray.cs
+++ b/src/System.Collections/src/System/Collections/BitArray.cs
@@ -527,7 +527,7 @@ namespace System.Collections
                     Array.Copy(m_array, 0, intArray, index, GetArrayLength(m_length, BitsPerInt32) - 1);
 
                     // the last int needs to be masked
-                    intArray[index + last] = m_array[last] & ((1 << extraBits) - 1);
+                    intArray[index + last] = m_array[last] & unchecked((1 << extraBits) - 1);
                 }
             }
             else if (array is byte[])
diff --git a/src/System.Data.Common/src/System/Data/RbTree.cs b/src/System.Data.Common/src/System/Data/RbTree.cs
index dd7549911c..230f4c514e 100644
--- a/src/System.Data.Common/src/System/Data/RbTree.cs
+++ b/src/System.Data.Common/src/System/Data/RbTree.cs
@@ -1991,10 +1991,10 @@ namespace System.Data
                     segmentPos = _nextFreeSlotLine;
                     while (segmentPos < _slotMap.Length)
                     {
-                        if (((uint)_slotMap[segmentPos]) < 0xFFFFFFFF)
+                        if (unchecked((uint)_slotMap[segmentPos]) < 0xFFFFFFFF)
                         {
                             freeSlotId = 0;
-                            freeSlot = (~(_slotMap[segmentPos])) & (_slotMap[segmentPos] + 1);
+                            freeSlot = (~(_slotMap[segmentPos])) & unchecked(_slotMap[segmentPos] + 1);
 
                             // avoid string concat to allow debug code to run faster
                             Debug.Assert((_slotMap[segmentPos] & freeSlot) == 0, "Slot position segment[segmentPos ]: [freeSlot] is in use. Expected to be empty");
@@ -2006,7 +2006,7 @@ namespace System.Data
                             tree._inUseNodeCount++;
 
                             // convert freeSlotPos to int value giving number of 0's to its right i.e. freeSlotId
-                            freeSlotId = GetIntValueFromBitMap((uint)freeSlot);
+                            freeSlotId = GetIntValueFromBitMap(unchecked((uint)freeSlot));
 
                             _nextFreeSlotLine = segmentPos;
                             freeSlotId = (segmentPos * TreePage.slotLineSize) + freeSlotId;
diff --git a/src/System.Data.Common/src/System/Data/SQLTypes/SQLByte.cs b/src/System.Data.Common/src/System/Data/SQLTypes/SQLByte.cs
index bd0d1fe420..68fcdc33e7 100644
--- a/src/System.Data.Common/src/System/Data/SQLTypes/SQLByte.cs
+++ b/src/System.Data.Common/src/System/Data/SQLTypes/SQLByte.cs
@@ -84,7 +84,7 @@ namespace System.Data.SqlTypes
         // Unary operators
         public static SqlByte operator ~(SqlByte x)
         {
-            return x.IsNull ? Null : new SqlByte((byte)~x._value);
+            return x.IsNull ? Null : new SqlByte(unchecked((byte)~x._value));
         }
 
 
diff --git a/src/System.Data.Common/src/System/Data/SQLTypes/SQLDecimal.cs b/src/System.Data.Common/src/System/Data/SQLTypes/SQLDecimal.cs
index 1304d66db1..20f83d398e 100644
--- a/src/System.Data.Common/src/System/Data/SQLTypes/SQLDecimal.cs
+++ b/src/System.Data.Common/src/System/Data/SQLTypes/SQLDecimal.cs
@@ -488,12 +488,16 @@ namespace System.Data.SqlTypes
             // m_data2 = *pInt++; // mid part
 
             int[] bits = decimal.GetBits(value);
+            uint sgnscl;
 
-            uint sgnscl = (uint)bits[3];
-            _data1 = (uint)bits[0];
-            _data2 = (uint)bits[1];
-            _data3 = (uint)bits[2];
-            _data4 = s_uiZero;
+            unchecked
+            {
+                sgnscl = (uint)bits[3];
+                _data1 = (uint)bits[0];
+                _data2 = (uint)bits[1];
+                _data3 = (uint)bits[2];
+                _data4 = s_uiZero;
+            }
 
             // set the sign bit
             _bStatus |= ((sgnscl & 0x80000000) == 0x80000000) ? s_bNegative : (byte)0;
@@ -523,7 +527,7 @@ namespace System.Data.SqlTypes
             // set the null bit
             _bStatus = s_bNotNull;
 
-            uint uiValue = (uint)value;
+            uint uiValue = unchecked((uint)value);
 
             // set the sign bit
             if (value < 0)
@@ -548,7 +552,7 @@ namespace System.Data.SqlTypes
             // set the null bit
             _bStatus = s_bNotNull;
 
-            ulong dwl = (ulong)value;
+            ulong dwl = unchecked((ulong)value);
 
             // set the sign bit
             if (value < 0)
@@ -861,7 +865,11 @@ namespace System.Data.SqlTypes
             {
                 if (IsNull)
                     throw new SqlNullValueException();
-                return new int[4] { (int)_data1, (int)_data2, (int)_data3, (int)_data4 };
+
+                unchecked
+                {
+                    return new int[4] { (int)_data1, (int)_data2, (int)_data3, (int)_data4 };
+                }
             }
         }
 
@@ -1135,7 +1143,10 @@ namespace System.Data.SqlTypes
             if ((int)_data4 != 0 || _bScale > 28)
                 throw new OverflowException(SQLResource.s_conversionOverflowMessage);
 
-            return new decimal((int)_data1, (int)_data2, (int)_data3, !IsPositive, _bScale);
+            unchecked
+            {
+                return new decimal((int)_data1, (int)_data2, (int)_data3, !IsPositive, _bScale);
+            }
         }
 
         // Implicit conversion from Decimal to SqlDecimal
@@ -1272,7 +1283,7 @@ namespace System.Data.SqlTypes
                     if (iulData < culOp2)
                         dwlAccum += rglData2[iulData];
 
-                    rglData1[iulData] = (uint)dwlAccum; // equiv to mod x_lInt32Base
+                    rglData1[iulData] = unchecked((uint)dwlAccum); // equiv to mod x_lInt32Base
                     dwlAccum >>= 32; // equiv to div x_lInt32Base
                 }
 
@@ -1317,7 +1328,7 @@ namespace System.Data.SqlTypes
                     if (iulData < culOp2)
                         dwlAccum -= rglData2[iulData];
 
-                    rglData1[iulData] = (uint)dwlAccum; // equiv to mod BaseUI4
+                    rglData1[iulData] = unchecked((uint)dwlAccum); // equiv to mod BaseUI4
                     if (rglData1[iulData] != 0)
                         iulLastNonZero = iulData;
                     dwlAccum >>= 32; // equiv to /= BaseUI4
@@ -1474,7 +1485,7 @@ namespace System.Data.SqlTypes
                         dwlNextAccum = 0;
 
                     // Update result and accum
-                    rgulRes[idRes++] = (uint)(dwlAccum);// & x_ulInt32BaseForMod); // equiv to mod x_lInt32Base
+                    rgulRes[idRes++] = unchecked((uint)dwlAccum);// & x_ulInt32BaseForMod); // equiv to mod x_lInt32Base
                     dwlAccum = (dwlAccum >> 32) + dwlNextAccum; // equiv to div BaseUI4 + dwlNAccum
 
                     // dwlNextAccum can't overflow next iteration
@@ -2137,8 +2148,8 @@ namespace System.Data.SqlTypes
                     dwlNextAccum = s_ulInt32Base;   // how much to add to dwlAccum after div x_dwlBaseUI4
                 else
                     dwlNextAccum = 0;
-                rguiData[iData] = (uint)dwlAccum;           // equivalent to mod x_dwlBaseUI4
-                dwlAccum = (dwlAccum >> 32) + dwlNextAccum; // equivalent to div x_dwlBaseUI4
+                rguiData[iData] = unchecked((uint)dwlAccum); // equivalent to mod x_dwlBaseUI4
+                dwlAccum = (dwlAccum >> 32) + dwlNextAccum;  // equivalent to div x_dwlBaseUI4
             }
 
             // If any carry,
diff --git a/src/System.Data.Common/src/System/Data/SQLTypes/SQLInt16.cs b/src/System.Data.Common/src/System/Data/SQLTypes/SQLInt16.cs
index 813fc41232..780bc216f1 100644
--- a/src/System.Data.Common/src/System/Data/SQLTypes/SQLInt16.cs
+++ b/src/System.Data.Common/src/System/Data/SQLTypes/SQLInt16.cs
@@ -173,7 +173,7 @@ namespace System.Data.SqlTypes
 
         public static SqlInt16 operator |(SqlInt16 x, SqlInt16 y)
         {
-            return (x.IsNull || y.IsNull) ? Null : new SqlInt16((short)((ushort)x._value | (ushort)y._value));
+            return (x.IsNull || y.IsNull) ? Null : new SqlInt16(unchecked((short)((ushort)x._value | (ushort)y._value)));
         }
 
         public static SqlInt16 operator ^(SqlInt16 x, SqlInt16 y)
diff --git a/src/System.Data.Common/src/System/Data/SQLTypes/SQLMoney.cs b/src/System.Data.Common/src/System/Data/SQLTypes/SQLMoney.cs
index 60244ab530..0f28570582 100644
--- a/src/System.Data.Common/src/System/Data/SQLTypes/SQLMoney.cs
+++ b/src/System.Data.Common/src/System/Data/SQLTypes/SQLMoney.cs
@@ -137,7 +137,7 @@ namespace System.Data.SqlTypes
             if (_value < 0)
             {
                 fNegative = true;
-                value = -_value;
+                value = unchecked(-_value);
             }
 
             return new decimal(unchecked((int)value), unchecked((int)(value >> 32)), 0, fNegative, (byte)s_iMoneyScale);
diff --git a/src/System.Diagnostics.Process/src/System/Diagnostics/ProcessManager.Windows.cs b/src/System.Diagnostics.Process/src/System/Diagnostics/ProcessManager.Windows.cs
index f391fc505e..3a04511b18 100644
--- a/src/System.Diagnostics.Process/src/System/Diagnostics/ProcessManager.Windows.cs
+++ b/src/System.Diagnostics.Process/src/System/Diagnostics/ProcessManager.Windows.cs
@@ -904,13 +904,13 @@ namespace System.Diagnostics
                         bufferSize,
                         out requiredSize);
 
-                    if ((uint)status == Interop.NtDll.STATUS_INFO_LENGTH_MISMATCH)
+                    if (unchecked((uint)status) == Interop.NtDll.STATUS_INFO_LENGTH_MISMATCH)
                     {
                         if (bufferHandle.IsAllocated) bufferHandle.Free();
                         buffer = null;
                         bufferSize = GetNewBufferSize(bufferSize, requiredSize);
                     }
-                } while ((uint)status == Interop.NtDll.STATUS_INFO_LENGTH_MISMATCH);
+                } while (unchecked((uint)status) == Interop.NtDll.STATUS_INFO_LENGTH_MISMATCH);
 
                 if (status < 0)
                 { // see definition of NT_SUCCESS(Status) in SDK
diff --git a/src/System.Drawing.Primitives/src/System/Drawing/Point.cs b/src/System.Drawing.Primitives/src/System/Drawing/Point.cs
index eb1de2208d..28b5a84c95 100644
--- a/src/System.Drawing.Primitives/src/System/Drawing/Point.cs
+++ b/src/System.Drawing.Primitives/src/System/Drawing/Point.cs
@@ -134,32 +134,32 @@ namespace System.Drawing
         ///       Translates a <see cref='System.Drawing.Point'/> by a given <see cref='System.Drawing.Size'/> .
         ///    </para>
         /// </summary>        
-        public static Point Add(Point pt, Size sz) => new Point(pt.X + sz.Width, pt.Y + sz.Height);
+        public static Point Add(Point pt, Size sz) => new Point(unchecked(pt.X + sz.Width), unchecked(pt.Y + sz.Height));
 
         /// <summary>
         ///    <para>
         ///       Translates a <see cref='System.Drawing.Point'/> by the negative of a given <see cref='System.Drawing.Size'/> .
         ///    </para>
         /// </summary>        
-        public static Point Subtract(Point pt, Size sz) => new Point(pt.X - sz.Width, pt.Y - sz.Height);
+        public static Point Subtract(Point pt, Size sz) => new Point(unchecked(pt.X - sz.Width), unchecked(pt.Y - sz.Height));
 
         /// <summary>
         ///   Converts a PointF to a Point by performing a ceiling operation on
         ///   all the coordinates.
         /// </summary>
-        public static Point Ceiling(PointF value) => new Point((int)Math.Ceiling(value.X), (int)Math.Ceiling(value.Y));
+        public static Point Ceiling(PointF value) => new Point(unchecked((int)Math.Ceiling(value.X)), unchecked((int)Math.Ceiling(value.Y)));
 
         /// <summary>
         ///   Converts a PointF to a Point by performing a truncate operation on
         ///   all the coordinates.
         /// </summary>
-        public static Point Truncate(PointF value) => new Point((int)value.X, (int)value.Y);
+        public static Point Truncate(PointF value) => new Point(unchecked((int)value.X), unchecked((int)value.Y));
 
         /// <summary>
         ///   Converts a PointF to a Point by performing a round operation on
         ///   all the coordinates.
         /// </summary>
-        public static Point Round(PointF value) => new Point((int)Math.Round(value.X), (int)Math.Round(value.Y));
+        public static Point Round(PointF value) => new Point(unchecked((int)Math.Round(value.X)), unchecked((int)Math.Round(value.Y)));
 
         /// <summary>
         ///    <para>
@@ -183,8 +183,11 @@ namespace System.Drawing
         /// </summary>
         public void Offset(int dx, int dy)
         {
-            X += dx;
-            Y += dy;
+            unchecked
+            {
+                X += dx;
+                Y += dy;
+            }
         }
 
         /// <summary>
@@ -201,8 +204,8 @@ namespace System.Drawing
         /// </summary>
         public override string ToString() => "{X=" + X.ToString() + ",Y=" + Y.ToString() + "}";
 
-        private static short HighInt16(int n) => (short)((n >> 16) & 0xffff);
+        private static short HighInt16(int n) => unchecked((short)((n >> 16) & 0xffff));
 
-        private static short LowInt16(int n) => (short)(n & 0xffff);
+        private static short LowInt16(int n) => unchecked((short)(n & 0xffff));
     }
 }
diff --git a/src/System.Drawing.Primitives/src/System/Drawing/Rectangle.cs b/src/System.Drawing.Primitives/src/System/Drawing/Rectangle.cs
index 8b3327d748..296796e14c 100644
--- a/src/System.Drawing.Primitives/src/System/Drawing/Rectangle.cs
+++ b/src/System.Drawing.Primitives/src/System/Drawing/Rectangle.cs
@@ -55,7 +55,7 @@ namespace System.Drawing
         ///    the specified location and size.
         /// </summary>
         public static Rectangle FromLTRB(int left, int top, int right, int bottom) =>
-            new Rectangle(left, top, right - left, bottom - top);
+            new Rectangle(left, top, unchecked(right - left), unchecked(bottom - top));
 
         /// <summary>
         ///    <para>
@@ -148,7 +148,7 @@ namespace System.Drawing
         ///       rectangular region defined by this <see cref='System.Drawing.Rectangle'/>.
         ///    </para>
         /// </summary>
-        public int Right => X + Width;
+        public int Right => unchecked(X + Width);
 
         /// <summary>
         ///    <para>
@@ -156,7 +156,7 @@ namespace System.Drawing
         ///       rectangular region defined by this <see cref='System.Drawing.Rectangle'/>.
         ///    </para>
         /// </summary>
-        public int Bottom => Y + Height;
+        public int Bottom => unchecked(Y + Height);
 
         /// <summary>
         ///    <para>
@@ -197,34 +197,49 @@ namespace System.Drawing
         ///   Converts a RectangleF to a Rectangle by performing a ceiling operation on
         ///   all the coordinates.
         /// </summary>
-        public static Rectangle Ceiling(RectangleF value) =>
-            new Rectangle(
-                (int)Math.Ceiling(value.X),
-                (int)Math.Ceiling(value.Y),
-                (int)Math.Ceiling(value.Width),
-                (int)Math.Ceiling(value.Height));
+        public static Rectangle Ceiling(RectangleF value)
+        {
+            unchecked
+            {
+                return new Rectangle(
+                    (int)Math.Ceiling(value.X),
+                    (int)Math.Ceiling(value.Y),
+                    (int)Math.Ceiling(value.Width),
+                    (int)Math.Ceiling(value.Height));
+            }
+        }
 
         /// <summary>
         ///   Converts a RectangleF to a Rectangle by performing a truncate operation on
         ///   all the coordinates.
         /// </summary>
-        public static Rectangle Truncate(RectangleF value) =>
-            new Rectangle(
-                (int)value.X,
-                (int)value.Y,
-                (int)value.Width,
-                (int)value.Height);
+        public static Rectangle Truncate(RectangleF value)
+        {
+            unchecked
+            {
+                return new Rectangle(
+                    (int)value.X,
+                    (int)value.Y,
+                    (int)value.Width,
+                    (int)value.Height);
+            }
+        }
 
         /// <summary>
         ///   Converts a RectangleF to a Rectangle by performing a round operation on
         ///   all the coordinates.
         /// </summary>
-        public static Rectangle Round(RectangleF value) =>
-            new Rectangle(
-                (int)Math.Round(value.X),
-                (int)Math.Round(value.Y),
-                (int)Math.Round(value.Width),
-                (int)Math.Round(value.Height));
+        public static Rectangle Round(RectangleF value)
+        {
+            unchecked
+            {
+                return new Rectangle(
+                    (int)Math.Round(value.X),
+                    (int)Math.Round(value.Y),
+                    (int)Math.Round(value.Width),
+                    (int)Math.Round(value.Height));
+            }
+        }
 
         /// <summary>
         ///    <para>
@@ -267,10 +282,14 @@ namespace System.Drawing
         /// </summary>
         public void Inflate(int width, int height)
         {
-            X -= width;
-            Y -= height;
-            Width += 2 * width;
-            Height += 2 * height;
+            unchecked
+            {
+                X -= width;
+                Y -= height;
+
+                Width += 2 * width;
+                Height += 2 * height;
+            }
         }
 
         /// <summary>
@@ -359,8 +378,11 @@ namespace System.Drawing
         /// </summary>
         public void Offset(int x, int y)
         {
-            X += x;
-            Y += y;
+            unchecked
+            {
+                X += x;
+                Y += y;
+            }
         }
 
         /// <summary>
diff --git a/src/System.Drawing.Primitives/src/System/Drawing/Size.cs b/src/System.Drawing.Primitives/src/System/Drawing/Size.cs
index 22a8a0a5f4..267a801f11 100644
--- a/src/System.Drawing.Primitives/src/System/Drawing/Size.cs
+++ b/src/System.Drawing.Primitives/src/System/Drawing/Size.cs
@@ -132,32 +132,36 @@ namespace System.Drawing
         ///       Performs vector addition of two <see cref='System.Drawing.Size'/> objects.
         ///    </para>
         /// </summary>
-        public static Size Add(Size sz1, Size sz2) => new Size(sz1.Width + sz2.Width, sz1.Height + sz2.Height);
+        public static Size Add(Size sz1, Size sz2) =>
+            new Size(unchecked(sz1.Width + sz2.Width), unchecked(sz1.Height + sz2.Height));
 
         /// <summary>
         ///   Converts a SizeF to a Size by performing a ceiling operation on
         ///   all the coordinates.
         /// </summary>
-        public static Size Ceiling(SizeF value) => new Size((int)Math.Ceiling(value.Width), (int)Math.Ceiling(value.Height));
+        public static Size Ceiling(SizeF value) =>
+            new Size(unchecked((int)Math.Ceiling(value.Width)), unchecked((int)Math.Ceiling(value.Height)));
 
         /// <summary>
         ///    <para>
         ///       Contracts a <see cref='System.Drawing.Size'/> by another <see cref='System.Drawing.Size'/> .
         ///    </para>
         /// </summary>
-        public static Size Subtract(Size sz1, Size sz2) => new Size(sz1.Width - sz2.Width, sz1.Height - sz2.Height);
+        public static Size Subtract(Size sz1, Size sz2) =>
+            new Size(unchecked(sz1.Width - sz2.Width), unchecked(sz1.Height - sz2.Height));
 
         /// <summary>
         ///   Converts a SizeF to a Size by performing a truncate operation on
         ///   all the coordinates.
         /// </summary>
-        public static Size Truncate(SizeF value) => new Size((int)value.Width, (int)value.Height);
+        public static Size Truncate(SizeF value) => new Size(unchecked((int)value.Width), unchecked((int)value.Height));
 
         /// <summary>
         ///   Converts a SizeF to a Size by performing a round operation on
         ///   all the coordinates.
         /// </summary>
-        public static Size Round(SizeF value) => new Size((int)Math.Round(value.Width), (int)Math.Round(value.Height));
+        public static Size Round(SizeF value) =>
+            new Size(unchecked((int)Math.Round(value.Width)), unchecked((int)Math.Round(value.Height)));
 
         /// <summary>
         ///    <para>
diff --git a/src/System.Drawing.Primitives/tests/PointTests.cs b/src/System.Drawing.Primitives/tests/PointTests.cs
index 0f38a0ca64..520cd7c491 100644
--- a/src/System.Drawing.Primitives/tests/PointTests.cs
+++ b/src/System.Drawing.Primitives/tests/PointTests.cs
@@ -35,7 +35,7 @@ namespace System.Drawing.PrimitivesTests
         public void SingleIntConstructorTest(int x)
         {
             Point p1 = new Point(x);
-            Point p2 = new Point((short)(x & 0xFFFF), (short)((x >> 16) & 0xFFFF));
+            Point p2 = new Point(unchecked((short)(x & 0xFFFF)), unchecked((short)((x >> 16) & 0xFFFF)));
 
             Assert.Equal(p1, p2);
         }
@@ -98,11 +98,14 @@ namespace System.Drawing.PrimitivesTests
         [InlineData(0, 0)]
         public void ArithmeticTest(int x, int y)
         {
-            Point p = new Point(x, y);
+            Point addExpected, subExpected, p = new Point(x, y);
             Size s = new Size(y, x);
 
-            Point addExpected = new Point(x + y, y + x);
-            Point subExpected = new Point(x - y, y - x);
+            unchecked
+            {
+                addExpected = new Point(x + y, y + x);
+                subExpected = new Point(x - y, y - x);
+            }
 
             Assert.Equal(addExpected, p + s);
             Assert.Equal(subExpected, p - s);
@@ -118,9 +121,14 @@ namespace System.Drawing.PrimitivesTests
         public void PointFMathematicalTest(float x, float y)
         {
             PointF pf = new PointF(x, y);
-            Point pCeiling = new Point((int)Math.Ceiling(x), (int)Math.Ceiling(y));
-            Point pTruncate = new Point((int)x, (int)y);
-            Point pRound = new Point((int)Math.Round(x), (int)Math.Round(y));
+            Point pCeiling, pTruncate, pRound;
+
+            unchecked
+            {
+                pCeiling = new Point((int)Math.Ceiling(x), (int)Math.Ceiling(y));
+                pTruncate = new Point((int)x, (int)y);
+                pRound = new Point((int)Math.Round(x), (int)Math.Round(y));
+            }
 
             Assert.Equal(pCeiling, Point.Ceiling(pf));
             Assert.Equal(pRound, Point.Round(pf));
@@ -139,7 +147,7 @@ namespace System.Drawing.PrimitivesTests
 
             p1.Offset(p2);
 
-            Assert.Equal(p2.X + p2.Y, p1.X);
+            Assert.Equal(unchecked(p2.X + p2.Y), p1.X);
             Assert.Equal(p1.X, p1.Y);
 
             p2.Offset(x, y);
diff --git a/src/System.Drawing.Primitives/tests/RectangleTests.cs b/src/System.Drawing.Primitives/tests/RectangleTests.cs
index b5bf6a0805..c04cdab224 100644
--- a/src/System.Drawing.Primitives/tests/RectangleTests.cs
+++ b/src/System.Drawing.Primitives/tests/RectangleTests.cs
@@ -35,7 +35,7 @@ namespace System.Drawing.PrimitivesTest
         [InlineData(0, int.MinValue, 0, int.MaxValue)]
         public void FromLTRBTest(int left, int top, int right, int bottom)
         {
-            Rectangle rect1 = new Rectangle(left, top, right - left, bottom - top);
+            Rectangle rect1 = new Rectangle(left, top, unchecked(right - left), unchecked(bottom - top));
             Rectangle rect2 = Rectangle.FromLTRB(left, top, right, bottom);
 
             Assert.Equal(rect1, rect2);
@@ -77,8 +77,8 @@ namespace System.Drawing.PrimitivesTest
             Assert.Equal(height, rect.Height);
             Assert.Equal(x, rect.Left);
             Assert.Equal(y, rect.Top);
-            Assert.Equal(x + width, rect.Right);
-            Assert.Equal(y + height, rect.Bottom);
+            Assert.Equal(unchecked(x + width), rect.Right);
+            Assert.Equal(unchecked(y + height), rect.Bottom);
 
             Point p = new Point(width, height);
             Size s = new Size(x, y);
@@ -94,8 +94,8 @@ namespace System.Drawing.PrimitivesTest
             Assert.Equal(y, rect.Height);
             Assert.Equal(width, rect.Left);
             Assert.Equal(height, rect.Top);
-            Assert.Equal(x + width, rect.Right);
-            Assert.Equal(y + height, rect.Bottom);
+            Assert.Equal(unchecked(x + width), rect.Right);
+            Assert.Equal(unchecked(y + height), rect.Bottom);
         }
 
         [Theory]
@@ -168,11 +168,16 @@ namespace System.Drawing.PrimitivesTest
         public void RectangleFConversionTest(float x, float y, float width, float height)
         {
             RectangleF rect = new RectangleF(x, y, width, height);
-            Rectangle rCeiling = new Rectangle((int)Math.Ceiling(x), (int)Math.Ceiling(y),
-                (int)Math.Ceiling(width), (int)Math.Ceiling(height));
-            Rectangle rTruncate = new Rectangle((int)x, (int)y, (int)width, (int)height);
-            Rectangle rRound = new Rectangle((int)Math.Round(x), (int)Math.Round(y),
-                (int)Math.Round(width), (int)Math.Round(height));
+            Rectangle rCeiling, rTruncate, rRound;
+
+            unchecked
+            {
+                rCeiling = new Rectangle((int)Math.Ceiling(x), (int)Math.Ceiling(y),
+                    (int)Math.Ceiling(width), (int)Math.Ceiling(height));
+                rTruncate = new Rectangle((int)x, (int)y, (int)width, (int)height);
+                rRound = new Rectangle((int)Math.Round(x), (int)Math.Round(y),
+                    (int)Math.Round(width), (int)Math.Round(height));
+            }
 
             Assert.Equal(rCeiling, Rectangle.Ceiling(rect));
             Assert.Equal(rTruncate, Rectangle.Truncate(rect));
@@ -184,7 +189,7 @@ namespace System.Drawing.PrimitivesTest
         [InlineData(0, int.MinValue, int.MaxValue, 0)]
         public void ContainsTest(int x, int y, int width, int height)
         {
-            Rectangle rect = new Rectangle(2 * x - width, 2 * y - height, width, height);
+            Rectangle rect = new Rectangle(unchecked(2 * x - width), unchecked(2 * y - height), width, height);
             Point p = new Point(x, y);
             Rectangle r = new Rectangle(x, y, width / 2, height / 2);
 
@@ -199,8 +204,11 @@ namespace System.Drawing.PrimitivesTest
         [InlineData(0, int.MinValue, int.MaxValue, 0)]
         public void InflateTest(int x, int y, int width, int height)
         {
-            Rectangle rect = new Rectangle(x, y, width, height);
-            Rectangle inflatedRect = new Rectangle(x - width, y - height, width + 2 * width, height + 2 * height);
+            Rectangle inflatedRect, rect = new Rectangle(x, y, width, height);
+            unchecked
+            {
+                inflatedRect = new Rectangle(x - width, y - height, width + 2 * width, height + 2 * height);
+            }
 
             Assert.Equal(inflatedRect, Rectangle.Inflate(rect, width, height));
 
@@ -208,7 +216,10 @@ namespace System.Drawing.PrimitivesTest
             Assert.Equal(inflatedRect, rect);
 
             Size s = new Size(x, y);
-            inflatedRect = new Rectangle(rect.X - x, rect.Y - y, rect.Width + 2 * x, rect.Height + 2 * y);
+            unchecked
+            {
+                inflatedRect = new Rectangle(rect.X - x, rect.Y - y, rect.Width + 2 * x, rect.Height + 2 * y);
+            }
 
             rect.Inflate(s);
             Assert.Equal(inflatedRect, rect);
diff --git a/src/System.Drawing.Primitives/tests/SizeFTests.cs b/src/System.Drawing.Primitives/tests/SizeFTests.cs
index 4d5278b249..0caa768e26 100644
--- a/src/System.Drawing.Primitives/tests/SizeFTests.cs
+++ b/src/System.Drawing.Primitives/tests/SizeFTests.cs
@@ -130,7 +130,7 @@ namespace System.Drawing.PrimitivesTest
         {
             SizeF s1 = new SizeF(width, height);
             PointF p1 = (PointF)s1;
-            Size s2 = new Size((int)width, (int)height);
+            Size s2 = new Size(unchecked((int)width), unchecked((int)height));
 
             Assert.Equal(new PointF(width, height), p1);
             Assert.Equal(p1, s1.ToPointF());
diff --git a/src/System.Drawing.Primitives/tests/SizeTests.cs b/src/System.Drawing.Primitives/tests/SizeTests.cs
index 8eeefaf873..84460e1f2a 100644
--- a/src/System.Drawing.Primitives/tests/SizeTests.cs
+++ b/src/System.Drawing.Primitives/tests/SizeTests.cs
@@ -94,9 +94,13 @@ namespace System.Drawing.PrimitivesTests
         {
             Size sz1 = new Size(width, height);
             Size sz2 = new Size(height, width);
+            Size addExpected, subExpected;
 
-            Size addExpected = new Size(width + height, height + width);
-            Size subExpected = new Size(width - height, height - width);
+            unchecked
+            {
+                addExpected = new Size(width + height, height + width);
+                subExpected = new Size(width - height, height - width);
+            }
 
             Assert.Equal(addExpected, sz1 + sz2);
             Assert.Equal(subExpected, sz1 - sz2);
@@ -112,9 +116,14 @@ namespace System.Drawing.PrimitivesTests
         public void PointFMathematicalTest(float width, float height)
         {
             SizeF szF = new SizeF(width, height);
-            Size pCeiling = new Size((int)Math.Ceiling(width), (int)Math.Ceiling(height));
-            Size pTruncate = new Size((int)width, (int)height);
-            Size pRound = new Size((int)Math.Round(width), (int)Math.Round(height));
+            Size pCeiling, pTruncate, pRound;
+
+            unchecked
+            {
+                pCeiling = new Size((int)Math.Ceiling(width), (int)Math.Ceiling(height));
+                pTruncate = new Size((int)width, (int)height);
+                pRound = new Size((int)Math.Round(width), (int)Math.Round(height));
+            }
 
             Assert.Equal(pCeiling, Size.Ceiling(szF));
             Assert.Equal(pRound, Size.Round(szF));
@@ -129,7 +138,7 @@ namespace System.Drawing.PrimitivesTests
         public void EqualityTest(int width, int height)
         {
             Size p1 = new Size(width, height);
-            Size p2 = new Size(width - 1, height - 1);
+            Size p2 = new Size(unchecked(width - 1), unchecked(height - 1));
             Size p3 = new Size(width, height);
 
             Assert.True(p1 == p3);
diff --git a/src/System.IO.Compression/src/System/IO/Compression/Crc32Helper.cs b/src/System.IO.Compression/src/System/IO/Compression/Crc32Helper.cs
index 47fdac1b38..0e0ca4bcb3 100644
--- a/src/System.IO.Compression/src/System/IO/Compression/Crc32Helper.cs
+++ b/src/System.IO.Compression/src/System/IO/Compression/Crc32Helper.cs
@@ -493,7 +493,7 @@ namespace System.IO.Compression
 
             for (int i = 0; i < runningLength / 8; i++)
             {
-                crc32 ^= (uint)(buffer[offset] | buffer[offset + 1] << 8 | buffer[offset + 2] << 16 | buffer[offset + 3] << 24);
+                crc32 ^= unchecked((uint)(buffer[offset] | buffer[offset + 1] << 8 | buffer[offset + 2] << 16 | buffer[offset + 3] << 24));
                 offset += 4;
                 term1 = s_crcTable_7[crc32 & 0x000000FF] ^
                         s_crcTable_6[(crc32 >> 8) & 0x000000FF];
@@ -503,7 +503,7 @@ namespace System.IO.Compression
                         s_crcTable_4[(term2 >> 8) & 0x000000FF];
 
 
-                term3 = (uint)(buffer[offset] | buffer[offset + 1] << 8 | buffer[offset + 2] << 16 | buffer[offset + 3] << 24);
+                term3 = unchecked((uint)(buffer[offset] | buffer[offset + 1] << 8 | buffer[offset + 2] << 16 | buffer[offset + 3] << 24));
                 offset += 4;
                 term1 = s_crcTable_3[term3 & 0x000000FF] ^
                         s_crcTable_2[(term3 >> 8) & 0x000000FF];
diff --git a/src/System.IO.MemoryMappedFiles/tests/MemoryMappedFile.CrossProcess.cs b/src/System.IO.MemoryMappedFiles/tests/MemoryMappedFile.CrossProcess.cs
index db8e827b2d..447057c259 100644
--- a/src/System.IO.MemoryMappedFiles/tests/MemoryMappedFile.CrossProcess.cs
+++ b/src/System.IO.MemoryMappedFiles/tests/MemoryMappedFile.CrossProcess.cs
@@ -22,7 +22,7 @@ namespace System.IO.MemoryMappedFiles.Tests
                 long capacity = acc.Capacity;
                 for (int i = 0; i < capacity; i++)
                 {
-                    acc.Write(i, (byte)i);
+                    acc.Write(i, unchecked((byte)i));
                 }
                 acc.Flush();
 
diff --git a/src/System.Linq.Expressions/src/System/Linq/Expressions/Compiler/ILGen.cs b/src/System.Linq.Expressions/src/System/Linq/Expressions/Compiler/ILGen.cs
index feb6aaf475..effbd8f1eb 100644
--- a/src/System.Linq.Expressions/src/System/Linq/Expressions/Compiler/ILGen.cs
+++ b/src/System.Linq.Expressions/src/System/Linq/Expressions/Compiler/ILGen.cs
@@ -431,7 +431,7 @@ namespace System.Linq.Expressions.Compiler
 
         internal static void EmitUInt(this ILGenerator il, uint value)
         {
-            il.EmitInt((int)value);
+            il.EmitInt(unchecked((int)value));
             il.Emit(OpCodes.Conv_U4);
         }
 
@@ -450,7 +450,7 @@ namespace System.Linq.Expressions.Compiler
 
         internal static void EmitULong(this ILGenerator il, ulong value)
         {
-            il.Emit(OpCodes.Ldc_I8, (long)value);
+            il.Emit(OpCodes.Ldc_I8, unchecked((long)value));
             il.Emit(OpCodes.Conv_U8);
         }
 
@@ -1127,7 +1127,7 @@ namespace System.Linq.Expressions.Compiler
             il.EmitInt(bits[1]);
             il.EmitInt(bits[2]);
             il.EmitBoolean((bits[3] & 0x80000000) != 0);
-            il.EmitByte((byte)(bits[3] >> 16));
+            il.EmitByte(unchecked((byte)(bits[3] >> 16)));
             il.EmitNew(Decimal_Ctor_Int32_Int32_Int32_Bool_Byte);
         }
 
diff --git a/src/System.Linq.Expressions/src/System/Linq/Expressions/Interpreter/DivInstruction.cs b/src/System.Linq.Expressions/src/System/Linq/Expressions/Interpreter/DivInstruction.cs
index 3aaaaaba79..f90587910f 100644
--- a/src/System.Linq.Expressions/src/System/Linq/Expressions/Interpreter/DivInstruction.cs
+++ b/src/System.Linq.Expressions/src/System/Linq/Expressions/Interpreter/DivInstruction.cs
@@ -30,7 +30,7 @@ namespace System.Linq.Expressions.Interpreter
                 }
                 else
                 {
-                    frame.Data[frame.StackIndex - 2] = (short)((short)l / (short)r);
+                    frame.Data[frame.StackIndex - 2] = unchecked((short)((short)l / (short)r));
                 }
                 frame.StackIndex--;
                 return 1;
diff --git a/src/System.Linq.Expressions/src/System/Linq/Expressions/Interpreter/LeftShiftInstruction.cs b/src/System.Linq.Expressions/src/System/Linq/Expressions/Interpreter/LeftShiftInstruction.cs
index 24b4c25196..96d9451869 100644
--- a/src/System.Linq.Expressions/src/System/Linq/Expressions/Interpreter/LeftShiftInstruction.cs
+++ b/src/System.Linq.Expressions/src/System/Linq/Expressions/Interpreter/LeftShiftInstruction.cs
@@ -29,7 +29,7 @@ namespace System.Linq.Expressions.Interpreter
                 }
                 else
                 {
-                    frame.Push((sbyte)((sbyte)value << (int)shift));
+                    frame.Push(unchecked((sbyte)((sbyte)value << (int)shift)));
                 }
                 return 1;
             }
@@ -47,7 +47,7 @@ namespace System.Linq.Expressions.Interpreter
                 }
                 else
                 {
-                    frame.Push((short)((short)value << (int)shift));
+                    frame.Push(unchecked((short)((short)value << (int)shift)));
                 }
                 return 1;
             }
@@ -101,7 +101,7 @@ namespace System.Linq.Expressions.Interpreter
                 }
                 else
                 {
-                    frame.Push((byte)((byte)value << (int)shift));
+                    frame.Push(unchecked((byte)((byte)value << (int)shift)));
                 }
                 return 1;
             }
@@ -119,7 +119,7 @@ namespace System.Linq.Expressions.Interpreter
                 }
                 else
                 {
-                    frame.Push((ushort)((ushort)value << (int)shift));
+                    frame.Push(unchecked((ushort)((ushort)value << (int)shift)));
                 }
                 return 1;
             }
diff --git a/src/System.Linq.Expressions/src/System/Linq/Expressions/Interpreter/NotInstruction.cs b/src/System.Linq.Expressions/src/System/Linq/Expressions/Interpreter/NotInstruction.cs
index e2fc2037d6..cd61d79e88 100644
--- a/src/System.Linq.Expressions/src/System/Linq/Expressions/Interpreter/NotInstruction.cs
+++ b/src/System.Linq.Expressions/src/System/Linq/Expressions/Interpreter/NotInstruction.cs
@@ -129,7 +129,7 @@ namespace System.Linq.Expressions.Interpreter
                 }
                 else
                 {
-                    frame.Push((ushort)(~(ushort)value));
+                    frame.Push(unchecked((ushort)(~(ushort)value)));
                 }
                 return 1;
             }
@@ -146,7 +146,7 @@ namespace System.Linq.Expressions.Interpreter
                 }
                 else
                 {
-                    frame.Push((byte)(~(byte)value));
+                    frame.Push(unchecked((byte)(~(byte)value)));
                 }
                 return 1;
             }
diff --git a/src/System.Private.Uri/src/System/Uri.cs b/src/System.Private.Uri/src/System/Uri.cs
index d59e26bffc..d4015681b3 100644
--- a/src/System.Private.Uri/src/System/Uri.cs
+++ b/src/System.Private.Uri/src/System/Uri.cs
@@ -2690,9 +2690,9 @@ namespace System
         private string GetEscapedParts(UriComponents uriParts)
         {
             // Which Uri parts are not escaped canonically ?
-            // Notice that public UriPart and private Flags must me in Sync so below code can work
+            // Notice that public UriPart and private Flags must be in Sync so below code can work
             //
-            ushort nonCanonical = (ushort)(((ushort)_flags & ((ushort)Flags.CannotDisplayCanonical << 7)) >> 6);
+            ushort nonCanonical = unchecked((ushort)(((ushort)_flags & ((ushort)Flags.CannotDisplayCanonical << 7)) >> 6));
             if (InFact(Flags.SchemeNotCanonical))
             {
                 nonCanonical |= (ushort)Flags.SchemeNotCanonical;
@@ -2712,7 +2712,7 @@ namespace System
                 }
             }
 
-            if (((ushort)uriParts & nonCanonical) == 0)
+            if ((unchecked((ushort)uriParts) & nonCanonical) == 0)
             {
                 string ret = GetUriPartsFromUserString(uriParts);
                 if ((object)ret != null)
@@ -2745,7 +2745,7 @@ namespace System
                 }
             }
 
-            if (((ushort)uriParts & nonCanonical) == 0)
+            if ((unchecked((ushort)uriParts) & nonCanonical) == 0)
             {
                 string ret = GetUriPartsFromUserString(uriParts);
                 if ((object)ret != null)
diff --git a/src/System.Private.Xml/src/System/Xml/Schema/XsdDateTime.cs b/src/System.Private.Xml/src/System/Xml/Schema/XsdDateTime.cs
index 2ccb65ea7c..b87cd3b2b2 100644
--- a/src/System.Private.Xml/src/System/Xml/Schema/XsdDateTime.cs
+++ b/src/System.Private.Xml/src/System/Xml/Schema/XsdDateTime.cs
@@ -987,7 +987,7 @@ namespace System.Xml.Schema
                         while (++start < _length)
                         {
                             int d = _text[start] - '0';
-                            if (9u < (uint)d)
+                            if (9u < unchecked((uint)d))
                             { // d < 0 || 9 < d
                                 break;
                             }
diff --git a/src/System.Runtime.Extensions/src/System/BitConverter.cs b/src/System.Runtime.Extensions/src/System/BitConverter.cs
index 8b03ffe081..9dd8a4135a 100644
--- a/src/System.Runtime.Extensions/src/System/BitConverter.cs
+++ b/src/System.Runtime.Extensions/src/System/BitConverter.cs
@@ -236,13 +236,13 @@ namespace System
                 {
                     int i1 = (*pbyte) | (*(pbyte + 1) << 8) | (*(pbyte + 2) << 16) | (*(pbyte + 3) << 24);
                     int i2 = (*(pbyte + 4)) | (*(pbyte + 5) << 8) | (*(pbyte + 6) << 16) | (*(pbyte + 7) << 24);
-                    return (uint)i1 | ((long)i2 << 32);
+                    return unchecked((uint)i1) | ((long)i2 << 32);
                 }
                 else
                 {
                     int i1 = (*pbyte << 24) | (*(pbyte + 1) << 16) | (*(pbyte + 2) << 8) | (*(pbyte + 3));
                     int i2 = (*(pbyte + 4) << 24) | (*(pbyte + 5) << 16) | (*(pbyte + 6) << 8) | (*(pbyte + 7));
-                    return (uint)i2 | ((long)i1 << 32);
+                    return unchecked((uint)i2) | ((long)i1 << 32);
                 }
             }
         }