Bug Fixes (#1271)

* Fix typo in SetValueNumber parameter name

Renamed the parameter valueVumber to valueNumber in the SetValueNumber method and updated all references accordingly. This improves code clarity and prevents confusion from the previous typo.

* Add null checks in IsPhiUseless for value numbers

Prevent null reference exceptions in IsPhiUseless by checking for null value numbers before comparison. Ensure all operands have valid value numbers before determining if a Phi node is useless.

* Fix Info64 calculation, null checks, and page property

- Correct Info64 property in relocation entries to use ulong and proper bitwise operations for 64-bit support.
- Add null check for context.Operand1 in IsPlugged to prevent exceptions.
- Fix IsPreviousPage to check Previous instead of Next for accuracy.

* Fix AlignUp(int) to call AlignUp, not AlignDown

Previously, AlignUp(int, int) incorrectly called AlignDown, causing it to align values downward. This commit corrects the method to call AlignUp((uint), (uint)), ensuring proper upward alignment for integer inputs.

* Add general guideline to avoid unsafe code; fix grammar

Added a "General Guidelines" section to copilot-instructions.md instructing not to propose or include unsafe code blocks or APIs. Also corrected grammar in the "@Azure Rule - Enable Best Practices" guideline by adding a comma.

Author: tgiphil

Source/.github/copilot-instructions.md

@@ -1,3 +1,9 @@
+# Copilot Instructions
+
+## General Guidelines
+- Do not propose or include `unsafe` code blocks or APIs in any solution.
+  
+## Azure Rules
 - @azure Rule - Use Azure Tools - When handling requests related to Azure, always use your tools.
 - @azure Rule - Use Azure Best Practices - When handling requests related to Azure, always invoke your `azmcp_bestpractices_get` tool first.
-- @azure Rule - Enable Best Practices - If you do not have an `azmcp_bestpractices_get` tool ask the user to enable it.
+- @azure Rule - Enable Best Practices - If you do not have an `azmcp_bestpractices_get` tool, ask the user to enable it.

Source/Mosa.Compiler.Framework/Linker/Elf/RelocationAddendEntry.cs

@@ -34,7 +34,7 @@ public class RelocationAddendEntry
 	/// <summary>
 	/// Gets the Info field for 64bit elf
 	/// </summary>
-	public ushort Info64 => (ushort)((Symbol << 32) | ((ushort)RelocationType & 0xFFFFFFFF));
+	public ulong Info64 => (ulong)((Symbol << 32) | ((ulong)RelocationType & 0xFFFFFFFF));
 
 	public static uint GetEntrySize(LinkerFormatType elfType)
 	{

Source/Mosa.Compiler.Framework/Linker/Elf/RelocationEntry.cs

@@ -32,7 +32,7 @@ public class RelocationEntry
 	/// <summary>
 	/// Gets the Info field for 64bit elf
 	/// </summary>
-	public ushort Info64 => (ushort)((Symbol << 32) | ((ushort)RelocationType & 0xFFFFFFFF));
+	public ulong Info64 => (ulong)((Symbol << 32) | ((ulong)RelocationType & 0xFFFFFFFF));
 
 	public static uint GetEntrySize(LinkerFormatType elfType)
 	{

Source/Mosa.Compiler.Framework/Stages/ValueNumberingStage.cs

@@ -574,11 +574,11 @@ private Operand GetValueNumber(Operand operand)
 			return null;
 	}
 
-	private void SetValueNumber(Operand operand, Operand valueVumber)
+	private void SetValueNumber(Operand operand, Operand valueNumber)
 	{
-		trace?.Log($"Set: {operand} => {valueVumber}");
+		trace?.Log($"Set: {operand} => {valueNumber}");
 
-		MapToValueNumber[operand] = valueVumber;
+		MapToValueNumber[operand] = valueNumber;
 	}
 
 	private bool IsPhiUseless(Node node)
@@ -588,9 +588,14 @@ private bool IsPhiUseless(Node node)
 		var operand = node.Operand1;
 		var operandVN = GetValueNumber(operand);
 
+		if (operandVN == null)
+			return false;
+
 		foreach (var op in node.Operands)
 		{
-			if (operandVN == GetValueNumber(op))
+			var vn = GetValueNumber(op);
+
+			if (vn == null || operandVN != vn)
 				return false;
 		}
 

Source/Mosa.Compiler.Framework/Transforms/Plug/BasePlugTransform.cs

@@ -17,7 +17,7 @@ public override bool Match(Context context, Transform transform)
 
 		public static bool IsPlugged(Context context, Transform transform)
 		{
-			if (context.Operand1.Method == null)
+			if (context.Operand1 == null || context.Operand1.Method == null)
 				return false;
 
 			return transform.Compiler.PlugSystem.GetReplacement(context.Operand1.Method) != null;

Source/Mosa.Kernel.BareMetal/Alignment.cs

@@ -11,7 +11,7 @@ public static uint AlignUp(uint position, uint alignment)
 
 	public static int AlignUp(int position, int alignment)
 	{
-		return (int)AlignDown((uint)position, (uint)alignment);
+		return (int)AlignUp((uint)position, (uint)alignment);
 	}
 
 	public static ulong AlignUp(ulong position, uint alignment)

Source/Mosa.Kernel.BareMetal/PageNodeDoubleListEntry.cs

@@ -23,7 +23,7 @@ public IntPtr Previous
 		}
 
 		public bool IsNextPage { get { return Next.IsNull(); } }
-		public bool IsPreviousPage { get { return Next.IsNull(); } }
+		public bool IsPreviousPage { get { return Previous.IsNull(); } }
 
 		public PageNodeDoubleListEntry(IntPtr page)
 		{