Compiler: Use exported names for functions, or at least better names

This change makes the compiler use a function's first exported name (if
any), or a name like `WasmFunction_N` where N is the function's index.
This helps in diagnosing issues in compilation, compared to the prior
code where function names were always new, random UUIDs.

Author: paulirwin

Diff for: WasmNet.Core/ILGeneration/MonoCecilCompilationAssembly.cs

@@ -33,7 +33,7 @@ public MonoCecilCompilationAssembly()
         {
             var typeDefinition = new TypeDefinition(
                 @namespace: assemblyName, 
-                name: $"Wasm{compilationType}Holder_{Id:N}", 
+                name: compilationType == CompilationType.Data ? "Data" : $"{compilationType}s", 
                 attributes: StaticClass,
                 baseType: objectType);
 

Diff for: WasmNet.Core/ILGeneration/ReflectionEmitCompilationAssembly.cs

@@ -28,10 +28,10 @@ public ReflectionEmitCompilationAssembly()
             $"WasmModule_{Id:N}"
         );
 
-        _compilations[CompilationType.Function] = new(Module.DefineType($"WasmFunctionHolder_{Id:N}", StaticClass));
-        _compilations[CompilationType.Global] = new(Module.DefineType($"WasmGlobalHolder_{Id:N}", StaticClass));
-        _compilations[CompilationType.Data] = new(Module.DefineType($"WasmDataHolder_{Id:N}", StaticClass));
-        _compilations[CompilationType.Element] = new(Module.DefineType($"WasmElementHolder_{Id:N}", StaticClass));
+        foreach (var compilationType in Enum.GetValues<CompilationType>())
+        {
+            _compilations[compilationType] = new(Module.DefineType(compilationType == CompilationType.Data ? "Data" : $"{compilationType}s", StaticClass));    
+        }
     }
 
     public Guid Id { get; } = Guid.NewGuid();

Diff for: WasmNet.Core/WasmFunctionInstance.cs

@@ -1,6 +1,6 @@
 namespace WasmNet.Core;
 
-public class WasmFunctionInstance(WasmType type, ModuleInstance module, WasmCode code) 
+public class WasmFunctionInstance(int index, WasmType type, ModuleInstance module, WasmCode code) 
     : IFunctionInstance
 {
     public WasmType Type { get; } = type;
@@ -9,7 +9,11 @@ public class WasmFunctionInstance(WasmType type, ModuleInstance module, WasmCode
 
     public WasmCode Code { get; } = code;
 
-    public string EmitName { get; } = $"WasmFunction_{Guid.NewGuid():N}";
+    public string EmitName { get; } = $"WasmFunction_{index}";
+    
+    public string Name => module.Module.ExportSection?.Exports
+        .FirstOrDefault(x => x.Index == index)
+        ?.Name ?? EmitName;
 
     public Type ReturnType =>
         Type.Results.Count == 0
@@ -20,7 +24,7 @@ public class WasmFunctionInstance(WasmType type, ModuleInstance module, WasmCode
 
     public object? Invoke(params object?[]? args)
     {
-        var method = Module.CompilationAssembly.GetCompiledMethod(CompilationType.Function, EmitName);
+        var method = Module.CompilationAssembly.GetCompiledMethod(CompilationType.Function, Name);
 
         var argsWithModule = new[] { Module }
             .Concat(args ?? Array.Empty<object?>())

Diff for: WasmNet.Core/WasmRuntime.cs

@@ -465,14 +465,16 @@ private void DeclareModuleFunctions(WasmModule module, ModuleInstance moduleInst
             var type = typeSection.Types[(int)func.FunctionSignatureIndex];
             var code = codeSection.Codes[i];
 
-            var funcInstance = new WasmFunctionInstance(type, moduleInstance, code);
+            var funcInstance = new WasmFunctionInstance(i, type, moduleInstance, code);
 
             var funcAddr = Store.AddFunction(funcInstance);
 
             moduleInstance.AddFunctionAddress(funcAddr);
+            
+            var funcExport = module.ExportSection?.Exports.FirstOrDefault(f => f.Index == i);
 
             moduleInstance.CompilationAssembly.DeclareMethod(CompilationType.Function, 
-                funcInstance.EmitName, 
+                funcExport?.Name ?? funcInstance.EmitName, 
                 funcInstance.ReturnType, 
                 funcInstance.ParameterTypes);
         }
@@ -487,7 +489,7 @@ private void CompileFunctionBodies(ModuleInstance moduleInstance)
             if (func is WasmFunctionInstance wasmFunc)
             {
                 moduleInstance.CompilationAssembly.CompileDeclaredMethod(moduleInstance, 
-                    wasmFunc.EmitName, 
+                    wasmFunc.Name, 
                     wasmFunc.Type, 
                     wasmFunc.Code);
             }