//
// codegen.cs: The code generator
//
// Author:
// Miguel de Icaza (miguel@ximian.com)
//
// (C) 2001 Ximian, Inc.
//
using System;
using System.IO;
using System.Collections;
using System.Reflection;
using System.Reflection.Emit;
namespace Mono.CSharp {
///
/// Code generator class.
///
public class CodeGen {
static AppDomain current_domain;
public static AssemblyBuilder AssemblyBuilder;
public static ModuleBuilder ModuleBuilder;
static public SymbolWriter SymbolWriter;
public static string Basename (string name)
{
int pos = name.LastIndexOf ("/");
if (pos != -1)
return name.Substring (pos + 1);
pos = name.LastIndexOf ("\\");
if (pos != -1)
return name.Substring (pos + 1);
return name;
}
public static string Dirname (string name)
{
int pos = name.LastIndexOf ("/");
if (pos != -1)
return name.Substring (0, pos);
pos = name.LastIndexOf ("\\");
if (pos != -1)
return name.Substring (0, pos);
return ".";
}
static string TrimExt (string name)
{
int pos = name.LastIndexOf (".");
return name.Substring (0, pos);
}
static public string FileName;
//
// Initializes the symbol writer
//
static void InitializeSymbolWriter ()
{
SymbolWriter = SymbolWriter.GetSymbolWriter (ModuleBuilder);
//
// If we got an ISymbolWriter instance, initialize it.
//
if (SymbolWriter == null) {
Report.Warning (
-18, "Could not find the symbol writer assembly (Mono.CSharp.Debugger.dll). This is normally an installation problem. Please make sure to compile and install the mcs/class/Mono.CSharp.Debugger directory.");
return;
}
}
//
// Initializes the code generator variables
//
static public void Init (string name, string output, bool want_debugging_support)
{
AssemblyName an;
FileName = output;
an = new AssemblyName ();
an.Name = Path.GetFileNameWithoutExtension (name);
current_domain = AppDomain.CurrentDomain;
AssemblyBuilder = current_domain.DefineDynamicAssembly (
an, AssemblyBuilderAccess.RunAndSave, Dirname (name));
//
// Pass a path-less name to DefineDynamicModule. Wonder how
// this copes with output in different directories then.
// FIXME: figure out how this copes with --output /tmp/blah
//
// If the third argument is true, the ModuleBuilder will dynamically
// load the default symbol writer.
//
ModuleBuilder = AssemblyBuilder.DefineDynamicModule (
Basename (name), Basename (output), want_debugging_support);
if (want_debugging_support)
InitializeSymbolWriter ();
}
static public void Save (string name)
{
try {
AssemblyBuilder.Save (Basename (name));
} catch (System.IO.IOException io){
Report.Error (16, "Could not write to file `"+name+"', cause: " + io.Message);
}
}
}
//
// Provides "local" store across code that can yield: locals
// or fields, notice that this should not be used by anonymous
// methods to create local storage, those only require
// variable mapping.
//
public class VariableStorage {
ILGenerator ig;
FieldBuilder fb;
LocalBuilder local;
static int count;
public VariableStorage (EmitContext ec, Type t)
{
count++;
if (ec.InIterator)
fb = IteratorHandler.Current.MapVariable ("s_", count.ToString (), t);
else
local = ec.ig.DeclareLocal (t);
ig = ec.ig;
}
public void EmitThis ()
{
if (fb != null)
ig.Emit (OpCodes.Ldarg_0);
}
public void EmitStore ()
{
if (fb == null)
ig.Emit (OpCodes.Stloc, local);
else
ig.Emit (OpCodes.Stfld, fb);
}
public void EmitLoad ()
{
if (fb == null)
ig.Emit (OpCodes.Ldloc, local);
else
ig.Emit (OpCodes.Ldfld, fb);
}
}
///
/// An Emit Context is created for each body of code (from methods,
/// properties bodies, indexer bodies or constructor bodies)
///
public class EmitContext {
public DeclSpace DeclSpace;
public DeclSpace TypeContainer;
public ILGenerator ig;
///
/// This variable tracks the `checked' state of the compilation,
/// it controls whether we should generate code that does overflow
/// checking, or if we generate code that ignores overflows.
///
/// The default setting comes from the command line option to generate
/// checked or unchecked code plus any source code changes using the
/// checked/unchecked statements or expressions. Contrast this with
/// the ConstantCheckState flag.
///
public bool CheckState;
///
/// The constant check state is always set to `true' and cant be changed
/// from the command line. The source code can change this setting with
/// the `checked' and `unchecked' statements and expressions.
///
public bool ConstantCheckState;
///
/// Whether we are emitting code inside a static or instance method
///
public bool IsStatic;
///
/// Whether we are emitting a field initializer
///
public bool IsFieldInitializer;
///
/// The value that is allowed to be returned or NULL if there is no
/// return type.
///
public Type ReturnType;
///
/// Points to the Type (extracted from the TypeContainer) that
/// declares this body of code
///
public Type ContainerType;
///
/// Whether this is generating code for a constructor
///
public bool IsConstructor;
///
/// Whether we're control flow analysis enabled
///
public bool DoFlowAnalysis;
///
/// Keeps track of the Type to LocalBuilder temporary storage created
/// to store structures (used to compute the address of the structure
/// value on structure method invocations)
///
public Hashtable temporary_storage;
public Block CurrentBlock;
public int CurrentFile;
///
/// The location where we store the return value.
///
LocalBuilder return_value;
///
/// The location where return has to jump to return the
/// value
///
public Label ReturnLabel;
///
/// If we already defined the ReturnLabel
///
public bool HasReturnLabel;
///
/// Whether we are in a Finally block
///
public bool InFinally;
///
/// Whether we are in a Try block
///
public bool InTry;
///
/// Whether we are inside an iterator block.
///
public bool InIterator;
///
/// Whether we need an explicit return statement at the end of the method.
///
public bool NeedExplicitReturn;
///
/// Whether remapping of locals, parameters and fields is turned on.
/// Used by iterators and anonymous methods.
///
public bool RemapToProxy;
///
/// Whether we are in a Catch block
///
public bool InCatch;
///
/// Whether we are inside an unsafe block
///
public bool InUnsafe;
///
/// Whether we are in a `fixed' initialization
///
public bool InFixedInitializer;
///
/// Whether we are inside an anonymous method.
///
public bool InAnonymousMethod;
///
/// Location for this EmitContext
///
public Location loc;
///
/// Used to flag that it is ok to define types recursively, as the
/// expressions are being evaluated as part of the type lookup
/// during the type resolution process
///
public bool ResolvingTypeTree;
///
/// Inside an enum definition, we do not resolve enumeration values
/// to their enumerations, but rather to the underlying type/value
/// This is so EnumVal + EnumValB can be evaluated.
///
/// There is no "E operator + (E x, E y)", so during an enum evaluation
/// we relax the rules
///
public bool InEnumContext;
protected Stack FlowStack;
public EmitContext (DeclSpace parent, DeclSpace ds, Location l, ILGenerator ig,
Type return_type, int code_flags, bool is_constructor)
{
this.ig = ig;
TypeContainer = parent;
DeclSpace = ds;
CheckState = RootContext.Checked;
ConstantCheckState = true;
IsStatic = (code_flags & Modifiers.STATIC) != 0;
InIterator = (code_flags & Modifiers.METHOD_YIELDS) != 0;
RemapToProxy = InIterator;
ReturnType = return_type;
IsConstructor = is_constructor;
CurrentBlock = null;
CurrentFile = 0;
if (parent != null){
// Can only be null for the ResolveType contexts.
ContainerType = parent.TypeBuilder;
if (parent.UnsafeContext)
InUnsafe = true;
else
InUnsafe = (code_flags & Modifiers.UNSAFE) != 0;
}
loc = l;
FlowStack = new Stack ();
if (ReturnType == TypeManager.void_type)
ReturnType = null;
}
public EmitContext (TypeContainer tc, Location l, ILGenerator ig,
Type return_type, int code_flags, bool is_constructor)
: this (tc, tc, l, ig, return_type, code_flags, is_constructor)
{
}
public EmitContext (TypeContainer tc, Location l, ILGenerator ig,
Type return_type, int code_flags)
: this (tc, tc, l, ig, return_type, code_flags, false)
{
}
public FlowBranching CurrentBranching {
get {
return (FlowBranching) FlowStack.Peek ();
}
}
//
// Starts a new code branching. This inherits the state of all local
// variables and parameters from the current branching.
//
public FlowBranching StartFlowBranching (FlowBranching.BranchingType type, Location loc)
{
FlowBranching cfb = FlowBranching.CreateBranching (CurrentBranching, type, null, loc);
FlowStack.Push (cfb);
return cfb;
}
//
// Starts a new code branching for block `block'.
//
public FlowBranching StartFlowBranching (Block block)
{
FlowBranching cfb;
FlowBranching.BranchingType type;
if (CurrentBranching.Type == FlowBranching.BranchingType.Switch)
type = FlowBranching.BranchingType.SwitchSection;
else
type = FlowBranching.BranchingType.Block;
cfb = FlowBranching.CreateBranching (CurrentBranching, type, block, block.StartLocation);
FlowStack.Push (cfb);
return cfb;
}
//
// Ends a code branching. Merges the state of locals and parameters
// from all the children of the ending branching.
//
public FlowBranching.FlowReturns EndFlowBranching ()
{
FlowBranching cfb = (FlowBranching) FlowStack.Pop ();
return CurrentBranching.MergeChild (cfb);
}
//
// Kills the current code branching. This throws away any changed state
// information and should only be used in case of an error.
//
public void KillFlowBranching ()
{
FlowBranching cfb = (FlowBranching) FlowStack.Pop ();
}
public void EmitTopBlock (Block block, InternalParameters ip, Location loc)
{
bool has_ret = false;
if (!Location.IsNull (loc))
CurrentFile = loc.File;
if (block != null){
try {
int errors = Report.Errors;
block.EmitMeta (this, ip);
if (Report.Errors == errors){
bool old_do_flow_analysis = DoFlowAnalysis;
DoFlowAnalysis = true;
FlowBranching cfb = FlowBranching.CreateBranching (
null, FlowBranching.BranchingType.Block, block, loc);
FlowStack.Push (cfb);
if (!block.Resolve (this)) {
FlowStack.Pop ();
DoFlowAnalysis = old_do_flow_analysis;
return;
}
cfb = (FlowBranching) FlowStack.Pop ();
FlowBranching.FlowReturns returns = cfb.MergeTopBlock ();
DoFlowAnalysis = old_do_flow_analysis;
has_ret = block.Emit (this);
if ((returns == FlowBranching.FlowReturns.Always) ||
(returns == FlowBranching.FlowReturns.Exception) ||
(returns == FlowBranching.FlowReturns.Unreachable))
has_ret = true;
if (Report.Errors == errors){
if (RootContext.WarningLevel >= 3)
block.UsageWarning ();
}
}
} catch {
Console.WriteLine ("Exception caught by the compiler while compiling:");
Console.WriteLine (" Block that caused the problem begin at: " + loc);
if (CurrentBlock != null){
Console.WriteLine (" Block being compiled: [{0},{1}]",
CurrentBlock.StartLocation, CurrentBlock.EndLocation);
}
throw;
}
}
if (ReturnType != null && !has_ret){
//
// FIXME: we need full flow analysis to implement this
// correctly and emit an error instead of a warning.
//
//
if (!InIterator){
Report.Error (161, loc, "Not all code paths return a value");
return;
}
}
if (HasReturnLabel)
ig.MarkLabel (ReturnLabel);
if (return_value != null){
ig.Emit (OpCodes.Ldloc, return_value);
ig.Emit (OpCodes.Ret);
} else {
if (!InTry){
if (InIterator)
has_ret = true;
if (!has_ret || HasReturnLabel) {
ig.Emit (OpCodes.Ret);
NeedExplicitReturn = false;
}
}
// Unfortunately, System.Reflection.Emit automatically emits a leave
// to the end of a finally block. This is a problem if no code is
// following the try/finally block since we may jump to a point after
// the end of the method. As a workaround, emit an explicit ret here.
if (NeedExplicitReturn) {
if (ReturnType != null)
ig.Emit (OpCodes.Ldloc, TemporaryReturn ());
ig.Emit (OpCodes.Ret);
}
}
}
///
/// This is called immediately before emitting an IL opcode to tell the symbol
/// writer to which source line this opcode belongs.
///
public void Mark (Location loc, bool check_file)
{
if ((CodeGen.SymbolWriter == null) || Location.IsNull (loc))
return;
if (check_file && (CurrentFile != loc.File))
return;
ig.MarkSequencePoint (null, loc.Row, 0, 0, 0);
}
///
/// Returns a temporary storage for a variable of type t as
/// a local variable in the current body.
///
public LocalBuilder GetTemporaryLocal (Type t)
{
LocalBuilder location = null;
if (temporary_storage != null){
object o = temporary_storage [t];
if (o != null){
if (o is ArrayList){
ArrayList al = (ArrayList) o;
for (int i = 0; i < al.Count; i++){
if (al [i] != null){
location = (LocalBuilder) al [i];
al [i] = null;
break;
}
}
} else
location = (LocalBuilder) o;
if (location != null)
return location;
}
}
return ig.DeclareLocal (t);
}
public void FreeTemporaryLocal (LocalBuilder b, Type t)
{
if (temporary_storage == null){
temporary_storage = new Hashtable ();
temporary_storage [t] = b;
return;
}
object o = temporary_storage [t];
if (o == null){
temporary_storage [t] = b;
return;
}
if (o is ArrayList){
ArrayList al = (ArrayList) o;
for (int i = 0; i < al.Count; i++){
if (al [i] == null){
al [i] = b;
return;
}
}
al.Add (b);
return;
}
ArrayList replacement = new ArrayList ();
replacement.Add (o);
temporary_storage.Remove (t);
temporary_storage [t] = replacement;
}
///
/// Current loop begin and end labels.
///
public Label LoopBegin, LoopEnd;
///
/// Whether we are inside a loop and break/continue are possible.
///
public bool InLoop;
///
/// This is incremented each time we enter a try/catch block and
/// decremented if we leave it.
///
public int TryCatchLevel;
///
/// The TryCatchLevel at the begin of the current loop.
///
public int LoopBeginTryCatchLevel;
///
/// Default target in a switch statement. Only valid if
/// InSwitch is true
///
public Label DefaultTarget;
///
/// If this is non-null, points to the current switch statement
///
public Switch Switch;
///
/// ReturnValue creates on demand the LocalBuilder for the
/// return value from the function. By default this is not
/// used. This is only required when returns are found inside
/// Try or Catch statements.
///
public LocalBuilder TemporaryReturn ()
{
if (return_value == null){
return_value = ig.DeclareLocal (ReturnType);
ReturnLabel = ig.DefineLabel ();
HasReturnLabel = true;
}
return return_value;
}
//
// Creates a field `name' with the type `t' on the proxy class
//
public FieldBuilder MapVariable (string name, Type t)
{
if (InIterator){
return IteratorHandler.Current.MapVariable ("v_", name, t);
}
throw new Exception ("MapVariable for an unknown state");
}
//
// Invoke this routine to remap a VariableInfo into the
// proper MemberAccess expression
//
public Expression RemapLocal (LocalInfo local_info)
{
FieldExpr fe = new FieldExpr (local_info.FieldBuilder, loc);
fe.InstanceExpression = new ProxyInstance ();
return fe.DoResolve (this);
}
public Expression RemapLocalLValue (LocalInfo local_info, Expression right_side)
{
FieldExpr fe = new FieldExpr (local_info.FieldBuilder, loc);
fe.InstanceExpression = new ProxyInstance ();
return fe.DoResolveLValue (this, right_side);
}
public Expression RemapParameter (int idx)
{
FieldExpr fe = new FieldExprNoAddress (IteratorHandler.Current.parameter_fields [idx], loc);
fe.InstanceExpression = new ProxyInstance ();
return fe.DoResolve (this);
}
public Expression RemapParameterLValue (int idx, Expression right_side)
{
FieldExpr fe = new FieldExprNoAddress (IteratorHandler.Current.parameter_fields [idx], loc);
fe.InstanceExpression = new ProxyInstance ();
return fe.DoResolveLValue (this, right_side);
}
//
// Emits the proper object to address fields on a remapped
// variable/parameter to field in anonymous-method/iterator proxy classes.
//
public void EmitThis ()
{
ig.Emit (OpCodes.Ldarg_0);
if (!IsStatic){
if (InIterator)
ig.Emit (OpCodes.Ldfld, IteratorHandler.Current.this_field);
else
throw new Exception ("EmitThis for an unknown state");
}
}
public Expression GetThis (Location loc)
{
This my_this;
if (CurrentBlock != null)
my_this = new This (CurrentBlock, loc);
else
my_this = new This (loc);
if (!my_this.ResolveBase (this))
my_this = null;
return my_this;
}
}
}