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Refactor Sweep step no to be recursive
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- Add more type forwarding tests
- Makes this step faster
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@marek-safar
marek-safar committed Sep 12, 2019
1 parent 0fd66c9 commit 6be2677
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Showing 12 changed files with 350 additions and 123 deletions.
267 changes: 146 additions & 121 deletions src/linker/Linker.Steps/SweepStep.cs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -35,11 +35,11 @@

namespace Mono.Linker.Steps {

public class SweepStep : BaseStep {

public class SweepStep : BaseStep
{
AssemblyDefinition [] assemblies;
HashSet<AssemblyDefinition> resolvedTypeReferences;
readonly bool sweepSymbols;
readonly HashSet<AssemblyDefinition> BypassNGenToSave = new HashSet<AssemblyDefinition> ();

public SweepStep (bool sweepSymbols = true)
{
Expand All @@ -49,61 +49,68 @@ public SweepStep (bool sweepSymbols = true)
protected override void Process ()
{
assemblies = Context.Annotations.GetAssemblies ().ToArray ();

foreach (var assembly in assemblies) {
RemoveUnusedAssembly (assembly);
}

foreach (var assembly in assemblies) {
ProcessAssemblyAction (assembly);
if ((Annotations.GetAction (assembly) == AssemblyAction.Copy) &&
!Context.KeepTypeForwarderOnlyAssemblies) {
// Copy assemblies can still contain Type references with
// type forwarders from Delete assemblies
// thus try to resolve all the type references and see
// if some changed the scope. if yes change the action to Save
if (ResolveAllTypeReferences (assembly))
Annotations.SetAction (assembly, AssemblyAction.Save);
}
}
}

AssemblyAction currentAction = Annotations.GetAction (assembly);
void RemoveUnusedAssembly (AssemblyDefinition assembly)
{
switch (Annotations.GetAction (assembly)) {
case AssemblyAction.AddBypassNGenUsed:
case AssemblyAction.CopyUsed:
case AssemblyAction.Link:
if (!IsUsedAssembly (assembly))
RemoveAssembly (assembly);

if ((currentAction == AssemblyAction.Link) || (currentAction == AssemblyAction.Save)) {
// if we save (only or by linking) then unmarked exports (e.g. forwarders) must be cleaned
// or they can point to nothing which will break later (e.g. when re-loading for stripping IL)
// reference: https://bugzilla.xamarin.com/show_bug.cgi?id=36577
if (assembly.MainModule.HasExportedTypes)
SweepCollectionNonAttributable (assembly.MainModule.ExportedTypes);
}
break;
}
}

protected void ProcessAssemblyAction (AssemblyDefinition assembly)
{
switch (Annotations.GetAction (assembly)) {
case AssemblyAction.Link:
if (!IsMarkedAssembly (assembly)) {
RemoveAssembly (assembly);
return;
}
break;
case AssemblyAction.AddBypassNGenUsed:
Annotations.SetAction (assembly, AssemblyAction.AddBypassNGen);
goto case AssemblyAction.AddBypassNGen;

case AssemblyAction.AddBypassNGen:
// FIXME: AddBypassNGen is just wrong, it should not be action as we need to
// turn it to Action.Save here to e.g. correctly update debug symbols
if (!Context.KeepTypeForwarderOnlyAssemblies || BypassNGenToSave.Contains (assembly)) {
goto case AssemblyAction.Save;
}

case AssemblyAction.AddBypassNGenUsed:
if (!IsMarkedAssembly (assembly)) {
RemoveAssembly (assembly);
} else {
Annotations.SetAction (assembly, AssemblyAction.AddBypassNGen);
}
return;
break;

case AssemblyAction.CopyUsed:
if (!IsMarkedAssembly (assembly)) {
RemoveAssembly (assembly);
} else {
Annotations.SetAction (assembly, AssemblyAction.Copy);
}
return;
case AssemblyAction.CopyUsed:
Annotations.SetAction (assembly, AssemblyAction.Copy);
goto case AssemblyAction.Copy;

case AssemblyAction.Copy:
// Copy assemblies can still contain Type references with
// type forwarders from Delete assemblies
// thus try to resolve all the type references and see
// if some changed the scope. if yes change the action to Save
if (!Context.KeepTypeForwarderOnlyAssemblies && SweepTypeForwarders (assembly)) {
Annotations.SetAction (assembly, AssemblyAction.Save);
}

break;

case AssemblyAction.Link:
SweepAssembly (assembly);
break;

default:
return;
case AssemblyAction.Save:
SweepTypeForwarders (assembly);
break;
}

SweepAssembly (assembly);
}

protected virtual void SweepAssembly (AssemblyDefinition assembly)
Expand Down Expand Up @@ -132,6 +139,19 @@ protected virtual void SweepAssembly (AssemblyDefinition assembly)

foreach (var module in assembly.Modules)
SweepCustomAttributes (module);

SweepTypeForwarders (assembly);
}

bool IsUsedAssembly (AssemblyDefinition assembly)
{
if (IsMarkedAssembly (assembly))
return true;

if (assembly.MainModule.HasExportedTypes && Context.KeepTypeForwarderOnlyAssemblies)
return true;

return false;
}

bool IsMarkedAssembly (AssemblyDefinition assembly)
Expand All @@ -143,7 +163,15 @@ protected virtual void RemoveAssembly (AssemblyDefinition assembly)
{
Annotations.SetAction (assembly, AssemblyAction.Delete);

SweepReferences (assembly);
foreach (var a in assemblies) {
switch (Annotations.GetAction (a)) {
case AssemblyAction.Skip:
case AssemblyAction.Delete:
continue;
}

SweepReferences (a, assembly);
}
}

void SweepResources (AssemblyDefinition assembly)
Expand All @@ -163,115 +191,117 @@ void SweepResources (AssemblyDefinition assembly)
}
}

void SweepReferences (AssemblyDefinition target)
{
foreach (var assembly in assemblies)
SweepReferences (assembly, target);
}

void SweepReferences (AssemblyDefinition assembly, AssemblyDefinition target)
void SweepReferences (AssemblyDefinition assembly, AssemblyDefinition referenceToRemove)
{
if (assembly == target)
if (assembly == referenceToRemove)
return;

bool reference_removed = false;

var references = assembly.MainModule.AssemblyReferences;
for (int i = 0; i < references.Count; i++) {
var reference = references [i];
AssemblyDefinition r = Context.Resolver.Resolve (reference);
if (r == null)
continue;
if (!AreSameReference (r.Name, target.Name))

AssemblyDefinition ad = Context.Resolver.Resolve (reference);
if (ad == null || !AreSameReference (ad.Name, referenceToRemove.Name))
continue;

ReferenceRemoved (assembly, reference);
// removal from `references` requires an adjustment to `i`
references.RemoveAt (i--);
// Removing the reference does not mean it will be saved back to disk!
// That depends on the AssemblyAction set for the `assembly`
reference_removed = true;
}

if (reference_removed) {
switch (Annotations.GetAction (assembly)) {
case AssemblyAction.CopyUsed:
if (IsUsedAssembly (assembly)) {
goto case AssemblyAction.Copy;
}
break;

case AssemblyAction.Copy:
// We need to save the assembly if a reference was removed, otherwise we can end up
// with an assembly that references an assembly that no longer exists
Annotations.SetAction (assembly, AssemblyAction.Save);
// Copy means even if "unlinked" we still want that assembly to be saved back
// to disk (OutputStep) without the (removed) reference
if (!Context.KeepTypeForwarderOnlyAssemblies) {
ResolveAllTypeReferences (assembly);
}
break;

case AssemblyAction.CopyUsed:
if (IsMarkedAssembly (assembly) && !Context.KeepTypeForwarderOnlyAssemblies) {
Annotations.SetAction (assembly, AssemblyAction.Save);
ResolveAllTypeReferences (assembly);
case AssemblyAction.AddBypassNGenUsed:
if (IsUsedAssembly (assembly)) {
Annotations.SetAction (assembly, AssemblyAction.AddBypassNGen);
goto case AssemblyAction.AddBypassNGen;
}
break;

case AssemblyAction.Save:
case AssemblyAction.Link:
case AssemblyAction.AddBypassNGen:
case AssemblyAction.AddBypassNGenUsed:
if (!Context.KeepTypeForwarderOnlyAssemblies) {
ResolveAllTypeReferences (assembly);
}
BypassNGenToSave.Add (assembly);
break;
}
}
}

bool ResolveAllTypeReferences (AssemblyDefinition assembly)
bool SweepTypeForwarders (AssemblyDefinition assembly)
{
if (resolvedTypeReferences == null)
resolvedTypeReferences = new HashSet<AssemblyDefinition> ();
if (resolvedTypeReferences.Contains (assembly))
return false;
resolvedTypeReferences.Add (assembly);
bool any_change = false;

// if we save (only or by linking) then unmarked exports (e.g. forwarders) must be cleaned
// or they can point to nothing which will break later (e.g. when re-loading for stripping IL)
// reference: https://bugzilla.xamarin.com/show_bug.cgi?id=36577
if (assembly.MainModule.HasExportedTypes) {

// TODO: This sweeps only type forwarders of types which are not marked. The types
// which are have their type forwarders keept even if they are unused
any_change = SweepCollectionMetadata (assembly.MainModule.ExportedTypes);
}

var hash = new Dictionary<TypeReference,IMetadataScope> ();
bool changes = false;
any_change |= UpdateForwardedTypesScope (assembly);
return any_change;
}

bool UpdateForwardedTypesScope (AssemblyDefinition assembly)
{
var changed_types = new Dictionary<TypeReference, IMetadataScope> ();

foreach (TypeReference tr in assembly.MainModule.GetTypeReferences ()) {
if (hash.ContainsKey (tr))
continue;
if (tr.IsWindowsRuntimeProjection)
continue;

var td = tr.Resolve ();
IMetadataScope scope = tr.Scope;
// at this stage reference might include things that can't be resolved
// and if it is (resolved) it needs to be kept only if marked (#16213)
if ((td != null) && Annotations.IsMarked (td)) {
scope = assembly.MainModule.ImportReference (td).Scope;
if (tr.Scope != scope)
changes = true;
hash.Add (tr, scope);
}
}
if (assembly.MainModule.HasExportedTypes) {
foreach (var et in assembly.MainModule.ExportedTypes) {
var td = et.Resolve ();
IMetadataScope scope = et.Scope;
if ((td != null) && Annotations.IsMarked (td)) {
scope = assembly.MainModule.ImportReference (td).Scope;
et.Scope = scope;
}
}
if (td == null || !Annotations.IsMarked (td))
continue;

IMetadataScope scope = assembly.MainModule.ImportReference (td).Scope;
if (tr.Scope != scope)
changed_types.Add (tr, scope);
}

// Resolve everything first before updating scopes.
//
// Resolved everything first before updating scopes.
// If we set the scope to null, then calling Resolve() on any of its
// nested types would crash.

foreach (var e in hash) {
//
foreach (var e in changed_types) {
e.Key.Scope = e.Value;
}

return changes;
if (assembly.MainModule.HasExportedTypes) {
foreach (var et in assembly.MainModule.ExportedTypes) {
var td = et.Resolve ();
if (td == null)
continue;

et.Scope = assembly.MainModule.ImportReference (td).Scope;
}
}

return changed_types.Count != 0;
}

protected virtual void SweepType (TypeDefinition type)
{
if (type.HasFields)
SweepCollection (type.Fields);
SweepCollectionWithCustomAttributes (type.Fields);

if (type.HasMethods)
SweepMethods (type.Methods);
Expand Down Expand Up @@ -398,7 +428,7 @@ protected void SweepCustomAttributeCollection<T> (Collection<T> providers) where

protected virtual void SweepMethods (Collection<MethodDefinition> methods)
{
SweepCollection (methods);
SweepCollectionWithCustomAttributes (methods);
if (sweepSymbols)
SweepDebugInfo (methods);

Expand Down Expand Up @@ -461,7 +491,7 @@ void SweepDebugInfo (Collection<MethodDefinition> methods)
}
}

protected void SweepCollection (IList<MethodDefinition> list)
protected void SweepCollectionWithCustomAttributes<T> (IList<T> list) where T : ICustomAttributeProvider
{
for (int i = 0; i < list.Count; i++)
if (ShouldRemove (list [i])) {
Expand All @@ -472,24 +502,19 @@ protected void SweepCollection (IList<MethodDefinition> list)
}
}

protected void SweepCollection<T> (IList<T> list) where T : ICustomAttributeProvider
protected bool SweepCollectionMetadata<T> (IList<T> list) where T : IMetadataTokenProvider
{
for (int i = 0; i < list.Count; i++)
if (ShouldRemove (list [i])) {
ElementRemoved (list [i]);
list.RemoveAt (i--);
} else {
SweepCustomAttributes (list [i]);
}
}
bool removed = false;

protected void SweepCollectionNonAttributable<T> (IList<T> list) where T : IMetadataTokenProvider
{
for (int i = 0; i < list.Count; i++)
for (int i = 0; i < list.Count; i++) {
if (ShouldRemove (list [i])) {
ElementRemoved (list [i]);
list.RemoveAt (i--);
removed = true;
}
}

return removed;
}

protected virtual bool ShouldRemove<T> (T element) where T : IMetadataTokenProvider
Expand Down
1 change: 1 addition & 0 deletions test/Mono.Linker.Tests.Cases/Mono.Linker.Tests.Cases.csproj
View file
Original file line number Diff line number Diff line change
Expand Up @@ -21,6 +21,7 @@
<Compile Remove="Attributes\OnlyKeepUsed\Dependencies\UnusedAttributeWithTypeForwarderIsRemoved_Forwarder.cs" />
<Compile Remove="LinkXml\Dependencies\CanPreserveAnExportedType_Forwarder.cs" />
<Compile Remove="TypeForwarding\Dependencies\ForwarderLibrary.cs" />
<Compile Remove="TypeForwarding\Dependencies\ForwarderLibrary_2.cs" />
</ItemGroup>
<ItemGroup>
<Content Include="Attributes\OnlyKeepUsed\Dependencies\UnusedAttributeWithTypeForwarderIsRemoved_Forwarder.cs" />
Expand Down
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