Add support for jump stub generation in CoreRT

- Handle both indirect and direct symbol references
- ARM, X86, and X64 architectures
- First need for these is for a stub that has a well known name which jumps to a specific symbol
- We will use these for custom linkage in scenarios involving multiple PE files on Windows

[tfs-changeset: 1661486]

11 files changed, 160 insertions, 5 deletions

diff --git a/src/ILCompiler.Compiler/src/Compiler/DependencyAnalysis/JumpStubNode.cs b/src/ILCompiler.Compiler/src/Compiler/DependencyAnalysis/JumpStubNode.cs
new file mode 100644
index 000000000..6c8c687d9
--- /dev/null
+++ b/src/ILCompiler.Compiler/src/Compiler/DependencyAnalysis/JumpStubNode.cs
@@ -0,0 +1,32 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+using System;
+
+using Internal.TypeSystem;
+
+using Internal.Text;
+
+namespace ILCompiler.DependencyAnalysis
+{
+    public abstract partial class JumpStubNode : AssemblyStubNode
+    {
+        private ISymbolNode _target;
+
+        public ISymbolNode Target
+        {
+            get
+            {
+                return _target;
+            }
+        }
+        
+        public JumpStubNode(ISymbolNode target)
+        {
+            _target = target;
+        }
+
+        protected override string GetName(NodeFactory factory) => this.GetMangledName(factory.NameMangler);
+    }
+}
diff --git a/src/ILCompiler.Compiler/src/Compiler/DependencyAnalysis/NamedJumpStubNode.cs b/src/ILCompiler.Compiler/src/Compiler/DependencyAnalysis/NamedJumpStubNode.cs
new file mode 100644
index 000000000..e3d4afaa4
--- /dev/null
+++ b/src/ILCompiler.Compiler/src/Compiler/DependencyAnalysis/NamedJumpStubNode.cs
@@ -0,0 +1,23 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+using Internal.Text;
+
+namespace ILCompiler.DependencyAnalysis
+{
+    class NamedJumpStubNode : JumpStubNode
+    {
+        Utf8String _name;
+
+        public NamedJumpStubNode(string name, ISymbolNode target) : base(target)
+        {
+            _name = new Utf8String(name);
+        }
+
+        public override void AppendMangledName(NameMangler nameMangler, Utf8StringBuilder sb)
+        {
+            sb.Append(_name);
+        }
+    }
+}
diff --git a/src/ILCompiler.Compiler/src/Compiler/DependencyAnalysis/NodeFactory.cs b/src/ILCompiler.Compiler/src/Compiler/DependencyAnalysis/NodeFactory.cs
index 1f1b76c3c..2fce7836c 100644
--- a/src/ILCompiler.Compiler/src/Compiler/DependencyAnalysis/NodeFactory.cs
+++ b/src/ILCompiler.Compiler/src/Compiler/DependencyAnalysis/NodeFactory.cs
@@ -401,7 +401,12 @@ namespace ILCompiler.DependencyAnalysis
                 Debug.Assert(TypeSystemContext.HasEagerStaticConstructor((MetadataType)method.OwningType));
                 return EagerCctorTable.NewNode(MethodEntrypoint(method));
             });
-            
+
+            _namedJumpStubNodes = new NodeCache<Tuple<string, ISymbolNode>, NamedJumpStubNode>((Tuple<string, ISymbolNode> id) =>
+            {
+                return new NamedJumpStubNode(id.Item1, id.Item2);
+            });
+
             _vTableNodes = new NodeCache<TypeDesc, VTableSliceNode>((TypeDesc type ) =>
             {
                 if (CompilationModuleGroup.ShouldProduceFullVTable(type))
@@ -934,6 +939,13 @@ namespace ILCompiler.DependencyAnalysis
             return ReadOnlyDataBlob(symbolName, stringBytes, 1);
         }
 
+        private NodeCache<Tuple<string, ISymbolNode>, NamedJumpStubNode> _namedJumpStubNodes;
+
+        public ISymbolNode NamedJumpStub(string name, ISymbolNode target)
+        {
+            return _namedJumpStubNodes.GetOrAdd(new Tuple<string, ISymbolNode>(name, target));
+        }
+        
         /// <summary>
         /// Returns alternative symbol name that object writer should produce for given symbols
         /// in addition to the regular one.
diff --git a/src/ILCompiler.Compiler/src/Compiler/DependencyAnalysis/Target_ARM/ARMEmitter.cs b/src/ILCompiler.Compiler/src/Compiler/DependencyAnalysis/Target_ARM/ARMEmitter.cs
index df063a9f8..38dd2edd7 100644
--- a/src/ILCompiler.Compiler/src/Compiler/DependencyAnalysis/Target_ARM/ARMEmitter.cs
+++ b/src/ILCompiler.Compiler/src/Compiler/DependencyAnalysis/Target_ARM/ARMEmitter.cs
@@ -52,11 +52,18 @@ namespace ILCompiler.DependencyAnalysis.ARM
         // b symbol
         public void EmitJMP(ISymbolNode symbol)
         {
+            Debug.Assert(!symbol.RepresentsIndirectionCell);
             Builder.EmitReloc(symbol, RelocType.IMAGE_REL_BASED_THUMB_BRANCH24);
             Builder.EmitByte(0);
             Builder.EmitByte(0xF0);
             Builder.EmitByte(0);
             Builder.EmitByte(0xB8);
         }
+
+        // bx reg
+        public void EmitJMP(Register destination)
+        {
+            Builder.EmitShort((short)(0x47 | ((byte)destination << 3)));
+        }
     }
 }
diff --git a/src/ILCompiler.Compiler/src/Compiler/DependencyAnalysis/Target_ARM/ARMJumpStubNode.cs b/src/ILCompiler.Compiler/src/Compiler/DependencyAnalysis/Target_ARM/ARMJumpStubNode.cs
new file mode 100644
index 000000000..afbc1a662
--- /dev/null
+++ b/src/ILCompiler.Compiler/src/Compiler/DependencyAnalysis/Target_ARM/ARMJumpStubNode.cs
@@ -0,0 +1,24 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+using ILCompiler.DependencyAnalysis.ARM;
+
+namespace ILCompiler.DependencyAnalysis
+{
+    public partial class JumpStubNode
+    {
+        protected override void EmitCode(NodeFactory factory, ref ARMEmitter encoder, bool relocsOnly)
+        {
+            if (!_target.RepresentsIndirectionCell)
+            {
+                encoder.EmitJMP(_target); // b methodEntryPoint
+            }
+            else
+            {
+                encoder.EmitMOV(encoder.TargetRegister.InterproceduralScratch, _target);
+                encoder.EmitJMP(encoder.TargetRegister.InterproceduralScratch);
+            }
+        }
+    }
+}
diff --git a/src/ILCompiler.Compiler/src/Compiler/DependencyAnalysis/Target_ARM/TargetRegisterMap.cs b/src/ILCompiler.Compiler/src/Compiler/DependencyAnalysis/Target_ARM/TargetRegisterMap.cs
index 5e0fde4fa..6ac115a14 100644
--- a/src/ILCompiler.Compiler/src/Compiler/DependencyAnalysis/Target_ARM/TargetRegisterMap.cs
+++ b/src/ILCompiler.Compiler/src/Compiler/DependencyAnalysis/Target_ARM/TargetRegisterMap.cs
@@ -16,12 +16,14 @@ namespace ILCompiler.DependencyAnalysis.ARM
         public readonly Register Arg0;
         public readonly Register Arg1;
         public readonly Register Result;
+        public readonly Register InterproceduralScratch;
 
         public TargetRegisterMap(TargetOS os)
         {
             Arg0 = Register.R0;
             Arg1 = Register.R1;
             Result = Register.R0;
+            InterproceduralScratch = Register.R12;
         }
     }
 }
diff --git a/src/ILCompiler.Compiler/src/Compiler/DependencyAnalysis/Target_X64/X64Emitter.cs b/src/ILCompiler.Compiler/src/Compiler/DependencyAnalysis/Target_X64/X64Emitter.cs
index 3ca448c3f..76c7aa37f 100644
--- a/src/ILCompiler.Compiler/src/Compiler/DependencyAnalysis/Target_X64/X64Emitter.cs
+++ b/src/ILCompiler.Compiler/src/Compiler/DependencyAnalysis/Target_X64/X64Emitter.cs
@@ -74,8 +74,17 @@ namespace ILCompiler.DependencyAnalysis.X64
 
         public void EmitJMP(ISymbolNode symbol)
         {
-            Builder.EmitByte(0xE9);
-            Builder.EmitReloc(symbol, RelocType.IMAGE_REL_BASED_REL32);
+            if (symbol.RepresentsIndirectionCell)
+            {
+                Builder.EmitByte(0xff);
+                Builder.EmitByte(0x25);
+                Builder.EmitReloc(symbol, RelocType.IMAGE_REL_BASED_REL32);
+            }
+            else
+            {
+                Builder.EmitByte(0xE9);
+                Builder.EmitReloc(symbol, RelocType.IMAGE_REL_BASED_REL32);
+            }
         }
 
         public void EmitINT3()
diff --git a/src/ILCompiler.Compiler/src/Compiler/DependencyAnalysis/Target_X64/X64JumpStubNode.cs b/src/ILCompiler.Compiler/src/Compiler/DependencyAnalysis/Target_X64/X64JumpStubNode.cs
new file mode 100644
index 000000000..ceaa37150
--- /dev/null
+++ b/src/ILCompiler.Compiler/src/Compiler/DependencyAnalysis/Target_X64/X64JumpStubNode.cs
@@ -0,0 +1,16 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+using ILCompiler.DependencyAnalysis.X64;
+
+namespace ILCompiler.DependencyAnalysis
+{
+    public partial class JumpStubNode
+    {
+        protected override void EmitCode(NodeFactory factory, ref X64Emitter encoder, bool relocsOnly)
+        {
+            encoder.EmitJMP(_target);
+        }
+    }
+}
diff --git a/src/ILCompiler.Compiler/src/Compiler/DependencyAnalysis/Target_X86/X86Emitter.cs b/src/ILCompiler.Compiler/src/Compiler/DependencyAnalysis/Target_X86/X86Emitter.cs
index 72068ff22..b44300b21 100644
--- a/src/ILCompiler.Compiler/src/Compiler/DependencyAnalysis/Target_X86/X86Emitter.cs
+++ b/src/ILCompiler.Compiler/src/Compiler/DependencyAnalysis/Target_X86/X86Emitter.cs
@@ -28,8 +28,17 @@ namespace ILCompiler.DependencyAnalysis.X86
 
         public void EmitJMP(ISymbolNode symbol)
         {
-            Builder.EmitByte(0xE9);
-            Builder.EmitReloc(symbol, RelocType.IMAGE_REL_BASED_REL32);
+            if (symbol.RepresentsIndirectionCell)
+            {
+                Builder.EmitByte(0xff);
+                Builder.EmitByte(0x25);
+                Builder.EmitReloc(symbol, RelocType.IMAGE_REL_BASED_REL32);
+            }
+            else
+            {
+                Builder.EmitByte(0xE9);
+                Builder.EmitReloc(symbol, RelocType.IMAGE_REL_BASED_REL32);
+            }
         }
         
         private bool InSignedByteRange(int i)
diff --git a/src/ILCompiler.Compiler/src/Compiler/DependencyAnalysis/Target_X86/X86JumpStubNode.cs b/src/ILCompiler.Compiler/src/Compiler/DependencyAnalysis/Target_X86/X86JumpStubNode.cs
new file mode 100644
index 000000000..b95bd1a54
--- /dev/null
+++ b/src/ILCompiler.Compiler/src/Compiler/DependencyAnalysis/Target_X86/X86JumpStubNode.cs
@@ -0,0 +1,16 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+using ILCompiler.DependencyAnalysis.X86;
+
+namespace ILCompiler.DependencyAnalysis
+{
+    public partial class JumpStubNode
+    {
+        protected override void EmitCode(NodeFactory factory, ref X86Emitter encoder, bool relocsOnly)
+        {
+            encoder.EmitJMP(_target);
+        }
+    }
+}
diff --git a/src/ILCompiler.Compiler/src/ILCompiler.Compiler.csproj b/src/ILCompiler.Compiler/src/ILCompiler.Compiler.csproj
index 475866398..25de949da 100644
--- a/src/ILCompiler.Compiler/src/ILCompiler.Compiler.csproj
+++ b/src/ILCompiler.Compiler/src/ILCompiler.Compiler.csproj
@@ -234,6 +234,8 @@
     <Compile Include="Compiler\DependencyAnalysis\INodeWithDebugInfo.cs" />
     <Compile Include="Compiler\DependencyAnalysis\IExportableSymbolNode.cs" />
     <Compile Include="Compiler\DependencyAnalysis\ISymbolNode.cs" />
+    <Compile Include="Compiler\DependencyAnalysis\JumpStubNode.cs" />
+    <Compile Include="Compiler\DependencyAnalysis\NamedJumpStubNode.cs" />
     <Compile Include="Compiler\DependencyAnalysis\NodeFactory.cs" />
     <Compile Include="Compiler\DependencyAnalysis\NodeFactory.GenericLookups.cs" />
     <Compile Include="Compiler\DependencyAnalysis\NodeFactory.NativeLayout.cs" />
@@ -258,6 +260,7 @@
     <Compile Include="Compiler\DependencyAnalysis\VirtualMethodUseNode.cs" />
     <Compile Include="Compiler\DependencyAnalysis\Target_X64\Register.cs" />
     <Compile Include="Compiler\DependencyAnalysis\Target_X64\X64Emitter.cs" />
+    <Compile Include="Compiler\DependencyAnalysis\Target_X64\X64JumpStubNode.cs" />
     <Compile Include="Compiler\DependencyAnalysis\Target_X64\X64ReadyToRunHelperNode.cs" />
     <Compile Include="Compiler\DependencyAnalysis\InterfaceDispatchMapNode.cs" />
     <Compile Include="Compiler\DependencyAnalysis\Target_X86\AddrMode.cs" />
@@ -265,12 +268,14 @@
     <Compile Include="Compiler\DependencyAnalysis\Target_X86\X86UnboxingStubNode.cs" />
     <Compile Include="Compiler\DependencyAnalysis\Target_X86\Register.cs" />
     <Compile Include="Compiler\DependencyAnalysis\Target_X86\X86Emitter.cs" />
+    <Compile Include="Compiler\DependencyAnalysis\Target_X86\X86JumpStubNode.cs" />
     <Compile Include="Compiler\DependencyAnalysis\Target_X86\X86ReadyToRunHelperNode.cs" />
     <Compile Include="Compiler\DependencyAnalysis\Target_X86\X86ReadyToRunGenericHelperNode.cs" />
     <Compile Include="Compiler\DependencyAnalysis\Target_ARM\TargetRegisterMap.cs" />
     <Compile Include="Compiler\DependencyAnalysis\Target_ARM\ARMUnboxingStubNode.cs" />
     <Compile Include="Compiler\DependencyAnalysis\Target_ARM\Register.cs" />
     <Compile Include="Compiler\DependencyAnalysis\Target_ARM\ARMEmitter.cs" />
+    <Compile Include="Compiler\DependencyAnalysis\Target_ARM\ARMJumpStubNode.cs" />
     <Compile Include="Compiler\DependencyAnalysis\Target_ARM\ARMReadyToRunHelperNode.cs" />
     <Compile Include="Compiler\DependencyAnalysis\Target_ARM\ARMReadyToRunGenericHelperNode.cs" />
     <Compile Include="Compiler\ExportedMethodsRootProvider.cs" />