[ORC][MachO] Enable customization of MachO-headers produced by MachOPlatform.

MachOPlatform users can now override the default MachO header graph produced
for JITDylibs when setupJITDylib is called.

Author: lhames

llvm/include/llvm/ExecutionEngine/Orc/MachOPlatform.h

@@ -47,6 +47,14 @@ class MachOPlatform : public Platform {
     LLVM_MARK_AS_BITMASK_ENUM(/* LargestValue = */ Callable)
   };
 
+  /// Used by setupJITDylib to create MachO header MaterializationUnits for
+  /// JITDylibs.
+  using MachOHeaderMUBuilder =
+      unique_function<std::unique_ptr<MaterializationUnit>(MachOPlatform &MOP)>;
+
+  static std::unique_ptr<MaterializationUnit>
+  defaultMachOHeaderBuilder(MachOPlatform &MOP);
+
   /// Try to create a MachOPlatform instance, adding the ORC runtime to the
   /// given JITDylib.
   ///
@@ -88,17 +96,23 @@ class MachOPlatform : public Platform {
   static Expected<std::unique_ptr<MachOPlatform>>
   Create(ExecutionSession &ES, ObjectLinkingLayer &ObjLinkingLayer,
          JITDylib &PlatformJD, std::unique_ptr<DefinitionGenerator> OrcRuntime,
+         MachOHeaderMUBuilder BuildMachOHeaderMU = defaultMachOHeaderBuilder,
          std::optional<SymbolAliasMap> RuntimeAliases = std::nullopt);
 
   /// Construct using a path to the ORC runtime.
   static Expected<std::unique_ptr<MachOPlatform>>
   Create(ExecutionSession &ES, ObjectLinkingLayer &ObjLinkingLayer,
          JITDylib &PlatformJD, const char *OrcRuntimePath,
+         MachOHeaderMUBuilder BuildMachOHeaderMU = defaultMachOHeaderBuilder,
          std::optional<SymbolAliasMap> RuntimeAliases = std::nullopt);
 
   ExecutionSession &getExecutionSession() const { return ES; }
   ObjectLinkingLayer &getObjectLinkingLayer() const { return ObjLinkingLayer; }
 
+  NonOwningSymbolStringPtr getMachOHeaderStartSymbol() const {
+    return NonOwningSymbolStringPtr(MachOHeaderStartSymbol);
+  }
+
   Error setupJITDylib(JITDylib &JD) override;
   Error teardownJITDylib(JITDylib &JD) override;
   Error notifyAdding(ResourceTracker &RT,
@@ -243,7 +257,7 @@ class MachOPlatform : public Platform {
   MachOPlatform(ExecutionSession &ES, ObjectLinkingLayer &ObjLinkingLayer,
                 JITDylib &PlatformJD,
                 std::unique_ptr<DefinitionGenerator> OrcRuntimeGenerator,
-                Error &Err);
+                MachOHeaderMUBuilder BuildMachOHeaderMU, Error &Err);
 
   // Associate MachOPlatform JIT-side runtime support functions with handlers.
   Error associateRuntimeSupportFunctions();
@@ -271,6 +285,7 @@ class MachOPlatform : public Platform {
   ExecutionSession &ES;
   JITDylib &PlatformJD;
   ObjectLinkingLayer &ObjLinkingLayer;
+  MachOHeaderMUBuilder BuildMachOHeaderMU;
 
   SymbolStringPtr MachOHeaderStartSymbol = ES.intern("___dso_handle");
 

llvm/lib/ExecutionEngine/Orc/MachOPlatform.cpp

@@ -15,6 +15,7 @@
 #include "llvm/ExecutionEngine/Orc/DebugUtils.h"
 #include "llvm/ExecutionEngine/Orc/ExecutionUtils.h"
 #include "llvm/ExecutionEngine/Orc/LookupAndRecordAddrs.h"
+#include "llvm/ExecutionEngine/Orc/MachOBuilder.h"
 #include "llvm/ExecutionEngine/Orc/Shared/ObjectFormats.h"
 #include "llvm/Support/BinaryByteStream.h"
 #include "llvm/Support/Debug.h"
@@ -119,8 +120,9 @@ std::unique_ptr<jitlink::LinkGraph> createPlatformGraph(MachOPlatform &MOP,
 class MachOHeaderMaterializationUnit : public MaterializationUnit {
 public:
   MachOHeaderMaterializationUnit(MachOPlatform &MOP,
-                                 const SymbolStringPtr &HeaderStartSymbol)
-      : MaterializationUnit(createHeaderInterface(MOP, HeaderStartSymbol)),
+                                 SymbolStringPtr HeaderStartSymbol)
+      : MaterializationUnit(
+            createHeaderInterface(MOP, std::move(HeaderStartSymbol))),
         MOP(MOP) {}
 
   StringRef getName() const override { return "MachOHeaderMU"; }
@@ -348,10 +350,17 @@ struct ObjCImageInfoFlags {
 namespace llvm {
 namespace orc {
 
+std::unique_ptr<MaterializationUnit>
+MachOPlatform::defaultMachOHeaderBuilder(MachOPlatform &MOP) {
+  return std::make_unique<MachOHeaderMaterializationUnit>(
+      MOP, SymbolStringPtr(MOP.getMachOHeaderStartSymbol()));
+}
+
 Expected<std::unique_ptr<MachOPlatform>>
 MachOPlatform::Create(ExecutionSession &ES, ObjectLinkingLayer &ObjLinkingLayer,
                       JITDylib &PlatformJD,
                       std::unique_ptr<DefinitionGenerator> OrcRuntime,
+                      MachOHeaderMUBuilder BuildMachOHeaderMU,
                       std::optional<SymbolAliasMap> RuntimeAliases) {
 
   // If the target is not supported then bail out immediately.
@@ -382,8 +391,9 @@ MachOPlatform::Create(ExecutionSession &ES, ObjectLinkingLayer &ObjLinkingLayer,
 
   // Create the instance.
   Error Err = Error::success();
-  auto P = std::unique_ptr<MachOPlatform>(new MachOPlatform(
-      ES, ObjLinkingLayer, PlatformJD, std::move(OrcRuntime), Err));
+  auto P = std::unique_ptr<MachOPlatform>(
+      new MachOPlatform(ES, ObjLinkingLayer, PlatformJD, std::move(OrcRuntime),
+                        std::move(BuildMachOHeaderMU), Err));
   if (Err)
     return std::move(Err);
   return std::move(P);
@@ -392,6 +402,7 @@ MachOPlatform::Create(ExecutionSession &ES, ObjectLinkingLayer &ObjLinkingLayer,
 Expected<std::unique_ptr<MachOPlatform>>
 MachOPlatform::Create(ExecutionSession &ES, ObjectLinkingLayer &ObjLinkingLayer,
                       JITDylib &PlatformJD, const char *OrcRuntimePath,
+                      MachOHeaderMUBuilder BuildMachOHeaderMU,
                       std::optional<SymbolAliasMap> RuntimeAliases) {
 
   // Create a generator for the ORC runtime archive.
@@ -402,12 +413,11 @@ MachOPlatform::Create(ExecutionSession &ES, ObjectLinkingLayer &ObjLinkingLayer,
 
   return Create(ES, ObjLinkingLayer, PlatformJD,
                 std::move(*OrcRuntimeArchiveGenerator),
-                std::move(RuntimeAliases));
+                std::move(BuildMachOHeaderMU), std::move(RuntimeAliases));
 }
 
 Error MachOPlatform::setupJITDylib(JITDylib &JD) {
-  if (auto Err = JD.define(std::make_unique<MachOHeaderMaterializationUnit>(
-          *this, MachOHeaderStartSymbol)))
+  if (auto Err = JD.define(BuildMachOHeaderMU(*this)))
     return Err;
 
   return ES.lookup({&JD}, MachOHeaderStartSymbol).takeError();
@@ -522,8 +532,10 @@ MachOPlatform::flagsForSymbol(jitlink::Symbol &Sym) {
 MachOPlatform::MachOPlatform(
     ExecutionSession &ES, ObjectLinkingLayer &ObjLinkingLayer,
     JITDylib &PlatformJD,
-    std::unique_ptr<DefinitionGenerator> OrcRuntimeGenerator, Error &Err)
-    : ES(ES), PlatformJD(PlatformJD), ObjLinkingLayer(ObjLinkingLayer) {
+    std::unique_ptr<DefinitionGenerator> OrcRuntimeGenerator,
+    MachOHeaderMUBuilder BuildMachOHeaderMU, Error &Err)
+    : ES(ES), PlatformJD(PlatformJD), ObjLinkingLayer(ObjLinkingLayer),
+      BuildMachOHeaderMU(std::move(BuildMachOHeaderMU)) {
   ErrorAsOutParameter _(&Err);
   ObjLinkingLayer.addPlugin(std::make_unique<MachOPlatformPlugin>(*this));
   PlatformJD.addGenerator(std::move(OrcRuntimeGenerator));