[ORC] Drop EHFrameRegistrar, register eh-frames with AllocActions (#130719)

This simplifies resource management, and should improve performance for most use
cases.

Author: lhames

llvm/include/llvm/ExecutionEngine/JITLink/EHFrameSupport.h

@@ -83,35 +83,9 @@ class EHFrameCFIBlockInspector {
   };
 };
 
-/// Supports registration/deregistration of EH-frames in a target process.
-class EHFrameRegistrar {
-public:
-  virtual ~EHFrameRegistrar();
-  virtual Error registerEHFrames(orc::ExecutorAddrRange EHFrameSection) = 0;
-  virtual Error deregisterEHFrames(orc::ExecutorAddrRange EHFrameSection) = 0;
-};
-
-/// Registers / Deregisters EH-frames in the current process.
-class InProcessEHFrameRegistrar final : public EHFrameRegistrar {
-public:
-  Error registerEHFrames(orc::ExecutorAddrRange EHFrameSection) override;
-
-  Error deregisterEHFrames(orc::ExecutorAddrRange EHFrameSection) override;
-};
-
-using StoreFrameRangeFunction = std::function<void(
-    orc::ExecutorAddr EHFrameSectionAddr, size_t EHFrameSectionSize)>;
-
-/// Creates a pass that records the address and size of the EH frame section.
-/// If no eh-frame section is found then the address and size will both be given
-/// as zero.
-///
-/// Authors of JITLinkContexts can use this function to register a post-fixup
-/// pass that records the range of the eh-frame section. This range can
-/// be used after finalization to register and deregister the frame.
-LinkGraphPassFunction
-createEHFrameRecorderPass(const Triple &TT,
-                          StoreFrameRangeFunction StoreFrameRange);
+/// Returns a pointer to the DWARF eh-frame section if the graph contains a
+/// non-empty one, otherwise returns null.
+Section *getEHFrameSection(LinkGraph &G);
 
 } // end namespace jitlink
 } // end namespace llvm

llvm/include/llvm/ExecutionEngine/Orc/EHFrameRegistrationPlugin.h

@@ -19,37 +19,37 @@
 #include <mutex>
 #include <vector>
 
-namespace llvm {
-
-namespace jitlink {
-class EHFrameRegistrar;
-} // namespace jitlink
-
-namespace orc {
+namespace llvm::orc {
 
+/// Adds AllocationActions to register and deregister eh-frame sections in the
+/// absence of native Platform support.
 class EHFrameRegistrationPlugin : public LinkGraphLinkingLayer::Plugin {
 public:
-  EHFrameRegistrationPlugin(
-      ExecutionSession &ES,
-      std::unique_ptr<jitlink::EHFrameRegistrar> Registrar);
+  static Expected<std::unique_ptr<EHFrameRegistrationPlugin>>
+  Create(ExecutionSession &ES);
+
+  EHFrameRegistrationPlugin(ExecutorAddr RegisterEHFrame,
+                            ExecutorAddr DeregisterEHFrame)
+      : RegisterEHFrame(RegisterEHFrame), DeregisterEHFrame(DeregisterEHFrame) {
+  }
+
   void modifyPassConfig(MaterializationResponsibility &MR,
                         jitlink::LinkGraph &G,
                         jitlink::PassConfiguration &PassConfig) override;
-  Error notifyEmitted(MaterializationResponsibility &MR) override;
-  Error notifyFailed(MaterializationResponsibility &MR) override;
-  Error notifyRemovingResources(JITDylib &JD, ResourceKey K) override;
+  Error notifyFailed(MaterializationResponsibility &MR) override {
+    return Error::success();
+  }
+  Error notifyRemovingResources(JITDylib &JD, ResourceKey K) override {
+    return Error::success();
+  }
   void notifyTransferringResources(JITDylib &JD, ResourceKey DstKey,
-                                   ResourceKey SrcKey) override;
+                                   ResourceKey SrcKey) override {}
 
 private:
-  std::mutex EHFramePluginMutex;
-  ExecutionSession &ES;
-  std::unique_ptr<jitlink::EHFrameRegistrar> Registrar;
-  DenseMap<MaterializationResponsibility *, ExecutorAddrRange> InProcessLinks;
-  DenseMap<ResourceKey, std::vector<ExecutorAddrRange>> EHFrameRanges;
+  ExecutorAddr RegisterEHFrame;
+  ExecutorAddr DeregisterEHFrame;
 };
 
-} // end namespace orc
-} // end namespace llvm
+} // namespace llvm::orc
 
 #endif // LLVM_EXECUTIONENGINE_ORC_EHFRAMEREGISTRATIONPLUGIN_H

llvm/include/llvm/ExecutionEngine/Orc/EPCEHFrameRegistrar.h

@@ -44,8 +44,8 @@ extern const char *MemoryWriteUInt64sWrapperName;
 extern const char *MemoryWriteBuffersWrapperName;
 extern const char *MemoryWritePointersWrapperName;
 
-extern const char *RegisterEHFrameSectionWrapperName;
-extern const char *DeregisterEHFrameSectionWrapperName;
+extern const char *RegisterEHFrameSectionAllocActionName;
+extern const char *DeregisterEHFrameSectionAllocActionName;
 
 extern const char *RunAsMainWrapperName;
 extern const char *RunAsVoidFunctionWrapperName;

llvm/include/llvm/ExecutionEngine/Orc/Shared/OrcRTBridge.h

@@ -35,9 +35,9 @@ Error deregisterEHFrameSection(const void *EHFrameSectionAddr,
 } // end namespace llvm
 
 extern "C" LLVM_ABI llvm::orc::shared::CWrapperFunctionResult
-llvm_orc_registerEHFrameSectionWrapper(const char *Data, uint64_t Size);
+llvm_orc_registerEHFrameSectionAllocAction(const char *Data, uint64_t Size);
 
 extern "C" LLVM_ABI llvm::orc::shared::CWrapperFunctionResult
-llvm_orc_deregisterEHFrameSectionWrapper(const char *Data, uint64_t Size);
+llvm_orc_deregisterEHFrameSectionAllocAction(const char *Data, uint64_t Size);
 
 #endif // LLVM_EXECUTIONENGINE_ORC_TARGETPROCESS_REGISTEREHFRAMES_H

llvm/include/llvm/ExecutionEngine/Orc/TargetProcess/RegisterEHFrames.h

@@ -639,20 +639,6 @@ Error EHFrameNullTerminator::operator()(LinkGraph &G) {
   return Error::success();
 }
 
-EHFrameRegistrar::~EHFrameRegistrar() = default;
-
-Error InProcessEHFrameRegistrar::registerEHFrames(
-    orc::ExecutorAddrRange EHFrameSection) {
-  return orc::registerEHFrameSection(EHFrameSection.Start.toPtr<void *>(),
-                                     EHFrameSection.size());
-}
-
-Error InProcessEHFrameRegistrar::deregisterEHFrames(
-    orc::ExecutorAddrRange EHFrameSection) {
-  return orc::deregisterEHFrameSection(EHFrameSection.Start.toPtr<void *>(),
-                                       EHFrameSection.size());
-}
-
 EHFrameCFIBlockInspector EHFrameCFIBlockInspector::FromEdgeScan(Block &B) {
   if (B.edges_empty())
     return EHFrameCFIBlockInspector(nullptr);
@@ -678,36 +664,24 @@ EHFrameCFIBlockInspector::EHFrameCFIBlockInspector(Edge &CIEEdge,
                                                    Edge *LSDAEdge)
     : CIEEdge(&CIEEdge), PCBeginEdge(&PCBeginEdge), LSDAEdge(LSDAEdge) {}
 
-LinkGraphPassFunction
-createEHFrameRecorderPass(const Triple &TT,
-                          StoreFrameRangeFunction StoreRangeAddress) {
+Section *getEHFrameSection(LinkGraph &G) {
   const char *EHFrameSectionName = nullptr;
-  if (TT.getObjectFormat() == Triple::MachO)
+  switch (G.getTargetTriple().getObjectFormat()) {
+  case Triple::MachO:
     EHFrameSectionName = "__TEXT,__eh_frame";
-  else
+    break;
+  case Triple::ELF:
     EHFrameSectionName = ".eh_frame";
+    break;
+  default:
+    return nullptr;
+  }
 
-  auto RecordEHFrame =
-      [EHFrameSectionName,
-       StoreFrameRange = std::move(StoreRangeAddress)](LinkGraph &G) -> Error {
-    // Search for a non-empty eh-frame and record the address of the first
-    // symbol in it.
-    orc::ExecutorAddr Addr;
-    size_t Size = 0;
-    if (auto *S = G.findSectionByName(EHFrameSectionName)) {
-      auto R = SectionRange(*S);
-      Addr = R.getStart();
-      Size = R.getSize();
-    }
-    if (!Addr && Size != 0)
-      return make_error<JITLinkError>(
-          StringRef(EHFrameSectionName) +
-          " section can not have zero address with non-zero size");
-    StoreFrameRange(Addr, Size);
-    return Error::success();
-  };
+  if (auto *S = G.findSectionByName(EHFrameSectionName))
+    if (!S->empty())
+      return S;
 
-  return RecordEHFrame;
+  return nullptr;
 }
 
 } // end namespace jitlink

llvm/lib/ExecutionEngine/JITLink/EHFrameSupport.cpp

@@ -18,7 +18,6 @@ add_llvm_component_library(LLVMOrcJIT
   EHFrameRegistrationPlugin.cpp
   EPCDynamicLibrarySearchGenerator.cpp
   EPCDebugObjectRegistrar.cpp
-  EPCEHFrameRegistrar.cpp
   EPCGenericDylibManager.cpp
   EPCGenericJITLinkMemoryManager.cpp
   EPCGenericRTDyldMemoryManager.cpp