Implement GDB integration for source level debugging of code JITed using

the MCJIT execution engine.

The GDB JIT debugging integration support works by registering a loaded
object image with a pre-defined function that GDB will monitor if GDB
is attached. GDB integration support is implemented for ELF only at this
time. This integration requires GDB version 7.0 or newer.

Patch by Andy Kaylor!

 


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@154868 91177308-0d34-0410-b5e6-96231b3b80d8

7 files changed, 226 insertions, 24 deletions

diff --git a/lib/ExecutionEngine/RuntimeDyld/CMakeLists.txt b/lib/ExecutionEngine/RuntimeDyld/CMakeLists.txt
index 002e63cd3b..cbf7cf14d4 100644
--- a/lib/ExecutionEngine/RuntimeDyld/CMakeLists.txt
+++ b/lib/ExecutionEngine/RuntimeDyld/CMakeLists.txt
@@ -1,5 +1,6 @@
 add_llvm_library(LLVMRuntimeDyld
+  GDBRegistrar.cpp
   RuntimeDyld.cpp
-  RuntimeDyldMachO.cpp
   RuntimeDyldELF.cpp
+  RuntimeDyldMachO.cpp
   )
diff --git a/lib/ExecutionEngine/RuntimeDyld/RuntimeDyld.cpp b/lib/ExecutionEngine/RuntimeDyld/RuntimeDyld.cpp
index 63cec1aca3..1b1840ae06 100644
--- a/lib/ExecutionEngine/RuntimeDyld/RuntimeDyld.cpp
+++ b/lib/ExecutionEngine/RuntimeDyld/RuntimeDyld.cpp
@@ -59,11 +59,17 @@ void RuntimeDyldImpl::mapSectionAddress(void *LocalAddress,
   llvm_unreachable("Attempting to remap address of unknown section!");
 }
 
+// Subclasses can implement this method to create specialized image instances
+// The caller owns the the pointer that is returned.
+ObjectImage *RuntimeDyldImpl::createObjectImage(const MemoryBuffer *InputBuffer) {
+  ObjectFile *ObjFile = ObjectFile::createObjectFile(const_cast<MemoryBuffer*>
+                                                                 (InputBuffer));
+  ObjectImage *Obj = new ObjectImage(ObjFile);
+  return Obj;
+}
+
 bool RuntimeDyldImpl::loadObject(const MemoryBuffer *InputBuffer) {
-  // FIXME: ObjectFile don't modify MemoryBuffer.
-  //        It should use const MemoryBuffer as parameter.
-  OwningPtr<ObjectFile> obj(ObjectFile::createObjectFile(
-                                       const_cast<MemoryBuffer*>(InputBuffer)));
+  OwningPtr<ObjectImage> obj(createObjectImage(InputBuffer));
   if (!obj)
     report_fatal_error("Unable to create object image from memory buffer!");
 
@@ -110,7 +116,8 @@ bool RuntimeDyldImpl::loadObject(const MemoryBuffer *InputBuffer) {
                                 (uintptr_t)FileOffset;
         uintptr_t SectOffset = (uintptr_t)(SymPtr - (const uint8_t*)sData.begin());
         unsigned SectionID =
-          findOrEmitSection(*si,
+          findOrEmitSection(*obj,
+                            *si,
                             SymType == object::SymbolRef::ST_Function,
                             LocalSections);
         bool isGlobal = flags & SymbolRef::SF_Global;
@@ -128,7 +135,7 @@ bool RuntimeDyldImpl::loadObject(const MemoryBuffer *InputBuffer) {
 
   // Allocate common symbols
   if (CommonSize != 0)
-    emitCommonSymbols(CommonSymbols, CommonSize, LocalSymbols);
+    emitCommonSymbols(*obj, CommonSymbols, CommonSize, LocalSymbols);
 
   // Parse and proccess relocations
   DEBUG(dbgs() << "Parse relocations:\n");
@@ -145,7 +152,7 @@ bool RuntimeDyldImpl::loadObject(const MemoryBuffer *InputBuffer) {
 
       // If it's first relocation in this section, find its SectionID
       if (isFirstRelocation) {
-        SectionID = findOrEmitSection(*si, true, LocalSections);
+        SectionID = findOrEmitSection(*obj, *si, true, LocalSections);
         DEBUG(dbgs() << "\tSectionID: " << SectionID << "\n");
         isFirstRelocation = false;
       }
@@ -164,10 +171,14 @@ bool RuntimeDyldImpl::loadObject(const MemoryBuffer *InputBuffer) {
       processRelocationRef(RI, *obj, LocalSections, LocalSymbols, Stubs);
     }
   }
+
+  handleObjectLoaded(obj.take());
+
   return false;
 }
 
-unsigned RuntimeDyldImpl::emitCommonSymbols(const CommonSymbolMap &Map,
+unsigned RuntimeDyldImpl::emitCommonSymbols(ObjectImage &Obj,
+                                            const CommonSymbolMap &Map,
                                             uint64_t TotalSize,
                                             LocalSymbolMap &LocalSymbols) {
   // Allocate memory for the section
@@ -191,6 +202,7 @@ unsigned RuntimeDyldImpl::emitCommonSymbols(const CommonSymbolMap &Map,
     uint64_t Size = it->second;
     StringRef Name;
     it->first.getName(Name);
+    Obj.updateSymbolAddress(it->first, (uint64_t)Addr);
     LocalSymbols[Name.data()] = SymbolLoc(SectionID, Offset);
     Offset += Size;
     Addr += Size;
@@ -199,7 +211,8 @@ unsigned RuntimeDyldImpl::emitCommonSymbols(const CommonSymbolMap &Map,
   return SectionID;
 }
 
-unsigned RuntimeDyldImpl::emitSection(const SectionRef &Section,
+unsigned RuntimeDyldImpl::emitSection(ObjectImage &Obj,
+                                      const SectionRef &Section,
                                       bool IsCode) {
 
   unsigned StubBufSize = 0,
@@ -257,6 +270,7 @@ unsigned RuntimeDyldImpl::emitSection(const SectionRef &Section,
                  << " StubBufSize: " << StubBufSize
                  << " Allocate: " << Allocate
                  << "\n");
+    Obj.updateSectionAddress(Section, (uint64_t)Addr);
   }
   else {
     // Even if we didn't load the section, we need to record an entry for it
@@ -277,7 +291,8 @@ unsigned RuntimeDyldImpl::emitSection(const SectionRef &Section,
   return SectionID;
 }
 
-unsigned RuntimeDyldImpl::findOrEmitSection(const SectionRef &Section,
+unsigned RuntimeDyldImpl::findOrEmitSection(ObjectImage &Obj,
+                                            const SectionRef &Section,
                                             bool IsCode,
                                             ObjSectionToIDMap &LocalSections) {
 
@@ -286,7 +301,7 @@ unsigned RuntimeDyldImpl::findOrEmitSection(const SectionRef &Section,
   if (i != LocalSections.end())
     SectionID = i->second;
   else {
-    SectionID = emitSection(Section, IsCode);
+    SectionID = emitSection(Obj, Section, IsCode);
     LocalSections[Section] = SectionID;
   }
   return SectionID;
diff --git a/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldELF.cpp b/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldELF.cpp
index 57fefee5de..e2ebc342ad 100644
--- a/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldELF.cpp
+++ b/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldELF.cpp
@@ -20,11 +20,176 @@
 #include "llvm/Object/ObjectFile.h"
 #include "llvm/Support/ELF.h"
 #include "llvm/ADT/Triple.h"
+#include "llvm/Object/ELF.h"
+#include "JITRegistrar.h"
 using namespace llvm;
 using namespace llvm::object;
 
+namespace {
+
+template<support::endianness target_endianness, bool is64Bits>
+class DyldELFObject : public ELFObjectFile<target_endianness, is64Bits> {
+  LLVM_ELF_IMPORT_TYPES(target_endianness, is64Bits)
+
+  typedef Elf_Shdr_Impl<target_endianness, is64Bits> Elf_Shdr;
+  typedef Elf_Sym_Impl<target_endianness, is64Bits> Elf_Sym;
+  typedef Elf_Rel_Impl<target_endianness, is64Bits, false> Elf_Rel;
+  typedef Elf_Rel_Impl<target_endianness, is64Bits, true> Elf_Rela;
+
+  typedef typename ELFObjectFile<target_endianness, is64Bits>::
+    Elf_Ehdr Elf_Ehdr;
+
+  typedef typename ELFDataTypeTypedefHelper<
+          target_endianness, is64Bits>::value_type addr_type;
+
+protected:
+  // This duplicates the 'Data' member in the 'Binary' base class
+  // but it is necessary to workaround a bug in gcc 4.2
+  MemoryBuffer *InputData;
+
+public:
+  DyldELFObject(MemoryBuffer *Object, error_code &ec);
+
+  void updateSectionAddress(const SectionRef &Sec, uint64_t Addr);
+  void updateSymbolAddress(const SymbolRef &Sym, uint64_t Addr);
+
+  const MemoryBuffer& getBuffer() const { return *InputData; }
+
+  // Methods for type inquiry through isa, cast, and dyn_cast
+  static inline bool classof(const Binary *v) {
+    return (isa<ELFObjectFile<target_endianness, is64Bits> >(v)
+            && classof(cast<ELFObjectFile<target_endianness, is64Bits> >(v)));
+  }
+  static inline bool classof(
+      const ELFObjectFile<target_endianness, is64Bits> *v) {
+    return v->isDyldType();
+  }
+  static inline bool classof(const DyldELFObject *v) {
+    return true;
+  }
+};
+
+template<support::endianness target_endianness, bool is64Bits>
+class ELFObjectImage : public ObjectImage {
+  protected:
+    DyldELFObject<target_endianness, is64Bits> *DyldObj;
+    bool Registered;
+
+  public:
+    ELFObjectImage(DyldELFObject<target_endianness, is64Bits> *Obj)
+    : ObjectImage(Obj),
+      DyldObj(Obj),
+      Registered(false) {}
+
+    virtual ~ELFObjectImage() {
+      if (Registered)
+        deregisterWithDebugger();
+    }
+
+    // Subclasses can override these methods to update the image with loaded
+    // addresses for sections and common symbols
+    virtual void updateSectionAddress(const SectionRef &Sec, uint64_t Addr)
+    {
+      DyldObj->updateSectionAddress(Sec, Addr);
+    }
+
+    virtual void updateSymbolAddress(const SymbolRef &Sym, uint64_t Addr)
+    {
+      DyldObj->updateSymbolAddress(Sym, Addr);
+    }
+
+    virtual void registerWithDebugger()
+    {
+      JITRegistrar::getGDBRegistrar().registerObject(DyldObj->getBuffer());
+      Registered = true;
+    }
+    virtual void deregisterWithDebugger()
+    {
+      JITRegistrar::getGDBRegistrar().deregisterObject(DyldObj->getBuffer());
+    }
+};
+
+template<support::endianness target_endianness, bool is64Bits>
+DyldELFObject<target_endianness, is64Bits>::DyldELFObject(MemoryBuffer *Object,
+                                                          error_code &ec)
+  : ELFObjectFile<target_endianness, is64Bits>(Object, ec),
+    InputData(Object) {
+  this->isDyldELFObject = true;
+}
+
+template<support::endianness target_endianness, bool is64Bits>
+void DyldELFObject<target_endianness, is64Bits>::updateSectionAddress(
+                                                       const SectionRef &Sec,
+                                                       uint64_t Addr) {
+  DataRefImpl ShdrRef = Sec.getRawDataRefImpl();
+  Elf_Shdr *shdr = const_cast<Elf_Shdr*>(
+                          reinterpret_cast<const Elf_Shdr *>(ShdrRef.p));
+
+  // This assumes the address passed in matches the target address bitness
+  // The template-based type cast handles everything else.
+  shdr->sh_addr = static_cast<addr_type>(Addr);
+}
+
+template<support::endianness target_endianness, bool is64Bits>
+void DyldELFObject<target_endianness, is64Bits>::updateSymbolAddress(
+                                                       const SymbolRef &SymRef,
+                                                       uint64_t Addr) {
+
+  Elf_Sym *sym = const_cast<Elf_Sym*>(
+                                 ELFObjectFile<target_endianness, is64Bits>::
+                                   getSymbol(SymRef.getRawDataRefImpl()));
+
+  // This assumes the address passed in matches the target address bitness
+  // The template-based type cast handles everything else.
+  sym->st_value = static_cast<addr_type>(Addr);
+}
+
+} // namespace
+
+
 namespace llvm {
 
+ObjectImage *RuntimeDyldELF::createObjectImage(
+                                         const MemoryBuffer *ConstInputBuffer) {
+  MemoryBuffer *InputBuffer = const_cast<MemoryBuffer*>(ConstInputBuffer);
+  std::pair<unsigned char, unsigned char> Ident = getElfArchType(InputBuffer);
+  error_code ec;
+
+  if (Ident.first == ELF::ELFCLASS32 && Ident.second == ELF::ELFDATA2LSB) {
+    DyldELFObject<support::little, false> *Obj =
+           new DyldELFObject<support::little, false>(InputBuffer, ec);
+    return new ELFObjectImage<support::little, false>(Obj);
+  }
+  else if (Ident.first == ELF::ELFCLASS32 && Ident.second == ELF::ELFDATA2MSB) {
+    DyldELFObject<support::big, false> *Obj =
+           new DyldELFObject<support::big, false>(InputBuffer, ec);
+    return new ELFObjectImage<support::big, false>(Obj);
+  }
+  else if (Ident.first == ELF::ELFCLASS64 && Ident.second == ELF::ELFDATA2MSB) {
+    DyldELFObject<support::big, true> *Obj =
+           new DyldELFObject<support::big, true>(InputBuffer, ec);
+    return new ELFObjectImage<support::big, true>(Obj);
+  }
+  else if (Ident.first == ELF::ELFCLASS64 && Ident.second == ELF::ELFDATA2LSB) {
+    DyldELFObject<support::little, true> *Obj =
+           new DyldELFObject<support::little, true>(InputBuffer, ec);
+    return new ELFObjectImage<support::little, true>(Obj);
+  }
+  else
+    llvm_unreachable("Unexpected ELF format");
+}
+
+void RuntimeDyldELF::handleObjectLoaded(ObjectImage *Obj)
+{
+  Obj->registerWithDebugger();
+  // Save the loaded object.  It will deregister itself when deleted
+  LoadedObject = Obj;
+}
+
+RuntimeDyldELF::~RuntimeDyldELF() {
+  if (LoadedObject)
+    delete LoadedObject;
+}
 
 void RuntimeDyldELF::resolveX86_64Relocation(uint8_t *LocalAddress,
                                              uint64_t FinalAddress,
@@ -167,7 +332,7 @@ void RuntimeDyldELF::resolveRelocation(uint8_t *LocalAddress,
 }
 
 void RuntimeDyldELF::processRelocationRef(const ObjRelocationInfo &Rel,
-                                          const ObjectFile &Obj,
+                                          ObjectImage &Obj,
                                           ObjSectionToIDMap &ObjSectionToID,
                                           LocalSymbolMap &Symbols,
                                           StubMap &Stubs) {
@@ -206,7 +371,7 @@ void RuntimeDyldELF::processRelocationRef(const ObjRelocationInfo &Rel,
           if (si == Obj.end_sections())
             llvm_unreachable("Symbol section not found, bad object file format!");
           DEBUG(dbgs() << "\t\tThis is section symbol\n");
-          Value.SectionID = findOrEmitSection((*si), true, ObjSectionToID);
+          Value.SectionID = findOrEmitSection(Obj, (*si), true, ObjSectionToID);
           Value.Addend = Addend;
           break;
         }
diff --git a/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldELF.h b/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldELF.h
index 36566da57a..e7f6fab16f 100644
--- a/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldELF.h
+++ b/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldELF.h
@@ -22,6 +22,8 @@ using namespace llvm;
 namespace llvm {
 class RuntimeDyldELF : public RuntimeDyldImpl {
 protected:
+  ObjectImage *LoadedObject;
+
   void resolveX86_64Relocation(uint8_t *LocalAddress,
                                uint64_t FinalAddress,
                                uint64_t Value,
@@ -47,12 +49,18 @@ protected:
                                  int64_t Addend);
 
   virtual void processRelocationRef(const ObjRelocationInfo &Rel,
-                                    const ObjectFile &Obj,
+                                    ObjectImage &Obj,
                                     ObjSectionToIDMap &ObjSectionToID,
                                     LocalSymbolMap &Symbols, StubMap &Stubs);
 
+  virtual ObjectImage *createObjectImage(const MemoryBuffer *InputBuffer);
+  virtual void handleObjectLoaded(ObjectImage *Obj);
+
 public:
-  RuntimeDyldELF(RTDyldMemoryManager *mm) : RuntimeDyldImpl(mm) {}
+  RuntimeDyldELF(RTDyldMemoryManager *mm)
+      : RuntimeDyldImpl(mm), LoadedObject(0) {}
+
+  virtual ~RuntimeDyldELF();
 
   bool isCompatibleFormat(const MemoryBuffer *InputBuffer) const;
 };
diff --git a/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldImpl.h b/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldImpl.h
index bf678af6ec..2dea13f15c 100644
--- a/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldImpl.h
+++ b/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldImpl.h
@@ -29,6 +29,7 @@
 #include "llvm/ADT/Triple.h"
 #include <map>
 #include "llvm/Support/Format.h"
+#include "ObjectImage.h"
 
 using namespace llvm;
 using namespace llvm::object;
@@ -154,7 +155,8 @@ protected:
 
   /// \brief Emits a section containing common symbols.
   /// \return SectionID.
-  unsigned emitCommonSymbols(const CommonSymbolMap &Map,
+  unsigned emitCommonSymbols(ObjectImage &Obj,
+                             const CommonSymbolMap &Map,
                              uint64_t TotalSize,
                              LocalSymbolMap &Symbols);
 
@@ -162,14 +164,18 @@ protected:
   /// \param IsCode if it's true then allocateCodeSection() will be
   ///        used for emmits, else allocateDataSection() will be used.
   /// \return SectionID.
-  unsigned emitSection(const SectionRef &Section, bool IsCode);
+  unsigned emitSection(ObjectImage &Obj,
+                       const SectionRef &Section,
+                       bool IsCode);
 
   /// \brief Find Section in LocalSections. If the secton is not found - emit
   ///        it and store in LocalSections.
   /// \param IsCode if it's true then allocateCodeSection() will be
   ///        used for emmits, else allocateDataSection() will be used.
   /// \return SectionID.
-  unsigned findOrEmitSection(const SectionRef &Section, bool IsCode,
+  unsigned findOrEmitSection(ObjectImage &Obj,
+                             const SectionRef &Section,
+                             bool IsCode,
                              ObjSectionToIDMap &LocalSections);
 
   /// \brief If Value.SymbolName is NULL then store relocation to the
@@ -200,11 +206,18 @@ protected:
   /// \brief Parses the object file relocation and store it to Relocations
   ///        or SymbolRelocations. Its depend from object file type.
   virtual void processRelocationRef(const ObjRelocationInfo &Rel,
-                                    const ObjectFile &Obj,
+                                    ObjectImage &Obj,
                                     ObjSectionToIDMap &ObjSectionToID,
                                     LocalSymbolMap &Symbols, StubMap &Stubs) = 0;
 
   void resolveSymbols();
+  virtual ObjectImage *createObjectImage(const MemoryBuffer *InputBuffer);
+  virtual void handleObjectLoaded(ObjectImage *Obj)
+  {
+    // Subclasses may choose to retain this image if they have a use for it
+    delete Obj;
+  }
+
 public:
   RuntimeDyldImpl(RTDyldMemoryManager *mm) : MemMgr(mm), HasError(false) {}
 
diff --git a/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldMachO.cpp b/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldMachO.cpp
index 1318b44542..b7f515d6ce 100644
--- a/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldMachO.cpp
+++ b/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldMachO.cpp
@@ -205,7 +205,7 @@ resolveARMRelocation(uint8_t *LocalAddress,
 }
 
 void RuntimeDyldMachO::processRelocationRef(const ObjRelocationInfo &Rel,
-                                            const ObjectFile &Obj,
+                                            ObjectImage &Obj,
                                             ObjSectionToIDMap &ObjSectionToID,
                                             LocalSymbolMap &Symbols,
                                             StubMap &Stubs) {
@@ -246,7 +246,7 @@ void RuntimeDyldMachO::processRelocationRef(const ObjRelocationInfo &Rel,
         break;
     }
     assert(si != se && "No section containing relocation!");
-    Value.SectionID = findOrEmitSection(*si, true, ObjSectionToID);
+    Value.SectionID = findOrEmitSection(Obj, *si, true, ObjSectionToID);
     Value.Addend = *(const intptr_t *)Target;
     if (Value.Addend) {
       // The MachO addend is offset from the current section, we need set it
diff --git a/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldMachO.h b/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldMachO.h
index 898b85190e..418d130f63 100644
--- a/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldMachO.h
+++ b/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldMachO.h
@@ -49,7 +49,7 @@ protected:
                             int64_t Addend);
 
   virtual void processRelocationRef(const ObjRelocationInfo &Rel,
-                                    const ObjectFile &Obj,
+                                    ObjectImage &Obj,
                                     ObjSectionToIDMap &ObjSectionToID,
                                     LocalSymbolMap &Symbols, StubMap &Stubs);
 
@@ -59,7 +59,7 @@ public:
                                  uint64_t Value,
                                  uint32_t Type,
                                  int64_t Addend);
-                                 
+
   RuntimeDyldMachO(RTDyldMemoryManager *mm) : RuntimeDyldImpl(mm) {}
 
   bool isCompatibleFormat(const MemoryBuffer *InputBuffer) const;