Add EH support to the MCJIT.

This gets exception handling working on ELF and Macho (x86-64 at least).
Other than the EH frame registration, this patch also implements support
for GOT relocations which are used to locate the personality function on
MachO.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@181167 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/ExecutionEngine/RuntimeDyld.h

@@ -66,6 +66,11 @@ public:
   ///
   /// Returns true if an error occurred, false otherwise.
   virtual bool applyPermissions(std::string *ErrMsg = 0) = 0;
+
+  /// Register the EH frames with the runtime so that c++ exceptions work. The
+  /// default implementation does nothing. Look at SectionMemoryManager for one
+  /// that uses __register_frame.
+  virtual void registerEHFrames(StringRef SectionData);
 };
 
 class RuntimeDyld {
@@ -109,6 +114,8 @@ public:
   void mapSectionAddress(const void *LocalAddress, uint64_t TargetAddress);
 
   StringRef getErrorString();
+
+  StringRef getEHFrameSection();
 };
 
 } // end namespace llvm

include/llvm/ExecutionEngine/SectionMemoryManager.h

@@ -72,6 +72,8 @@ public:
   /// \returns true if an error occurred, false otherwise.
   virtual bool applyPermissions(std::string *ErrMsg = 0);
 
+  void registerEHFrames(StringRef SectionData);
+
   /// This method returns the address of the specified function. As such it is
   /// only useful for resolving library symbols, not code generated symbols.
   ///

lib/ExecutionEngine/MCJIT/MCJIT.cpp

@@ -168,15 +168,14 @@ void MCJIT::finalizeObject() {
     // If the call to Dyld.resolveRelocations() is removed from loadObject()
     // we'll need to do that here.
     loadObject(M);
-
-    // Set page permissions.
-    MemMgr->applyPermissions();
-
-    return;
+  } else {
+    // Resolve any relocations.
+    Dyld.resolveRelocations();
   }
 
-  // Resolve any relocations.
-  Dyld.resolveRelocations();
+  StringRef EHData = Dyld.getEHFrameSection();
+  if (!EHData.empty())
+    MemMgr->registerEHFrames(EHData);
 
   // Set page permissions.
   MemMgr->applyPermissions();

lib/ExecutionEngine/MCJIT/SectionMemoryManager.cpp

@@ -146,6 +146,38 @@ bool SectionMemoryManager::applyPermissions(std::string *ErrMsg)
   return false;
 }
 
+// Determine whether we can register EH tables.
+#if (defined(__GNUC__) && !defined(__ARM_EABI__) && \
+     !defined(__USING_SJLJ_EXCEPTIONS__))
+#define HAVE_EHTABLE_SUPPORT 1
+#else
+#define HAVE_EHTABLE_SUPPORT 0
+#endif
+
+#if HAVE_EHTABLE_SUPPORT
+extern "C" void __register_frame(void*);
+
+static const char *processFDE(const char *Entry) {
+  const char *P = Entry;
+  uint32_t Length = *((uint32_t*)P);
+  P += 4;
+  uint32_t Offset = *((uint32_t*)P);
+  if (Offset != 0)
+    __register_frame((void*)Entry);
+  return P + Length;
+}
+#endif
+
+void SectionMemoryManager::registerEHFrames(StringRef SectionData) {
+#if HAVE_EHTABLE_SUPPORT
+  const char *P = SectionData.data();
+  const char *End = SectionData.data() + SectionData.size();
+  do  {
+    P = processFDE(P);
+  } while(P != End);
+#endif
+}
+
 error_code SectionMemoryManager::applyMemoryGroupPermissions(MemoryGroup &MemGroup,
                                                              unsigned Permissions) {
 

lib/ExecutionEngine/RuntimeDyld/RuntimeDyld.cpp

@@ -25,10 +25,15 @@ using namespace llvm::object;
 
 // Empty out-of-line virtual destructor as the key function.
 RTDyldMemoryManager::~RTDyldMemoryManager() {}
+void RTDyldMemoryManager::registerEHFrames(StringRef SectionData) {}
 RuntimeDyldImpl::~RuntimeDyldImpl() {}
 
 namespace llvm {
 
+StringRef RuntimeDyldImpl::getEHFrameSection() {
+  return StringRef();
+}
+
 // Resolve the relocations for all symbols we currently know about.
 void RuntimeDyldImpl::resolveRelocations() {
   // First, resolve relocations associated with external symbols.
@@ -174,7 +179,7 @@ void RuntimeDyldImpl::emitCommonSymbols(ObjectImage &Obj,
   if (!Addr)
     report_fatal_error("Unable to allocate memory for common symbols!");
   uint64_t Offset = 0;
-  Sections.push_back(SectionEntry(StringRef(), Addr, TotalSize, TotalSize, 0));
+  Sections.push_back(SectionEntry(StringRef(), Addr, TotalSize, 0));
   memset(Addr, 0, TotalSize);
 
   DEBUG(dbgs() << "emitCommonSection SectionID: " << SectionID
@@ -292,8 +297,7 @@ unsigned RuntimeDyldImpl::emitSection(ObjectImage &Obj,
                  << "\n");
   }
 
-  Sections.push_back(SectionEntry(Name, Addr, Allocate, DataSize,
-				  (uintptr_t)pData));
+  Sections.push_back(SectionEntry(Name, Addr, DataSize, (uintptr_t)pData));
   return SectionID;
 }
 
@@ -544,4 +548,8 @@ StringRef RuntimeDyld::getErrorString() {
   return Dyld->getErrorString();
 }
 
+StringRef RuntimeDyld::getEHFrameSection() {
+  return Dyld->getEHFrameSection();
+}
+
 } // end namespace llvm

lib/ExecutionEngine/RuntimeDyld/RuntimeDyldELF.cpp

@@ -151,6 +151,14 @@ void DyldELFObject<ELFT>::updateSymbolAddress(const SymbolRef &SymRef,
 
 namespace llvm {
 
+StringRef RuntimeDyldELF::getEHFrameSection() {
+  for (int i = 0, e = Sections.size(); i != e; ++i) {
+    if (Sections[i].Name == ".eh_frame")
+      return StringRef((const char*)Sections[i].Address, Sections[i].Size);
+  }
+  return StringRef();
+}
+
 ObjectImage *RuntimeDyldELF::createObjectImage(ObjectBuffer *Buffer) {
   if (Buffer->getBufferSize() < ELF::EI_NIDENT)
     llvm_unreachable("Unexpected ELF object size");

lib/ExecutionEngine/RuntimeDyld/RuntimeDyldELF.h

@@ -96,6 +96,7 @@ public:
                                     StubMap &Stubs);
   virtual bool isCompatibleFormat(const ObjectBuffer *Buffer) const;
   virtual ObjectImage *createObjectImage(ObjectBuffer *InputBuffer);
+  virtual StringRef getEHFrameSection();
   virtual ~RuntimeDyldELF();
 };
 

lib/ExecutionEngine/RuntimeDyld/RuntimeDyldImpl.h

@@ -49,7 +49,7 @@ public:
   /// Address - address in the linker's memory where the section resides.
   uint8_t *Address;
 
-  /// Size - section size.
+  /// Size - section size. Doesn't include the stubs.
   size_t Size;
 
   /// LoadAddress - the address of the section in the target process's memory.
@@ -67,9 +67,9 @@ public:
   uintptr_t ObjAddress;
 
   SectionEntry(StringRef name, uint8_t *address, size_t size,
-	       uintptr_t stubOffset, uintptr_t objAddress)
+               uintptr_t objAddress)
     : Name(name), Address(address), Size(size), LoadAddress((uintptr_t)address),
-      StubOffset(stubOffset), ObjAddress(objAddress) {}
+      StubOffset(size), ObjAddress(objAddress) {}
 };
 
 /// RelocationEntry - used to represent relocations internally in the dynamic
@@ -174,6 +174,8 @@ protected:
       return 16;
     else if (Arch == Triple::ppc64)
       return 44;
+    else if (Arch == Triple::x86_64)
+      return 8; // GOT
     else if (Arch == Triple::systemz)
       return 16;
     else
@@ -332,6 +334,8 @@ public:
   StringRef getErrorString() { return ErrorStr; }
 
   virtual bool isCompatibleFormat(const ObjectBuffer *Buffer) const = 0;
+
+  virtual StringRef getEHFrameSection();
 };
 
 } // end namespace llvm

lib/ExecutionEngine/RuntimeDyld/RuntimeDyldMachO.cpp

@@ -21,6 +21,69 @@ using namespace llvm::object;
 
 namespace llvm {
 
+static unsigned char *processFDE(unsigned char *P, intptr_t DeltaForText, intptr_t DeltaForEH) {
+  uint32_t Length = *((uint32_t*)P);
+  P += 4;
+  unsigned char *Ret = P + Length;
+  uint32_t Offset = *((uint32_t*)P);
+  if (Offset == 0) // is a CIE
+    return Ret;
+
+  P += 4;
+  intptr_t FDELocation = *((intptr_t*)P);
+  intptr_t NewLocation = FDELocation - DeltaForText;
+  *((intptr_t*)P) = NewLocation;
+  P += sizeof(intptr_t);
+
+  // Skip the FDE address range
+  P += sizeof(intptr_t);
+
+  uint8_t Augmentationsize = *P;
+  P += 1;
+  if (Augmentationsize != 0) {
+    intptr_t LSDA = *((intptr_t*)P);
+    intptr_t NewLSDA = LSDA - DeltaForEH;
+    *((intptr_t*)P) = NewLSDA;
+  }
+
+  return Ret;
+}
+
+static intptr_t computeDelta(SectionEntry *A, SectionEntry *B) {
+  intptr_t ObjDistance = A->ObjAddress  - B->ObjAddress;
+  intptr_t MemDistance = A->LoadAddress - B->LoadAddress;
+  return ObjDistance - MemDistance;
+}
+
+StringRef RuntimeDyldMachO::getEHFrameSection() {
+  SectionEntry *Text = NULL;
+  SectionEntry *EHFrame = NULL;
+  SectionEntry *ExceptTab = NULL;
+  for (int i = 0, e = Sections.size(); i != e; ++i) {
+    if (Sections[i].Name == "__eh_frame")
+      EHFrame = &Sections[i];
+    else if (Sections[i].Name == "__text")
+      Text = &Sections[i];
+    else if (Sections[i].Name == "__gcc_except_tab")
+      ExceptTab = &Sections[i];
+  }
+  if (Text == NULL || EHFrame == NULL)
+    return StringRef();
+
+  intptr_t DeltaForText = computeDelta(Text, EHFrame);
+  intptr_t DeltaForEH = 0;
+  if (ExceptTab)
+    DeltaForEH = computeDelta(ExceptTab, EHFrame);
+
+  unsigned char *P = EHFrame->Address;
+  unsigned char *End = P + EHFrame->Size;
+  do  {
+    P = processFDE(P, DeltaForText, DeltaForEH);
+  } while(P != End);
+
+  return StringRef((char*)EHFrame->Address, EHFrame->Size);
+}
+
 void RuntimeDyldMachO::resolveRelocation(const RelocationEntry &RE,
                                          uint64_t Value) {
   const SectionEntry &Section = Sections[RE.SectionID];
@@ -267,7 +330,30 @@ void RuntimeDyldMachO::processRelocationRef(unsigned SectionID,
     Value.Addend = Addend - Addr;
   }
 
-  if (Arch == Triple::arm && (RelType & 0xf) == macho::RIT_ARM_Branch24Bit) {
+  if (Arch == Triple::x86_64 && RelType == macho::RIT_X86_64_GOT) {
+    assert(IsPCRel);
+    assert(Size == 2);
+    StubMap::const_iterator i = Stubs.find(Value);
+    uint8_t *Addr;
+    if (i != Stubs.end()) {
+      Addr = Section.Address + i->second;
+    } else {
+      Stubs[Value] = Section.StubOffset;
+      uint8_t *GOTEntry = Section.Address + Section.StubOffset;
+      RelocationEntry RE(SectionID, Section.StubOffset,
+                         macho::RIT_X86_64_Unsigned, Value.Addend - 4, false,
+                         3);
+      if (Value.SymbolName)
+        addRelocationForSymbol(RE, Value.SymbolName);
+      else
+        addRelocationForSection(RE, Value.SectionID);
+      Section.StubOffset += 8;
+      Addr = GOTEntry;
+    }
+    resolveRelocation(Section, Offset, (uint64_t)Addr,
+                      macho::RIT_X86_64_Unsigned, 4, true, 2);
+  } else if (Arch == Triple::arm &&
+             (RelType & 0xf) == macho::RIT_ARM_Branch24Bit) {
     // This is an ARM branch relocation, need to use a stub function.
 
     //  Look up for existing stub.

lib/ExecutionEngine/RuntimeDyld/RuntimeDyldMachO.h

@@ -65,6 +65,7 @@ public:
                                     const SymbolTableMap &Symbols,
                                     StubMap &Stubs);
   virtual bool isCompatibleFormat(const ObjectBuffer *Buffer) const;
+  virtual StringRef getEHFrameSection();
 };
 
 } // end namespace llvm

test/ExecutionEngine/MCJIT/eh.ll

@@ -0,0 +1,26 @@
+; RUN: %lli_mcjit %s
+declare i8* @__cxa_allocate_exception(i64)
+declare void @__cxa_throw(i8*, i8*, i8*)
+declare i32 @__gxx_personality_v0(...)
+
+@_ZTIi = external constant i8*
+
+define void @throwException() {
+  %exception = tail call i8* @__cxa_allocate_exception(i64 4)
+  call void @__cxa_throw(i8* %exception, i8* bitcast (i8** @_ZTIi to i8*), i8* null)
+  unreachable
+}
+
+define i32 @main() {
+entry:
+  invoke void @throwException()
+          to label %try.cont unwind label %lpad
+
+lpad:
+  %p = landingpad { i8*, i32 } personality i8* bitcast (i32 (...)* @__gxx_personality_v0 to i8*)
+          catch i8* bitcast (i8** @_ZTIi to i8*)
+  br label %try.cont
+
+try.cont:
+  ret i32 0
+}