[llvm] r358840 - [JITLink] Remove an overly strict error check in JITLink's eh-frame parser.

[Lang Hames via llvm-commits]

Author: lhames
Date: Sat Apr 20 21:48:32 2019
New Revision: 358840

URL: http://llvm.org/viewvc/llvm-project?rev=358840&view=rev
Log:
[JITLink] Remove an overly strict error check in JITLink's eh-frame parser.

The error check required FDEs to refer to the most recent CIE, but the eh-frame
spec allows them to refer to any previously seen CIE. This patch removes the
offending check.

Modified:
    llvm/trunk/lib/ExecutionEngine/JITLink/JITLink_EHFrameSupport.cpp
    llvm/trunk/lib/ExecutionEngine/JITLink/JITLink_EHFrameSupportImpl.h

Modified: llvm/trunk/lib/ExecutionEngine/JITLink/JITLink_EHFrameSupport.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/ExecutionEngine/JITLink/JITLink_EHFrameSupport.cpp?rev=358840&r1=358839&r2=358840&view=diff
==============================================================================
--- llvm/trunk/lib/ExecutionEngine/JITLink/JITLink_EHFrameSupport.cpp (original)
+++ llvm/trunk/lib/ExecutionEngine/JITLink/JITLink_EHFrameSupport.cpp Sat Apr 20 21:48:32 2019
@@ -164,7 +164,6 @@ Error EHFrameParser::processCIE() {
   LLVM_DEBUG(dbgs() << "  Record is CIE\n");
 
   /// Reset state for the new CIE.
-  MostRecentCIE = CurRecordAtom;
   LSDAFieldPresent = false;
 
   uint8_t Version = 0;
@@ -276,26 +275,19 @@ Error EHFrameParser::processFDE(JITTarge
                                 uint32_t CIEPointer) {
   LLVM_DEBUG(dbgs() << "  Record is FDE\n");
 
-  // Sanity check the CIE pointer: if this is an FDE it must be proceeded by
-  // a CIE.
-  if (MostRecentCIE == nullptr)
-    return make_error<JITLinkError>("__eh_frame must start with CIE, not "
-                                    "FDE");
-
   LLVM_DEBUG({
     dbgs() << "  CIE pointer: "
            << format("0x%016" PRIx64, CIEPointerAddress - CIEPointer) << "\n";
   });
 
-  // Verify that this FDE's CIE pointer points to the most recent CIE entry.
-  if (CIEPointerAddress - CIEPointer != MostRecentCIE->getAddress())
-    return make_error<JITLinkError>("__eh_frame FDE's CIE Pointer does not "
-                                    "point at the most recent CIE");
+  auto CIEAtom = G.findAtomByAddress(CIEPointerAddress - CIEPointer);
+  if (!CIEAtom)
+    return CIEAtom.takeError();
 
   // The CIEPointer looks good. Add a relocation.
   CurRecordAtom->addEdge(FDEToCIERelocKind,
                          CIEPointerAddress - CurRecordAtom->getAddress(),
-                         *MostRecentCIE, 0);
+                         *CIEAtom, 0);
 
   // Read and sanity check the PC-start pointer and size.
   JITTargetAddress PCBeginAddress = EHFrameAddress + EHFrameReader.getOffset();

Modified: llvm/trunk/lib/ExecutionEngine/JITLink/JITLink_EHFrameSupportImpl.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/ExecutionEngine/JITLink/JITLink_EHFrameSupportImpl.h?rev=358840&r1=358839&r2=358840&view=diff
==============================================================================
--- llvm/trunk/lib/ExecutionEngine/JITLink/JITLink_EHFrameSupportImpl.h (original)
+++ llvm/trunk/lib/ExecutionEngine/JITLink/JITLink_EHFrameSupportImpl.h Sat Apr 20 21:48:32 2019
@@ -50,7 +50,6 @@ private:
   JITTargetAddress EHFrameAddress;
   BinaryStreamReader EHFrameReader;
   DefinedAtom *CurRecordAtom = nullptr;
-  DefinedAtom *MostRecentCIE = nullptr;
   bool LSDAFieldPresent = false;
   Edge::Kind FDEToCIERelocKind;
   Edge::Kind FDEToTargetRelocKind;