Fixed dangling reference in RuntimeDyldELF

[MoritzS]

Fixed build error

[MoritzS]

ping

[lhames]

Looks good to me. Thanks Moritz!

If you have commit access please go ahead and land this. If not then let me know and I can commit on your behalf.

[MoritzS]

I don't have commit access, so please go ahead and commit it.

Thanks!

[MoritzS]

Rebased onto master

[MoritzS]

Rebased onto master

[MoritzS]

Rebased onto master

llvm/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldELF.cpp

 //===-- RuntimeDyldELF.cpp - Run-time dynamic linker for MC-JIT -*- C++ -*-===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 //
if (RelType == ELF::R_X86_64_PLT32) {
       // can't be sure the function will be within 2^32 bytes of the call site, so
       // we need to create a stub, which calls into the GOT.  This case is
       // equivalent to the usual PLT implementation except that we use the stub
       // mechanism in RuntimeDyld (which puts stubs at the end of the section)
       // rather than allocating a PLT section.
       if (Value.SymbolName) {
         // This is a call to an external function.
         // Look for an existing stub.
-        SectionEntry &Section = Sections[SectionID];
+        SectionEntry *Section = &Sections[SectionID];
         StubMap::const_iterator i = Stubs.find(Value);
         uintptr_t StubAddress;
         if (i != Stubs.end()) {
-          StubAddress = uintptr_t(Section.getAddress()) + i->second;
+          StubAddress = uintptr_t(Section->getAddress()) + i->second;
           LLVM_DEBUG(dbgs() << " Stub function found\n");
         } else {
           // Create a new stub function (equivalent to a PLT entry).
           LLVM_DEBUG(dbgs() << " Create a new stub function\n");
 
-          uintptr_t BaseAddress = uintptr_t(Section.getAddress());
+          uintptr_t BaseAddress = uintptr_t(Section->getAddress());
           uintptr_t StubAlignment = getStubAlignment();
           StubAddress =
-              (BaseAddress + Section.getStubOffset() + StubAlignment - 1) &
+              (BaseAddress + Section->getStubOffset() + StubAlignment - 1) &
               -StubAlignment;
           unsigned StubOffset = StubAddress - BaseAddress;
           Stubs[Value] = StubOffset;
           createStubFunction((uint8_t *)StubAddress);
 
           // Bump our stub offset counter
-          Section.advanceStubOffset(getMaxStubSize());
+          Section->advanceStubOffset(getMaxStubSize());
 
           // Allocate a GOT Entry
           uint64_t GOTOffset = allocateGOTEntries(1);
+          // This potentially creates a new Section which potentially
+          // invalidates the Section pointer, so reload it.
+          Section = &Sections[SectionID];
 
           // The load of the GOT address has an addend of -4
           resolveGOTOffsetRelocation(SectionID, StubOffset + 2, GOTOffset - 4,
                                      ELF::R_X86_64_PC32);
 
           // Fill in the value of the symbol we're targeting into the GOT
           addRelocationForSymbol(
               computeGOTOffsetRE(GOTOffset, 0, ELF::R_X86_64_64),
               Value.SymbolName);
         }
 
         // Make the target call a call into the stub table.
-        resolveRelocation(Section, Offset, StubAddress, ELF::R_X86_64_PC32,
+        resolveRelocation(*Section, Offset, StubAddress, ELF::R_X86_64_PC32,
                           Addend);
       } else {
         RelocationEntry RE(SectionID, Offset, ELF::R_X86_64_PC32, Value.Addend,
                   Value.Offset);
         addRelocationForSection(RE, Value.SectionID);
       }
     } else if (RelType == ELF::R_X86_64_GOTPCREL ||
                RelType == ELF::R_X86_64_GOTPCRELX ||