[RuntimeDyld, PowerPC] Fix regression from r303637

Actually, to identify external symbols, we need to check for
*either* non-null Value.SymbolName *or* a SymType of
Symbol::ST_Unknown.

The former may happen for symbols not known to the JIT at all
(e.g. defined in a native library), while the latter happens
for symbols known to the JIT, but defined in a different module.

Fixed several regressions on big-endian ppc64.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@303655 91177308-0d34-0410-b5e6-96231b3b80d8

lib/ExecutionEngine/RuntimeDyld/RuntimeDyldELF.cpp

@@ -1324,12 +1324,13 @@ RuntimeDyldELF::processRelocationRef(
       Obj.getPlatformFlags(AbiVariant);
       AbiVariant &= ELF::EF_PPC64_ABI;
       // A PPC branch relocation will need a stub function if the target is
-      // an external symbol (Value.SymbolName set) or if the target address
-      // is not within the signed 24-bits branch address.
+      // an external symbol (either Value.SymbolName is set, or SymType is
+      // Symbol::ST_Unknown) or if the target address is not within the
+      // signed 24-bits branch address.
       SectionEntry &Section = Sections[SectionID];
       uint8_t *Target = Section.getAddressWithOffset(Offset);
       bool RangeOverflow = false;
-      if (!Value.SymbolName) {
+      if (!Value.SymbolName && SymType != SymbolRef::ST_Unknown) {
         if (AbiVariant != 2) {
           // In the ELFv1 ABI, a function call may point to the .opd entry,
           // so the final symbol value is calculated based on the relocation
@@ -1353,9 +1354,10 @@ RuntimeDyldELF::processRelocationRef(
           RangeOverflow = true;
         }
       }
-      if (Value.SymbolName || RangeOverflow) {
-        // It is an external symbol (SymbolRef::ST_Unknown) or within a range
-        // larger than 24-bits.
+      if (Value.SymbolName || SymType == SymbolRef::ST_Unknown ||
+          RangeOverflow) {
+        // It is an external symbol (either Value.SymbolName is set, or
+        // SymType is SymbolRef::ST_Unknown) or out of range.
         StubMap::const_iterator i = Stubs.find(Value);
         if (i != Stubs.end()) {
           // Symbol function stub already created, just relocate to it
@@ -1409,7 +1411,7 @@ RuntimeDyldELF::processRelocationRef(
                             RelType, 0);
           Section.advanceStubOffset(getMaxStubSize());
         }
-        if (Value.SymbolName) {
+        if (Value.SymbolName || SymType == SymbolRef::ST_Unknown) {
           // Restore the TOC for external calls
           if (AbiVariant == 2)
             writeInt32BE(Target + 4, 0xE8410018); // ld r2,28(r1)