From 7a598477aaf742ab4c771be79d532fd2dfc87fbe Mon Sep 17 00:00:00 2001
From: Lang Hames <lhames@gmail.com>
Date: Thu, 5 Apr 2018 19:37:05 +0000
Subject: [PATCH] [RuntimeDyld][PowerPC] Use global entry points for calls
 between sections.

Functions in different objects may use different TOCs, so calls between such
functions should use the global entry point of the callee which updates the
TOC pointer.

This should fix a bug that the Numba developers encountered (see
https://github.com/numba/numba/issues/2451).

Patch by Olexa Bilaniuk. Thanks Olexa!

No RuntimeDyld checker test case yet as I am not familiar enough with how
RuntimeDyldELF fixes up call-sites, but I do not want to hold up landing
this. I will continue to work on it and see if I can rope some powerpc
experts in.

llvm-svn: 329335
---
 .../ExecutionEngine/RuntimeDyld/RuntimeDyldELF.cpp | 22 +++++++++++++---------
 1 file changed, 13 insertions(+), 9 deletions(-)

diff --git a/llvm/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldELF.cpp b/llvm/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldELF.cpp
index 36b43ec9..b6992f6 100644
--- a/llvm/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldELF.cpp
+++ b/llvm/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldELF.cpp
@@ -1423,7 +1423,8 @@ RuntimeDyldELF::processRelocationRef(
       SectionEntry &Section = Sections[SectionID];
       uint8_t *Target = Section.getAddressWithOffset(Offset);
       bool RangeOverflow = false;
-      if (!Value.SymbolName && SymType != SymbolRef::ST_Unknown) {
+      bool IsExtern = Value.SymbolName || SymType == SymbolRef::ST_Unknown;
+      if (!IsExtern) {
         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
@@ -1433,21 +1434,24 @@ RuntimeDyldELF::processRelocationRef(
         } else {
           // In the ELFv2 ABI, a function symbol may provide a local entry
           // point, which must be used for direct calls.
-          uint8_t SymOther = Symbol->getOther();
-          Value.Addend += ELF::decodePPC64LocalEntryOffset(SymOther);
+          if (Value.SectionID == SectionID){
+            uint8_t SymOther = Symbol->getOther();
+            Value.Addend += ELF::decodePPC64LocalEntryOffset(SymOther);
+          }
         }
         uint8_t *RelocTarget =
             Sections[Value.SectionID].getAddressWithOffset(Value.Addend);
         int64_t delta = static_cast<int64_t>(Target - RelocTarget);
         // If it is within 26-bits branch range, just set the branch target
-        if (SignExtend64<26>(delta) == delta) {
+        if (SignExtend64<26>(delta) != delta) {
+          RangeOverflow = true;
+        } else if ((AbiVariant != 2) ||
+                   (AbiVariant == 2  && Value.SectionID == SectionID)) {
           RelocationEntry RE(SectionID, Offset, RelType, Value.Addend);
           addRelocationForSection(RE, Value.SectionID);
-        } else {
-          RangeOverflow = true;
         }
       }
-      if (Value.SymbolName || SymType == SymbolRef::ST_Unknown ||
+      if (IsExtern || (AbiVariant == 2 && Value.SectionID != SectionID) ||
           RangeOverflow) {
         // It is an external symbol (either Value.SymbolName is set, or
         // SymType is SymbolRef::ST_Unknown) or out of range.
@@ -1504,10 +1508,10 @@ RuntimeDyldELF::processRelocationRef(
                             RelType, 0);
           Section.advanceStubOffset(getMaxStubSize());
         }
-        if (Value.SymbolName || SymType == SymbolRef::ST_Unknown) {
+        if (IsExtern || (AbiVariant == 2 && Value.SectionID != SectionID)) {
           // Restore the TOC for external calls
           if (AbiVariant == 2)
-            writeInt32BE(Target + 4, 0xE8410018); // ld r2,28(r1)
+            writeInt32BE(Target + 4, 0xE8410018); // ld r2,24(r1)
           else
             writeInt32BE(Target + 4, 0xE8410028); // ld r2,40(r1)
         }
-- 
2.7.4