[JITLink][ELF] Fix reading target architecture when the ELF object is big-endian

Reviewed By: lhames

Differential Revision: https://reviews.llvm.org/D156982

Author: Kai Luo

llvm/lib/ExecutionEngine/JITLink/ELF.cpp

@@ -52,6 +52,22 @@ Expected<uint16_t> readTargetMachineArch(StringRef Buffer) {
     }
   }
 
+  if (Data[ELF::EI_DATA] == ELF::ELFDATA2MSB) {
+    if (Data[ELF::EI_CLASS] == ELF::ELFCLASS64) {
+      if (auto File = llvm::object::ELF64BEFile::create(Buffer)) {
+        return File->getHeader().e_machine;
+      } else {
+        return File.takeError();
+      }
+    } else if (Data[ELF::EI_CLASS] == ELF::ELFCLASS32) {
+      if (auto File = llvm::object::ELF32BEFile::create(Buffer)) {
+        return File->getHeader().e_machine;
+      } else {
+        return File.takeError();
+      }
+    }
+  }
+
   return ELF::EM_NONE;
 }
 

llvm/test/ExecutionEngine/JITLink/ppc64/ppc64-relocs.s

@@ -2,7 +2,7 @@
 # RUN: llvm-jitlink -abs external_var=0xffff0000 -abs puts=0xffff6400 -abs \
 # RUN:   foo=0xffff8800 -noexec %t
 # RUN: llvm-mc -triple=powerpc64-unknown-linux-gnu -filetype=obj -o %t %s
-# RUN: not llvm-jitlink -abs external_var=0xffff0000 -abs puts=0xffff6400 -abs \
+# RUN: llvm-jitlink -abs external_var=0xffff0000 -abs puts=0xffff6400 -abs \
 # RUN:   foo=0xffff8800 -noexec %t
 #
 # Check typical relocations involving external function call, external variable