Fix PR1679, by printing GEP indices as signed values instead of unsigned.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@42239 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/CBackend/CBackend.cpp b/lib/Target/CBackend/CBackend.cpp
index 294f975..bc08524 100644
--- a/lib/Target/CBackend/CBackend.cpp
+++ b/lib/Target/CBackend/CBackend.cpp
@@ -1238,6 +1238,7 @@
       shouldCast = true;
       castIsSigned = false;
       break;
+    case Instruction::GetElementPtr:
     case Instruction::AShr:
     case Instruction::SDiv:
     case Instruction::SRem: // Cast to signed first
@@ -2859,7 +2860,7 @@
       Out << ".field" << cast<ConstantInt>(I.getOperand())->getZExtValue();
     } else {
       Out << '[';
-      writeOperand(I.getOperand());
+      writeOperandWithCast(I.getOperand(), Instruction::GetElementPtr);
       Out << ']';
     }
 }