Add register Mips::GP to the list of reserved registers if target is bare-metal
to prevent it from being clobbered. mips uses $gp to access small data section.

This bug was originally reported by Carl Norum.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@162340 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/Mips/MipsISelLowering.cpp b/lib/Target/Mips/MipsISelLowering.cpp
index c5207c6..91f91b1 100644
--- a/lib/Target/Mips/MipsISelLowering.cpp
+++ b/lib/Target/Mips/MipsISelLowering.cpp
@@ -1578,8 +1578,8 @@
       SDValue GA = DAG.getTargetGlobalAddress(GV, dl, MVT::i32, 0,
                                               MipsII::MO_GPREL);
       SDValue GPRelNode = DAG.getNode(MipsISD::GPRel, dl, VTs, &GA, 1);
-      SDValue GOT = DAG.getGLOBAL_OFFSET_TABLE(MVT::i32);
-      return DAG.getNode(ISD::ADD, dl, MVT::i32, GOT, GPRelNode);
+      SDValue GPReg = DAG.getRegister(Mips::GP, MVT::i32);
+      return DAG.getNode(ISD::ADD, dl, MVT::i32, GPReg, GPRelNode);
     }
     // %hi/%lo relocation
     SDValue GAHi = DAG.getTargetGlobalAddress(GV, dl, MVT::i32, 0,