Remove SPARC backend getpcx instruction's Uses. Also, insert an assert to 
ensure %o7 is not assigned as the destination of getpcx instruction.

llvm-svn: 123304
diff --git a/llvm/lib/Target/Sparc/SparcInstrInfo.td b/llvm/lib/Target/Sparc/SparcInstrInfo.td
index 94e1f7a..44b7e43 100644
--- a/llvm/lib/Target/Sparc/SparcInstrInfo.td
+++ b/llvm/lib/Target/Sparc/SparcInstrInfo.td
@@ -205,7 +205,7 @@
    : InstSP<outs, ins, asmstr, pattern>;
 
 // GETPCX for PIC
-let Defs = [O7], Uses = [O7] in {
+let Defs = [O7] in {
   def GETPCX : Pseudo<(outs getPCX:$getpcseq), (ins), "$getpcseq", [] >;
 }