[PowerPC] Remove UseVSXReg

The UseVSXReg flag can be safely removed and the code cleaned up.

Patch By: Yi-Hong Liu

Differential Revision: https://reviews.llvm.org/D58685

llvm-svn: 357028
diff --git a/llvm/lib/Target/PowerPC/PPCAsmPrinter.cpp b/llvm/lib/Target/PowerPC/PPCAsmPrinter.cpp
index 568ad3b..79f0ad8 100644
--- a/llvm/lib/Target/PowerPC/PPCAsmPrinter.cpp
+++ b/llvm/lib/Target/PowerPC/PPCAsmPrinter.cpp
@@ -168,10 +168,7 @@
   switch (MO.getType()) {
   case MachineOperand::MO_Register: {
     // The MI is INLINEASM ONLY and UseVSXReg is always false.
-    unsigned Reg =
-        PPCInstrInfo::getRegNumForOperand(MI->getDesc(), MO.getReg(), OpNo);
-
-    const char *RegName = PPCInstPrinter::getRegisterName(Reg);
+    const char *RegName = PPCInstPrinter::getRegisterName(MO.getReg());
 
     // Linux assembler (Others?) does not take register mnemonics.
     // FIXME - What about special registers used in mfspr/mtspr?