[AMDGPU][MC][GFX8+] Added syntactic sugar for 'vgpr index' operand of instructions s_set_gpr_idx_on and s_set_gpr_idx_mode

See bug 39331: https://bugs.llvm.org/show_bug.cgi?id=39331

Reviewers: artem.tamazov, arsenm

Differential Revision: https://reviews.llvm.org/D58288

llvm-svn: 354969
diff --git a/llvm/lib/Target/AMDGPU/SIISelLowering.cpp b/llvm/lib/Target/AMDGPU/SIISelLowering.cpp
index adb9ed4..3873c46 100644
--- a/llvm/lib/Target/AMDGPU/SIISelLowering.cpp
+++ b/llvm/lib/Target/AMDGPU/SIISelLowering.cpp
@@ -2911,7 +2911,7 @@
         .addImm(Offset);
     }
     unsigned IdxMode = IsIndirectSrc ?
-      VGPRIndexMode::SRC0_ENABLE : VGPRIndexMode::DST_ENABLE;
+      AMDGPU::VGPRIndexMode::SRC0_ENABLE : AMDGPU::VGPRIndexMode::DST_ENABLE;
     MachineInstr *SetOn =
       BuildMI(LoopBB, I, DL, TII->get(AMDGPU::S_SET_GPR_IDX_ON))
       .addReg(IdxReg, RegState::Kill)
@@ -3042,7 +3042,7 @@
 
   if (UseGPRIdxMode) {
     unsigned IdxMode = IsIndirectSrc ?
-      VGPRIndexMode::SRC0_ENABLE : VGPRIndexMode::DST_ENABLE;
+      AMDGPU::VGPRIndexMode::SRC0_ENABLE : AMDGPU::VGPRIndexMode::DST_ENABLE;
     if (Offset == 0) {
       MachineInstr *SetOn =
           BuildMI(*MBB, I, DL, TII->get(AMDGPU::S_SET_GPR_IDX_ON))