R600: Fix R600ControlFlowFinalizer not considering VTX_READ 128 bit dst reg

Patch by: Vincent Lejeune

https://bugs.freedesktop.org/show_bug.cgi?id=64877

NOTE: This is a candidate for the 3.3 branch.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@182600 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/R600/R600ControlFlowFinalizer.cpp b/lib/Target/R600/R600ControlFlowFinalizer.cpp
index d447f08..832c375 100644
--- a/lib/Target/R600/R600ControlFlowFinalizer.cpp
+++ b/lib/Target/R600/R600ControlFlowFinalizer.cpp
@@ -117,8 +117,15 @@
       const MachineOperand &MO = *I;
       if (!MO.isReg())
         continue;
-      if (MO.isDef())
-        DstMI = MO.getReg();
+      if (MO.isDef()) {
+        unsigned Reg = MO.getReg();
+        if (AMDGPU::R600_Reg128RegClass.contains(Reg))
+          DstMI = Reg;
+        else
+          DstMI = TRI.getMatchingSuperReg(Reg,
+              TRI.getSubRegFromChannel(TRI.getHWRegChan(Reg)),
+              &AMDGPU::R600_Reg128RegClass);
+      }
       if (MO.isUse()) {
         unsigned Reg = MO.getReg();
         if (AMDGPU::R600_Reg128RegClass.contains(Reg))