Revert "Better support for x86 XMM registers"

The invalid usage of loc.fp must be corrected before this change can be submitted.

This reverts commit 766a5e5940b469ab40e52770862c81cfec1d835b.

Change-Id: I1173a9bf829da89cccd9c2898f5e11164987a22b
diff --git a/compiler/dex/quick/ralloc_util.cc b/compiler/dex/quick/ralloc_util.cc
index 32c22f2..cef013e 100644
--- a/compiler/dex/quick/ralloc_util.cc
+++ b/compiler/dex/quick/ralloc_util.cc
@@ -602,7 +602,6 @@
 }
 
 void Mir2Lir::MarkPair(int low_reg, int high_reg) {
-  DCHECK_NE(low_reg, high_reg);
   RegisterInfo* info_lo = GetRegInfo(low_reg);
   RegisterInfo* info_hi = GetRegInfo(high_reg);
   info_lo->pair = info_hi->pair = true;
@@ -808,10 +807,7 @@
   if (update) {
     loc.location = kLocPhysReg;
     MarkLive(loc.low_reg, loc.s_reg_low);
-    // Does this wide value live in two registers or one vector register?
-    if (loc.low_reg != loc.high_reg) {
-      MarkLive(loc.high_reg, GetSRegHi(loc.s_reg_low));
-    }
+    MarkLive(loc.high_reg, GetSRegHi(loc.s_reg_low));
   }
   DCHECK(!IsFpReg(loc.low_reg) || ((loc.low_reg & 0x1) == 0));
   return loc;
@@ -1063,10 +1059,7 @@
   Clobber(res.high_reg);
   LockTemp(res.low_reg);
   LockTemp(res.high_reg);
-  // Does this wide value live in two registers or one vector register?
-  if (res.low_reg != res.high_reg) {
-    MarkPair(res.low_reg, res.high_reg);
-  }
+  MarkPair(res.low_reg, res.high_reg);
   return res;
 }