ART: Rework TargetReg(symbolic_reg, wide)

Make the standard implementation in Mir2Lir and the specialized one
in the x86 backend return a pair when wide = "true". Introduce
WideKind enumeration to improve code readability. Simplify generic
code based on this implementation.

Change-Id: I670d45aa2572eedfdc77ac763e6486c83f8e26b4
diff --git a/compiler/dex/quick/arm64/call_arm64.cc b/compiler/dex/quick/arm64/call_arm64.cc
index d24f419..8117c62 100644
--- a/compiler/dex/quick/arm64/call_arm64.cc
+++ b/compiler/dex/quick/arm64/call_arm64.cc
@@ -195,7 +195,7 @@
   // TUNING: How much performance we get when we inline this?
   // Since we've already flush all register.
   FlushAllRegs();
-  LoadValueDirectFixed(rl_src, rs_x0);  // = TargetRefReg(kArg0)
+  LoadValueDirectFixed(rl_src, rs_x0);  // = TargetReg(kArg0, kRef)
   LockCallTemps();  // Prepare for explicit register usage
   LIR* null_check_branch = nullptr;
   if ((opt_flags & MIR_IGNORE_NULL_CHECK) && !(cu_->disable_opt & (1 << kNullCheckElimination))) {
diff --git a/compiler/dex/quick/arm64/codegen_arm64.h b/compiler/dex/quick/arm64/codegen_arm64.h
index 7d75da9..81ba8bc 100644
--- a/compiler/dex/quick/arm64/codegen_arm64.h
+++ b/compiler/dex/quick/arm64/codegen_arm64.h
@@ -100,18 +100,14 @@
 
     // Required for target - register utilities.
     RegStorage TargetReg(SpecialTargetRegister reg) OVERRIDE;
-    RegStorage TargetReg(SpecialTargetRegister symbolic_reg, bool is_wide) OVERRIDE {
+    RegStorage TargetReg(SpecialTargetRegister symbolic_reg, WideKind wide_kind) OVERRIDE {
       RegStorage reg = TargetReg(symbolic_reg);
-      if (is_wide) {
+      if (wide_kind == kWide || wide_kind == kRef) {
         return (reg.Is64Bit()) ? reg : As64BitReg(reg);
       } else {
         return (reg.Is32Bit()) ? reg : As32BitReg(reg);
       }
     }
-    RegStorage TargetRefReg(SpecialTargetRegister symbolic_reg) OVERRIDE {
-      RegStorage reg = TargetReg(symbolic_reg);
-      return (reg.Is64Bit() ? reg : As64BitReg(reg));
-    }
     RegStorage TargetPtrReg(SpecialTargetRegister symbolic_reg) OVERRIDE {
       RegStorage reg = TargetReg(symbolic_reg);
       return (reg.Is64Bit() ? reg : As64BitReg(reg));
diff --git a/compiler/dex/quick/arm64/target_arm64.cc b/compiler/dex/quick/arm64/target_arm64.cc
index 8264a06..2212380 100644
--- a/compiler/dex/quick/arm64/target_arm64.cc
+++ b/compiler/dex/quick/arm64/target_arm64.cc
@@ -1111,7 +1111,7 @@
 
       // Instead of allocating a new temp, simply reuse one of the registers being used
       // for argument passing.
-      RegStorage temp = TargetReg(kArg3, false);
+      RegStorage temp = TargetReg(kArg3, kNotWide);
 
       // Now load the argument VR and store to the outs.
       Load32Disp(TargetReg(kSp), current_src_offset, temp);