Revert "Don't block quick callee saved registers for optimizing."

X64 has one libcore test failing, and codegen_test on
arm is failing.

This reverts commit 6004796d6c630696127df2494dcd4f30d1367a34.

Change-Id: I20e00431fa18e11ce4c0cb6fffa91977fa8e9b4f
diff --git a/compiler/optimizing/code_generator.cc b/compiler/optimizing/code_generator.cc
index 5334031..461409d 100644
--- a/compiler/optimizing/code_generator.cc
+++ b/compiler/optimizing/code_generator.cc
@@ -177,31 +177,6 @@
   }
 }
 
-void CodeGenerator::MaybeBlockPhysicalRegisters(Location loc, bool is_output) const {
-  // The DCHECKS below check that a register is not specified twice in
-  // the summary.
-  // Note that fixed output registers are allowed to overlap with fixed input and
-  // temp registers: the writer of the location summary has to make sure they
-  // don't conflict with each other.
-  if (loc.IsRegister()) {
-    DCHECK(is_output || !blocked_core_registers_[loc.reg()]);
-    blocked_core_registers_[loc.reg()] = true;
-  } else if (loc.IsFpuRegister()) {
-    DCHECK(is_output || !blocked_fpu_registers_[loc.reg()]);
-    blocked_fpu_registers_[loc.reg()] = true;
-  } else if (loc.IsFpuRegisterPair()) {
-    DCHECK(is_output || !blocked_fpu_registers_[loc.AsFpuRegisterPairLow<int>()]);
-    blocked_fpu_registers_[loc.AsFpuRegisterPairLow<int>()] = true;
-    DCHECK(is_output || !blocked_fpu_registers_[loc.AsFpuRegisterPairHigh<int>()]);
-    blocked_fpu_registers_[loc.AsFpuRegisterPairHigh<int>()] = true;
-  } else if (loc.IsRegisterPair()) {
-    DCHECK(is_output || !blocked_core_registers_[loc.AsRegisterPairLow<int>()]);
-    blocked_core_registers_[loc.AsRegisterPairLow<int>()] = true;
-    DCHECK(is_output || !blocked_core_registers_[loc.AsRegisterPairHigh<int>()]);
-    blocked_core_registers_[loc.AsRegisterPairHigh<int>()] = true;
-  }
-}
-
 void CodeGenerator::AllocateRegistersLocally(HInstruction* instruction) const {
   LocationSummary* locations = instruction->GetLocations();
   if (locations == nullptr) return;
@@ -221,18 +196,43 @@
   // Mark all fixed input, temp and output registers as used.
   for (size_t i = 0, e = locations->GetInputCount(); i < e; ++i) {
     Location loc = locations->InAt(i);
-    MaybeBlockPhysicalRegisters(loc, false);
+    // The DCHECKS below check that a register is not specified twice in
+    // the summary.
+    if (loc.IsRegister()) {
+      DCHECK(!blocked_core_registers_[loc.reg()]);
+      blocked_core_registers_[loc.reg()] = true;
+    } else if (loc.IsFpuRegister()) {
+      DCHECK(!blocked_fpu_registers_[loc.reg()]);
+      blocked_fpu_registers_[loc.reg()] = true;
+    } else if (loc.IsFpuRegisterPair()) {
+      DCHECK(!blocked_fpu_registers_[loc.AsFpuRegisterPairLow<int>()]);
+      blocked_fpu_registers_[loc.AsFpuRegisterPairLow<int>()] = true;
+      DCHECK(!blocked_fpu_registers_[loc.AsFpuRegisterPairHigh<int>()]);
+      blocked_fpu_registers_[loc.AsFpuRegisterPairHigh<int>()] = true;
+    } else if (loc.IsRegisterPair()) {
+      DCHECK(!blocked_core_registers_[loc.AsRegisterPairLow<int>()]);
+      blocked_core_registers_[loc.AsRegisterPairLow<int>()] = true;
+      DCHECK(!blocked_core_registers_[loc.AsRegisterPairHigh<int>()]);
+      blocked_core_registers_[loc.AsRegisterPairHigh<int>()] = true;
+    }
   }
 
   for (size_t i = 0, e = locations->GetTempCount(); i < e; ++i) {
     Location loc = locations->GetTemp(i);
-    MaybeBlockPhysicalRegisters(loc, false);
+    // The DCHECKS below check that a register is not specified twice in
+    // the summary.
+    if (loc.IsRegister()) {
+      DCHECK(!blocked_core_registers_[loc.reg()]);
+      blocked_core_registers_[loc.reg()] = true;
+    } else if (loc.IsFpuRegister()) {
+      DCHECK(!blocked_fpu_registers_[loc.reg()]);
+      blocked_fpu_registers_[loc.reg()] = true;
+    } else {
+      DCHECK(loc.GetPolicy() == Location::kRequiresRegister
+             || loc.GetPolicy() == Location::kRequiresFpuRegister);
+    }
   }
 
-  // If the output is a fixed register, mark it as used.
-  Location result_location = locations->Out();
-  MaybeBlockPhysicalRegisters(result_location, true);
-
   SetupBlockedRegisters();
 
   // Allocate all unallocated input locations.
@@ -276,11 +276,9 @@
                      << loc.GetPolicy();
       }
       locations->SetTempAt(i, loc);
-    } else {
-      DCHECK(loc.IsFpuRegister() || loc.IsRegister());
     }
   }
-
+  Location result_location = locations->Out();
   if (result_location.IsUnallocated()) {
     switch (result_location.GetPolicy()) {
       case Location::kAny: