ART: Implement HSelect

This patch adds a new HIR instruction to Optimizing. HSelect returns
one of two inputs based on the outcome of a condition.

This is only initial implementation which:
 - defines the new instruction,
 - repurposes BooleanSimplifier to emit it,
 - extends InstructionSimplifier to statically resolve it,
 - updates existing code and tests accordingly.

Code generators currently emit fallback if/then/else code and will be
updated in follow-up CLs to use platform-specific conditional moves
when possible.

Change-Id: Ib61b17146487ebe6b55350c2b589f0b971dcaaee
diff --git a/compiler/optimizing/code_generator_x86_64.cc b/compiler/optimizing/code_generator_x86_64.cc
index 1781f41..895e7c3 100644
--- a/compiler/optimizing/code_generator_x86_64.cc
+++ b/compiler/optimizing/code_generator_x86_64.cc
@@ -1558,10 +1558,36 @@
 
 void InstructionCodeGeneratorX86_64::VisitDeoptimize(HDeoptimize* deoptimize) {
   SlowPathCode* slow_path = deopt_slow_paths_.NewSlowPath<DeoptimizationSlowPathX86_64>(deoptimize);
-  GenerateTestAndBranch(deoptimize,
-                        /* condition_input_index */ 0,
-                        slow_path->GetEntryLabel(),
-                        /* false_target */ static_cast<Label*>(nullptr));
+  GenerateTestAndBranch<Label>(deoptimize,
+                               /* condition_input_index */ 0,
+                               slow_path->GetEntryLabel(),
+                               /* false_target */ nullptr);
+}
+
+void LocationsBuilderX86_64::VisitSelect(HSelect* select) {
+  LocationSummary* locations = new (GetGraph()->GetArena()) LocationSummary(select);
+  if (Primitive::IsFloatingPointType(select->GetType())) {
+    locations->SetInAt(0, Location::RequiresFpuRegister());
+    locations->SetInAt(1, Location::RequiresFpuRegister());
+  } else {
+    locations->SetInAt(0, Location::RequiresRegister());
+    locations->SetInAt(1, Location::RequiresRegister());
+  }
+  if (IsBooleanValueOrMaterializedCondition(select->GetCondition())) {
+    locations->SetInAt(2, Location::RequiresRegister());
+  }
+  locations->SetOut(Location::SameAsFirstInput());
+}
+
+void InstructionCodeGeneratorX86_64::VisitSelect(HSelect* select) {
+  LocationSummary* locations = select->GetLocations();
+  NearLabel false_target;
+  GenerateTestAndBranch<NearLabel>(select,
+                                   /* condition_input_index */ 2,
+                                   /* true_target */ nullptr,
+                                   &false_target);
+  codegen_->MoveLocation(locations->Out(), locations->InAt(1), select->GetType());
+  __ Bind(&false_target);
 }
 
 void LocationsBuilderX86_64::VisitNativeDebugInfo(HNativeDebugInfo* info) {