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/graph_checker.cc b/compiler/optimizing/graph_checker.cc
index 3113677..962e77d 100644
--- a/compiler/optimizing/graph_checker.cc
+++ b/compiler/optimizing/graph_checker.cc
@@ -859,8 +859,12 @@
           value));
     }
   } else if (input->GetType() == Primitive::kPrimInt
-             && (input->IsPhi() || input->IsAnd() || input->IsOr() || input->IsXor())) {
-    // TODO: We need a data-flow analysis to determine if the Phi or
+             && (input->IsPhi() ||
+                 input->IsAnd() ||
+                 input->IsOr() ||
+                 input->IsXor() ||
+                 input->IsSelect())) {
+    // TODO: We need a data-flow analysis to determine if the Phi or Select or
     //       binary operation is actually Boolean. Allow for now.
   } else if (input->GetType() != Primitive::kPrimBoolean) {
     AddError(StringPrintf(
@@ -893,6 +897,11 @@
   HandleBooleanInput(instruction, 0);
 }
 
+void SSAChecker::VisitSelect(HSelect* instruction) {
+  VisitInstruction(instruction);
+  HandleBooleanInput(instruction, 2);
+}
+
 void SSAChecker::VisitBooleanNot(HBooleanNot* instruction) {
   VisitInstruction(instruction);
   HandleBooleanInput(instruction, 0);