Optimizing: Clean up graph visiting.

Change `PrepareForRegisterAllocation` to `HOptimization` and
use a helper visitor class.

Make some visitor classes final.

Test: m test-art-host-gtest
Test: testrunner.py --host --optimizing
Bug: 181943478
Change-Id: I87700b92e06ff1a6cf7cd8a1e3ab8b7a87568dae

1 files changed, 1 insertions, 1 deletions

diff --git a/compiler/optimizing/constant_folding.cc b/compiler/optimizing/constant_folding.cc
index e31de9e1da..0ec60b5ead 100644
--- a/compiler/optimizing/constant_folding.cc
+++ b/compiler/optimizing/constant_folding.cc
@@ -72,7 +72,7 @@ class HConstantFoldingVisitor final : public HGraphDelegateVisitor {
 // This visitor tries to simplify operations with an absorbing input,
 // yielding a constant. For example `input * 0` is replaced by a
 // null constant.
-class InstructionWithAbsorbingInputSimplifier : public HGraphVisitor {
+class InstructionWithAbsorbingInputSimplifier final : public HGraphVisitor {
  public:
   explicit InstructionWithAbsorbingInputSimplifier(HGraph* graph) : HGraphVisitor(graph) {}