[vm, compiler] Allow further folding of UnboxInt64(Constant) to UnboxedConstant.

TEST=ci
Change-Id: I3a55a007d4b8510faa33593698554f7e9bf982e2
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/196225
Reviewed-by: Alexander Markov <alexmarkov@google.com>
Reviewed-by: Vyacheslav Egorov <vegorov@google.com>
Commit-Queue: Ryan Macnak <rmacnak@google.com>

Author: rmacnak-google

runtime/vm/compiler/backend/flow_graph.cc

@@ -1809,6 +1809,7 @@ void FlowGraph::InsertConversion(Representation from,
                                  Representation to,
                                  Value* use,
                                  bool is_environment_use) {
+  ASSERT(from != to);
   Instruction* insert_before;
   Instruction* deopt_target;
   PhiInstr* phi = use->instruction()->AsPhi();

runtime/vm/compiler/backend/il.cc

@@ -3288,12 +3288,9 @@ Definition* UnboxInt64Instr::Canonicalize(FlowGraph* flow_graph) {
     return replacement;
   }
 
-  // Currently we perform this only on 64-bit architectures.
-  if (compiler::target::kBitsPerWord == 64) {
-    ConstantInstr* c = value()->definition()->AsConstant();
-    if (c != NULL && c->value().IsInteger()) {
-      return flow_graph->GetConstant(c->value(), kUnboxedInt64);
-    }
+  ConstantInstr* c = value()->definition()->AsConstant();
+  if (c != NULL && c->value().IsInteger()) {
+    return flow_graph->GetConstant(c->value(), kUnboxedInt64);
   }
 
   return this;

runtime/vm/compiler/backend/il.h

@@ -6475,6 +6475,7 @@ class StoreUntaggedInstr : public TemplateInstruction<2, NoThrow> {
   Value* value() const { return inputs_[1]; }
   intptr_t offset() const { return offset_; }
 
+  virtual intptr_t DeoptimizationTarget() const { return GetDeoptId(); }
   virtual bool ComputeCanDeoptimize() const { return false; }
   virtual bool HasUnknownSideEffects() const { return false; }
   virtual bool AttributesEqual(const Instruction& other) const {

runtime/vm/compiler/backend/inliner_test.cc

@@ -220,11 +220,6 @@ ISOLATE_UNIT_TEST_CASE(Inliner_List_generate) {
       kMoveGlob,
       kMatchAndMoveCreateArray,
       kMatchAndMoveUnboxInt64,
-#if defined(TARGET_ARCH_IS_32_BIT)
-      // TODO(rmacnak): Implement missing ops to allow 32-bit architectures in
-      // UnboxInt64Instr::Canonicalize.
-      kMatchAndMoveUnboxInt64,
-#endif
       kMatchAndMoveGoto,
 
       // Loop header