Reapply "Deoptimization support in inlined code."

runtime/vm/flow_graph_allocator.cc

Index: runtime/vm/flow_graph_allocator.cc
diff --git a/runtime/vm/flow_graph_allocator.cc b/runtime/vm/flow_graph_allocator.cc
index 2118c08fb44d5cee13d1d9f4921779269795ed71..458533da7dbbf09aeab10563cade4a58d56228e1 100644
--- a/runtime/vm/flow_graph_allocator.cc
+++ b/runtime/vm/flow_graph_allocator.cc
@@ -149,9 +149,12 @@ void FlowGraphAllocator::ComputeInitialSets() {
       // Add non-argument uses from the deoptimization environment (pushed
       // arguments are not allocated by the register allocator).
       if (current->env() != NULL) {
-        for (intptr_t i = 0; i < current->env()->Length(); ++i) {
-          Value* value = current->env()->ValueAt(i);
-          if (!value->definition()->IsPushArgument()) {
+        for (Environment::DeepIterator env_it(current->env());
+             !env_it.Done();
+             env_it.Advance()) {
+          Value* value = env_it.CurrentValue();
+          if (!value->definition()->IsPushArgument() &&
+              !value->BindsToConstant()) {
             live_in->Add(value->definition()->ssa_temp_index());
           }
         }
@@ -738,49 +741,53 @@ void FlowGraphAllocator::ConnectIncomingPhiMoves(BlockEntryInstr* block) {
 void FlowGraphAllocator::ProcessEnvironmentUses(BlockEntryInstr* block,
                                                 Instruction* current) {
   ASSERT(current->env() != NULL);
-
   Environment* env = current->env();
+  while (env != NULL) {
+    // Any value mentioned in the deoptimization environment should survive
+    // until the end of instruction but it does not need to be in the register.
+    // Expected shape of live range:
+    //
+    //                 i  i'
+    //      value    -----*
+    //
 
-  // Any value mentioned in the deoptimization environment should survive
-  // until the end of instruction but it does not need to be in the register.
-  // Expected shape of live range:
-  //
-  //                 i  i'
-  //      value    -----*
-  //
+    if (env->Length() == 0) {
+      env = env->outer();
+      continue;
+    }
 
-  if (env->Length() == 0) return;
+    const intptr_t block_start_pos = block->start_pos();
+    const intptr_t use_pos = current->lifetime_position() + 1;
 
-  const intptr_t block_start_pos = block->start_pos();
-  const intptr_t use_pos = current->lifetime_position() + 1;
+    Location* locations =
+        Isolate::Current()->current_zone()->Alloc<Location>(env->Length());
 
-  Location* locations =
-      Isolate::Current()->current_zone()->Alloc<Location>(env->Length());
+    for (intptr_t i = 0; i < env->Length(); ++i) {
+      Value* value = env->ValueAt(i);
+      locations[i] = Location::Any();
+      Definition* def = value->definition();
 
-  for (intptr_t i = 0; i < env->Length(); ++i) {
-    Value* value = env->ValueAt(i);
-    locations[i] = Location::Any();
-    Definition* def = value->definition();
+      if (def->IsPushArgument()) {
+        // Frame size is unknown until after allocation.
+        locations[i] = Location::NoLocation();
+        continue;
+      }
 
-    if (def->IsPushArgument()) {
-      // Frame size is unknown until after allocation.
-      locations[i] = Location::NoLocation();
-      continue;
-    }
+      ConstantInstr* constant = def->AsConstant();
+      if (constant != NULL) {
+        locations[i] = Location::Constant(constant->value());
+        continue;
+      }
 
-    ConstantInstr* constant = def->AsConstant();
-    if (constant != NULL) {
-      locations[i] = Location::Constant(constant->value());
-      continue;
+      const intptr_t vreg = def->ssa_temp_index();
+      LiveRange* range = GetLiveRange(vreg);
+      range->AddUseInterval(block_start_pos, use_pos);
+      range->AddUse(use_pos, &locations[i]);
     }
 
-    const intptr_t vreg = def->ssa_temp_index();
-    LiveRange* range = GetLiveRange(vreg);
-    range->AddUseInterval(block_start_pos, use_pos);
-    range->AddUse(use_pos, &locations[i]);
+    env->set_locations(locations);
+    env = env->outer();
   }
-
-  env->set_locations(locations);
 }
 
 
@@ -1371,6 +1378,7 @@ LiveRange* LiveRange::SplitAt(intptr_t split_pos) {
     last_before_split = interval;
   }
 
+  ASSERT(last_before_split != NULL);
   ASSERT(last_before_split->next() == first_after_split);
   ASSERT(last_before_split->end() <= split_pos);
   ASSERT(split_pos <= first_after_split->start());