Revert "Compute local variable liveness before translation to SSA."

runtime/vm/intermediate_language.cc

Index: runtime/vm/intermediate_language.cc
diff --git a/runtime/vm/intermediate_language.cc b/runtime/vm/intermediate_language.cc
index 4f1663a0e78a690cb2487342013a35b94134f6cf..058b3ca1879a86856ed8ce8096b2b3a50f5f39fe 100644
--- a/runtime/vm/intermediate_language.cc
+++ b/runtime/vm/intermediate_language.cc
@@ -458,6 +458,27 @@ intptr_t JoinEntryInstr::IndexOfPredecessor(BlockEntryInstr* pred) const {
 }
 
 
+// ==== Recording assigned variables.
+void Definition::RecordAssignedVars(BitVector* assigned_vars,
+                                    intptr_t fixed_parameter_count) {
+  // Nothing to do for the base class.
+}
+
+
+void StoreLocalInstr::RecordAssignedVars(BitVector* assigned_vars,
+                                         intptr_t fixed_parameter_count) {
+  if (!local().is_captured()) {
+    assigned_vars->Add(local().BitIndexIn(fixed_parameter_count));
+  }
+}
+
+
+void Instruction::RecordAssignedVars(BitVector* assigned_vars,
+                                     intptr_t fixed_parameter_count) {
+  // Nothing to do for the base class.
+}
+
+
 void Value::AddToList(Value* value, Value** list) {
   Value* next = *list;
   *list = value;
@@ -637,6 +658,7 @@ void BlockEntryInstr::DiscoverBlocks(
     GrowableArray<BlockEntryInstr*>* preorder,
     GrowableArray<BlockEntryInstr*>* postorder,
     GrowableArray<intptr_t>* parent,
+    GrowableArray<BitVector*>* assigned_vars,
     intptr_t variable_count,
     intptr_t fixed_parameter_count) {
   // If this block has a predecessor (i.e., is not the graph entry) we can
@@ -665,12 +687,16 @@ void BlockEntryInstr::DiscoverBlocks(
   parent->Add(parent_number);
 
   // 4. Assign the preorder number and add the block entry to the list.
+  // Allocate an empty set of assigned variables for the block.
   set_preorder_number(preorder->length());
   preorder->Add(this);
-
-  // The preorder and parent arrays are indexed by
+  BitVector* vars =
+      (variable_count == 0) ? NULL : new BitVector(variable_count);
+  assigned_vars->Add(vars);
+  // The preorder, parent, and assigned_vars arrays are all indexed by
   // preorder block number, so they should stay in lockstep.
   ASSERT(preorder->length() == parent->length());
+  ASSERT(preorder->length() == assigned_vars->length());
 
   // 5. Iterate straight-line successors to record assigned variables and
   // find the last instruction in the block.  The graph entry block consists
@@ -679,18 +705,18 @@ void BlockEntryInstr::DiscoverBlocks(
   Instruction* last = this;
   for (ForwardInstructionIterator it(this); !it.Done(); it.Advance()) {
     last = it.Current();
+    if (vars != NULL) {
+      last->RecordAssignedVars(vars, fixed_parameter_count);
+    }
   }
   set_last_instruction(last);
 
   // Visit the block's successors in reverse so that they appear forwards
   // the reverse postorder block ordering.
   for (intptr_t i = last->SuccessorCount() - 1; i >= 0; --i) {
-    last->SuccessorAt(i)->DiscoverBlocks(this,
-                                         preorder,
-                                         postorder,
-                                         parent,
-                                         variable_count,
-                                         fixed_parameter_count);
+    last->SuccessorAt(i)->DiscoverBlocks(this, preorder, postorder,
+                                         parent, assigned_vars,
+                                         variable_count, fixed_parameter_count);
   }
 
   // 6. Assign postorder number and add the block entry to the list.