Reapply "Incrementally recompute dominators when inlining."

runtime/vm/flow_graph.cc

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/flow_graph.h"
 
 #include "vm/bit_vector.h"
 #include "vm/flow_graph_builder.h"
 #include "vm/intermediate_language.h"
 #include "vm/longjump.h"
@@ skipping 11 matching lines @@
     assigned_vars_(),
     current_ssa_temp_index_(0),
     max_block_id_(max_block_id),
     parsed_function_(builder.parsed_function()),
     num_copied_params_(builder.num_copied_params()),
     num_non_copied_params_(builder.num_non_copied_params()),
     num_stack_locals_(builder.num_stack_locals()),
     graph_entry_(graph_entry),
     preorder_(),
     postorder_(),
-    reverse_postorder_(),
-    invalid_dominator_tree_(true) {
+    reverse_postorder_() {
   DiscoverBlocks();
 }
 
 
 ConstantInstr* FlowGraph::AddConstantToInitialDefinitions(
     const Object& object) {
   // Check if the constant is already in the pool.
   for (intptr_t i = 0; i < graph_entry_->initial_definitions()->length(); ++i) {
     ConstantInstr* constant =
         (*graph_entry_->initial_definitions())[i]->AsConstant();
@@ skipping 180 matching lines @@
 
 // Compute immediate dominators and the dominance frontier for each basic
 // block.  As a side effect of the algorithm, sets the immediate dominator
 // of each basic block.
 //
 // dominance_frontier: an output parameter encoding the dominance frontier.
 //     The array maps the preorder block number of a block to the set of
 //     (preorder block numbers of) blocks in the dominance frontier.
 void FlowGraph::ComputeDominators(
     GrowableArray<BitVector*>* dominance_frontier) {
-  invalid_dominator_tree_ = false;
   // Use the SEMI-NCA algorithm to compute dominators.  This is a two-pass
   // version of the Lengauer-Tarjan algorithm (LT is normally three passes)
   // that eliminates a pass by using nearest-common ancestor (NCA) to
   // compute immediate dominators from semidominators.  It also removes a
   // level of indirection in the link-eval forest data structure.
   //
   // The algorithm is described in Georgiadis, Tarjan, and Werneck's
   // "Finding Dominators in Practice".
   // See http://www.cs.princeton.edu/~rwerneck/dominators/ .
 
@@ skipping 421 matching lines @@
   const char* function_name = parsed_function_.function().ToCString();
   intptr_t len = OS::SNPrint(NULL, 0, kFormat, function_name, reason) + 1;
   char* chars = Isolate::Current()->current_zone()->Alloc<char>(len);
   OS::SNPrint(chars, len, kFormat, function_name, reason);
   const Error& error = Error::Handle(
       LanguageError::New(String::Handle(String::New(chars))));
   Isolate::Current()->long_jump_base()->Jump(1, error);
 }
 
 
-void FlowGraph::RepairGraphAfterInlining() {
-  DiscoverBlocks();
-  if (invalid_dominator_tree_) {
-    GrowableArray<BitVector*> dominance_frontier;
-    ComputeDominators(&dominance_frontier);
-  }
-}
-
-
 intptr_t FlowGraph::InstructionCount() const {
   intptr_t size = 0;
   // Iterate each block, skipping the graph entry.
   for (intptr_t i = 1; i < preorder_.length(); ++i) {
     for (ForwardInstructionIterator it(preorder_[i]);
          !it.Done();
          it.Advance()) {
       ++size;
     }
   }
   return size;
 }
 
 }  // namespace dart