Fix bailout from the optimizing-mode compiler and put SSA construction under a flag.

vm/flow_graph_builder.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_builder.h"
 
 #include "vm/ast_printer.h"
 #include "vm/bit_vector.h"
 #include "vm/code_descriptors.h"
 #include "vm/dart_entry.h"
 #include "vm/flags.h"
 #include "vm/il_printer.h"
 #include "vm/intermediate_language.h"
 #include "vm/longjump.h"
 #include "vm/object_store.h"
 #include "vm/os.h"
 #include "vm/parser.h"
 #include "vm/resolver.h"
 #include "vm/stub_code.h"
 
 namespace dart {
 
 DEFINE_FLAG(bool, eliminate_type_checks, true,
             "Eliminate type checks when allowed by static type analysis");
 DEFINE_FLAG(bool, print_ast, false, "Print abstract syntax tree.");
 DEFINE_FLAG(bool, print_flow_graph, false, "Print the IR flow graph.");
+DEFINE_FLAG(bool, use_ssa, false, "Use SSA form");
 DECLARE_FLAG(bool, enable_type_checks);
 
 
 FlowGraphBuilder::FlowGraphBuilder(const ParsedFunction& parsed_function)
   : parsed_function_(parsed_function),
     preorder_block_entries_(),
     postorder_block_entries_(),
     context_level_(0),
     last_used_try_index_(CatchClauseNode::kInvalidTryIndex),
     try_index_(CatchClauseNode::kInvalidTryIndex),
@@ skipping 2296 matching lines @@
                                &preorder_block_entries_,
                                &postorder_block_entries_,
                                &parent,
                                &assigned_vars,
                                variable_count);
   // Number blocks in reverse postorder.
   intptr_t block_count = postorder_block_entries_.length();
   for (intptr_t i = 0; i < block_count; ++i) {
     postorder_block_entries_[i]->set_block_id(block_count - i - 1);
   }
-  if (for_optimized) {
+  if (for_optimized && FLAG_use_ssa) {
     GrowableArray<BitVector*> dominance_frontier;
     ComputeDominators(&preorder_block_entries_, &parent, &dominance_frontier);
     InsertPhis(preorder_block_entries_,
                assigned_vars,
                variable_count,
                dominance_frontier);
     // TODO(fschneider): Perform SSA renaming.
   }
   if (FLAG_print_flow_graph || (Dart::flow_graph_writer() != NULL)) {
     intptr_t length = postorder_block_entries_.length();
     GrowableArray<BlockEntryInstr*> reverse_postorder(length);
     for (intptr_t i = length - 1; i >= 0; --i) {
       reverse_postorder.Add(postorder_block_entries_[i]);
     }
     if (FLAG_print_flow_graph) {
       // Print flow graph to stdout.
       FlowGraphPrinter printer(function, reverse_postorder);
       printer.PrintBlocks();
     }
     if (Dart::flow_graph_writer() != NULL) {
       // Write flow graph to file.
       FlowGraphVisualizer printer(function, reverse_postorder);
       printer.PrintFunction();
     }
   }
+
+  if (for_optimized && FLAG_use_ssa) {
+    Bailout("No SSA code generation support.");
+  }
 }
 
 
 // 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.
 //
 // preorder: an input list of basic block entries in preorder.  The
 //     algorithm relies on the block ordering.
 //
@@ skipping 177 matching lines @@
   char* chars = reinterpret_cast<char*>(
       Isolate::Current()->current_zone()->Allocate(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);
 }
 
 
 }  // namespace dart