Basic support for LICM of fully invariant loads.

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 18 matching lines @@
     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_(),
     block_effects_(NULL),
-    licm_allowed_(true) {
+    licm_allowed_(true),
+    loop_headers_(NULL),
+    loop_invariant_loads_(NULL) {
   DiscoverBlocks();
 }
 
 
 ConstantInstr* FlowGraph::GetConstant(const Object& object) {
   // Check if the constant is already in the pool.
   GrowableArray<Definition*>* pool = graph_entry_->initial_definitions();
   for (intptr_t i = 0; i < pool->length(); ++i) {
     ConstantInstr* constant = (*pool)[i]->AsConstant();
     if ((constant != NULL) && (constant->value().raw() == object.raw())) {
@@ skipping 53 matching lines @@
                                variable_count(),
                                num_non_copied_params());
   // Create an array of blocks in reverse postorder.
   intptr_t block_count = postorder_.length();
   for (intptr_t i = 0; i < block_count; ++i) {
     reverse_postorder_.Add(postorder_[block_count - i - 1]);
   }
 
   // Block effects are using postorder numbering. Discard computed information.
   block_effects_ = NULL;
+  loop_headers_ = NULL;
+  loop_invariant_loads_ = NULL;
 }
 
 
 #ifdef DEBUG
 // Debugging code to verify the construction of use lists.
 
 static intptr_t MembershipCount(Value* use, Value* list) {
   intptr_t count = 0;
   while (list != NULL) {
     if (list == use) ++count;
@@ skipping 827 matching lines @@
   }
   n->set_loop_info(loop);
   if (FLAG_trace_optimization) {
     for (BitVector::Iterator it(loop); !it.Done(); it.Advance()) {
       OS::Print("  B%"Pd"\n", it.Current());
     }
   }
 }
 
 
-void FlowGraph::ComputeLoops(GrowableArray<BlockEntryInstr*>* loop_headers) {
-  ASSERT(loop_headers->is_empty());
+ZoneGrowableArray<BlockEntryInstr*>* FlowGraph::ComputeLoops() {
+  ZoneGrowableArray<BlockEntryInstr*>* loop_headers =
+      new ZoneGrowableArray<BlockEntryInstr*>();
+
   for (BlockIterator it = postorder_iterator();
        !it.Done();
        it.Advance()) {
     BlockEntryInstr* block = it.Current();
     for (intptr_t i = 0; i < block->PredecessorCount(); ++i) {
       BlockEntryInstr* pred = block->PredecessorAt(i);
       if (block->Dominates(pred)) {
         if (FLAG_trace_optimization) {
           OS::Print("Back edge B%"Pd" -> B%"Pd"\n", pred->block_id(),
                     block->block_id());
         }
         FindLoop(pred, block, preorder_.length());
         loop_headers->Add(block);
       }
     }
   }
+
+  return loop_headers;
 }
 
 
 void FlowGraph::Bailout(const char* reason) const {
   const char* kFormat = "FlowGraph Bailout: %s %s";
   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(
@@ skipping 119 matching lines @@
 }
 
 
 bool BlockEffects::IsSideEffectFreePath(BlockEntryInstr* from,
                                         BlockEntryInstr* to) const {
   return available_at_[to->postorder_number()]->Contains(
       from->postorder_number());
 }
 
 }  // namespace dart