Cosmetic cleanup for GVN.

src/hydrogen-gvn.cc

 // Copyright 2013 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 346 matching lines @@
     GVNFlag changes_flag = HValue::ChangesFlagFromInt(i);
     if (flags.Contains(changes_flag)) {
       if (data_[i] == NULL) count_++;
       data_[i] = instr;
     }
   }
 }
 
 
 HGlobalValueNumberingPhase::HGlobalValueNumberingPhase(HGraph* graph)
-      : HPhase("H_Global value numbering", graph),
-        removed_side_effects_(false),
-        block_side_effects_(graph->blocks()->length(), zone()),
-        loop_side_effects_(graph->blocks()->length(), zone()),
-        visited_on_paths_(graph->blocks()->length(), zone()) {
-    ASSERT(!AllowHandleAllocation::IsAllowed());
-    block_side_effects_.AddBlock(GVNFlagSet(), graph->blocks()->length(),
-                                 zone());
-    loop_side_effects_.AddBlock(GVNFlagSet(), graph->blocks()->length(),
+    : HPhase("H_Global value numbering", graph),
+      removed_side_effects_(false),
+      block_side_effects_(graph->blocks()->length(), zone()),
+      loop_side_effects_(graph->blocks()->length(), zone()),
+      visited_on_paths_(graph->blocks()->length(), zone()) {
+  ASSERT(!AllowHandleAllocation::IsAllowed());
+  block_side_effects_.AddBlock(GVNFlagSet(), graph->blocks()->length(),
                                 zone());
+  loop_side_effects_.AddBlock(GVNFlagSet(), graph->blocks()->length(),
+                              zone());
 }
 
 
-void HGlobalValueNumberingPhase::Reset() {
-  ASSERT(block_side_effects_.length() == graph()->blocks()->length());
-  ASSERT(loop_side_effects_.length() == graph()->blocks()->length());
-  for (int i = 0; i < graph()->blocks()->length(); ++i) {
-    block_side_effects_[i] = GVNFlagSet();
-    loop_side_effects_[i] = GVNFlagSet();
+void HGlobalValueNumberingPhase::Run() {
+  ASSERT(!removed_side_effects_);
+  for (int i = FLAG_gvn_iterations; i > 0; --i) {
+    // Compute the side effects.
+    ComputeBlockSideEffects();
+
+    // Perform loop invariant code motion if requested.
+    if (FLAG_loop_invariant_code_motion) LoopInvariantCodeMotion();
+
+    // Perform the actual value numbering.
+    AnalyzeGraph();
+
+    // Continue GVN if we removed any side effects.
+    if (!removed_side_effects_) break;
+    removed_side_effects_ = false;
+
+    // Clear all side effects.
+    ASSERT_EQ(block_side_effects_.length(), graph()->blocks()->length());
+    ASSERT_EQ(loop_side_effects_.length(), graph()->blocks()->length());
+    for (int i = 0; i < graph()->blocks()->length(); ++i) {
+      block_side_effects_[i].RemoveAll();
+      loop_side_effects_[i].RemoveAll();
+    }
+    visited_on_paths_.Clear();
   }
-  visited_on_paths_.Clear();
-}
-
-
-void HGlobalValueNumberingPhase::Analyze() {
-  removed_side_effects_ = false;
-  ComputeBlockSideEffects();
-  if (FLAG_loop_invariant_code_motion) {
-    LoopInvariantCodeMotion();
-  }
-  AnalyzeGraph();
 }
 
 
 void HGlobalValueNumberingPhase::ComputeBlockSideEffects() {
-  // The Analyze phase of GVN can be called multiple times. Clear loop side
-  // effects before computing them to erase the contents from previous Analyze
-  // passes.
-  for (int i = 0; i < loop_side_effects_.length(); ++i) {
-    loop_side_effects_[i].RemoveAll();
-  }
   for (int i = graph()->blocks()->length() - 1; i >= 0; --i) {
     // Compute side effects for the block.
     HBasicBlock* block = graph()->blocks()->at(i);
     GVNFlagSet side_effects;
     if (block->IsReachable() && !block->IsDeoptimizing()) {
       int id = block->block_id();
       for (HInstructionIterator it(block); !it.Done(); it.Advance()) {
         HInstruction* instr = it.Current();
         side_effects.Add(instr->ChangesFlags());
       }
@@ skipping 444 matching lines @@
                                                       dominated);
         successor_map->Kill(side_effects_on_all_paths);
         successor_dominators->Kill(side_effects_on_all_paths);
       }
     }
     current = next;
   }
 }
 
 } }  // namespace v8::internal