SSI implementation.

src/hydrogen.cc

 // Copyright 2012 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 579 matching lines @@
   if (!pointer->is_set()) {
     HConstant* constant =
         new(zone()) HConstant(value, Representation::Integer32());
     constant->InsertAfter(GetConstantUndefined());
     pointer->set(constant);
   }
   return pointer->get();
 }
 
 
+HConstant* HGraph::GetConstant0() {
+  return GetConstantInt32(&constant_0_, 0);
+}
+
+
 HConstant* HGraph::GetConstant1() {
   return GetConstantInt32(&constant_1_, 1);
 }
 
 
 HConstant* HGraph::GetConstantMinus1() {
   return GetConstantInt32(&constant_minus1_, -1);
 }
 
 
@@ skipping 2882 matching lines @@
   if (FLAG_use_range) {
     HRangeAnalysis rangeAnalysis(this);
     rangeAnalysis.Analyze();
   }
   ComputeMinusZeroChecks();
 
   // Eliminate redundant stack checks on backwards branches.
   HStackCheckEliminator sce(this);
   sce.Process();
 
+  if (FLAG_use_ssi) {
+    BuildSsi();
+    CleanupSsi();
+  }
+
   EliminateRedundantBoundsChecks();
   DehoistSimpleArrayIndexComputations();
   if (FLAG_dead_code_elimination) DeadCodeElimination();
 
   return true;
 }
 
 
 // We try to "factor up" HBoundsCheck instructions towards the root of the
 // dominator tree.
@@ skipping 420 matching lines @@
         array_instruction = static_cast<ArrayInstructionInterface*>(op);
       } else {
         continue;
       }
       DehoistArrayIndex(array_instruction);
     }
   }
 }
 
 
+void HGraph::BuildSsi() {
+  HPhase phase("H_Build SSI", this);
+  entry_block()->BuildSsiRecursively();
+}
+
+
+void HGraph::CleanupSsi() {
+  HPhase phase("H_Cleanup SSI", this);
+  for (int b_index = 0; b_index < blocks()->length(); b_index++) {
+    HBasicBlock* block = blocks()->at(b_index);
+    HInstruction* current = block->first();
+    while (current != NULL) {
+      HInstruction* next = current->next();
+      if (current->IsSsiDefinition()) {
+        current->DeleteAndReplaceWith(current->ValueBeforeSsi());
+      }
+      current = next;
+    }
+  }
+}
+
+
 void HGraph::DeadCodeElimination() {
   HPhase phase("H_Dead code elimination", this);
   ZoneList<HInstruction*> worklist(blocks_.length(), zone());
   for (int i = 0; i < blocks()->length(); ++i) {
     for (HInstruction* instr = blocks()->at(i)->first();
          instr != NULL;
          instr = instr->next()) {
       if (instr->IsDead()) worklist.Add(instr, zone());
     }
   }
@@ skipping 6242 matching lines @@
     }
   }
 
 #ifdef DEBUG
   if (graph_ != NULL) graph_->Verify(false);  // No full verify.
   if (allocator_ != NULL) allocator_->Verify();
 #endif
 }
 
 } }  // namespace v8::internal