Disable aggressive optimizations on the last optimization attempt.

Only has effect on the loop invariant code motion and Check instructions
for now.

Review URL: http://codereview.chromium.org/6321007

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@6363 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/compiler.cc

@@ -207,7 +207,8 @@ static bool MakeCrankshaftCode(CompilationInfo* info) {
 
   // Limit the number of times we re-compile a functions with
   // the optimizing compiler.
-  const int kMaxOptCount = FLAG_deopt_every_n_times == 0 ? 10 : 1000;
+  const int kMaxOptCount =
+      FLAG_deopt_every_n_times == 0 ? Compiler::kDefaultMaxOptCount : 1000;
   if (info->shared_info()->opt_count() > kMaxOptCount) {
     AbortAndDisable(info);
     // True indicates the compilation pipeline is still going, not

src/compiler.h

@@ -209,9 +209,13 @@ class CompilationInfo BASE_EMBEDDED {
 
 class Compiler : public AllStatic {
  public:
-  // All routines return a JSFunction.
-  // If an error occurs an exception is raised and
-  // the return handle contains NULL.
+  // Default maximum number of function optimization attempts before we
+  // give up.
+  static const int kDefaultMaxOptCount = 10;
+
+  // All routines return a SharedFunctionInfo.
+  // If an error occurs an exception is raised and the return handle
+  // contains NULL.
 
   // Compile a String source within a context.
   static Handle<SharedFunctionInfo> Compile(Handle<String> source,

src/hydrogen-instructions.h

@@ -773,6 +773,10 @@ class HInstruction: public HValue {
   virtual void Verify() const;
 #endif
 
+  // Returns whether this is some kind of deoptimizing check
+  // instruction.
+  virtual bool IsCheckInstruction() const { return false; }
+
   DECLARE_INSTRUCTION(Instruction)
 
  protected:
@@ -1504,6 +1508,8 @@ class HCheckMap: public HUnaryOperation {
     SetFlag(kDependsOnMaps);
   }
 
+  virtual bool IsCheckInstruction() const { return true; }
+
   virtual Representation RequiredInputRepresentation(int index) const {
     return Representation::Tagged();
   }
@@ -1537,6 +1543,8 @@ class HCheckFunction: public HUnaryOperation {
     SetFlag(kUseGVN);
   }
 
+  virtual bool IsCheckInstruction() const { return true; }
+
   virtual Representation RequiredInputRepresentation(int index) const {
     return Representation::Tagged();
   }
@@ -1573,6 +1581,8 @@ class HCheckInstanceType: public HUnaryOperation {
     SetFlag(kUseGVN);
   }
 
+  virtual bool IsCheckInstruction() const { return true; }
+
   virtual Representation RequiredInputRepresentation(int index) const {
     return Representation::Tagged();
   }
@@ -1610,6 +1620,8 @@ class HCheckNonSmi: public HUnaryOperation {
     SetFlag(kUseGVN);
   }
 
+  virtual bool IsCheckInstruction() const { return true; }
+
   virtual Representation RequiredInputRepresentation(int index) const {
     return Representation::Tagged();
   }
@@ -1632,6 +1644,8 @@ class HCheckPrototypeMaps: public HInstruction {
     SetFlag(kDependsOnMaps);
   }
 
+  virtual bool IsCheckInstruction() const { return true; }
+
 #ifdef DEBUG
   virtual void Verify() const;
 #endif
@@ -1668,6 +1682,8 @@ class HCheckSmi: public HUnaryOperation {
     SetFlag(kUseGVN);
   }
 
+  virtual bool IsCheckInstruction() const { return true; }
+
   virtual Representation RequiredInputRepresentation(int index) const {
     return Representation::Tagged();
   }
@@ -1996,6 +2012,8 @@ class HBoundsCheck: public HBinaryOperation {
     SetFlag(kUseGVN);
   }
 
+  virtual bool IsCheckInstruction() const { return true; }
+
   virtual Representation RequiredInputRepresentation(int index) const {
     return Representation::Integer32();
   }

src/hydrogen.cc

@@ -687,6 +687,11 @@ HGraph::HGraph(CompilationInfo* info)
 }
 
 
+bool HGraph::AllowAggressiveOptimizations() const {
+  return info()->shared_info()->opt_count() + 1 < Compiler::kDefaultMaxOptCount;
+}
+
+
 Handle<Code> HGraph::Compile() {
   int values = GetMaximumValueID();
   if (values > LAllocator::max_initial_value_ids()) {
@@ -1453,8 +1458,12 @@ void HGlobalValueNumberer::ProcessLoopBlock(HBasicBlock* block,
 // about code that was never executed.
 bool HGlobalValueNumberer::ShouldMove(HInstruction* instr,
                                       HBasicBlock* loop_header) {
-  if (!instr->IsChange() &&
-      FLAG_aggressive_loop_invariant_motion) return true;
+  if (FLAG_aggressive_loop_invariant_motion &&
+      !instr->IsChange() &&
+      (!instr->IsCheckInstruction() ||
+       graph_->AllowAggressiveOptimizations())) {
+    return true;
+  }
   HBasicBlock* block = instr->block();
   bool result = true;
   if (block != loop_header) {

src/hydrogen.h

@@ -296,6 +296,9 @@ class HGraph: public HSubgraph {
   explicit HGraph(CompilationInfo* info);
 
   CompilationInfo* info() const { return info_; }
+
+  bool AllowAggressiveOptimizations() const;
+
   const ZoneList<HBasicBlock*>* blocks() const { return &blocks_; }
   const ZoneList<HPhi*>* phi_list() const { return phi_list_; }
   Handle<String> debug_name() const { return info_->function()->debug_name(); }