Change the handling of stack check on backward branches

src/x64/lithium-codegen-x64.cc

 // Copyright 2011 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 1407 matching lines @@
       __ push(reg);
       __ CallStub(&stub);
       __ testq(rax, rax);
       __ Popad();
       EmitBranch(true_block, false_block, not_zero);
     }
   }
 }
 
 
-void LCodeGen::EmitGoto(int block, LDeferredCode* deferred_stack_check) {
+void LCodeGen::EmitGoto(int block) {
   block = chunk_->LookupDestination(block);
   int next_block = GetNextEmittedBlock(current_block_);
   if (block != next_block) {
-    // Perform stack overflow check if this goto needs it before jumping.
-    if (deferred_stack_check != NULL) {
-      __ CompareRoot(rsp, Heap::kStackLimitRootIndex);
-      __ j(above_equal, chunk_->GetAssemblyLabel(block));
-      __ jmp(deferred_stack_check->entry());
-      deferred_stack_check->SetExit(chunk_->GetAssemblyLabel(block));
-    } else {
-      __ jmp(chunk_->GetAssemblyLabel(block));
-    }
+    __ jmp(chunk_->GetAssemblyLabel(block));
   }
 }
 
 
-void LCodeGen::DoDeferredStackCheck(LGoto* instr) {
-  PushSafepointRegistersScope scope(this);
-  CallRuntimeFromDeferred(Runtime::kStackGuard, 0, instr);
+void LCodeGen::DoGoto(LGoto* instr) {
+  EmitGoto(instr->block_id());
 }
 
 
-void LCodeGen::DoGoto(LGoto* instr) {
-  class DeferredStackCheck: public LDeferredCode {
-   public:
-    DeferredStackCheck(LCodeGen* codegen, LGoto* instr)
-        : LDeferredCode(codegen), instr_(instr) { }
-    virtual void Generate() { codegen()->DoDeferredStackCheck(instr_); }
-   private:
-    LGoto* instr_;
-  };
-
-  DeferredStackCheck* deferred = NULL;
-  if (instr->include_stack_check()) {
-    deferred = new DeferredStackCheck(this, instr);
-  }
-  EmitGoto(instr->block_id(), deferred);
-}
-
-
 inline Condition LCodeGen::TokenToCondition(Token::Value op, bool is_unsigned) {
   Condition cond = no_condition;
   switch (op) {
     case Token::EQ:
     case Token::EQ_STRICT:
       cond = equal;
       break;
     case Token::LT:
       cond = is_unsigned ? below : less;
       break;
@@ skipping 2804 matching lines @@
   // Create safepoint generator that will also ensure enough space in the
   // reloc info for patching in deoptimization (since this is invoking a
   // builtin)
   SafepointGenerator safepoint_generator(this,
                                          pointers,
                                          env->deoptimization_index());
   __ InvokeBuiltin(Builtins::IN, CALL_FUNCTION, safepoint_generator);
 }
 
 
+void LCodeGen::DoDeferredStackCheck(LStackCheck* instr) {
+  PushSafepointRegistersScope scope(this);
+  CallRuntimeFromDeferred(Runtime::kStackGuard, 0, instr);
+}
+
+
 void LCodeGen::DoStackCheck(LStackCheck* instr) {
-  // Perform stack overflow check.
-  Label done;
-  __ CompareRoot(rsp, Heap::kStackLimitRootIndex);
-  __ j(above_equal, &done, Label::kNear);
+  class DeferredStackCheck: public LDeferredCode {
+   public:
+    DeferredStackCheck(LCodeGen* codegen, LStackCheck* instr)
+        : LDeferredCode(codegen), instr_(instr) { }
+    virtual void Generate() { codegen()->DoDeferredStackCheck(instr_); }
+   private:
+    LStackCheck* instr_;
+  };
 
-  StackCheckStub stub;
-  CallCode(stub.GetCode(), RelocInfo::CODE_TARGET, instr);
-  __ bind(&done);
+  if (instr->hydrogen()->is_function_entry()) {
+    // Perform stack overflow check.
+    Label done;
+    __ CompareRoot(rsp, Heap::kStackLimitRootIndex);
+    __ j(above_equal, &done, Label::kNear);
+    StackCheckStub stub;
+    CallCode(stub.GetCode(), RelocInfo::CODE_TARGET, instr);
+    __ bind(&done);
+  } else {
+    ASSERT(instr->hydrogen()->is_backwards_branch());
+    // Perform stack overflow check if this goto needs it before jumping.
+    DeferredStackCheck* deferred_stack_check =
+        new DeferredStackCheck(this, instr);
+    __ CompareRoot(rsp, Heap::kStackLimitRootIndex);
+    __ j(below, deferred_stack_check->entry());
+    __ bind(instr->done_label());
+    deferred_stack_check->SetExit(instr->done_label());
+  }
 }
 
 
 void LCodeGen::DoOsrEntry(LOsrEntry* instr) {
   // This is a pseudo-instruction that ensures that the environment here is
   // properly registered for deoptimization and records the assembler's PC
   // offset.
   LEnvironment* environment = instr->environment();
   environment->SetSpilledRegisters(instr->SpilledRegisterArray(),
                                    instr->SpilledDoubleRegisterArray());
 
   // If the environment were already registered, we would have no way of
   // backpatching it with the spill slot operands.
   ASSERT(!environment->HasBeenRegistered());
   RegisterEnvironmentForDeoptimization(environment);
   ASSERT(osr_pc_offset_ == -1);
   osr_pc_offset_ = masm()->pc_offset();
 }
 
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_X64