Insert proper padding between lazy deoptimization points and safepoints.

On x64 we need 13 bytes for patching the call for lazy deopt. We have to
make sure that patching does not overwrite the code at the safepoint.

BUG=v8:1847
Review URL: http://codereview.chromium.org/8775009

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@10126 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/x64/lithium-codegen-x64.cc

@@ -49,7 +49,9 @@ class SafepointGenerator : public CallWrapper {
         deopt_mode_(mode) { }
   virtual ~SafepointGenerator() { }
 
-  virtual void BeforeCall(int call_size) const { }
+  virtual void BeforeCall(int call_size) const {
+    codegen_->EnsureSpaceForLazyDeopt(Deoptimizer::patch_size() - call_size);
+  }
 
   virtual void AfterCall() const {
     codegen_->RecordSafepoint(pointers_, deopt_mode_);
@@ -241,7 +243,7 @@ bool LCodeGen::GenerateBody() {
       instr->CompileToNative(this);
     }
   }
-  EnsureSpaceForLazyDeopt();
+  EnsureSpaceForLazyDeopt(Deoptimizer::patch_size());
   return !is_aborted();
 }
 
@@ -439,6 +441,7 @@ void LCodeGen::CallCodeGeneric(Handle<Code> code,
                                LInstruction* instr,
                                SafepointMode safepoint_mode,
                                int argc) {
+  EnsureSpaceForLazyDeopt(Deoptimizer::patch_size() - masm()->CallSize(code));
   ASSERT(instr != NULL);
   LPointerMap* pointers = instr->pointer_map();
   RecordPosition(pointers->position());
@@ -4176,25 +4179,24 @@ void LCodeGen::EmitIsConstructCall(Register temp) {
 }
 
 
-void LCodeGen::EnsureSpaceForLazyDeopt() {
+void LCodeGen::EnsureSpaceForLazyDeopt(int space_needed) {
   // Ensure that we have enough space after the previous lazy-bailout
   // instruction for patching the code here.
   int current_pc = masm()->pc_offset();
-  int patch_size = Deoptimizer::patch_size();
-  if (current_pc < last_lazy_deopt_pc_ + patch_size) {
-    int padding_size = last_lazy_deopt_pc_ + patch_size - current_pc;
+  if (current_pc < last_lazy_deopt_pc_ + space_needed) {
+    int padding_size = last_lazy_deopt_pc_ + space_needed - current_pc;
     while (padding_size > 0) {
       int nop_size = padding_size > 9 ? 9 : padding_size;
       __ nop(nop_size);
       padding_size -= nop_size;
     }
   }
-  last_lazy_deopt_pc_ = masm()->pc_offset();
 }
 
 
 void LCodeGen::DoLazyBailout(LLazyBailout* instr) {
-  EnsureSpaceForLazyDeopt();
+  EnsureSpaceForLazyDeopt(Deoptimizer::patch_size());
+  last_lazy_deopt_pc_ = masm()->pc_offset();
   ASSERT(instr->HasEnvironment());
   LEnvironment* env = instr->environment();
   RegisterEnvironmentForDeoptimization(env, Safepoint::kLazyDeopt);
@@ -4265,7 +4267,7 @@ void LCodeGen::DoStackCheck(LStackCheck* instr) {
       new DeferredStackCheck(this, instr);
   __ CompareRoot(rsp, Heap::kStackLimitRootIndex);
   __ j(below, deferred_stack_check->entry());
-  EnsureSpaceForLazyDeopt();
+  EnsureSpaceForLazyDeopt(Deoptimizer::patch_size());
   __ bind(instr->done_label());
   deferred_stack_check->SetExit(instr->done_label());
   // There is no LLazyBailout instruction for stack-checks. We have to

src/x64/lithium-codegen-x64.h

@@ -305,7 +305,7 @@ class LCodeGen BASE_EMBEDDED {
     Address address;
   };
 
-  void EnsureSpaceForLazyDeopt();
+  void EnsureSpaceForLazyDeopt(int space_needed);
 
   LChunk* const chunk_;
   MacroAssembler* const masm_;