From 8acd4accacbc1e0891ee81275c3d20088ccca84d Mon Sep 17 00:00:00 2001
From: "fschneider@chromium.org"
 <fschneider@chromium.org@ce2b1a6d-e550-0410-aec6-3dcde31c8c00>
Date: Thu, 1 Dec 2011 14:19:34 +0000
Subject: [PATCH] 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 | 20 +++++++++++---------
 src/x64/lithium-codegen-x64.h  |  2 +-
 2 files changed, 12 insertions(+), 10 deletions(-)

diff --git a/src/x64/lithium-codegen-x64.cc b/src/x64/lithium-codegen-x64.cc
index 23bd952..02c36a3 100644
--- a/src/x64/lithium-codegen-x64.cc
+++ b/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
diff --git a/src/x64/lithium-codegen-x64.h b/src/x64/lithium-codegen-x64.h
index 868f75e..7bd7fe6 100644
--- a/src/x64/lithium-codegen-x64.h
+++ b/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_;
-- 
2.7.4