Introduce DontEmitDebugCodeScope to fix the x64 nosnapshot build.

R=yangguo@chromium.org

Review URL: https://codereview.chromium.org/232673003

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@20784 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/assembler.h

@@ -107,6 +107,22 @@ class AssemblerBase: public Malloced {
 };
 
 
+// Avoids emitting debug code during the lifetime of this scope object.
+class DontEmitDebugCodeScope BASE_EMBEDDED {
+ public:
+  explicit DontEmitDebugCodeScope(AssemblerBase* assembler)
+      : assembler_(assembler), old_value_(assembler->emit_debug_code()) {
+    assembler_->set_emit_debug_code(false);
+  }
+  ~DontEmitDebugCodeScope() {
+    assembler_->set_emit_debug_code(old_value_);
+  };
+ private:
+  AssemblerBase* assembler_;
+  bool old_value_;
+};
+
+
 // Avoids using instructions that vary in size in unpredictable ways between the
 // snapshot and the running VM.
 class PredictableCodeSizeScope {

src/x64/full-codegen-x64.cc

@@ -363,6 +363,9 @@ void FullCodeGenerator::EmitProfilingCounterReset() {
 }
 
 
+static const byte kJnsOffset = kPointerSize == kInt64Size ? 0x1d : 0x14;
+
+
 void FullCodeGenerator::EmitBackEdgeBookkeeping(IterationStatement* stmt,
                                                 Label* back_edge_target) {
   Comment cmnt(masm_, "[ Back edge bookkeeping");
@@ -373,7 +376,11 @@ void FullCodeGenerator::EmitBackEdgeBookkeeping(IterationStatement* stmt,
   int weight = Min(kMaxBackEdgeWeight,
                    Max(1, distance / kCodeSizeMultiplier));
   EmitProfilingCounterDecrement(weight);
+
   __ j(positive, &ok, Label::kNear);
+  {
+    PredictableCodeSizeScope predictible_code_size_scope(masm_, kJnsOffset);
+    DontEmitDebugCodeScope dont_emit_debug_code_scope(masm_);
     __ call(isolate()->builtins()->InterruptCheck(), RelocInfo::CODE_TARGET);
 
     // Record a mapping of this PC offset to the OSR id.  This is used to find
@@ -382,8 +389,9 @@ void FullCodeGenerator::EmitBackEdgeBookkeeping(IterationStatement* stmt,
     RecordBackEdge(stmt->OsrEntryId());
 
     EmitProfilingCounterReset();
-
+  }
   __ bind(&ok);
+
   PrepareForBailoutForId(stmt->EntryId(), NO_REGISTERS);
   // Record a mapping of the OSR id to this PC.  This is used if the OSR
   // entry becomes the target of a bailout.  We don't expect it to be, but
@@ -4844,7 +4852,6 @@ FullCodeGenerator::NestedStatement* FullCodeGenerator::TryFinally::Exit(
 
 
 static const byte kJnsInstruction = 0x79;
-static const byte kJnsOffset = kPointerSize == kInt64Size ? 0x1d : 0x14;
 static const byte kNopByteOne = 0x66;
 static const byte kNopByteTwo = 0x90;
 #ifdef DEBUG