improve perf_basic_prof filename reporting

src/log.cc

 // Copyright 2011 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/log.h"
 
 #include <cstdarg>
 #include <sstream>
 
 #include "src/bailout-reason.h"
@@ skipping 105 matching lines @@
   void AppendBytes(const char* bytes) {
     AppendBytes(bytes, StrLength(bytes));
   }
 
   void AppendByte(char c) {
     if (utf8_pos_ >= kUtf8BufferSize) return;
     utf8_buffer_[utf8_pos_++] = c;
   }
 
   void AppendInt(int n) {
-    Vector<char> buffer(utf8_buffer_ + utf8_pos_,
-                        kUtf8BufferSize - utf8_pos_);
+    int space = kUtf8BufferSize - utf8_pos_;
+    if (space <= 0) return;
+    Vector<char> buffer(utf8_buffer_ + utf8_pos_, space);
     int size = SNPrintF(buffer, "%d", n);
     if (size > 0 && utf8_pos_ + size <= kUtf8BufferSize) {
       utf8_pos_ += size;
     }
   }
 
   void AppendHex(uint32_t n) {
-    Vector<char> buffer(utf8_buffer_ + utf8_pos_,
-                        kUtf8BufferSize - utf8_pos_);
+    int space = kUtf8BufferSize - utf8_pos_;
+    if (space <= 0) return;
+    Vector<char> buffer(utf8_buffer_ + utf8_pos_, space);
     int size = SNPrintF(buffer, "%x", n);
     if (size > 0 && utf8_pos_ + size <= kUtf8BufferSize) {
       utf8_pos_ += size;
     }
   }
 
   const char* get() { return utf8_buffer_; }
   int size() const { return utf8_pos_; }
 
  private:
   static const int kUtf8BufferSize = 512;
-  static const int kUtf16BufferSize = 128;
+  static const int kUtf16BufferSize = kUtf8BufferSize;
 
   int utf8_pos_;
   char utf8_buffer_[kUtf8BufferSize];
   uc16 utf16_buffer[kUtf16BufferSize];
 };
 
 
 CodeEventLogger::CodeEventLogger() : name_buffer_(new NameBuffer) { }
 
 CodeEventLogger::~CodeEventLogger() { delete name_buffer_; }
@@ skipping 1748 matching lines @@
     removeCodeEventListener(jit_logger_);
     delete jit_logger_;
     jit_logger_ = NULL;
   }
 
   return log_->Close();
 }
 
 }  // namespace internal
 }  // namespace v8