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Commit 3574c37f authored by Tom Cherry's avatar Tom Cherry
Browse files

liblog: add __attribute__((uninitialized)) to liblog buffers 

These buffers are immediately written into with *printf() and are in
the hot path, so do not initialize them.  This saves ~70ns off of each
log message, which is ~14% of the overhead within
__android_log_print() when writing to a no-op logger.

Test: liblog benchmarks
Change-Id: I2b898e72c75b57bc63fee565b49a4e00e377ed1a
parent e53f8b8f

liblog/logger_write.cpp

+4 −4
Original line number Diff line number Diff line
@@ -348,7 +348,7 @@ int __android_log_vprint(int prio, const char* tag, const char* fmt, va_list ap) 
    return 0;

  }



  char buf[LOG_BUF_SIZE];

  __attribute__((uninitialized)) char buf[LOG_BUF_SIZE];



  vsnprintf(buf, LOG_BUF_SIZE, fmt, ap);
@@ -366,7 +366,7 @@ int __android_log_print(int prio, const char* tag, const char* fmt, ...) { 
  }



  va_list ap;

  char buf[LOG_BUF_SIZE];

  __attribute__((uninitialized)) char buf[LOG_BUF_SIZE];



  va_start(ap, fmt);

  vsnprintf(buf, LOG_BUF_SIZE, fmt, ap);
@@ -386,7 +386,7 @@ int __android_log_buf_print(int bufID, int prio, const char* tag, const char* fm 
  }



  va_list ap;

  char buf[LOG_BUF_SIZE];

  __attribute__((uninitialized)) char buf[LOG_BUF_SIZE];



  va_start(ap, fmt);

  vsnprintf(buf, LOG_BUF_SIZE, fmt, ap);
@@ -398,7 +398,7 @@ int __android_log_buf_print(int bufID, int prio, const char* tag, const char* fm 
}



void __android_log_assert(const char* cond, const char* tag, const char* fmt, ...) {

  char buf[LOG_BUF_SIZE];

  __attribute__((uninitialized)) char buf[LOG_BUF_SIZE];



  if (fmt) {

    va_list ap;