[llvm-commits] CVS: llvm/include/llvm/Support/Debug.h

[Reid Spencer]

Bill,

On Thu, 2006-11-16 at 18:49 -0600, Bill Wendling wrote:
> 
> Changes in directory llvm/include/llvm/Support:
> 
> Debug.h updated: 1.7 -> 1.8
> ---
> Log message:
> 
> Added "DOUT" macro. This is used as a replacement for the std::cerr
> stream. It centralizes the use of std::cerr so that static c'tor/d'tors
> aren't scattered around all over the place. The way to use it is like this:
> 
>        DOUT << "This is a status line: " << Var << "\n";
> 
> If "-debug" is specified, it will print. Otherwise, it'll not print. If
> NDEBUG is defined, the DOUT does nothing.

While this may not print anything when NDEBUG is *not* defined, it isn't
sufficient. You're going to leave template functions scattered all over
the place and calls to them. The existing solution completely eliminates
the code from an NDEBUG build. That's what we want. What's wrong with
the existing solution?  Or, perhaps a combination is needed. Something
like:

DEBUG(DOUT << "This is a debug message\n");

> 
> 
> ---
> Diffs of the changes:  (+30 -0)
> 
>  Debug.h |   30 ++++++++++++++++++++++++++++++
>  1 files changed, 30 insertions(+)
> 
> 
> Index: llvm/include/llvm/Support/Debug.h
> diff -u llvm/include/llvm/Support/Debug.h:1.7 llvm/include/llvm/Support/Debug.h:1.8
> --- llvm/include/llvm/Support/Debug.h:1.7	Sun Jan 22 16:54:51 2006
> +++ llvm/include/llvm/Support/Debug.h	Thu Nov 16 18:49:12 2006
> @@ -26,6 +26,8 @@
>  #ifndef LLVM_SUPPORT_DEBUG_H
>  #define LLVM_SUPPORT_DEBUG_H
>  
> +#include <ostream>              // Doesn't have static d'tors!!
> +
>  namespace llvm {
>  
>  // DebugFlag - This boolean is set to true if the '-debug' command line option
> @@ -59,6 +61,34 @@
>    do { if (DebugFlag && isCurrentDebugType(DEBUG_TYPE)) { X; } } while (0)
>  #endif
>  
> +// llvm_ostream - Acts like an ostream. However, it doesn't print things out if
> +// an ostream isn't specified.
> +// 
> +class llvm_ostream {
> +  std::ostream* Stream;
> +public:
> +  llvm_ostream() : Stream(0) {}
> +  llvm_ostream(std::ostream& OStream) : Stream(&OStream) {}
> +
> +  template <typename Ty>
> +  llvm_ostream& operator << (const Ty& Thing) {
> +    if (Stream) *Stream << Thing;
> +    return *this;
> +  }
> +};
> +
> +// getErrorOutputStream - Returns the error output stream (std::cerr). This
> +// places the std::c* I/O streams into one .cpp file and relieves the whole
> +// program from having to have hundreds of static c'tor/d'tors for them.
> +// 
> +llvm_ostream getErrorOutputStream(const char *DebugType);
> +
> +#ifdef NDEBUG
> +#define DOUT llvm_ostream()
> +#else
> +#define DOUT getErrorOutputStream(DEBUG_TYPE)
> +#endif
> +
>  } // End llvm namespace
>  
>  #endif
> 
> 
> 
> _______________________________________________
> llvm-commits mailing list
> llvm-commits at cs.uiuc.edu
> http://lists.cs.uiuc.edu/mailman/listinfo/llvm-commits