[llvm-commits] [llvm] r77397 - in /llvm/trunk: include/llvm/Support/FormattedStream.h lib/Support/FormattedStream.cpp

[Daniel Dunbar]

Hi David,

On Tue, Jul 28, 2009 at 4:26 PM, David Greene<greened at obbligato.org> wrote:
> Author: greened
> Date: Tue Jul 28 18:26:34 2009
> New Revision: 77397
>
> URL: http://llvm.org/viewvc/llvm-project?rev=77397&view=rev
> Log:
>
> Improve performance of PadToColumn by eliminating flushes.

Did you time this? I had to revert this patch, it was causing
significant regressions on nightlytest, and in my local timings (llc
-fast-isel -regalloc=local on instcombine.bc) it was almost twice as
slow!

ddunbar at giles:regr-2009-07-28_19-23$ for r in llc.r7739*; do echo "--
$r --"; runN 10 ./$r -fast-isel -regalloc=local instcombine.bc -f -o
/dev/null; done
-- llc.r77396 --
name	  avg  	  min  	  med  	  max  	   SD  	 total
user	 1.7877	 1.6809	 1.7959	 1.9022	 0.0668	17.8772
 sys	 0.2849	 0.2735	 0.2865	 0.3035	 0.0107	 2.8489
wall	 2.0794	 1.9574	 2.0865	 2.2134	 0.0775	20.7939
-- llc.r77397 --
name	  avg  	  min  	  med  	  max  	   SD  	 total
user	 3.3274	 3.1411	 3.3089	 3.5753	 0.1541	33.2742
 sys	 0.0586	 0.0596	 0.0581	 0.0617	 0.0037	 0.5862
wall	 3.3922	 3.2062	 3.3750	 3.6403	 0.1550	33.9220

(runN is a timing tool of mine, like 'time' with more goodies)

 - Daniel

> Modified:
>    llvm/trunk/include/llvm/Support/FormattedStream.h
>    llvm/trunk/lib/Support/FormattedStream.cpp
>
> Modified: llvm/trunk/include/llvm/Support/FormattedStream.h
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/Support/FormattedStream.h?rev=77397&r1=77396&r2=77397&view=diff
>
> ==============================================================================
> --- llvm/trunk/include/llvm/Support/FormattedStream.h (original)
> +++ llvm/trunk/include/llvm/Support/FormattedStream.h Tue Jul 28 18:26:34 2009
> @@ -49,13 +49,13 @@
>     ///
>     bool DeleteStream;
>
> -    /// Column - The current output column of the stream.  The column
> -    /// scheme is zero-based.
> +    /// ColumnFlushed - The current output column of the data that's
> +    /// been flushed.  The column scheme is zero-based.
>     ///
> -    unsigned Column;
> +    unsigned ColumnFlushed;
>
>     virtual void write_impl(const char *Ptr, size_t Size) {
> -      ComputeColumn(Ptr, Size);
> +      ComputeColumn(ColumnFlushed);
>       TheStream->write(Ptr, Size);
>     }
>
> @@ -67,10 +67,10 @@
>       return TheStream->tell() - TheStream->GetNumBytesInBuffer();
>     }
>
> -    /// ComputeColumn - Examine the current output and figure out
> -    /// which column we end up in after output.
> +    /// ComputeColumn - Examine the current buffer and figure out
> +    /// which column we're in.
>     ///
> -    void ComputeColumn(const char *Ptr, size_t Size);
> +    void ComputeColumn(unsigned &Column);
>
>   public:
>     /// formatted_raw_ostream - Open the specified file for
> @@ -84,11 +84,11 @@
>     /// underneath it.
>     ///
>     formatted_raw_ostream(raw_ostream &Stream, bool Delete = false)
> -      : raw_ostream(), TheStream(0), DeleteStream(false), Column(0) {
> +      : raw_ostream(), TheStream(0), DeleteStream(false), ColumnFlushed(0) {
>       setStream(Stream, Delete);
>     }
>     explicit formatted_raw_ostream()
> -      : raw_ostream(), TheStream(0), DeleteStream(false), Column(0) {}
> +      : raw_ostream(), TheStream(0), DeleteStream(false), ColumnFlushed(0) {}
>
>     ~formatted_raw_ostream() {
>       if (DeleteStream)
>
> Modified: llvm/trunk/lib/Support/FormattedStream.cpp
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Support/FormattedStream.cpp?rev=77397&r1=77396&r2=77397&view=diff
>
> ==============================================================================
> --- llvm/trunk/lib/Support/FormattedStream.cpp (original)
> +++ llvm/trunk/lib/Support/FormattedStream.cpp Tue Jul 28 18:26:34 2009
> @@ -19,11 +19,11 @@
>  /// ComputeColumn - Examine the current output and figure out which
>  /// column we end up in after output.
>  ///
> -void formatted_raw_ostream::ComputeColumn(const char *Ptr, size_t Size) {
> +void formatted_raw_ostream::ComputeColumn(unsigned &Column) {
>   // Keep track of the current column by scanning the string for
>   // special characters
>
> -  for (const char *epos = Ptr + Size; Ptr != epos; ++Ptr) {
> +  for (const char *Ptr = begin(); Ptr != end(); ++Ptr) {
>     ++Column;
>     if (*Ptr == '\n' || *Ptr == '\r')
>       Column = 0;
> @@ -38,8 +38,13 @@
>  /// \param MinPad - The minimum space to give after the most recent
>  /// I/O, even if the current column + minpad > newcol.
>  ///
> -void formatted_raw_ostream::PadToColumn(unsigned NewCol, unsigned MinPad) {
> -  flush();
> +void formatted_raw_ostream::PadToColumn(unsigned NewCol, unsigned MinPad) {
> +  // Start out from the last flush position.
> +  unsigned Column = ColumnFlushed;
> +
> +  // Now figure out what's in the buffer and add it to the column
> +  // count.
> +  ComputeColumn(Column);
>
>   // Output spaces until we reach the desired column.
>   unsigned num = NewCol - Column;
>
>
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