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

Chris Lattner clattner at apple.com
Tue Jul 28 21:35:31 PDT 2009


On Jul 28, 2009, at 9:32 PM, Evan Cheng wrote:

> Have we recovered the previous lost compile time?

No, this patch made it worse because of the N^2 algorithm.

-Chris

>
>
> Evan
>
> On Jul 28, 2009, at 8:04 PM, Daniel Dunbar wrote:
>
>> 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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>>
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