qpt_stats(1)        UNIX Programmer's Manual         qpt_stats(1)



NAME
     qpt2_stats - Produce Program Profiles for qpt2

SYNTAX
     qpt2_stats [-c file -f file -i file -Rd -Rh# -Rp# -Rs -v -Wd
     file -Wfb file] a.out

DESCRIPTION
     qpt2 is an exact and efficient profiler profiler.  When a
     profiled program executes, it writes a count file that
     records the execution frequency of all basic blocks
     (``slow'' mode) or an infrequently executed subset of the
     edges (``quick'' mode).  qpt2_stats reads the count file and
     reports the number of instructions executed in a variety of
     formats.

OPTIONS
     The following options control which information is reported.

     -Rd       Report the dynamic execution frequency of classes
               of instructions.

     -Rs       Report the static execution frequency of classes
               of instructions.

     -Rh#      Print a hierarchical (gprof-like) count of the
               execution cost of the procedures in the program.
               # is an optional integer that specifies the
               instruction-count cutoff-threshold, below which a
               procedure is not reported.

     -Rp#      Print a flat (prof-like) count of the execution
               cost of the procedures in the program.  # is an
               optional integer that specifies the instruction-
               count cutoff-threshold, below which a procedure is
               not reported.

     The rest of the options specify the names of the input and
     output files:

     -c file   Read counters from a file called ``file''.  The
               default is to read a file whose name is formed by
               appending ``.QCounts'' to the name of the execut-
               able file, so the counts for ``myprog'' are read
               from ``myprog.QCounts''.

     -f file   Use the feedback file called ``file'' produced by
               qpt2_stats to determine the locations of the
               counters.  The default name is the program's name
               followed by ``.FB''.

     -Wd file  Write the derived counts for each basic block from



Printed 6/2/95                                                  1






qpt_stats(1)        UNIX Programmer's Manual         qpt_stats(1)



               a quick profile to a file called ``file''.

     -Wfb file Write a feedback file that records the frequency
               of each edge in the program's control-flow graph.
               This information can be used to place counters
               more effectively in qpt.

EXAMPLE
     In the following example, the program myprog is profiled
     while running on a small input data set.  The profile is
     used to build a feedback file, which is used to profile the
     program again.

          qpt2 -q myprog
          myprog.qpt small_input
          qpt2_stats -Wfb myprog
          qpt2 -q -fb myprog
          myprog.qpt very_large_input

BUGS
     Quick profiling may produce incorrect counts in programs
     that execute interprocedural jumps.  setjmp/longjmp are
     interprocedural jumps.  These jumps also occur in handwrit-
     ten code.  An indication that this error happened is that
     qpt2_stats complains about negative edge counts.

SEE ALSO
     qpt2(1), prof(1), gprof(1), pixie(1)
     Thomas Ball and James Larus, ``Optimally Profiling and Trac-
     ing Programs,'' ACM Transactions on Programming Languages
     and Systems (TOPLAS), pp. 1319--1360, July 1994.

AUTHOR
     James R. Larus (larus@cs.wisc.edu), Computer Sciences
     Department, University of Wisconsin-Madison.




















Printed 6/2/95                                                  2