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Browse Prior Art Database

Trace Directed Program Restructuring Improvement Using Ctrace Technique

IP.com Disclosure Number: IPCOM000118995D
Original Publication Date: 1997-Oct-01
Included in the Prior Art Database: 2005-Apr-01
Document File: 2 page(s) / 50K

Publishing Venue

IBM

Related People

Heisch, RR: AUTHOR [+3]

Abstract

Disclosed is a technique to improve the trace directed program restructuring process and eliminate some of its restrictions by using a ctrace method to collect basic block and profile information.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 57% of the total text.

Trace Directed Program Restructuring Improvement Using Ctrace Technique

      Disclosed is a technique to improve the trace directed program
restructuring process and eliminate some of its restrictions by using
a ctrace method to collect basic block and profile information.

      Trace directed program restructuring is typically done in four
phases.  The first step consists of statically instrumenting the
executable to be restructured.  Next, the executable is run to
collect profiling information about its basic blocks.  The third
phase is the building of a callgraph based on a static analysis of
the object file and the reordering of the code.

      This approach has several limitations that can make the process
fail.  First of all, the instrumented object file does not always
run, mainly because some data areas were mistakenly taken for
instructions and  instrumented.  There are also several size
limitations inherent to this  process.  For instance, since this tool
runs in user mode, segments have  to be available to store the
profiling information; and AIX* has a limit  of ten user segments
available.  For some programs which already use all  ten segments,
this process is not possible at all.  The instrumentation  code has
to be stored somewhere and because of the limited number of
displacement bits in all the POWER* and POWERPC* processors, there is
a hard limit on the size of the instrumentation zone.

      The FDPR product shipping toda...