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72 lines
2.5 KiB
Plaintext
72 lines
2.5 KiB
Plaintext
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Notes on the porting of regex to GNO
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Dave Tribby * November 7, 1997
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Devin Reade did the initial conversion of the BSD sources to compile
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under GNO 2.0.6 headers with ORCA/C on the Apple IIGS.
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I completed the porting to the extent that the program sed (which
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uses regex) works for many different test cases.
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The most time-comsuming aspect of the port was finding all the places
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where long integers should be used instead of int or unsigned int.
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DEBUGGING
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The file engine.c is used in an interesting way by regexec.c:
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it includes engine.c *twice*, after muchos fiddling with the
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macros that code uses. This lets the same code operate on two
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different representations for state sets.
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When it was necessary to do source-level debugging, Splat! got
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very confused about line numbers until I added the following at
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the beginning of the file:
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#ifdef __ORCAC__
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#line 2 "engine.c"
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#endif
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The regex code had an compilation macro, REDEBUG, that would
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turn on diagnostic messages when defined. I added additional
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output statements that are turned on by REDEBUG.
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PERFORMANCE ENHANCEMENT
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The program sed took a long time to execute a compilcated sed
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program (provided with the BSD source code) that evaluates
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expressions. I attempted to speed up the regex routines by
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recoding two routines in assembly language (using the asm {}
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construct available in ORCA/C). The two routines are
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isinsets() and samesets() in regcomp.c. The C code was left
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in place and can be turned on by compiling with the macro
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__NOASM__ set.
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I also noticed an instance in regcomp.c where many fields of
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a structure were individually set to 0 at initialization. I
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recoded to set all the fields to 0 by a call to memset() and
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then set only the non-zero fields individually.
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The following script was used to time the results:
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cd /src/gno/usr.bin/sed
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echo '(4+4)*3' | time ./sed -f tests/math.sed
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The unmodified code took 51 seconds to run on my 8MHz Apple IIGS.
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It took 49 seconds after I recoded isinsets() in asm, and 48 seconds
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after I recoded samesets(). Initializing fields via memset() brought
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it down to 47 seconds.
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I saw no other obvious candidates for recoding. The modest results
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from these changes (even though they were made in routines that
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ranked high in the profile) did not warrent further efforts.
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BUILDING
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Because I did not rebuild all of libc, I created a library called
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regex that only includes the regex routines. The commands I used
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to build regex are included in the file make.cmds. I will leave it
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to Devin to incorporate regex into the full libc build structure.
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