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Re: Serious performane degradation in bison (1.35 -> 1.75)

From: Akim Demaille
Subject: Re: Serious performane degradation in bison (1.35 -> 1.75)
Date: 12 Nov 2002 12:19:08 +0100
User-agent: Gnus/5.0808 (Gnus v5.8.8) XEmacs/21.4 (Honest Recruiter)

| I was looking into updating our build environment to bison 1.75 (and
| possibly trying out the GLR parser).  Besides the annoyance that bison
| will not run if not installed (can't find m4sugar otherwise),

Run tests/bison, not src/bison.

| I ran into this:
| address@hidden /home/tim/gnu/bison-cvs/src>time ./bison
| ~/xtools/src/coco/cobol.y -o tmp/cobol-grammar.c -d -g
| real    0m11.567s
| user    0m10.600s
| sys     0m0.391s
| address@hidden /home/tim/gnu/bison-cvs/src>time bison
| ~/xtools/src/coco/cobol.y -o tmp/cobol-grammar.c -d -g
| real    0m0.627s
| user    0m0.381s
| sys     0m0.064s
| I fear this is to blame on the m4 integration; given that this is a
| HUGE performance loss (2000% slower!!!), this should probably be
| addressed somehow.  Just try to avoid bison4te.cache directories :-)

Yes, we are aware of this :(  There are means to fix this issue: back
onto M4 again.  The cycle is not completed yet, but M4 is scheduled.

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