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flex: input rules are too complicated (>= 32000 NFA states)" #57

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srivasta opened this issue Feb 17, 2016 · 0 comments
Open

flex: input rules are too complicated (>= 32000 NFA states)" #57

srivasta opened this issue Feb 17, 2016 · 0 comments
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2.7.0

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@srivasta
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Hi,

This bug was reported by a Debian user in:
https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=642040

I'm trying to compile libsbook from here: https://simson.net/ref/sbook5/
During compilation, i get:

 flex -tL8B  -i parse_address.flex  | sed s/yy/yyaddress/g | grep -v unistd.h > parse_address.cpp
 flex: input rules are too complicated (>= 32000 NFA states)

A web search points me to this FAQ:
https://flex.sourceforge.net/manual/unnamed_002dfaq_002d88.html#unnamed_002dfaq_002d88
which contains this suggestion from Vern Paxson:

Increase the definitions in flexdef.h for:

define JAMSTATE -32766 /* marks a reference to the state that always jams */

define MAXIMUM_MNS 31999

define BAD_SUBSCRIPT -32767

recompile everything, and it should all work.

Is there a reason to avoid making these changes in flex? Or can this be chosen as a run-time option? Processing power even on netbooks is demonstrated to be enough to handle instructions much more complex than this.

Manoj
@westes westes modified the milestone: 2.7.0 Jul 3, 2017
eric-s-raymond added a commit to eric-s-raymond/flex that referenced this issue Oct 3, 2020
@eric-s-raymond
As of this commit, all mode symbolds are finally visible.
ea32296 
All symbols except a handful dependent on nultrans and the number of
backups are now written in one visible group right at the start of m4
generation.  The exception are exceptions because their values
are not known until after DFA computation.

Has comment diffs in generated test code due to one symbol rename and
symbols beoming visible. Should be the last time the latter happens.

westes#57 in the retargeting patch series
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