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Updated to dense switches generation

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ceriel 1988-06-22 17:04:52 +00:00
parent a717832bfb
commit 416944b293
1 changed files with 35 additions and 21 deletions
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56
util/LLgen/LLgen.1
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@ -6,7 +6,16 @@ LLgen, an extended LL(1) parser generator
.SH SYNOPSIS .SH SYNOPSIS
\fBLLgen\fP \fBLLgen\fP
[ [
\fB\-vVxX\fP \fB\-vxjw\fP
]
[
\fB\-m\fP\fInum\fP
]
[
\fB\-l\fP\fInum\fP
]
[
\fB\-h\fP\fInum\fP
] ]
file ... file ...
.SH DESCRIPTION .SH DESCRIPTION
@ -62,35 +71,40 @@ an error reporting routine;
by by
\fILLgen\fP. \fILLgen\fP.
.PP .PP
If the \fILLgen\fP accepts the following flags:
\fB\-v\fP .IP \fB\-v\fP
or the create a file called
\fB\-V\fP \fILL.output\fP,
flag is given, the file which contains a description of the conflicts that
\fILL.output\fP
is prepared, which contains a description of the conflicts that
were not resolved. were not resolved.
If it is given more than once, If the flag is given more than once,
\fILLgen\fP \fILLgen\fP
will be more "verbose". will be more "verbose".
If it is given three times, a complete description of the If it is given three times, a complete description of the
grammar will be supplied. grammar will be supplied.
.PP .IP \fB\-x\fP
If the
\fB\-x\fP
or the
\fB\-X\fP
flag is given,
the sets that are computed are extended with the nonterminal the sets that are computed are extended with the nonterminal
symbols and these extended sets are also included in the symbols and these extended sets are also included in the
\fILL.output\fP \fILL.output\fP
file. file.
.PP .IP \fB\-w\fP
If the no warnings are given.
\fB\-w\fP .IP \fB\-j\fP
or the when this flag is given, \fILLgen\fP will generate dense switches,
\fB\-W\fP so that the compiler can generate a jump table for it. This will only be
flag is given, no warnings are given. done for switches that have density between
\fIlow_percentage\fP and \fIhigh_percentage\fP, as explained below.
Usually, compilers generate a jumptable when the density of the switch
is above a certain threshold. If you want jump tables in more cases,
set \fIhigh_percentage\fP to this threshold, and \fIlow_percentage\fP to
a minimum threshold. There is a time-space trade-off here.
.IP \fB\-m\fP\fInum\fP
minimum number of cases in a switch for the \fB\-j\fP option to be
effective. The default value is 8.
.IP \fB\-l\fP\fInum\fP
The \fIlow_percentage\fP, as described above. Default value is 10.
.IP \fB\-h\fP\fInum\fP
The \fIhigh_percentage\fP, as described above. Default value is 30.
.SH FILES .SH FILES
LL.output verbose output file LL.output verbose output file
.br .br