58 lines
1.7 KiB
Plaintext
58 lines
1.7 KiB
Plaintext
.NH
|
|
Outline of the program
|
|
.PP
|
|
The program can be divided into three parts. A first pass, which
|
|
parses C program files and outputs definitions, a second pass which
|
|
processes the definitions and a driver,
|
|
which feeds the set of files to the first pass and
|
|
directs its output to the second pass. Both passes produce the
|
|
warnings on standard error output, which are redirected to standard
|
|
output by the driver.
|
|
.PP
|
|
The first pass is based on an existing C front end, called
|
|
.I cem
|
|
[3].
|
|
.I Cem
|
|
is part of the Amsterdam Compiler Kit (ACK), as described in [4].
|
|
.PP
|
|
Most of the code of
|
|
.I cem
|
|
is left unchanged. This has several reasons. A lot of work, which
|
|
is done by
|
|
.I cem
|
|
, must also be done by
|
|
.I lint.
|
|
E.g. the lexical analysis, the macro expansions,
|
|
the parsing part and the semantical analysis.
|
|
Only the code generation part is turned off.
|
|
An advantage of this approach is, that a person who understands
|
|
.I cem
|
|
will not have to spend to much time in understanding
|
|
.I lint.
|
|
.PP
|
|
All changes and extensions to
|
|
.I cem
|
|
can be turned off by not defining the compiler directive
|
|
.ft CW
|
|
LINT.
|
|
.R
|
|
Compiling should then result in the original C compiler.
|
|
.PP
|
|
The second pass is a much less complex program.
|
|
It reads simple definitions generated by the first pass and
|
|
checks their consistency.
|
|
This second pass gives warnings
|
|
about wrong usage of function arguments, their results and
|
|
about external variables, which are used and defined in more
|
|
than one file.
|
|
.PP
|
|
The driver is a shell program, to be executed by the
|
|
.UX
|
|
shell
|
|
.I sh.
|
|
It executes the two passes and let them communicate through a
|
|
filter (sort).
|
|
Actually it is simplex communication: the first pass only talks to
|
|
the second pass through the filter.
|
|
.bp
|