Analyze control flow in C source files

 GNU cflow analyzes a collection of C source files and prints a graph, charting
 control flow within the program.
 .
 GNU cflow is able to produce both direct and inverted flowgraphs for C
 sources. Optionally a cross-reference listing can be generated. Two output
 formats are implemented: POSIX and GNU (extended).
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 Input files can optionally be preprocessed before analyzing.