python: add graphviz callgraphs

Uses the JSON data extracted from LLVM bitcode by tools/frr-llvm-cg.

Signed-off-by: David Lamparter <equinox@opensourcerouting.org>

.gitignore

@@ -57,6 +57,8 @@
 *_clippy.c
 *.bc
 *.cg.json
+*.cg.dot
+*.cg.svg
 
 ### gcov outputs
 

Makefile.am

@@ -252,6 +252,15 @@ SUFFIXES += .lo.bc .o.bc
 
 %.cg.json: %.bc tools/frr-llvm-cg
 	tools/frr-llvm-cg -o $@ $<
+%.cg.dot: %.cg.json
+	$(PYTHON) $(top_srcdir)/python/callgraph-dot.py $< $@
+%.cg.svg: %.cg.dot
+	@echo if the following command fails, you need to install graphviz.
+	@echo also, the output is nondeterministic. run it multiple times and use the nicest output.
+	@echo tuning parameters may yield nicer looking graphs as well.
+	fdp -GK=0.7 -Gstart=42231337 -Gmaxiter=2000 -Elen=2 -Gnodesep=1.5 -Tsvg -o$@ $<
+# don't delete intermediaries
+.PRECIOUS: %.cg.json %.cg.dot
 
 # <lib>.la.bc, <lib>.a.bc and <daemon>.bc targets are generated by
 # python/makefile.py
@@ -264,7 +273,7 @@ clean-python:
 	find . -name "*.pyc" -o -name "*_clippy.c" | xargs rm -f
 
 clean-llvm-bitcode:
-	find . -name "*.bc" -o -name "*.cg.json" | xargs rm -f
+	find . -name "*.bc" -o -name "*.cg.json" -o -name "*.cg.dot" -o -name "*.cg.svg" | xargs rm -f
 
 redistclean:
 	$(MAKE) distclean CONFIG_CLEAN_FILES="$(filter-out $(EXTRA_DIST), $(CONFIG_CLEAN_FILES))"