webserver.fz: DFA is very slow

[maxteufel]

With tokiwa-software/fzweb#5, compiling the webserver seems to be stuck during the DFA phase:

$ make run_fz 
~/src/fuzion/build/bin/fz -verbose=2 -unsafeIntrinsics=on -modules=lock_free,java.base,java.desktop,java.datatransfer,java.xml,java.logging,java.security.sasl,webserver -sourceDirs=src run
2870 features 1453 types and 21 source files includes in fum file.
DFA iteration #1: --------------------------------------------------
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DFA iteration #28: --------------------------------------------------
^Cmake: *** [Makefile:24: run_fz] Error 130

it just keeps going from there

[maxteufel]

This also seems to be happening without tokiwa-software/fzweb#5 and #3987. In that case, it ends:

Elapsed time for phases: prep 50ms, fe 1430ms, createMIR 307ms, ir 11ms, dfa 214953ms, be 1595ms

...which is way longer than before the DFA changes.

[maxteufel]

Original also terminates, it seems:

Elapsed time for phases: prep 51ms, fe 1341ms, createMIR 284ms, ir 9ms, dfa 198790ms, be 1757ms

[michaellilltokiwa]

@tokiwa-software/developers Perfect showcase that we need more examples with 1000+ lines of code.

[fridis]

Here are some first insights that might help until this is solved:

I build the webserver with the -jar target have a simple benchmark, result measured on my machine using different configs:

• 3m16s using PRECONDITION=true and POSTCONDITIONS=true is slowest
• 2m2s with PRECONDITION=false and POSTCONDITIONS=false
• 0m53s with dev_flang_fuir_analysis_dfa_DFA_SITE_SENSITIVE=false added (which causes some tests to fail but seems to be fine for fzweb)
• 0m42s with dev_flang_fuir_analysis_dfa_DFA_USE_EMBEDDED_VALUES=false added (which is required for the C backend only)

Still very slow, working on it...