On Sat, 17 Feb 2018, Robert Larice wrote:
> Julia Lawall <julia.law...@lip6.fr> writes: > > > On Sat, 10 Feb 2018, Robert Larice wrote: > > > >> Julia Lawall <julia.law...@lip6.fr> writes: > >> > >> > On Sat, 10 Feb 2018, Robert Larice wrote: > >> > > >> >> Dear People, > >> >> > >> >> I'm completely new here. > >> >> > >> >> Attached is a small piece of .c and a .cocci file. > >> >> There is a "return 41;" in both files, commented out. > >> >> If I uncomment this "return 41;" in both files then > >> >> spatch will not match the pieces any more. > >> >> > >> >> Could you please help me to undertand and circumvent this issue ? > >> > > >> > I have not noticed this problem before, but I suspect that it is due to > >> > the fact that Coccinelle is matching the control-flow path and not the > >> > abstract syntax tree. In a control-flow graph, nothing follows a return. > >> > > >> > julia > >> > >> Thank You, > >> I tried to sneak around the problem with a second "rule" which > >> translates "return 42" to "auxiliary(42)". > >> My intention was to first change the source in such a way > >> that the "control-flow" graph does not end at the "return", > >> and then hope that the second (accordingly modified) rule would > >> match. > >> This didn't work, I assume I would have to express the idea of > >> first applying the first rule > >> then to rebuild the control-flow graph > >> then try the second rule. > >> (and finally undo the changes of the first rule in a third rule) > >> I can not force "rebuild" without invoking spatch myself a second time. > > > > If you change all the returns to something else and then match your > > pattern, and then change them it should work. > > > >> > >> --- > >> I'm a bit of a maintainer for the "ngspice" project, which has a vast > >> amount of very old files, and lots of semi duplicated stuff often crying > >> for a thourough hair wash, > >> stumbled over this intresting tool, and am tying it for a certain > >> rewrite I'm currently busy with. > > > > OK,feel free to ask more questions if you run into further issues. > > > > julia > > Hello, > > Thank you for your help. I've four or five .cocci files now which > do the job at hand for ngspice quite well. The rewrite of return > to something else with two times invocation of spatch did work. > Then I found another simpler way. So thats done. > > Playing around, trying to better understand what it means > to have more than one rule, their interaction etc .. > I came to the attached example. > Here I have basically tried to remove the whole body of a function > iff the function matches two other @rules@ > It seems to work if I use the '*' notation, but doesnt if I use > '+/-' > Can you give me a hint which helps me to understand this ? For -+, Coccinelle requires that all control-flow paths from the starting point of the match match the complete rule. So for example a() ... b() would match the following: a(); if (x) b(); else b(); For *, it only requires the existence of such a path. If you have a -+ somewhere in the semantic patch, then all rules use the forall semantics. If you have a * somewhere in the semantic patch, then all rules use the exists semantics. In your rule r2, you have ... Label: but this label is not reached on the execution path that ends in return 1. When you have -+ somewhere in the semantic patch this rule is not satisfied. If you want to change the default for a rule, you can add exists for forall to the rule header, or put when exists or when forall on the ... julia _______________________________________________ Cocci mailing list Cocci@systeme.lip6.fr https://systeme.lip6.fr/mailman/listinfo/cocci
