Merged backends (#80)

* Add scala backend for BASIL

* Add C++ Backend for LLVM 

* add aslBackwardsVisitor

* aslVisitor: change vstmt to return stmt list

BREAKING!
This change affects the signature of the Asl_visitor.visit_stmt method.
For compatibility, a visit_stmt_single method is provided with
equivalent behaviour to the old visit_stmt. There is also an added
helper function to convert visitActions on single statements to
visitActions on a list of statements.

Both of these compatibility helpers WILL THROW if used with a visitor
that returns non-singleton statement lists.

This gives the user the flexibility to insert new statements or delete
statements entirely. On the other hand, post-functions in
ChangeDoChildrenPost will need to handle lists of functions as well.

This follows the original CIL visitor: https://people.eecs.berkeley.edu/~necula/cil/api/Cil.cilVisitor.html

* fix backwards visitor and rearrange code

it is no longer a good idea for the backwards and forwards visitors to have a subtyping relation.

* support -x 0 to print encoding name. (#78)

this is very useful when looking for the name of an encoding,
without cluttering the output with the disassembly trace.

the default debug_level has been lowered to -1 to support -x 0
as a non-default level. we cannot print by default since that
would clutter stdout when used as a library.



Co-authored-by: rina <[email protected]>

.gitignore

@@ -19,3 +19,6 @@ scripts/result.txt
 scripts/output.txt
 scripts/cntlm.bir
 scripts/total.txt
+
+.cache/
+build/

bin/asli.ml

@@ -26,7 +26,7 @@ let opt_no_default_aarch64 = ref false
 let opt_print_aarch64_dir = ref false
 let opt_verbose = ref false
 
-let opt_debug_level = ref 0
+let opt_debug_level = ref (-1)
 
 
 let () = Printexc.register_printer
@@ -60,6 +60,7 @@ let help_msg = [
 let gen_backends = [
     ("ocaml", (Cpu.Ocaml, "offlineASL"));
     ("cpp",   (Cpu.Cpp, "offlineASL-cpp"));
+    ("scala",   (Cpu.Scala, "offlineASL-cpp"));
 ]
 
 let flags = [
@@ -325,7 +326,7 @@ let rec repl (tcenv: TC.Env.t) (cpu: Cpu.cpu): unit =
     )
 
 let options = Arg.align ([
-    ( "-x", Arg.Set_int opt_debug_level,      "       Debugging output");
+    ( "-x", Arg.Set_int opt_debug_level,      "       Partial evaluation debugging (requires debug level argument >= 0)");
     ( "-v", Arg.Set opt_verbose,              "       Verbose output");
     ( "--no-aarch64", Arg.Set opt_no_default_aarch64 , "       Disable bundled AArch64 semantics");
     ( "--aarch64-dir", Arg.Set opt_print_aarch64_dir, "       Print directory of bundled AArch64 semantics");

libASL/asl_utils.ml

@@ -226,7 +226,7 @@ let fv_stmts stmts =
 
 let fv_stmt stmt =
     let fvs = new freevarClass in
-    ignore (visit_stmt (fvs :> aslVisitor) stmt);
+    ignore (visit_stmt_single (fvs :> aslVisitor) stmt);
     fvs#result
 
 let fv_decl decl =
@@ -295,7 +295,7 @@ end
 
 let locals_of_stmts stmts =
     let lc = new localsClass in
-    ignore (Visitor.mapNoCopy (visit_stmt (lc :> aslVisitor)) stmts);
+    ignore @@ Asl_visitor.visit_stmts lc stmts;
     lc#locals
 
 let locals_of_decl decl =
@@ -423,7 +423,7 @@ let subst_type (s: expr Bindings.t) (x: ty): ty =
 
 let subst_stmt (s: expr Bindings.t) (x: stmt): stmt =
     let subst = new substClass s in
-    visit_stmt subst x
+    visit_stmt_single subst x
 
 
 (** More flexible substitution class - takes a function instead