Example #1
0
        private void UntangleProcedureScc(IList<Procedure> procs)
        {
            if (procs.Count == 1)
            {
                var proc = procs[0];
                Aliases alias = new Aliases(proc, program.Architecture, flow);
                alias.Transform();
                
                // Transform the procedure to SSA state. When encountering 'call' instructions,
                // they can be to functions already visited. If so, they have a "ProcedureFlow" 
                // associated with them. If they have not been visited, or are computed destinations
                // (e.g. vtables) they will have no "ProcedureFlow" associated with them yet, in
                // which case the the SSA treats the call as a "hell node".
                var doms = proc.CreateBlockDominatorGraph();
                var sst = new SsaTransform(flow, proc, doms);
                var ssa = sst.SsaState;

                // Propagate condition codes and registers. At the end, the hope is that 
                // all statements like (x86) mem[esp_42+4] will have been converted to
                // mem[fp - 30]. We also hope that procedure constants kept in registers
                // are propagated to the corresponding call sites.
                var cce = new ConditionCodeEliminator(ssa.Identifiers, program.Platform);
                cce.Transform();
                var vp = new ValuePropagator(ssa.Identifiers, proc);
                vp.Transform();

                // Now compute SSA for the stack-based variables as well. That is:
                // mem[fp - 30] becomes wLoc30, while 
                // mem[fp + 30] becomes wArg30.
                // This allows us to compute the dataflow of this procedure.
                sst.RenameFrameAccesses = true;
                sst.AddUseInstructions = true;
                sst.Transform();

                // Propagate those newly discovered identifiers.
                vp.Transform();

                // At this point, the computation of _actual_ ProcedureFlow should be possible.
                var tid = new TrashedRegisterFinder2(program.Architecture, flow, proc, ssa.Identifiers, this.eventListener);
                tid.Compute();
                DeadCode.Eliminate(proc, ssa);

                // Build expressions. A definition with a single use can be subsumed
                // into the using expression. 

                var coa = new Coalescer(proc, ssa);
                coa.Transform();
                DeadCode.Eliminate(proc, ssa);

                var liv = new LinearInductionVariableFinder(
                    proc,
                    ssa.Identifiers,
                    new BlockDominatorGraph(proc.ControlGraph, proc.EntryBlock));
                liv.Find();

                foreach (var de in liv.Contexts)
                {
                    var str = new StrengthReduction(ssa, de.Key, de.Value);
                    str.ClassifyUses();
                    str.ModifyUses();
                }
                proc.Dump(true, false);
                //var opt = new OutParameterTransformer(proc, ssa.Identifiers);
                //opt.Transform();
                DeadCode.Eliminate(proc, ssa);

                // Definitions with multiple uses and variables joined by PHI functions become webs.
                var web = new WebBuilder(proc, ssa.Identifiers, program.InductionVariables);
                web.Transform();
                ssa.ConvertBack(false);
            }
            else
            {

            }
        }
        private Procedure RunTest(string sExp, IProcessorArchitecture arch, Func<Procedure> mkProc)
        {
            var proc = mkProc();
            progBuilder.ResolveUnresolved();

            var ssa = new SsaTransform(pf, proc, proc.CreateBlockDominatorGraph());
            var vp = new ValuePropagator(ssa.SsaState.Identifiers, proc);
            vp.Transform();

            ssa.RenameFrameAccesses = true;
            ssa.AddUseInstructions = true;
            ssa.Transform();

            vp.Transform();

            var trf = new TrashedRegisterFinder2(
                arch, 
                pf,
                proc, 
                ssa.SsaState.Identifiers,
                NullDecompilerEventListener.Instance);
            var flow = trf.Compute();
            var sw = new StringWriter();
            sw.Write("Preserved: ");
            sw.WriteLine(string.Join(",", flow.Preserved.OrderBy(p => p.ToString())));
            sw.Write("Trashed: ");
            sw.WriteLine(string.Join(",", flow.Trashed.OrderBy(p => p.ToString())));
            if (flow.Constants.Count > 0)
            {
                sw.Write("Constants: ");
                sw.WriteLine(string.Join(
                    ",",
                    flow.Constants
                        .OrderBy(kv => kv.Key.ToString())
                        .Select(kv => string.Format(
                            "{0}:{1}", kv.Key, kv.Value))));
            }
            var sActual = sw.ToString();
            if (sActual != sExp)
            {
                proc.Dump(true, false);
                Debug.WriteLine(sActual);
                Assert.AreEqual(sExp, sActual);
            }
            pf.ProcedureFlows2.Add(proc, flow);
            return proc;
        }