1 files changed, 380 insertions, 0 deletions
diff --git a/compilerplugins/clang/methodcycles.cxx b/compilerplugins/clang/methodcycles.cxx
new file mode 100644
index 000000000..7fd74b10d
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+++ b/compilerplugins/clang/methodcycles.cxx
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+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/*
+ * This file is part of the LibreOffice project.
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ */
+
+#include <cassert>
+#include <string>
+#include <iostream>
+#include <fstream>
+#include <set>
+#include <unordered_set>
+#include <map>
+
+#include "clang/AST/Attr.h"
+
+#include "plugin.hxx"
+
+/**
+What we are looking for here are methods that are not reachable from any of the program
+entry points.
+"Entry points" includes main, and various binary API
+
+Mostly that means we end up finding cycles of methods i.e. methods that refer to each
+other, but are not reachable.
+
+It does so, by dumping various call/definition info to a log file.
+Be warned that it produces around 20G of log file.
+
+Then we will post-process the log file with a python script, which takes about
+15min to run on a fast machine.
+
+The process goes something like this:
+  $ make check
+  $ make FORCE_COMPILE_ALL=1 COMPILER_PLUGIN_TOOL='methodcycles' check
+  $ ./compilerplugins/clang/methodcycles.py
+
+Note that the actual process may involve a fair amount of undoing, hand editing, and general messing around
+to get it to work :-)
+
+*/
+
+namespace
+{
+struct MyFuncInfo
+{
+    std::string returnType;
+    std::string nameAndParams;
+    std::string sourceLocation;
+};
+bool operator<(const MyFuncInfo& lhs, const MyFuncInfo& rhs)
+{
+    return std::tie(lhs.returnType, lhs.nameAndParams)
+           < std::tie(rhs.returnType, rhs.nameAndParams);
+}
+
+// try to limit the voluminous output a little
+static std::multimap<const FunctionDecl*, const FunctionDecl*> callMap;
+static std::set<MyFuncInfo> definitionSet;
+
+class MethodCycles : public RecursiveASTVisitor<MethodCycles>, public loplugin::Plugin
+{
+public:
+    explicit MethodCycles(loplugin::InstantiationData const& data)
+        : Plugin(data)
+    {
+    }
+
+    virtual void run() override
+    {
+        TraverseDecl(compiler.getASTContext().getTranslationUnitDecl());
+
+        // dump all our output in one write call - this is to try and limit IO "crosstalk" between multiple processes
+        // writing to the same logfile
+
+        std::string output;
+        for (const MyFuncInfo& s : definitionSet)
+            output += "definition:\t" + s.returnType + "\t" + s.nameAndParams + "\t"
+                      + s.sourceLocation + "\n";
+        for (const auto& pair : callMap)
+        {
+            if (!isLocationMine(pair.first->getLocation())
+                || !isLocationMine(pair.second->getLocation()))
+                continue;
+            auto niceNameFrom = niceName(pair.first);
+            auto niceNameTo = niceName(pair.second);
+            output += "call:\t" + niceNameFrom.returnType + "\t" + niceNameFrom.nameAndParams + "\t"
+                      + niceNameTo.returnType + "\t" + niceNameTo.nameAndParams + "\n";
+        }
+        std::ofstream myfile;
+        myfile.open(WORKDIR "/loplugin.methodcycles.log", std::ios::app | std::ios::out);
+        myfile << output;
+        myfile.close();
+    }
+
+    bool shouldVisitTemplateInstantiations() const { return true; }
+    bool shouldVisitImplicitCode() const { return true; }
+
+    bool VisitCallExpr(CallExpr*);
+    bool VisitFunctionDecl(const FunctionDecl* decl);
+    bool VisitDeclRefExpr(const DeclRefExpr*);
+    bool VisitCXXConstructExpr(const CXXConstructExpr*);
+
+    bool TraverseFunctionDecl(FunctionDecl*);
+    bool TraverseCXXMethodDecl(CXXMethodDecl*);
+    bool TraverseCXXConstructorDecl(CXXConstructorDecl*);
+    bool TraverseCXXConversionDecl(CXXConversionDecl*);
+    bool TraverseCXXDestructorDecl(CXXDestructorDecl*);
+    bool TraverseCXXDeductionGuideDecl(CXXDeductionGuideDecl*);
+
+private:
+    void logCallToRootMethods(const FunctionDecl* functionDeclFrom,
+                              const FunctionDecl* functionDeclTo);
+    void findRoots(const FunctionDecl* functionDecl,
+                   std::unordered_set<const FunctionDecl*>& roots);
+    MyFuncInfo niceName(const FunctionDecl* functionDecl);
+    bool isLocationMine(SourceLocation loc);
+    std::string toString(SourceLocation loc);
+    FunctionDecl const* currentFunctionDecl = nullptr;
+};
+
+MyFuncInfo MethodCycles::niceName(const FunctionDecl* functionDecl)
+{
+    if (functionDecl->getInstantiatedFromMemberFunction())
+        functionDecl = functionDecl->getInstantiatedFromMemberFunction();
+#if CLANG_VERSION < 90000
+    else if (functionDecl->getClassScopeSpecializationPattern())
+        functionDecl = functionDecl->getClassScopeSpecializationPattern();
+#endif
+    else if (functionDecl->getTemplateInstantiationPattern())
+        functionDecl = functionDecl->getTemplateInstantiationPattern();
+
+    MyFuncInfo aInfo;
+    if (!isa<CXXConstructorDecl>(functionDecl))
+    {
+        aInfo.returnType = functionDecl->getReturnType().getCanonicalType().getAsString();
+    }
+    else
+    {
+        aInfo.returnType = "";
+    }
+
+    if (auto methodDecl = dyn_cast<CXXMethodDecl>(functionDecl))
+    {
+        const CXXRecordDecl* recordDecl = methodDecl->getParent();
+        aInfo.nameAndParams
+            = recordDecl->getQualifiedNameAsString() + "::" + functionDecl->getNameAsString() + "(";
+    }
+    else
+    {
+        aInfo.nameAndParams = functionDecl->getQualifiedNameAsString() + "(";
+    }
+    bool bFirst = true;
+    for (const ParmVarDecl* pParmVarDecl : functionDecl->parameters())
+    {
+        if (bFirst)
+            bFirst = false;
+        else
+            aInfo.nameAndParams += ",";
+        aInfo.nameAndParams += pParmVarDecl->getType().getCanonicalType().getAsString();
+    }
+    aInfo.nameAndParams += ")";
+    if (isa<CXXMethodDecl>(functionDecl) && dyn_cast<CXXMethodDecl>(functionDecl)->isConst())
+    {
+        aInfo.nameAndParams += " const";
+    }
+
+    aInfo.sourceLocation = toString(functionDecl->getLocation());
+
+    return aInfo;
+}
+
+std::string MethodCycles::toString(SourceLocation loc)
+{
+    SourceLocation expansionLoc = compiler.getSourceManager().getExpansionLoc(loc);
+    StringRef name = getFilenameOfLocation(expansionLoc);
+    std::string sourceLocation
+        = std::string(name.substr(strlen(SRCDIR) + 1)) + ":"
+          + std::to_string(compiler.getSourceManager().getSpellingLineNumber(expansionLoc));
+    loplugin::normalizeDotDotInFilePath(sourceLocation);
+    return sourceLocation;
+}
+
+bool MethodCycles::isLocationMine(SourceLocation loc)
+{
+    SourceLocation expansionLoc = compiler.getSourceManager().getExpansionLoc(loc);
+    if (compiler.getSourceManager().isInSystemHeader(expansionLoc))
+        return false;
+    const char* bufferName = compiler.getSourceManager().getPresumedLoc(expansionLoc).getFilename();
+    if (bufferName == NULL)
+        return false;
+    if (loplugin::hasPathnamePrefix(bufferName, WORKDIR "/")
+        || loplugin::hasPathnamePrefix(bufferName, BUILDDIR "/")
+        || loplugin::hasPathnamePrefix(bufferName, SRCDIR "/"))
+        return true; // ok
+    return false;
+}
+
+void MethodCycles::logCallToRootMethods(const FunctionDecl* functionDeclFrom,
+                                        const FunctionDecl* functionDeclTo)
+{
+    if (!functionDeclFrom)
+    {
+        // template magic mostly, but also things called from initialisers
+        return;
+    }
+    functionDeclFrom = functionDeclFrom->getCanonicalDecl();
+    functionDeclTo = functionDeclTo->getCanonicalDecl();
+
+    std::unordered_set<const FunctionDecl*> fromRoots;
+    findRoots(functionDeclFrom, fromRoots);
+    std::unordered_set<const FunctionDecl*> toRoots;
+    findRoots(functionDeclTo, toRoots);
+
+    for (auto const& from : fromRoots)
+        for (auto const& to : toRoots)
+            callMap.insert({ from, to });
+}
+
+void MethodCycles::findRoots(const FunctionDecl* functionDecl,
+                             std::unordered_set<const FunctionDecl*>& roots)
+{
+    bool bCalledSuperMethod = false;
+    if (auto methodDecl = dyn_cast<CXXMethodDecl>(functionDecl))
+    {
+        // For virtual/overriding methods, we need to pretend we called from/to root method(s),
+        // so that they get marked as used.
+        for (auto it = methodDecl->begin_overridden_methods();
+             it != methodDecl->end_overridden_methods(); ++it)
+        {
+            findRoots(*it, roots);
+            bCalledSuperMethod = true;
+        }
+    }
+    if (!bCalledSuperMethod)
+    {
+        while (functionDecl->getTemplateInstantiationPattern())
+            functionDecl = functionDecl->getTemplateInstantiationPattern();
+        if (functionDecl->getLocation().isValid())
+            roots.insert(functionDecl);
+    }
+}
+
+bool MethodCycles::VisitCallExpr(CallExpr* expr)
+{
+    // Note that I don't ignore ANYTHING here, because I want to get calls to my code that result
+    // from template instantiation deep inside the STL and other external code
+
+    FunctionDecl* calleeFunctionDecl = expr->getDirectCallee();
+    if (calleeFunctionDecl == nullptr)
+    {
+        Expr* callee = expr->getCallee()->IgnoreParenImpCasts();
+        DeclRefExpr* dr = dyn_cast<DeclRefExpr>(callee);
+        if (dr)
+        {
+            calleeFunctionDecl = dyn_cast<FunctionDecl>(dr->getDecl());
+            if (calleeFunctionDecl)
+                goto gotfunc;
+        }
+        return true;
+    }
+
+gotfunc:
+
+    if (currentFunctionDecl != calleeFunctionDecl)
+        // ignore recursive calls
+        logCallToRootMethods(currentFunctionDecl, calleeFunctionDecl);
+
+    return true;
+}
+
+bool MethodCycles::VisitCXXConstructExpr(const CXXConstructExpr* constructExpr)
+{
+    // Note that I don't ignore ANYTHING here, because I want to get calls to my code that result
+    // from template instantiation deep inside the STL and other external code
+
+    const CXXConstructorDecl* constructorDecl = constructExpr->getConstructor();
+    constructorDecl = constructorDecl->getCanonicalDecl();
+
+    if (!constructorDecl->getLocation().isValid())
+    {
+        return true;
+    }
+
+    logCallToRootMethods(currentFunctionDecl, constructorDecl);
+
+    return true;
+}
+
+bool MethodCycles::VisitFunctionDecl(const FunctionDecl* functionDecl)
+{
+    const FunctionDecl* canonicalFunctionDecl = functionDecl->getCanonicalDecl();
+    if (functionDecl->isDeleted())
+        return true;
+    // don't care about compiler-generated functions
+    if (functionDecl->isImplicit())
+        return true;
+    if (!canonicalFunctionDecl->getLocation().isValid())
+        return true;
+    // ignore method overrides, since the call will show up as being directed to the root method
+    const CXXMethodDecl* methodDecl = dyn_cast<CXXMethodDecl>(functionDecl);
+    if (methodDecl
+        && (methodDecl->size_overridden_methods() != 0 || methodDecl->hasAttr<OverrideAttr>()))
+        return true;
+    if (!isLocationMine(canonicalFunctionDecl->getLocation()))
+        return true;
+
+    MyFuncInfo funcInfo = niceName(canonicalFunctionDecl);
+    definitionSet.insert(funcInfo);
+    return true;
+}
+
+bool MethodCycles::VisitDeclRefExpr(const DeclRefExpr* declRefExpr)
+{
+    const FunctionDecl* functionDecl = dyn_cast<FunctionDecl>(declRefExpr->getDecl());
+    if (!functionDecl)
+    {
+        return true;
+    }
+    logCallToRootMethods(currentFunctionDecl, functionDecl->getCanonicalDecl());
+
+    return true;
+}
+
+bool MethodCycles::TraverseFunctionDecl(FunctionDecl* f)
+{
+    auto copy = currentFunctionDecl;
+    currentFunctionDecl = f;
+    bool ret = RecursiveASTVisitor::TraverseFunctionDecl(f);
+    currentFunctionDecl = copy;
+    return ret;
+}
+bool MethodCycles::TraverseCXXMethodDecl(CXXMethodDecl* f)
+{
+    auto copy = currentFunctionDecl;
+    currentFunctionDecl = f;
+    bool ret = RecursiveASTVisitor::TraverseCXXMethodDecl(f);
+    currentFunctionDecl = copy;
+    return ret;
+}
+bool MethodCycles::TraverseCXXConversionDecl(CXXConversionDecl* f)
+{
+    auto copy = currentFunctionDecl;
+    currentFunctionDecl = f;
+    bool ret = RecursiveASTVisitor::TraverseCXXConversionDecl(f);
+    currentFunctionDecl = copy;
+    return ret;
+}
+bool MethodCycles::TraverseCXXDeductionGuideDecl(CXXDeductionGuideDecl* f)
+{
+    auto copy = currentFunctionDecl;
+    currentFunctionDecl = f;
+    bool ret = RecursiveASTVisitor::TraverseCXXDeductionGuideDecl(f);
+    currentFunctionDecl = copy;
+    return ret;
+}
+bool MethodCycles::TraverseCXXConstructorDecl(CXXConstructorDecl* f)
+{
+    auto copy = currentFunctionDecl;
+    currentFunctionDecl = f;
+    bool ret = RecursiveASTVisitor::TraverseCXXConstructorDecl(f);
+    currentFunctionDecl = copy;
+    return ret;
+}
+bool MethodCycles::TraverseCXXDestructorDecl(CXXDestructorDecl* f)
+{
+    auto copy = currentFunctionDecl;
+    currentFunctionDecl = f;
+    bool ret = RecursiveASTVisitor::TraverseCXXDestructorDecl(f);
+    currentFunctionDecl = copy;
+    return ret;
+}
+
+loplugin::Plugin::Registration<MethodCycles> X("methodcycles", false);
+}
+
+/* vim:set shiftwidth=4 softtabstop=4 expandtab: */