new loplugin: unusedmethods

Change-Id: I72574e354aadf357d6d8181a514efb4783e79e28

compilerplugins/clang/unusedmethods.cxx

+/* -*- 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 <set>
+#include "plugin.hxx"
+#include "compat.hxx"
+
+/**
+Dump a list of calls to methods, and a list of method definitions.
+Then we will post-process the 2 lists and find the set of unused methods.
+
+Be warned that it produces around 3G of log file.
+
+The process goes something like this:
+  $ make check
+  $ make FORCE_COMPILE_ALL=1 COMPILER_PLUGIN_TOOL='unusedmethods' check > log.txt
+  $ grep -P '(call:)|(definition:)' log.txt | sort -u > log2.txt
+  $ ./compilerplugins/clang/unusedmethods.py log2.txt > result.txt
+
+and then
+  $ for dir in *; do make FORCE_COMPILE_ALL=1 UPDATE_FILES=$dir COMPILER_PLUGIN_TOOL='unusedmethodsremove' $dir; done
+to auto-remove the method declarations
+
+Note that the actual process may involve a fair amount of undoing, hand editing, and general messing around
+to get it to work :-)
+
+TODO ignore calls from a method to itself, so we can eliminate unused recursive methods
+TODO deal with calls to superclass/member constructors from other constructors, so
+     we can find unused constructors
+TODO need to handle places where the code takes the address of a method, that needs to count
+     as a use-site.
+TODO deal with free functions and static methods
+TODO track instantiations of template class constructor methods
+*/
+
+namespace {
+
+class UnusedMethods:
+    public RecursiveASTVisitor<UnusedMethods>, public loplugin::Plugin
+{
+public:
+    explicit UnusedMethods(InstantiationData const & data): Plugin(data) {}
+
+    virtual void run() override { TraverseDecl(compiler.getASTContext().getTranslationUnitDecl()); }
+
+    bool VisitCallExpr(CallExpr* );
+    bool VisitCXXMethodDecl( const CXXMethodDecl* decl );
+    bool VisitDeclRefExpr( const DeclRefExpr* );
+    bool TraverseCXXMethodDecl(CXXMethodDecl * decl) { return RecursiveASTVisitor::TraverseCXXMethodDecl(decl); }
+};
+
+static std::string niceName(const CXXMethodDecl* functionDecl)
+{
+    std::string s =
+        compat::getReturnType(*functionDecl).getCanonicalType().getAsString()
+        + " " + functionDecl->getParent()->getQualifiedNameAsString()
+        + "::" + functionDecl->getNameAsString()
+        + "(";
+    bool bFirst = true;
+    for (const ParmVarDecl *pParmVarDecl : functionDecl->params()) {
+        if (bFirst)
+            bFirst = false;
+        else
+            s += ",";
+        s += pParmVarDecl->getType().getCanonicalType().getAsString();
+    }
+    s += ")";
+    if (functionDecl->isConst()) {
+        s += " const";
+    }
+    return s;
+}
+
+// try to limit the volumninous output a little
+static std::set<std::string> alreadySeenCallSet;
+
+static void logCallToRootMethods(const CXXMethodDecl* decl)
+{
+    // For virtual/overriding methods, we need to pretend we called the root method(s),
+    // so that they get marked as used.
+    bool bPrinted = false;
+    for(CXXMethodDecl::method_iterator it = decl->begin_overridden_methods();
+        it != decl->end_overridden_methods(); ++it)
+    {
+        logCallToRootMethods(*it);
+        bPrinted = true;
+    }
+    if (!bPrinted)
+    {
+        std::string s = niceName(decl);
+        if (alreadySeenCallSet.insert(s).second)
+            cout << "call:\t" << niceName(decl) << endl;
+    }
+}
+
+static bool startsWith(const std::string& s, const char* other)
+{
+    return s.compare(0, strlen(other), other) == 0;
+}
+
+static bool isStandardStuff(const std::string& s)
+{
+    // ignore UNO interface definitions, cannot change those
+    return startsWith(s, "com::sun::star::")
+          // ignore stuff in the C++ stdlib and boost
+          || startsWith(s, "std::") || startsWith(s, "boost::") || startsWith(s, "class boost::") || startsWith(s, "__gnu_debug::")
+          // can't change our rtl layer
+          || startsWith(s, "rtl::")
+          // ignore anonymous namespace stuff, it is compilation-unit-local and the compiler will detect any
+          // unused code there
+          || startsWith(s, "(anonymous namespace)::");
+}
+
+bool UnusedMethods::VisitCallExpr(CallExpr* expr)
+{
+    if (ignoreLocation(expr)) {
+        return true;
+    }
+    CXXMethodDecl* decl = dyn_cast_or_null<CXXMethodDecl>(
+        expr->getDirectCallee());
+    if (decl == nullptr) {
+        return true;
+    }
+    logCallToRootMethods(decl);
+    // if we see a call to a templated method, it effectively instantiates a new method,
+    // so we need to examine it's interior to see if it in turn calls anything else
+    if (decl->getTemplatedKind() != clang::FunctionDecl::TemplatedKind::TK_NonTemplate
+        || decl->isFunctionTemplateSpecialization())
+    {
+        TraverseCXXMethodDecl(decl);
+    }
+    return true;
+}
+
+bool UnusedMethods::VisitCXXMethodDecl( const CXXMethodDecl* functionDecl )
+{
+    if (ignoreLocation(functionDecl)) {
+        return true;
+    }
+    functionDecl = functionDecl->getCanonicalDecl();
+    // ignore method overrides, since the call will show up as being directed to the root method
+    if (functionDecl->size_overridden_methods() != 0 || functionDecl->hasAttr<OverrideAttr>()) {
+        return true;
+    }
+    // ignore static's for now. Would require generalising this plugin a little
+    if (functionDecl->isStatic()) {
+        return true;
+    }
+    // ignore stuff that forms part of the stable URE interface
+    if (isInUnoIncludeFile(compiler.getSourceManager().getSpellingLoc(
+                              functionDecl->getNameInfo().getLoc()))) {
+        return true;
+    }
+    if (isStandardStuff(functionDecl->getParent()->getQualifiedNameAsString())) {
+        return true;
+    }
+    if (isa<CXXDestructorDecl>(functionDecl)) {
+        return true;
+    }
+    if (isa<CXXConstructorDecl>(functionDecl)) {
+        return true;
+    }
+    if (functionDecl->isDeleted()) {
+        return true;
+    }
+
+    cout << "definition:\t" << niceName(functionDecl) << endl;
+    return true;
+}
+
+// this catches places that take the address of a method
+bool UnusedMethods::VisitDeclRefExpr( const DeclRefExpr* declRefExpr )
+{
+    if (ignoreLocation(declRefExpr)) {
+        return true;
+    }
+    const Decl* functionDecl = declRefExpr->getDecl();
+    if (!isa<CXXMethodDecl>(functionDecl)) {
+        return true;
+    }
+    logCallToRootMethods(dyn_cast<CXXMethodDecl>(functionDecl));
+    return true;
+}
+
+loplugin::Plugin::Registration< UnusedMethods > X("unusedmethods", false);
+
+}
+
+/* vim:set shiftwidth=4 softtabstop=4 expandtab: */

compilerplugins/clang/unusedmethods.py

+#!/usr/bin/python
+
+import sys
+
+definitionSet = set()
+callSet = set()
+# things we need to exclude for reasons like :
+# - it's a weird template thingy that confuses the plugin
+exclusionSet = set([
+    "double basegfx::DoubleTraits::maxVal()",
+    "double basegfx::DoubleTraits::minVal()",
+    "double basegfx::DoubleTraits::neutral()",
+    "int basegfx::Int32Traits::maxVal()",
+    "int basegfx::Int32Traits::minVal()",
+    "int basegfx::Int32Traits::neutral()",
+    "unsigned long UniqueIndexImpl::Insert(void *)",
+    # used from a yacc lexer
+    "class rtl::OUString unoidl::detail::SourceProviderType::getName() const",
+    "_Bool unoidl::detail::SourceProviderType::equals(const struct unoidl::detail::SourceProviderType &) const",
+    "_Bool unoidl::detail::SourceProviderEntityPad::isPublished() const",
+    "_Bool unoidl::detail::SourceProviderInterfaceTypeEntityPad::checkMemberClashes(int,void *,struct unoidl::detail::SourceProviderScannerData *,const class rtl::OUString &,const class rtl::OUString &,_Bool) const",
+    "_Bool unoidl::detail::SourceProviderInterfaceTypeEntityPad::checkBaseClashes(int,void *,struct unoidl::detail::SourceProviderScannerData *,const class rtl::OUString &,const class rtl::Reference<class unoidl::InterfaceTypeEntity> &,_Bool,_Bool,_Bool,class std::__debug::set<class rtl::OUString, struct std::less<class rtl::OUString>, class std::allocator<class rtl::OUString> > *) const",
+    "_Bool unoidl::detail::SourceProviderInterfaceTypeEntityPad::addDirectBase(int,void *,struct unoidl::detail::SourceProviderScannerData *,const struct unoidl::detail::SourceProviderInterfaceTypeEntityPad::DirectBase &,_Bool)",
+    "_Bool unoidl::detail::SourceProviderInterfaceTypeEntityPad::addBase(int,void *,struct unoidl::detail::SourceProviderScannerData *,const class rtl::OUString &,const class rtl::OUString &,const class rtl::Reference<class unoidl::InterfaceTypeEntity> &,_Bool,_Bool)",
+    "_Bool unoidl::detail::SourceProviderInterfaceTypeEntityPad::addDirectMember(int,void *,struct unoidl::detail::SourceProviderScannerData *,const class rtl::OUString &)",
+    "_Bool unoidl::detail::SourceProviderInterfaceTypeEntityPad::addOptionalBaseMembers(int,void *,struct unoidl::detail::SourceProviderScannerData *,const class rtl::OUString &,const class rtl::Reference<class unoidl::InterfaceTypeEntity> &)",
+    "void unoidl::detail::SourceProviderScannerData::setSource(const void *,unsigned long)",
+    # TODO track instantiations of template class constructors
+    "void comphelper::IEventProcessor::release()",
+    # used by Windows build
+    "_Bool basegfx::B2ITuple::equalZero() const",
+    "class basegfx::B2DPolyPolygon basegfx::unotools::UnoPolyPolygon::getPolyPolygonUnsafe() const",
+    ])
+
+
+with open(sys.argv[1]) as txt:
+    for line in txt:
+        if line.startswith("definition:\t"):
+            idx1 = line.find("\t")
+            clazzName = line[idx1+1 : len(line)-1]
+            definitionSet.add(clazzName)
+        elif line.startswith("call:\t"):
+            idx1 = line.find("\t")
+            clazzName = line[idx1+1 : len(line)-1]
+            callSet.add(clazzName)
+
+for clazz in sorted(definitionSet - callSet - exclusionSet):
+    # ignore operators, they are normally called from inside STL code
+    if (clazz.find("::operator") != -1):
+        continue
+    # ignore the custom RTTI stuff
+    if (    (clazz.find("::CreateType()") != -1)
+         or (clazz.find("::IsA(") != -1)
+         or (clazz.find("::Type()") != -1)):
+        continue
+    # if this method is const, and there is a non-const variant of it, and the non-const variant is in use, then leave it alone
+    if (clazz.endswith(" const")
+        and clazz[6:len(clazz)-6] in definitionSet
+        and clazz[6:len(clazz)-6] in callSet):
+       continue
+    # if this method is non-const, and there is a const variant of it, and the const variant is in use, then leave it alone
+    if ((not clazz.endswith(" const"))
+        and ("const " + clazz + " const") in definitionSet
+        and ("const " + clazz + " const") in callSet):
+       continue
+    # There is lots of macro magic going on in /home/noel/libo4/include/sax/fshelper.hxx that should be using C++11 varag templates
+    if clazz.startswith("void sax_fastparser::FastSerializerHelper::"):
+       continue
+    # used by Windows build
+    if clazz.find("DdeTopic::") != -1 or clazz.find("DdeData::") != -1 or clazz.find("DdeService::") != -1:
+       continue
+    print clazz
+
+# add an empty line at the end to make it easier for the unusedmethodsremove plugin to mmap() the output file 
+print
+        
+

compilerplugins/clang/unusedmethodsremove.cxx

+/* -*- 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 "plugin.hxx"
+#include "compat.hxx"
+#include <sys/mman.h>
+#include <sys/types.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <sys/stat.h>
+#include <assert.h>
+#include <cstring>
+
+/**
+  This is intended to be run as the second stage of the "unusedmethods" clang plugin.
+*/
+
+namespace {
+
+class UnusedMethodsRemove:
+    public RecursiveASTVisitor<UnusedMethodsRemove>, public loplugin::RewritePlugin
+{
+public:
+    explicit UnusedMethodsRemove(InstantiationData const & data);
+    ~UnusedMethodsRemove();
+
+    virtual void run() override { TraverseDecl(compiler.getASTContext().getTranslationUnitDecl()); }
+
+    bool VisitCXXMethodDecl( const CXXMethodDecl* var );
+private:
+    // I use a brute-force approach - mmap the results file and do a linear search on it
+    // It works surprisingly well, because the file is small enough to fit into L2 cache on modern CPU's
+    size_t mmapFilesize;
+    int mmapFD;
+    char* mmappedData;
+};
+
+static size_t getFilesize(const char* filename)
+{
+    struct stat st;
+    stat(filename, &st);
+    return st.st_size;
+}
+
+UnusedMethodsRemove::UnusedMethodsRemove(InstantiationData const & data): RewritePlugin(data)
+{
+    static const char sInputFile[] = "/home/noel/libo4/result.txt";
+    mmapFilesize = getFilesize(sInputFile);
+    //Open file
+    mmapFD = open(sInputFile, O_RDONLY, 0);
+    assert(mmapFD != -1);
+    //Execute mmap
+    mmappedData = static_cast<char*>(mmap(NULL, mmapFilesize, PROT_READ, MAP_PRIVATE | MAP_POPULATE, mmapFD, 0));
+    assert(mmappedData != NULL);
+}
+
+UnusedMethodsRemove::~UnusedMethodsRemove()
+{
+    //Cleanup
+    int rc = munmap(mmappedData, mmapFilesize);
+    assert(rc == 0);
+    close(mmapFD);
+}
+
+static std::string niceName(const CXXMethodDecl* functionDecl)
+{
+    std::string s =
+        compat::getReturnType(*functionDecl).getCanonicalType().getAsString()
+        + " " + functionDecl->getParent()->getQualifiedNameAsString()
+        + "::" + functionDecl->getNameAsString()
+        + "(";
+    bool bFirst = true;
+    for (const ParmVarDecl *pParmVarDecl : functionDecl->params()) {
+        if (bFirst)
+            bFirst = false;
+        else
+            s += ",";
+        s += pParmVarDecl->getType().getCanonicalType().getAsString();
+    }
+    s += ")";
+    if (functionDecl->isConst()) {
+        s += " const";
+    }
+    return s;
+}
+
+bool UnusedMethodsRemove::VisitCXXMethodDecl( const CXXMethodDecl* functionDecl )
+{
+    if (rewriter == nullptr) {
+        return true;
+    }
+    if (ignoreLocation(functionDecl)) {
+        return true;
+    }
+    // ignore stuff that forms part of the stable URE interface
+    if (isInUnoIncludeFile(compiler.getSourceManager().getSpellingLoc(
+                              functionDecl->getCanonicalDecl()->getNameInfo().getLoc()))) {
+        return true;
+    }
+
+    // don't mess with templates
+    if (functionDecl->getParent()->getDescribedClassTemplate() != nullptr) {
+        return true;
+    }
+    if (functionDecl->getTemplatedKind() != FunctionDecl::TK_NonTemplate) {
+        return true;
+    }
+
+    std::string aNiceName = "\n" + niceName(functionDecl) + "\n";
+    const char *aNiceNameStr = aNiceName.c_str();
+    char* found = std::search(mmappedData, mmappedData + mmapFilesize, aNiceNameStr, aNiceNameStr + strlen(aNiceNameStr));
+    if(!(found < mmappedData + mmapFilesize)) {
+        return true;
+    }
+    // sometimes the declaration has a semicolon just after it, and it's much neater to remove that too.
+    SourceRange replaceRange(functionDecl->getSourceRange());
+    if (rewriter->getRewrittenText(SourceRange(replaceRange.getEnd(), replaceRange.getEnd().getLocWithOffset(1))) == ";") {
+        replaceRange.setEnd(replaceRange.getEnd().getLocWithOffset(1));
+    }
+    if (!replaceText(replaceRange, "")) {
+        report(
+            DiagnosticsEngine::Warning,
+            "Could not remove unused method (" + niceName(functionDecl) + ")",
+            functionDecl->getLocStart())
+          << functionDecl->getSourceRange();
+    }
+    return true;
+}
+
+
+
+loplugin::Plugin::Registration< UnusedMethodsRemove > X("unusedmethodsremove", false);
+
+}
+
+/* vim:set shiftwidth=4 softtabstop=4 expandtab: */