office-gobmx/compilerplugins/clang/singlevalfields.cxx
Stephan Bergmann 0792b85914 Adapt loplugin:singlevalfields to AtomicExpr
> AtomicExpr 0xcb01120 'std::__detail::__platform_wait_t':'int'
> |-ImplicitCastExpr 0xcb01108 'std::__detail::__platform_wait_t *' <LValueToRValue>
> | `-MemberExpr 0xcb01048 'std::__detail::__platform_wait_t *' lvalue ->_M_addr 0xcafd9c8
> |   `-CXXThisExpr 0xcb01038 '__waiter_base<_Tp> *' implicit this
> |-IntegerLiteral 0xcb01098 'int' 5
> `-IntegerLiteral 0xcb01078 'int' 1
> AtomicExpr 0xd1e2d08 'std::__detail::__platform_wait_t':'int'
> |-ImplicitCastExpr 0xd1e2cf0 'std::__detail::__platform_wait_t *' <LValueToRValue>
> | `-MemberExpr 0xd1e2cc0 'std::__detail::__platform_wait_t *' lvalue ->_M_addr 0xcb02bf8
> |   `-CXXThisExpr 0xd1e2cb0 'struct std::__detail::__waiter_base<struct std::__detail::__waiter_pool> *' implicit this
> |-IntegerLiteral 0xcb01098 'int' 5
> `-IntegerLiteral 0xcb01078 'int' 1
> error: 'error' diagnostics seen but not expected:
>   File ~/gcc/trunk/inst/lib/gcc/x86_64-pc-linux-gnu/12.0.1/../../../../include/c++/12.0.1/bits/atomic_wait.h Line 312: oh dear, what can the matter be? [loplugin:singlevalfields]
>   File ~/gcc/trunk/inst/lib/gcc/x86_64-pc-linux-gnu/12.0.1/../../../../include/c++/12.0.1/bits/atomic_wait.h Line 312: oh dear, what can the matter be? [loplugin:singlevalfields]

Change-Id: I71c43b482aaa0992b7ce131d27e262b8e3b4087f
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/132160
Tested-by: Jenkins
Reviewed-by: Stephan Bergmann <sbergman@redhat.com>
2022-03-28 10:23:20 +02:00

577 lines
21 KiB
C++

/* -*- 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 "config_clang.h"
#include "compat.hxx"
#include "plugin.hxx"
#include "clang/AST/ParentMapContext.h"
/**
Look for fields that are only ever assigned a single constant value.
We dmp a list of values assigned to fields, and a list of field definitions.
Then we will post-process the 2 lists and find the set of interesting fields.
Be warned that it produces around 5G of log file.
The process goes something like this:
$ make check
$ make FORCE_COMPILE=all COMPILER_PLUGIN_TOOL='singlevalfields' check
$ ./compilerplugins/clang/singlevalfields.py
Note that the actual process may involve a fair amount of undoing, hand editing, and general messing around
to get it to work :-)
@TODO we don't spot fields that have been zero-initialised via calloc or rtl_allocateZeroMemory or memset
@TODO calls to lambdas where a reference to the field is taken
*/
namespace {
struct MyFieldInfo
{
FieldDecl const * fieldDecl;
std::string parentClass;
std::string fieldName;
std::string fieldType;
std::string sourceLocation;
};
bool operator < (const MyFieldInfo &lhs, const MyFieldInfo &rhs)
{
return std::tie(lhs.parentClass, lhs.fieldName)
< std::tie(rhs.parentClass, rhs.fieldName);
}
struct MyFieldAssignmentInfo : public MyFieldInfo
{
std::string value;
};
bool operator < (const MyFieldAssignmentInfo &lhs, const MyFieldAssignmentInfo &rhs)
{
return std::tie(lhs.parentClass, lhs.fieldName, lhs.value)
< std::tie(rhs.parentClass, rhs.fieldName, rhs.value);
}
// try to limit the voluminous output a little
static std::set<MyFieldAssignmentInfo> assignedSet;
static std::set<MyFieldInfo> definitionSet;
/** escape the value string to make it easier to parse the output file in python */
std::string escape(std::string s)
{
std::string out;
for (size_t i=0; i<s.length(); ++i)
if (int(s[i]) >= 32)
out += s[i];
else
out += "\\" + std::to_string((int)s[i]);
return out;
}
class SingleValFields:
public RecursiveASTVisitor<SingleValFields>, public loplugin::Plugin
{
public:
explicit SingleValFields(loplugin::InstantiationData const & data):
Plugin(data) {}
virtual void run() override
{
TraverseDecl(compiler.getASTContext().getTranslationUnitDecl());
if (!isUnitTestMode())
{
// 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 MyFieldAssignmentInfo & s : assignedSet)
output += "asgn:\t" + s.parentClass + "\t" + s.fieldName + "\t" + escape(s.value) + "\n";
for (const MyFieldInfo & s : definitionSet)
output += "defn:\t" + s.parentClass + "\t" + s.fieldName + "\t" + s.fieldType + "\t" + s.sourceLocation + "\n";
std::ofstream myfile;
myfile.open( WORKDIR "/loplugin.singlevalfields.log", std::ios::app | std::ios::out);
myfile << output;
myfile.close();
}
else
{
for (const MyFieldAssignmentInfo & s : assignedSet)
if (s.fieldDecl && compiler.getSourceManager().isInMainFile(s.fieldDecl->getBeginLoc()))
report(
DiagnosticsEngine::Warning,
"assign %0",
s.fieldDecl->getBeginLoc())
<< s.value;
}
}
bool shouldVisitTemplateInstantiations () const { return true; }
// to catch compiler-generated constructors
bool shouldVisitImplicitCode() const { return true; }
bool VisitFieldDecl( const FieldDecl* );
bool VisitVarDecl( const VarDecl* );
bool VisitMemberExpr( const MemberExpr* );
bool VisitDeclRefExpr( const DeclRefExpr* );
bool VisitCXXConstructorDecl( const CXXConstructorDecl* );
// bool VisitUnaryExprOrTypeTraitExpr( const UnaryExprOrTypeTraitExpr* );
private:
void niceName(const DeclaratorDecl*, MyFieldInfo&);
void walkPotentialAssign( const DeclaratorDecl* fieldOrVarDecl, const Stmt* stmt );
std::string getExprValue(const Expr*);
const FunctionDecl* get_top_FunctionDecl_from_Stmt(const Stmt&);
void checkCallExpr(const Stmt* child, const CallExpr* callExpr, std::string& assignValue, bool& bPotentiallyAssignedTo);
};
void SingleValFields::niceName(const DeclaratorDecl* fieldOrVarDecl, MyFieldInfo& aInfo)
{
const VarDecl* varDecl = dyn_cast<VarDecl>(fieldOrVarDecl);
const FieldDecl* fieldDecl = dyn_cast<FieldDecl>(fieldOrVarDecl);
aInfo.fieldDecl = fieldDecl;
if (fieldDecl)
aInfo.parentClass = fieldDecl->getParent()->getQualifiedNameAsString();
else
{
if (auto parentRecordDecl = dyn_cast<CXXRecordDecl>(varDecl->getDeclContext()))
aInfo.parentClass = parentRecordDecl->getQualifiedNameAsString();
else if (auto parentMethodDecl = dyn_cast<CXXMethodDecl>(varDecl->getDeclContext()))
aInfo.parentClass = parentMethodDecl->getQualifiedNameAsString();
else if (auto parentFunctionDecl = dyn_cast<FunctionDecl>(varDecl->getDeclContext()))
aInfo.parentClass = parentFunctionDecl->getQualifiedNameAsString();
else if (isa<TranslationUnitDecl>(varDecl->getDeclContext()))
aInfo.parentClass = handler.getMainFileName().str();
else if (auto parentNamespaceDecl = dyn_cast<NamespaceDecl>(varDecl->getDeclContext()))
aInfo.parentClass = parentNamespaceDecl->getQualifiedNameAsString();
else if (isa<LinkageSpecDecl>(varDecl->getDeclContext()))
aInfo.parentClass = "extern"; // what to do here?
else
{
std::cout << "what is this? " << varDecl->getDeclContext()->getDeclKindName() << std::endl;
exit(1);
}
}
aInfo.fieldName = fieldOrVarDecl->getNameAsString();
aInfo.fieldType = fieldOrVarDecl->getType().getAsString();
SourceLocation expansionLoc = compiler.getSourceManager().getExpansionLoc( fieldOrVarDecl->getLocation() );
StringRef name = getFilenameOfLocation(expansionLoc);
aInfo.sourceLocation = std::string(name.substr(strlen(SRCDIR)+1)) + ":" + std::to_string(compiler.getSourceManager().getSpellingLineNumber(expansionLoc));
loplugin::normalizeDotDotInFilePath(aInfo.sourceLocation);
}
bool SingleValFields::VisitFieldDecl( const FieldDecl* fieldDecl )
{
auto canonicalDecl = fieldDecl->getCanonicalDecl();
if( isInUnoIncludeFile( compiler.getSourceManager().getSpellingLoc(canonicalDecl->getLocation())) )
return true;
MyFieldInfo aInfo;
niceName(canonicalDecl, aInfo);
definitionSet.insert(aInfo);
if (fieldDecl->getInClassInitializer())
{
MyFieldAssignmentInfo aInfo;
niceName(canonicalDecl, aInfo);
aInfo.value = getExprValue(fieldDecl->getInClassInitializer());
assignedSet.insert(aInfo);
}
return true;
}
bool SingleValFields::VisitVarDecl( const VarDecl* varDecl )
{
if (isa<ParmVarDecl>(varDecl))
return true;
if (varDecl->getType().isConstQualified())
return true;
if (!(varDecl->isStaticLocal() || varDecl->isStaticDataMember() || varDecl->hasGlobalStorage()))
return true;
auto canonicalDecl = varDecl->getCanonicalDecl();
if (!canonicalDecl->getLocation().isValid())
return true;
if( isInUnoIncludeFile( compiler.getSourceManager().getSpellingLoc(canonicalDecl->getLocation())) )
return true;
MyFieldInfo aInfo;
niceName(canonicalDecl, aInfo);
definitionSet.insert(aInfo);
if (varDecl->getInit())
{
MyFieldAssignmentInfo aInfo;
niceName(canonicalDecl, aInfo);
aInfo.value = getExprValue(varDecl->getInit());
assignedSet.insert(aInfo);
}
return true;
}
bool SingleValFields::VisitCXXConstructorDecl( const CXXConstructorDecl* decl )
{
// doesn't count as a write to fields because it's self->self
if (decl->isCopyOrMoveConstructor())
return true;
for(auto it = decl->init_begin(); it != decl->init_end(); ++it)
{
const CXXCtorInitializer* init = *it;
const FieldDecl* fieldDecl = init->getMember();
if( !fieldDecl )
continue;
MyFieldAssignmentInfo aInfo;
niceName(fieldDecl, aInfo);
const Expr * expr = init->getInit();
// unwrap any single-arg constructors, this helps to find smart pointers
// that are only assigned nullptr
if (auto cxxConstructExpr = dyn_cast<CXXConstructExpr>(expr))
if (cxxConstructExpr->getNumArgs() == 1)
expr = cxxConstructExpr->getArg(0);
aInfo.value = getExprValue(expr);
assignedSet.insert(aInfo);
}
return true;
}
bool SingleValFields::VisitMemberExpr( const MemberExpr* memberExpr )
{
const ValueDecl* decl = memberExpr->getMemberDecl();
const FieldDecl* fieldDecl = dyn_cast<FieldDecl>(decl);
if (!fieldDecl)
return true;
walkPotentialAssign(fieldDecl, memberExpr);
return true;
}
bool SingleValFields::VisitDeclRefExpr( const DeclRefExpr* declRefExpr )
{
const VarDecl* varDecl = dyn_cast_or_null<VarDecl>(declRefExpr->getDecl());
if (!varDecl)
return true;
if (isa<ParmVarDecl>(varDecl))
return true;
if (varDecl->getType().isConstQualified())
return true;
if (!(varDecl->isStaticLocal() || varDecl->isStaticDataMember() || varDecl->hasGlobalStorage()))
return true;
walkPotentialAssign(varDecl, declRefExpr);
return true;
}
void SingleValFields::walkPotentialAssign( const DeclaratorDecl* fieldOrVarDecl, const Stmt* memberExpr )
{
const FunctionDecl* parentFunction = getParentFunctionDecl(memberExpr);
if (parentFunction)
{
auto methodDecl = dyn_cast<CXXMethodDecl>(parentFunction);
if (methodDecl && (methodDecl->isCopyAssignmentOperator() || methodDecl->isMoveAssignmentOperator()))
return;
if (methodDecl && methodDecl->getIdentifier()
&& (methodDecl->getName().startswith("Clone") || methodDecl->getName().startswith("clone")))
return;
auto cxxConstructorDecl = dyn_cast<CXXConstructorDecl>(parentFunction);
if (cxxConstructorDecl && cxxConstructorDecl->isCopyOrMoveConstructor())
return;
}
// walk up the tree until we find something interesting
const Stmt* child = memberExpr;
const Stmt* parent = getParentStmt(memberExpr);
bool bPotentiallyAssignedTo = false;
bool bDump = false;
std::string assignValue = "?";
// check for field being returned by non-const ref eg. Foo& getFoo() { return f; }
if (parentFunction && parent && isa<ReturnStmt>(parent)) {
const Stmt* parent2 = getParentStmt(parent);
if (parent2 && isa<CompoundStmt>(parent2)) {
QualType qt = parentFunction->getReturnType().getDesugaredType(compiler.getASTContext());
if (!qt.isConstQualified() && qt->isReferenceType()) {
bPotentiallyAssignedTo = true;
}
}
}
while (!bPotentiallyAssignedTo) {
// check for field being accessed by a reference variable e.g. Foo& f = m.foo;
auto parentsList = compiler.getASTContext().getParents(*child);
auto it = parentsList.begin();
if (it != parentsList.end()) {
const VarDecl *varDecl = it->get<VarDecl>();
if (varDecl) {
QualType qt = varDecl->getType().getDesugaredType(compiler.getASTContext());
if (!qt.isConstQualified() && qt->isReferenceType()) {
bPotentiallyAssignedTo = true;
break;
}
}
}
if (!parent) {
return;
}
if (isa<CastExpr>(parent) || isa<MemberExpr>(parent) || isa<ParenExpr>(parent) || isa<ParenListExpr>(parent)
|| isa<ExprWithCleanups>(parent))
{
child = parent;
parent = getParentStmt(parent);
}
else if (isa<UnaryOperator>(parent))
{
const UnaryOperator* unaryOperator = dyn_cast<UnaryOperator>(parent);
int x = unaryOperator->getOpcode();
if (x == UO_AddrOf || x == UO_PostInc || x == UO_PostDec || x == UO_PreInc || x == UO_PreDec) {
assignValue = "?";
bPotentiallyAssignedTo = true;
break;
}
// cannot be assigned to anymore
break;
}
else if (auto callExpr = dyn_cast<CallExpr>(parent))
{
checkCallExpr(child, callExpr, assignValue, bPotentiallyAssignedTo);
break;
}
else if (isa<CXXConstructExpr>(parent))
{
const CXXConstructExpr* consExpr = dyn_cast<CXXConstructExpr>(parent);
const CXXConstructorDecl* consDecl = consExpr->getConstructor();
for (unsigned i = 0; i < consExpr->getNumArgs(); ++i) {
if (i >= consDecl->getNumParams()) // can happen in template code
break;
if (consExpr->getArg(i) == child) {
const ParmVarDecl* parmVarDecl = consDecl->getParamDecl(i);
QualType qt = parmVarDecl->getType().getDesugaredType(compiler.getASTContext());
if (!qt.isConstQualified() && qt->isReferenceType()) {
bPotentiallyAssignedTo = true;
}
break;
}
}
break;
}
else if (isa<BinaryOperator>(parent))
{
const BinaryOperator* binaryOp = dyn_cast<BinaryOperator>(parent);
auto op = binaryOp->getOpcode();
if ( binaryOp->getLHS() != child ) {
// if the expr is on the RHS, do nothing
}
else if ( op == BO_Assign ) {
assignValue = getExprValue(binaryOp->getRHS());
bPotentiallyAssignedTo = true;
} else if ( op == BO_MulAssign || op == BO_DivAssign
|| op == BO_RemAssign || op == BO_AddAssign
|| op == BO_SubAssign || op == BO_ShlAssign
|| op == BO_ShrAssign || op == BO_AndAssign
|| op == BO_XorAssign || op == BO_OrAssign )
{
bPotentiallyAssignedTo = true;
}
break;
}
else if ( isa<CompoundStmt>(parent)
|| isa<SwitchStmt>(parent) || isa<CaseStmt>(parent) || isa<DefaultStmt>(parent)
|| isa<DoStmt>(parent) || isa<WhileStmt>(parent)
|| isa<IfStmt>(parent)
|| isa<ForStmt>(parent)
|| isa<ReturnStmt>(parent)
|| isa<CXXNewExpr>(parent)
|| isa<CXXDeleteExpr>(parent)
|| isa<ConditionalOperator>(parent)
|| isa<CXXTypeidExpr>(parent)
|| isa<ArraySubscriptExpr>(parent)
|| isa<CXXDependentScopeMemberExpr>(parent)
|| isa<DeclStmt>(parent)
|| isa<UnaryExprOrTypeTraitExpr>(parent)
|| isa<UnresolvedMemberExpr>(parent)
|| isa<MaterializeTemporaryExpr>(parent) //???
|| isa<InitListExpr>(parent)
|| isa<CXXUnresolvedConstructExpr>(parent)
|| isa<LambdaExpr>(parent)
|| isa<PackExpansionExpr>(parent)
|| isa<CXXPseudoDestructorExpr>(parent)
)
{
break;
}
else if ( isa<ArrayInitLoopExpr>(parent) || isa<AtomicExpr>(parent) || isa<GCCAsmStmt>(parent) || isa<VAArgExpr>(parent))
{
bPotentiallyAssignedTo = true;
break;
}
else {
bPotentiallyAssignedTo = true;
bDump = true;
break;
}
}
if (bDump)
{
report(
DiagnosticsEngine::Warning,
"oh dear, what can the matter be?",
memberExpr->getBeginLoc())
<< memberExpr->getSourceRange();
parent->dump();
}
if (bPotentiallyAssignedTo)
{
MyFieldAssignmentInfo aInfo;
niceName(fieldOrVarDecl, aInfo);
aInfo.value = assignValue;
assignedSet.insert(aInfo);
}
}
void SingleValFields::checkCallExpr(const Stmt* child, const CallExpr* callExpr, std::string& assignValue, bool& bPotentiallyAssignedTo)
{
if (callExpr->getCallee() == child) {
return;
}
const FunctionDecl* functionDecl;
if (auto memberCallExpr = dyn_cast<CXXMemberCallExpr>(callExpr)) {
functionDecl = memberCallExpr->getMethodDecl();
} else {
functionDecl = callExpr->getDirectCallee();
}
if (functionDecl) {
if (auto operatorCallExpr = dyn_cast<CXXOperatorCallExpr>(callExpr)) {
if (operatorCallExpr->getArg(0) == child) {
const CXXMethodDecl* calleeMethodDecl = dyn_cast_or_null<CXXMethodDecl>(operatorCallExpr->getDirectCallee());
if (calleeMethodDecl) {
if (operatorCallExpr->getOperator() == OO_Equal) {
assignValue = getExprValue(operatorCallExpr->getArg(1));
bPotentiallyAssignedTo = true;
return;
}
}
}
}
for (unsigned i = 0; i < callExpr->getNumArgs(); ++i) {
if (i >= functionDecl->getNumParams()) // can happen in template code
break;
if (callExpr->getArg(i) == child) {
const ParmVarDecl* parmVarDecl = functionDecl->getParamDecl(i);
QualType qt = parmVarDecl->getType().getDesugaredType(compiler.getASTContext());
if (!qt.isConstQualified() && qt->isReferenceType()) {
assignValue = "?";
bPotentiallyAssignedTo = true;
}
break;
}
}
return;
}
// check for function pointers
const FieldDecl* calleeFieldDecl = dyn_cast_or_null<FieldDecl>(callExpr->getCalleeDecl());
if (!calleeFieldDecl) {
return;
}
QualType qt = calleeFieldDecl->getType().getDesugaredType(compiler.getASTContext());
if (!qt->isPointerType()) {
return;
}
qt = qt->getPointeeType().getDesugaredType(compiler.getASTContext());
const FunctionProtoType* proto = qt->getAs<FunctionProtoType>();
if (!proto) {
return;
}
for (unsigned i = 0; i < callExpr->getNumArgs(); ++i) {
if (i >= proto->getNumParams()) // can happen in template code
break;
if (callExpr->getArg(i) == child) {
QualType qt = proto->getParamType(i).getDesugaredType(compiler.getASTContext());
if (!qt.isConstQualified() && qt->isReferenceType()) {
assignValue = "?";
bPotentiallyAssignedTo = true;
}
break;
}
}
}
std::string SingleValFields::getExprValue(const Expr* arg)
{
if (!arg)
return "?";
arg = arg->IgnoreParenCasts();
arg = arg->IgnoreImplicit();
// ignore this, it seems to trigger an infinite recursion
if (isa<UnaryExprOrTypeTraitExpr>(arg))
return "?";
if (arg->isValueDependent())
return "?";
// for stuff like: OUString foo = "xxx";
if (auto stringLiteral = dyn_cast<clang::StringLiteral>(arg))
{
if (stringLiteral->getCharByteWidth() == 1)
return stringLiteral->getString().str();
return "?";
}
// ParenListExpr containing a CXXNullPtrLiteralExpr and has a NULL type pointer
if (auto parenListExpr = dyn_cast<ParenListExpr>(arg))
{
if (parenListExpr->getNumExprs() == 1)
return getExprValue(parenListExpr->getExpr(0));
return "?";
}
if (auto constructExpr = dyn_cast<CXXConstructExpr>(arg))
{
if (constructExpr->getNumArgs() >= 1
&& isa<clang::StringLiteral>(constructExpr->getArg(0)))
{
auto stringLiteral = dyn_cast<clang::StringLiteral>(constructExpr->getArg(0));
if (stringLiteral->getCharByteWidth() == 1)
return stringLiteral->getString().str();
return "?";
}
}
if (arg->getType()->isFloatingType())
{
APFloat x1(0.0f);
if (arg->EvaluateAsFloat(x1, compiler.getASTContext()))
{
std::string s;
llvm::raw_string_ostream os(s);
x1.print(os);
return os.str();
}
}
APSInt x1;
if (compat::EvaluateAsInt(arg, x1, compiler.getASTContext()))
return compat::toString(x1, 10);
if (isa<CXXNullPtrLiteralExpr>(arg))
return "0";
return "?";
}
loplugin::Plugin::Registration< SingleValFields > X("singlevalfields", false);
}
/* vim:set shiftwidth=4 softtabstop=4 expandtab: */