forked from OSchip/llvm-project
205 lines
6.6 KiB
C++
205 lines
6.6 KiB
C++
//===--- InfiniteLoopCheck.cpp - clang-tidy -------------------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#include "InfiniteLoopCheck.h"
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#include "clang/AST/ASTContext.h"
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#include "clang/ASTMatchers/ASTMatchFinder.h"
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#include "clang/Analysis/Analyses/ExprMutationAnalyzer.h"
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using namespace clang::ast_matchers;
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namespace clang {
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namespace tidy {
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namespace bugprone {
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static internal::Matcher<Stmt>
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loopEndingStmt(internal::Matcher<Stmt> Internal) {
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return stmt(anyOf(breakStmt(Internal), returnStmt(Internal),
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gotoStmt(Internal), cxxThrowExpr(Internal),
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callExpr(Internal, callee(functionDecl(isNoReturn())))));
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}
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/// Return whether `S` is a reference to the declaration of `Var`.
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static bool isAccessForVar(const Stmt *S, const VarDecl *Var) {
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if (const auto *DRE = dyn_cast<DeclRefExpr>(S))
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return DRE->getDecl() == Var;
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return false;
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}
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/// Return whether `Var` has a pointer or reference in `S`.
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static bool isPtrOrReferenceForVar(const Stmt *S, const VarDecl *Var) {
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if (const auto *DS = dyn_cast<DeclStmt>(S)) {
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for (const Decl *D : DS->getDeclGroup()) {
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if (const auto *LeftVar = dyn_cast<VarDecl>(D)) {
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if (LeftVar->hasInit() && LeftVar->getType()->isReferenceType()) {
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return isAccessForVar(LeftVar->getInit(), Var);
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}
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}
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}
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} else if (const auto *UnOp = dyn_cast<UnaryOperator>(S)) {
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if (UnOp->getOpcode() == UO_AddrOf)
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return isAccessForVar(UnOp->getSubExpr(), Var);
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}
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return false;
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}
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/// Return whether `Var` has a pointer or reference in `S`.
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static bool hasPtrOrReferenceInStmt(const Stmt *S, const VarDecl *Var) {
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if (isPtrOrReferenceForVar(S, Var))
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return true;
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for (const Stmt *Child : S->children()) {
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if (!Child)
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continue;
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if (hasPtrOrReferenceInStmt(Child, Var))
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return true;
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}
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return false;
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}
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/// Return whether `Var` has a pointer or reference in `Func`.
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static bool hasPtrOrReferenceInFunc(const FunctionDecl *Func,
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const VarDecl *Var) {
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return hasPtrOrReferenceInStmt(Func->getBody(), Var);
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}
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/// Return whether `Var` was changed in `LoopStmt`.
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static bool isChanged(const Stmt *LoopStmt, const VarDecl *Var,
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ASTContext *Context) {
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if (const auto *ForLoop = dyn_cast<ForStmt>(LoopStmt))
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return (ForLoop->getInc() &&
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ExprMutationAnalyzer(*ForLoop->getInc(), *Context)
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.isMutated(Var)) ||
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(ForLoop->getBody() &&
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ExprMutationAnalyzer(*ForLoop->getBody(), *Context)
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.isMutated(Var)) ||
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(ForLoop->getCond() &&
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ExprMutationAnalyzer(*ForLoop->getCond(), *Context).isMutated(Var));
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return ExprMutationAnalyzer(*LoopStmt, *Context).isMutated(Var);
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}
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/// Return whether `Cond` is a variable that is possibly changed in `LoopStmt`.
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static bool isVarThatIsPossiblyChanged(const FunctionDecl *Func,
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const Stmt *LoopStmt, const Stmt *Cond,
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ASTContext *Context) {
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if (const auto *DRE = dyn_cast<DeclRefExpr>(Cond)) {
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if (const auto *Var = dyn_cast<VarDecl>(DRE->getDecl())) {
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if (!Var->isLocalVarDeclOrParm())
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return true;
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if (Var->getType().isVolatileQualified())
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return true;
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if (!Var->getType().getTypePtr()->isIntegerType())
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return true;
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return hasPtrOrReferenceInFunc(Func, Var) ||
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isChanged(LoopStmt, Var, Context);
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// FIXME: Track references.
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}
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} else if (isa<MemberExpr>(Cond) || isa<CallExpr>(Cond)) {
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// FIXME: Handle MemberExpr.
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return true;
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}
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return false;
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}
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/// Return whether at least one variable of `Cond` changed in `LoopStmt`.
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static bool isAtLeastOneCondVarChanged(const FunctionDecl *Func,
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const Stmt *LoopStmt, const Stmt *Cond,
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ASTContext *Context) {
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if (isVarThatIsPossiblyChanged(Func, LoopStmt, Cond, Context))
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return true;
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for (const Stmt *Child : Cond->children()) {
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if (!Child)
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continue;
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if (isAtLeastOneCondVarChanged(Func, LoopStmt, Child, Context))
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return true;
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}
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return false;
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}
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/// Return the variable names in `Cond`.
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static std::string getCondVarNames(const Stmt *Cond) {
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if (const auto *DRE = dyn_cast<DeclRefExpr>(Cond)) {
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if (const auto *Var = dyn_cast<VarDecl>(DRE->getDecl()))
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return std::string(Var->getName());
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}
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std::string Result;
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for (const Stmt *Child : Cond->children()) {
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if (!Child)
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continue;
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std::string NewNames = getCondVarNames(Child);
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if (!Result.empty() && !NewNames.empty())
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Result += ", ";
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Result += NewNames;
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}
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return Result;
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}
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void InfiniteLoopCheck::registerMatchers(MatchFinder *Finder) {
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const auto LoopCondition = allOf(
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hasCondition(
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expr(forFunction(functionDecl().bind("func"))).bind("condition")),
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unless(hasBody(hasDescendant(
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loopEndingStmt(forFunction(equalsBoundNode("func")))))));
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Finder->addMatcher(stmt(anyOf(whileStmt(LoopCondition), doStmt(LoopCondition),
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forStmt(LoopCondition)))
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.bind("loop-stmt"),
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this);
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}
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void InfiniteLoopCheck::check(const MatchFinder::MatchResult &Result) {
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const auto *Cond = Result.Nodes.getNodeAs<Expr>("condition");
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const auto *LoopStmt = Result.Nodes.getNodeAs<Stmt>("loop-stmt");
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const auto *Func = Result.Nodes.getNodeAs<FunctionDecl>("func");
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bool ShouldHaveConditionVariables = true;
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if (const auto *While = dyn_cast<WhileStmt>(LoopStmt)) {
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if (const VarDecl *LoopVarDecl = While->getConditionVariable()) {
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if (const Expr *Init = LoopVarDecl->getInit()) {
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ShouldHaveConditionVariables = false;
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Cond = Init;
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}
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}
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}
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if (isAtLeastOneCondVarChanged(Func, LoopStmt, Cond, Result.Context))
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return;
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std::string CondVarNames = getCondVarNames(Cond);
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if (ShouldHaveConditionVariables && CondVarNames.empty())
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return;
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if (CondVarNames.empty()) {
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diag(LoopStmt->getBeginLoc(),
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"this loop is infinite; it does not check any variables in the"
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" condition");
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} else {
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diag(LoopStmt->getBeginLoc(),
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"this loop is infinite; none of its condition variables (%0)"
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" are updated in the loop body")
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<< CondVarNames;
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}
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}
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} // namespace bugprone
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} // namespace tidy
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} // namespace clang
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