Adding upstream version 4:7.4.7.upstream/4%7.4.7upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 246 insertions, 0 deletions

diff --git a/compilerplugins/clang/loopvartoosmall.cxx b/compilerplugins/clang/loopvartoosmall.cxx
new file mode 100644
index 000000000..bc03e94ca
--- /dev/null
+++ b/compilerplugins/clang/loopvartoosmall.cxx
@@ -0,0 +1,246 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/*
+ * This file is part of the LibreOffice project.
+ *
+ * Based on LLVM/Clang.
+ *
+ * This file is distributed under the University of Illinois Open Source
+ * License. See LICENSE.TXT for details.
+ *
+*/
+
+#ifndef LO_CLANG_SHARED_PLUGINS
+
+#include <algorithm>
+#include <cassert>
+#include <list>
+#include <map>
+
+#include "compat.hxx"
+#include "plugin.hxx"
+//#include "clang/AST/CXXInheritance.h"
+
+// Idea from bubli. Check that the index variable in a for loop is able to cover the range
+// revealed by the terminating condition.
+// If not, we might end up in an endless loop, or just not process certain parts.
+
+namespace
+{
+
+class LoopVarTooSmall:
+    public loplugin::FilteringPlugin<LoopVarTooSmall>
+{
+public:
+    explicit LoopVarTooSmall(loplugin::InstantiationData const & data):
+        FilteringPlugin(data) {}
+
+    virtual void run() override {
+        TraverseDecl(compiler.getASTContext().getTranslationUnitDecl());
+    }
+
+    bool VisitForStmt( const ForStmt* stmt ) {
+        checkExpr(stmt->getCond());
+        return true;
+    }
+
+    bool VisitWhileStmt(WhileStmt const * stmt) {
+        checkExpr(stmt->getCond());
+        return true;
+    }
+
+    bool VisitDoStmt(DoStmt const * stmt) {
+        checkExpr(stmt->getCond());
+        return true;
+    }
+
+private:
+    unsigned getIntValueWidth(QualType type) const;
+
+    void checkSubExpr(Expr const * expr, bool positive);
+
+    void checkExpr(Expr const * expr);
+
+    struct Comparison {
+        BinaryOperator const * op;
+        unsigned rhsWidth;
+    };
+
+    struct Comparisons {
+        std::list<Comparison> comparisons;
+        unsigned lhsWidth;
+    };
+
+    std::map<Decl const *, Comparisons> comparisons_;
+};
+
+unsigned LoopVarTooSmall::getIntValueWidth(QualType type) const {
+    if (auto const et = type->getAs<EnumType>()) {
+        auto const ed = et->getDecl();
+        if (!ed->isFixed()) {
+            unsigned pos = ed->getNumPositiveBits();
+            unsigned neg = ed->getNumNegativeBits();
+            return neg == 0 ? std::max(pos, 1U) : std::max(pos + 1, neg);
+        }
+    }
+    return compiler.getASTContext().getIntWidth(type);
+}
+
+void LoopVarTooSmall::checkSubExpr(Expr const * expr, bool positive) {
+    auto const e = expr->IgnoreImplicit()->IgnoreParenImpCasts();
+    if (auto const uo = dyn_cast<UnaryOperator>(e)) {
+        if (uo->getOpcode() == UO_LNot) {
+            checkSubExpr(uo->getSubExpr(), !positive);
+        }
+        return;
+    }
+    const BinaryOperator* binOp = dyn_cast<BinaryOperator>(e);
+    if (!binOp)
+        return;
+    bool less;
+    if (positive) {
+        switch (binOp->getOpcode()) {
+        case BO_LAnd:
+            checkSubExpr(binOp->getLHS(), true);
+            checkSubExpr(binOp->getRHS(), true);
+            return;
+        case BO_LT:
+        case BO_NE:
+            less = true;
+            break;
+        case BO_LE:
+            less = false;
+            break;
+        default:
+            return;
+        }
+    } else {
+        switch (binOp->getOpcode()) {
+        case BO_LOr:
+            checkSubExpr(binOp->getLHS(), false);
+            checkSubExpr(binOp->getRHS(), false);
+            return;
+        case BO_GE:
+        case BO_EQ:
+            less = true;
+            break;
+        case BO_GT:
+            less = false;
+            break;
+        default:
+            return;
+        }
+    }
+    auto lhs = dyn_cast<DeclRefExpr>(binOp->getLHS()->IgnoreParenImpCasts());
+    if (!lhs)
+        return;
+    QualType qt = lhs->getType();
+    if (!qt->isIntegralOrEnumerationType())
+        return;
+    unsigned qt1BitWidth = getIntValueWidth(qt);
+    auto lhsDecl = lhs->getDecl();
+    if (!isa<VarDecl>(lhsDecl)) {
+        if (auto fd = dyn_cast<FieldDecl>(lhsDecl)) {
+            if (fd->isBitField()) {
+                qt1BitWidth = std::max(
+                    qt1BitWidth,
+                    fd->getBitWidthValue(compiler.getASTContext()));
+            }
+        } else {
+            return;
+        }
+    }
+    const Expr* binOpRHS = binOp->getRHS()->IgnoreParenImpCasts();
+    QualType qt2 = binOpRHS->getType();
+    if (!qt2->isIntegralType(compiler.getASTContext()))
+        return;
+    unsigned qt2BitWidth;
+    llvm::APSInt aIntResult;
+    // Work around missing Clang 3.9 fix <https://reviews.llvm.org/rL271762>
+    // "Sema: do not attempt to sizeof a dependent type", causing Clang 3.8 to
+    // crash during EvaluateAsInt() on expressions of the form
+    //
+    //   sizeof (T)
+    //
+    // with dependent type T:
+    if (!binOpRHS->isValueDependent()
+        && compat::EvaluateAsInt(binOpRHS, aIntResult, compiler.getASTContext()))
+    {
+        if (less && aIntResult.isStrictlyPositive()) {
+            --aIntResult;
+        }
+        qt2BitWidth = aIntResult.isUnsigned() || !aIntResult.isNegative()
+            ? std::max(aIntResult.getActiveBits(), 1U)
+            : aIntResult.getBitWidth() - aIntResult.countLeadingOnes() + 1;
+    } else {
+        // Ignore complex expressions for now, promotion rules on conditions
+        // like "i < (size()+1)" make it hard to guess at a correct type:
+        if (isa<BinaryOperator>(binOpRHS) || isa<ConditionalOperator>(binOpRHS))
+        {
+            return;
+        }
+        qt2BitWidth = getIntValueWidth(qt2);
+        if (auto dre = dyn_cast<DeclRefExpr>(binOpRHS)) {
+            if (auto fd = dyn_cast<FieldDecl>(dre->getDecl())) {
+                if (fd->isBitField()) {
+                    qt2BitWidth = std::max(
+                        qt2BitWidth,
+                        fd->getBitWidthValue(compiler.getASTContext()));
+                }
+            }
+        }
+    }
+
+    auto i = comparisons_.find(lhsDecl);
+    if (i == comparisons_.end()) {
+        i = (comparisons_.insert(
+                 decltype(comparisons_)::value_type(lhsDecl, {{}, qt1BitWidth}))
+             .first);
+    } else {
+        assert(i->second.lhsWidth == qt1BitWidth);
+    }
+    bool ins = true;
+    for (auto j = i->second.comparisons.begin();
+         j != i->second.comparisons.end();)
+    {
+        if (qt2BitWidth > j->rhsWidth) {
+            ins = false;
+            break;
+        } else if (qt2BitWidth < j->rhsWidth) {
+            j = i->second.comparisons.erase(j);
+        } else {
+            ++j;
+        }
+    }
+    if (ins) {
+        i->second.comparisons.push_back({binOp, qt2BitWidth});
+    }
+}
+
+void LoopVarTooSmall::checkExpr(Expr const * expr) {
+    if (expr != nullptr && !ignoreLocation(expr)) {
+        assert(comparisons_.empty());
+        checkSubExpr(expr, true);
+        for (auto const & i: comparisons_) {
+            for (auto const & j: i.second.comparisons) {
+                if (i.second.lhsWidth < j.rhsWidth) {
+                    report(
+                        DiagnosticsEngine::Warning,
+                        "loop index type %0 is narrower than length type %1",
+                        j.op->getExprLoc())
+                        << j.op->getLHS()->IgnoreImpCasts()->getType()
+                        << j.op->getRHS()->IgnoreImpCasts()->getType()
+                        << j.op->getSourceRange();
+                }
+            }
+        }
+        comparisons_.clear();
+    }
+}
+
+loplugin::Plugin::Registration< LoopVarTooSmall > loopvartoosmall("loopvartoosmall");
+
+}
+
+#endif // LO_CLANG_SHARED_PLUGINS
+
+/* vim:set shiftwidth=4 softtabstop=4 expandtab: */