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-rw-r--r--clang/lib/Analysis/CloneDetection.cpp146
-rw-r--r--clang/test/Analysis/copypaste/false-positives.cpp21
-rw-r--r--clang/test/Analysis/copypaste/functions.cpp10
3 files changed, 152 insertions, 25 deletions
diff --git a/clang/lib/Analysis/CloneDetection.cpp b/clang/lib/Analysis/CloneDetection.cpp
index 1babbb3c15e..5e241bfe172 100644
--- a/clang/lib/Analysis/CloneDetection.cpp
+++ b/clang/lib/Analysis/CloneDetection.cpp
@@ -80,6 +80,102 @@ SourceLocation StmtSequence::getStartLoc() const {
SourceLocation StmtSequence::getEndLoc() const { return back()->getLocEnd(); }
namespace {
+
+/// \brief Analyzes the pattern of the referenced variables in a statement.
+class VariablePattern {
+
+ /// \brief Describes an occurence of a variable reference in a statement.
+ struct VariableOccurence {
+ /// The index of the associated VarDecl in the Variables vector.
+ size_t KindID;
+
+ VariableOccurence(size_t KindID) : KindID(KindID) {}
+ };
+
+ /// All occurences of referenced variables in the order of appearance.
+ std::vector<VariableOccurence> Occurences;
+ /// List of referenced variables in the order of appearance.
+ /// Every item in this list is unique.
+ std::vector<const VarDecl *> Variables;
+
+ /// \brief Adds a new variable referenced to this pattern.
+ /// \param VarDecl The declaration of the variable that is referenced.
+ void addVariableOccurence(const VarDecl *VarDecl) {
+ // First check if we already reference this variable
+ for (size_t KindIndex = 0; KindIndex < Variables.size(); ++KindIndex) {
+ if (Variables[KindIndex] == VarDecl) {
+ // If yes, add a new occurence that points to the existing entry in
+ // the Variables vector.
+ Occurences.emplace_back(KindIndex);
+ return;
+ }
+ }
+ // If this variable wasn't already referenced, add it to the list of
+ // referenced variables and add a occurence that points to this new entry.
+ Occurences.emplace_back(Variables.size());
+ Variables.push_back(VarDecl);
+ }
+
+ /// \brief Adds each referenced variable from the given statement.
+ void addVariables(const Stmt *S) {
+ // Sometimes we get a nullptr (such as from IfStmts which often have nullptr
+ // children). We skip such statements as they don't reference any
+ // variables.
+ if (!S)
+ return;
+
+ // Check if S is a reference to a variable. If yes, add it to the pattern.
+ if (auto D = dyn_cast<DeclRefExpr>(S)) {
+ if (auto VD = dyn_cast<VarDecl>(D->getDecl()->getCanonicalDecl()))
+ addVariableOccurence(VD);
+ }
+
+ // Recursively check all children of the given statement.
+ for (const Stmt *Child : S->children()) {
+ addVariables(Child);
+ }
+ }
+
+public:
+ /// \brief Creates an VariablePattern object with information about the given
+ /// StmtSequence.
+ VariablePattern(const StmtSequence &Sequence) {
+ for (const Stmt *S : Sequence)
+ addVariables(S);
+ }
+
+ /// \brief Compares this pattern with the given one.
+ /// \param Other The given VariablePattern to compare with.
+ /// \return Returns true if and only if the references variables in this
+ /// object follow the same pattern than the ones in the given
+ /// VariablePattern.
+ ///
+ /// For example, the following statements all have the same pattern:
+ ///
+ /// if (a < b) return a; return b;
+ /// if (x < y) return x; return y;
+ /// if (u2 < u1) return u2; return u1;
+ ///
+ /// but the following statement has a different pattern (note the changed
+ /// variables in the return statements).
+ ///
+ /// if (a < b) return b; return a;
+ ///
+ /// This function should only be called if the related statements of the given
+ /// pattern and the statements of this objects are clones of each other.
+ bool comparePattern(const VariablePattern &Other) {
+ assert(Other.Occurences.size() == Occurences.size());
+ for (unsigned i = 0; i < Occurences.size(); ++i) {
+ if (Occurences[i].KindID != Other.Occurences[i].KindID) {
+ return false;
+ }
+ }
+ return true;
+ }
+};
+}
+
+namespace {
/// \brief Collects the data of a single Stmt.
///
/// This class defines what a code clone is: If it collects for two statements
@@ -374,8 +470,7 @@ void CloneDetector::add(const StmtSequence &S,
namespace {
/// \brief Returns true if and only if \p Stmt contains at least one other
/// sequence in the \p Group.
-bool containsAnyInGroup(StmtSequence &Stmt,
- CloneDetector::CloneGroup &Group) {
+bool containsAnyInGroup(StmtSequence &Stmt, CloneDetector::CloneGroup &Group) {
for (StmtSequence &GroupStmt : Group.Sequences) {
if (Stmt.contains(GroupStmt))
return true;
@@ -402,12 +497,57 @@ bool containsGroup(CloneDetector::CloneGroup &Group,
}
} // end anonymous namespace
+/// \brief Finds all actual clone groups in a single group of presumed clones.
+/// \param Result Output parameter to which all found groups are added. Every
+/// clone in a group that was added this way follows the same
+/// variable pattern as the other clones in its group.
+/// \param Group A group of clones. The clones are allowed to have a different
+/// variable pattern.
+static void createCloneGroups(std::vector<CloneDetector::CloneGroup> &Result,
+ const CloneDetector::CloneGroup &Group) {
+ // We remove the Sequences one by one, so a list is more appropriate.
+ std::list<StmtSequence> UnassignedSequences(Group.Sequences.begin(),
+ Group.Sequences.end());
+
+ // Search for clones as long as there could be clones in UnassignedSequences.
+ while (UnassignedSequences.size() > 1) {
+
+ // Pick the first Sequence as a protoype for a new clone group.
+ StmtSequence Prototype = UnassignedSequences.front();
+ UnassignedSequences.pop_front();
+
+ CloneDetector::CloneGroup FilteredGroup(Prototype, Group.Complexity);
+
+ // Analyze the variable pattern of the prototype. Every other StmtSequence
+ // needs to have the same pattern to get into the new clone group.
+ VariablePattern PrototypeFeatures(Prototype);
+
+ // Search all remaining StmtSequences for an identical variable pattern
+ // and assign them to our new clone group.
+ auto I = UnassignedSequences.begin(), E = UnassignedSequences.end();
+ while (I != E) {
+ if (VariablePattern(*I).comparePattern(PrototypeFeatures)) {
+ FilteredGroup.Sequences.push_back(*I);
+ I = UnassignedSequences.erase(I);
+ continue;
+ }
+ ++I;
+ }
+
+ // Add a valid clone group to the list of found clone groups.
+ if (!FilteredGroup.isValid())
+ continue;
+
+ Result.push_back(FilteredGroup);
+ }
+}
+
void CloneDetector::findClones(std::vector<CloneGroup> &Result,
unsigned MinGroupComplexity) {
// Add every valid clone group that fulfills the complexity requirement.
for (const CloneGroup &Group : CloneGroups) {
if (Group.isValid() && Group.Complexity >= MinGroupComplexity) {
- Result.push_back(Group);
+ createCloneGroups(Result, Group);
}
}
diff --git a/clang/test/Analysis/copypaste/false-positives.cpp b/clang/test/Analysis/copypaste/false-positives.cpp
deleted file mode 100644
index 4c6275949da..00000000000
--- a/clang/test/Analysis/copypaste/false-positives.cpp
+++ /dev/null
@@ -1,21 +0,0 @@
-// RUN: %clang_cc1 -analyze -std=c++11 -analyzer-checker=alpha.clone.CloneChecker -verify %s
-
-// This test contains false-positive reports from the CloneChecker that need to
-// be fixed.
-
-void log();
-
-int max(int a, int b) { // expected-warning{{Detected code clone.}}
- log();
- if (a > b)
- return a;
- return b;
-}
-
-// FIXME: Detect different variable patterns.
-int min2(int a, int b) { // expected-note{{Related code clone is here.}}
- log();
- if (b > a)
- return a;
- return b;
-}
diff --git a/clang/test/Analysis/copypaste/functions.cpp b/clang/test/Analysis/copypaste/functions.cpp
index bedd374b79d..2a871f74b03 100644
--- a/clang/test/Analysis/copypaste/functions.cpp
+++ b/clang/test/Analysis/copypaste/functions.cpp
@@ -37,7 +37,7 @@ int testBaseClass2(int a, int b) { // no-warning
return b;
}
-
+// No clone because of the different comparison operator.
int min1(int a, int b) { // no-warning
log();
if (a < b)
@@ -45,6 +45,14 @@ int min1(int a, int b) { // no-warning
return b;
}
+// No clone because of the different pattern in which the variables are used.
+int min2(int a, int b) { // no-warning
+ log();
+ if (a > b)
+ return b;
+ return a;
+}
+
int foo(int a, int b) { // no-warning
return a + b;
}
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