Merge from 'master' to 'sycl-web' (#57)

  CONFLICT (content): Merge conflict in clang/lib/AST/DeclPrinter.cpp

clang-tools-extra/clang-tidy/misc/CMakeLists.txt

@@ -5,6 +5,7 @@ add_clang_library(clangTidyMiscModule
  MiscTidyModule.cpp
  MisplacedConstCheck.cpp
  NewDeleteOverloadsCheck.cpp
+ NoRecursionCheck.cpp
  NonCopyableObjects.cpp
  NonPrivateMemberVariablesInClassesCheck.cpp
  RedundantExpressionCheck.cpp

clang-tools-extra/clang-tidy/misc/MiscTidyModule.cpp

@@ -12,6 +12,7 @@
 #include "DefinitionsInHeadersCheck.h"
 #include "MisplacedConstCheck.h"
 #include "NewDeleteOverloadsCheck.h"
+#include "NoRecursionCheck.h"
 #include "NonCopyableObjects.h"
 #include "NonPrivateMemberVariablesInClassesCheck.h"
 #include "RedundantExpressionCheck.h"
@@ -35,6 +36,7 @@ class MiscModule : public ClangTidyModule {
  CheckFactories.registerCheck<MisplacedConstCheck>("misc-misplaced-const");
  CheckFactories.registerCheck<NewDeleteOverloadsCheck>(
  "misc-new-delete-overloads");
+ CheckFactories.registerCheck<NoRecursionCheck>("misc-no-recursion");
  CheckFactories.registerCheck<NonCopyableObjectsCheck>(
  "misc-non-copyable-objects");
  CheckFactories.registerCheck<NonPrivateMemberVariablesInClassesCheck>(

clang-tools-extra/clang-tidy/misc/NoRecursionCheck.cpp

@@ -0,0 +1,276 @@
+//===--- NoRecursionCheck.cpp - clang-tidy --------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "NoRecursionCheck.h"
+#include "clang/AST/ASTContext.h"
+#include "clang/ASTMatchers/ASTMatchFinder.h"
+#include "clang/Analysis/CallGraph.h"
+#include "llvm/ADT/DenseMapInfo.h"
+#include "llvm/ADT/SCCIterator.h"
+
+using namespace clang::ast_matchers;
+
+namespace clang {
+namespace tidy {
+namespace misc {
+
+namespace {
+
+/// Much like SmallSet, with two differences:
+/// 1. It can *only* be constructed from an ArrayRef<>. If the element count
+/// is small, there is no copy and said storage *must* outlive us.
+/// 2. it is immutable, the way it was constructed it will stay.
+template <typename T, unsigned SmallSize> class ImmutableSmallSet {
+ ArrayRef<T> Vector;
+ llvm::DenseSet<T> Set;
+
+ static_assert(SmallSize <= 32, "N should be small");
+
+ bool isSmall() const { return Set.empty(); }
+
+public:
+ using size_type = size_t;
+
+ ImmutableSmallSet() = delete;
+ ImmutableSmallSet(const ImmutableSmallSet &) = delete;
+ ImmutableSmallSet(ImmutableSmallSet &&) = delete;
+ T &operator=(const ImmutableSmallSet &) = delete;
+ T &operator=(ImmutableSmallSet &&) = delete;
+
+ // WARNING: Storage *must* outlive us if we decide that the size is small.
+ ImmutableSmallSet(ArrayRef<T> Storage) {
+ // Is size small-enough to just keep using the existing storage?
+ if (Storage.size() <= SmallSize) {
+ Vector = Storage;
+ return;
+ }
+
+ // We've decided that it isn't performant to keep using vector.
+ // Let's migrate the data into Set.
+ Set.reserve(Storage.size());
+ Set.insert(Storage.begin(), Storage.end());
+ }
+
+ /// count - Return 1 if the element is in the set, 0 otherwise.
+ size_type count(const T &V) const {
+ if (isSmall()) {
+ // Since the collection is small, just do a linear search.
+ return llvm::find(Vector, V) == Vector.end() ? 0 : 1;
+ }
+
+ return Set.count(V);
+ }
+};
+
+/// Much like SmallSetVector, but with one difference:
+/// when the size is \p SmallSize or less, when checking whether an element is
+/// already in the set or not, we perform linear search over the vector,
+/// but if the size is larger than \p SmallSize, we look in set.
+/// FIXME: upstream this into SetVector/SmallSetVector itself.
+template <typename T, unsigned SmallSize> class SmartSmallSetVector {
+public:
+ using size_type = size_t;
+
+private:
+ SmallVector<T, SmallSize> Vector;
+ llvm::DenseSet<T> Set;
+
+ static_assert(SmallSize <= 32, "N should be small");
+
+ // Are we still using Vector for uniqness tracking?
+ bool isSmall() const { return Set.empty(); }
+
+ // Will one more entry cause Vector to switch away from small-size storage?
+ bool entiretyOfVectorSmallSizeIsOccupied() const {
+ assert(isSmall() && Vector.size() <= SmallSize &&
+ "Shouldn't ask if we have already [should have] migrated into Set.");
+ return Vector.size() == SmallSize;
+ }
+
+ void populateSet() {
+ assert(Set.empty() && "Should not have already utilized the Set.");
+ // Magical growth factor prediction - to how many elements do we expect to
+ // sanely grow after switching away from small-size storage?
+ const size_t NewMaxElts = 4 * Vector.size();
+ Vector.reserve(NewMaxElts);
+ Set.reserve(NewMaxElts);
+ Set.insert(Vector.begin(), Vector.end());
+ }
+
+ /// count - Return 1 if the element is in the set, 0 otherwise.
+ size_type count(const T &V) const {
+ if (isSmall()) {
+ // Since the collection is small, just do a linear search.
+ return llvm::find(Vector, V) == Vector.end() ? 0 : 1;
+ }
+ // Look-up in the Set.
+ return Set.count(V);
+ }
+
+ bool setInsert(const T &V) {
+ if (count(V) != 0)
+ return false; // Already exists.
+ // Does not exist, Can/need to record it.
+ if (isSmall()) { // Are we still using Vector for uniqness tracking?
+ // Will one more entry fit within small-sized Vector?
+ if (!entiretyOfVectorSmallSizeIsOccupied())
+ return true; // We'll insert into vector right afterwards anyway.
+ // Time to switch to Set.
+ populateSet();
+ }
+ // Set time!
+ // Note that this must be after `populateSet()` might have been called.
+ bool SetInsertionSucceeded = Set.insert(V).second;
+ (void)SetInsertionSucceeded;
+ assert(SetInsertionSucceeded && "We did check that no such value existed");
+ return true;
+ }
+
+public:
+ /// Insert a new element into the SmartSmallSetVector.
+ /// \returns true if the element was inserted into the SmartSmallSetVector.
+ bool insert(const T &X) {
+ bool result = setInsert(X);
+ if (result)
+ Vector.push_back(X);
+ return result;
+ }
+
+ /// Clear the SmartSmallSetVector and return the underlying vector.
+ decltype(Vector) takeVector() {
+ Set.clear();
+ return std::move(Vector);
+ }
+};
+
+constexpr unsigned SmallCallStackSize = 16;
+constexpr unsigned SmallSCCSize = 32;
+
+using CallStackTy =
+ llvm::SmallVector<CallGraphNode::CallRecord, SmallCallStackSize>;
+
+// In given SCC, find *some* call stack that will be cyclic.
+// This will only find *one* such stack, it might not be the smallest one,
+// and there may be other loops.
+CallStackTy PathfindSomeCycle(ArrayRef<CallGraphNode *> SCC) {
+ // We'll need to be able to performantly look up whether some CallGraphNode
+ // is in SCC or not, so cache all the SCC elements in a set.
+ const ImmutableSmallSet<CallGraphNode *, SmallSCCSize> SCCElts(SCC);
+
+ // Is node N part if the current SCC?
+ auto NodeIsPartOfSCC = [&SCCElts](CallGraphNode *N) {
+ return SCCElts.count(N) != 0;
+ };
+
+ // Track the call stack that will cause a cycle.
+ SmartSmallSetVector<CallGraphNode::CallRecord, SmallCallStackSize>
+ CallStackSet;
+
+ // Arbitrairly take the first element of SCC as entry point.
+ CallGraphNode::CallRecord EntryNode(SCC.front(), /*CallExpr=*/nullptr);
+ // Continue recursing into subsequent callees that are part of this SCC,
+ // and are thus known to be part of the call graph loop, until loop forms.
+ CallGraphNode::CallRecord *Node = &EntryNode;
+ while (true) {
+ // Did we see this node before?
+ if (!CallStackSet.insert(*Node))
+ break; // Cycle completed! Note that didn't insert the node into stack!
+ // Else, perform depth-first traversal: out of all callees, pick first one
+ // that is part of this SCC. This is not guaranteed to yield shortest cycle.
+ Node = llvm::find_if(Node->Callee->callees(), NodeIsPartOfSCC);
+ }
+
+ // Note that we failed to insert the last node, that completes the cycle.
+ // But we really want to have it. So insert it manually into stack only.
+ CallStackTy CallStack = CallStackSet.takeVector();
+ CallStack.emplace_back(*Node);
+
+ return CallStack;
+}
+
+} // namespace
+
+void NoRecursionCheck::registerMatchers(MatchFinder *Finder) {
+ Finder->addMatcher(translationUnitDecl().bind("TUDecl"), this);
+}
+
+void NoRecursionCheck::handleSCC(ArrayRef<CallGraphNode *> SCC) {
+ assert(!SCC.empty() && "Empty SCC does not make sense.");
+
+ // First of all, call out every stongly connected function.
+ for (CallGraphNode *N : SCC) {
+ Decl *D = N->getDecl();
+ diag(D->getLocation(), "function %0 is within a recursive call chain")
+ << cast<NamedDecl>(D);
+ }
+
+ // Now, SCC only tells us about strongly connected function declarations in
+ // the call graph. It doesn't *really* tell us about the cycles they form.
+ // And there may be more than one cycle in SCC.
+ // So let's form a call stack that eventually exposes *some* cycle.
+ const CallStackTy EventuallyCyclicCallStack = PathfindSomeCycle(SCC);
+ assert(!EventuallyCyclicCallStack.empty() && "We should've found the cycle");
+
+ // While last node of the call stack does cause a loop, due to the way we
+ // pathfind the cycle, the loop does not nessesairly begin at the first node
+ // of the call stack, so drop front nodes of the call stack until it does.
+ const auto CyclicCallStack =
+ ArrayRef<CallGraphNode::CallRecord>(EventuallyCyclicCallStack)
+ .drop_until([LastNode = EventuallyCyclicCallStack.back()](
+ CallGraphNode::CallRecord FrontNode) {
+ return FrontNode == LastNode;
+ });
+ assert(CyclicCallStack.size() >= 2 && "Cycle requires at least 2 frames");
+
+ // Which function we decided to be the entry point that lead to the recursion?
+ Decl *CycleEntryFn = CyclicCallStack.front().Callee->getDecl();
+ // And now, for ease of understanding, let's print the call sequence that
+ // forms the cycle in question.
+ diag(CycleEntryFn->getLocation(),
+ "example recursive call chain, starting from function %0",
+ DiagnosticIDs::Note)
+ << cast<NamedDecl>(CycleEntryFn);
+ for (int CurFrame = 1, NumFrames = CyclicCallStack.size();
+ CurFrame != NumFrames; ++CurFrame) {
+ CallGraphNode::CallRecord PrevNode = CyclicCallStack[CurFrame - 1];
+ CallGraphNode::CallRecord CurrNode = CyclicCallStack[CurFrame];
+
+ Decl *PrevDecl = PrevNode.Callee->getDecl();
+ Decl *CurrDecl = CurrNode.Callee->getDecl();
+
+ diag(CurrNode.CallExpr->getBeginLoc(),
+ "Frame #%0: function %1 calls function %2 here:", DiagnosticIDs::Note)
+ << CurFrame << cast<NamedDecl>(PrevDecl) << cast<NamedDecl>(CurrDecl);
+ }
+
+ diag(CyclicCallStack.back().CallExpr->getBeginLoc(),
+ "... which was the starting point of the recursive call chain; there "
+ "may be other cycles",
+ DiagnosticIDs::Note);
+}
+
+void NoRecursionCheck::check(const MatchFinder::MatchResult &Result) {
+ // Build call graph for the entire translation unit.
+ const auto *TU = Result.Nodes.getNodeAs<TranslationUnitDecl>("TUDecl");
+ CallGraph CG;
+ CG.addToCallGraph(const_cast<TranslationUnitDecl *>(TU));
+
+ // Look for cycles in call graph,
+ // by looking for Strongly Connected Comonents (SCC's)
+ for (llvm::scc_iterator<CallGraph *> SCCI = llvm::scc_begin(&CG),
+ SCCE = llvm::scc_end(&CG);
+ SCCI != SCCE; ++SCCI) {
+ if (!SCCI.hasLoop()) // We only care about cycles, not standalone nodes.
+ continue;
+ handleSCC(*SCCI);
+ }
+}
+
+} // namespace misc
+} // namespace tidy
+} // namespace clang

clang-tools-extra/clang-tidy/misc/NoRecursionCheck.h

@@ -0,0 +1,42 @@
+//===--- NoRecursionCheck.h - clang-tidy ------------------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_MISC_NORECURSIONCHECK_H
+#define LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_MISC_NORECURSIONCHECK_H
+
+#include "../ClangTidyCheck.h"
+
+namespace clang {
+
+class CallGraphNode;
+
+namespace tidy {
+namespace misc {
+
+/// Finds strongly connected functions (by analyzing call graph for SCC's
+/// that are loops), diagnoses each function in the cycle,
+/// and displays one example of possible call graph loop (recursion).
+///
+/// For the user-facing documentation see:
+/// http://clang.llvm.org/extra/clang-tidy/checks/misc-no-recursion.html
+class NoRecursionCheck : public ClangTidyCheck {
+public:
+ NoRecursionCheck(StringRef Name, ClangTidyContext *Context)
+ : ClangTidyCheck(Name, Context) {}
+ void registerMatchers(ast_matchers::MatchFinder *Finder) override;
+ void check(const ast_matchers::MatchFinder::MatchResult &Result) override;
+
+private:
+ void handleSCC(ArrayRef<CallGraphNode *> SCC);
+};
+
+} // namespace misc
+} // namespace tidy
+} // namespace clang
+
+#endif // LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_MISC_NORECURSIONCHECK_H

clang-tools-extra/clangd/unittests/FindTargetTests.cpp

@@ -215,8 +215,7 @@ TEST_F(TargetDeclTest, NestedNameSpecifier) {
  template <typename T>
  int x = [[T::]]y;
  )cpp";
- // FIXME: We don't do a good job printing TemplateTypeParmDecls, apparently!
- EXPECT_DECLS("NestedNameSpecifierLoc", "");
+ EXPECT_DECLS("NestedNameSpecifierLoc", "typename T");
 
  Code = R"cpp(
  namespace a { int x; }
@@ -256,8 +255,7 @@ TEST_F(TargetDeclTest, Types) {
  template<class T>
  void foo() { [[T]] x; }
  )cpp";
- // FIXME: We don't do a good job printing TemplateTypeParmDecls, apparently!
- EXPECT_DECLS("TemplateTypeParmTypeLoc", "");
+ EXPECT_DECLS("TemplateTypeParmTypeLoc", "class T");
  Flags.clear();
 
  // FIXME: Auto-completion in a template requires disabling delayed template
@@ -290,8 +288,7 @@ TEST_F(TargetDeclTest, Types) {
  static const int size = sizeof...([[E]]);
  };
  )cpp";
- // FIXME: We don't do a good job printing TemplateTypeParmDecls, apparently!
- EXPECT_DECLS("SizeOfPackExpr", "");
+ EXPECT_DECLS("SizeOfPackExpr", "typename ...E");
 
  Code = R"cpp(
  template <typename T>

clang-tools-extra/docs/ReleaseNotes.rst

@@ -93,6 +93,11 @@ New checks
 
  Finds implementations of -dealloc in Objective-C categories.
 
+- New :doc:`misc-no-recursion
+ <clang-tidy/checks/misc-no-recursion>` check.
+
+ Finds recursive functions and diagnoses them.
+
 New check aliases
 ^^^^^^^^^^^^^^^^^
 

clang-tools-extra/docs/clang-tidy/checks/list.rst

@@ -189,6 +189,7 @@ Clang-Tidy Checks
  `misc-definitions-in-headers <misc-definitions-in-headers.html>`_, "Yes"
  `misc-misplaced-const <misc-misplaced-const.html>`_,
  `misc-new-delete-overloads <misc-new-delete-overloads.html>`_,
+ `misc-no-recursion <misc-no-recursion>`_,
  `misc-non-copyable-objects <misc-non-copyable-objects.html>`_,
  `misc-non-private-member-variables-in-classes <misc-non-private-member-variables-in-classes.html>`_,
  `misc-redundant-expression <misc-redundant-expression.html>`_, "Yes"