LLVM and SPIRV-LLVM-Translator pulldown (WW52)

.github/workflows/libcxx-build-and-test.yaml

@@ -185,7 +185,7 @@ jobs:
           std_modules: 'OFF'
         # Use a larger machine for MSAN to avoid timeout and memory allocation issues.
         - config: 'generic-msan'
-          machine: libcxx-runners-32-set
+          machine: libcxx-runners-8-set
           std_modules: 'OFF'
     runs-on: ${{ matrix.machine }}
     steps:

bolt/lib/Core/DIEBuilder.cpp

@@ -266,13 +266,11 @@ void DIEBuilder::buildCompileUnits(const bool Init) {
 }
 void DIEBuilder::buildCompileUnits(const std::vector<DWARFUnit *> &CUs) {
   BuilderState.reset(new State());
-  // Initializing to full size because there could be cross CU references with
-  // different abbrev offsets. LLVM happens to output CUs that have cross CU
-  // references with the same abbrev table. So destinations end up in the first
-  // set, even if they themselves don't have src cross cu ref. We could have
-  // cases where this is not the case. In which case this container needs to be
-  // big enough for all.
-  getState().CloneUnitCtxMap.resize(DwarfContext->getNumCompileUnits());
+  // Allocating enough for current batch being processed.
+  // In real use cases we either processing a batch of CUs with no cross
+  // references, or if they do have them it is due to LTO. With clang they will
+  // share the same abbrev table. In either case this vector will not grow.
+  getState().CloneUnitCtxMap.resize(CUs.size());
   getState().Type = ProcessingType::CUs;
   for (DWARFUnit *CU : CUs)
     registerUnit(*CU, false);
@@ -897,6 +895,10 @@ void DIEBuilder::registerUnit(DWARFUnit &DU, bool NeedSort) {
                 });
   }
   getState().UnitIDMap[getHash(DU)] = getState().DUList.size();
+  // This handles the case where we do have cross cu references, but CUs do not
+  // share the same abbrev table.
+  if (getState().DUList.size() == getState().CloneUnitCtxMap.size())
+    getState().CloneUnitCtxMap.emplace_back();
   getState().DUList.push_back(&DU);
 }
 

bolt/lib/Passes/SplitFunctions.cpp

@@ -175,8 +175,12 @@ struct SplitCacheDirected final : public SplitStrategy {
   void fragment(const BlockIt Start, const BlockIt End) override {
     BasicBlockOrder BlockOrder(Start, End);
     BinaryFunction &BF = *BlockOrder.front()->getFunction();
+    // No need to re-split small functions.
+    if (BlockOrder.size() <= 2)
+      return;
 
     size_t BestSplitIndex = findSplitIndex(BF, BlockOrder);
+    assert(BestSplitIndex < BlockOrder.size());
 
     // Assign fragments based on the computed best split index.
     // All basic blocks with index up to the best split index become hot.
@@ -200,10 +204,12 @@ struct SplitCacheDirected final : public SplitStrategy {
   };
 
   struct SplitScore {
-    size_t SplitIndex;
+    size_t SplitIndex = size_t(-1);
     size_t HotSizeReduction = 0;
     double LocalScore = 0;
     double CoverCallScore = 0;
+
+    double sum() const { return LocalScore + CoverCallScore; }
   };
 
   // Auxiliary variables used by the algorithm.
@@ -303,7 +309,7 @@ struct SplitCacheDirected final : public SplitStrategy {
                              const size_t SplitIndex) {
     assert(SplitIndex < BlockOrder.size() && "Invalid split index");
 
-    // Update function layout assuming hot-warm splitting at SplitIndex
+    // Update function layout assuming hot-warm splitting at SplitIndex.
     for (size_t Index = 0; Index < BlockOrder.size(); Index++) {
       BinaryBasicBlock *BB = BlockOrder[Index];
       if (BB->getFragmentNum() == FragmentNum::cold())
@@ -319,8 +325,8 @@ struct SplitCacheDirected final : public SplitStrategy {
     // Populate BB.OutputAddressRange with estimated new start and end addresses
     // and compute the old end address of the hot section and the new end
     // address of the hot section.
-    size_t OldHotEndAddr;
-    size_t NewHotEndAddr;
+    size_t OldHotEndAddr{0};
+    size_t NewHotEndAddr{0};
     size_t CurrentAddr = BBOffsets[BlockOrder[0]];
     for (BinaryBasicBlock *BB : BlockOrder) {
       // We only care about new addresses of blocks in hot/warm.
@@ -492,20 +498,15 @@ struct SplitCacheDirected final : public SplitStrategy {
   }
 
   /// Compute the split score of splitting a function at a given index.
-  /// The split score consists of local score and cover score. Cover call score
-  /// is expensive to compute. As a result, we pass in a \p ReferenceScore and
-  /// compute cover score only when the local score exceeds that in the
-  /// ReferenceScore or that the size reduction of the hot fragment is larger
-  /// than that achieved by the split index of the ReferenceScore. This function
-  /// returns \p Score of SplitScore type. It contains the local score and cover
-  /// score (if computed) of the current splitting index. For easier book
-  /// keeping and comparison, it also stores the split index and the resulting
-  /// reduction in hot fragment size.
+  /// The split score consists of local score and cover score. This function
+  /// returns \p Score of SplitScore type. It contains the local score and
+  /// cover score of the current splitting index. For easier book keeping and
+  /// comparison, it also stores the split index and the resulting reduction
+  /// in hot fragment size.
   SplitScore computeSplitScore(const BinaryFunction &BF,
                                const BasicBlockOrder &BlockOrder,
                                const size_t SplitIndex,
-                               const std::vector<CallInfo> &CoverCalls,
-                               const SplitScore &ReferenceScore) {
+                               const std::vector<CallInfo> &CoverCalls) {
     // Populate BinaryBasicBlock::OutputAddressRange with estimated
     // new start and end addresses after hot-warm splitting at SplitIndex.
     size_t OldHotEnd;
@@ -533,47 +534,74 @@ struct SplitCacheDirected final : public SplitStrategy {
     // increamented in place.
     computeJumpScore(BlockOrder, SplitIndex, Score);
 
-    // There is no need to compute CoverCallScore if we have already found
-    // another split index with a bigger LocalScore and bigger HotSizeReduction.
-    if (Score.LocalScore <= ReferenceScore.LocalScore &&
-        Score.HotSizeReduction <= ReferenceScore.HotSizeReduction)
-      return Score;
-
     // Compute CoverCallScore and store in Score in place.
     computeCoverCallScore(BlockOrder, SplitIndex, CoverCalls, Score);
     return Score;
   }
 
+  /// Find the most likely successor of a basic block when it has one or two
+  /// successors. Return nullptr otherwise.
+  const BinaryBasicBlock *getMostLikelySuccessor(const BinaryBasicBlock *BB) {
+    if (BB->succ_size() == 1)
+      return BB->getSuccessor();
+    if (BB->succ_size() == 2) {
+      uint64_t TakenCount = BB->getTakenBranchInfo().Count;
+      assert(TakenCount != BinaryBasicBlock::COUNT_NO_PROFILE);
+      uint64_t NonTakenCount = BB->getFallthroughBranchInfo().Count;
+      assert(NonTakenCount != BinaryBasicBlock::COUNT_NO_PROFILE);
+      if (TakenCount > NonTakenCount)
+        return BB->getConditionalSuccessor(true);
+      else if (TakenCount < NonTakenCount)
+        return BB->getConditionalSuccessor(false);
+    }
+    return nullptr;
+  }
+
   /// Find the best index for splitting. The returned value is the index of the
   /// last hot basic block. Hence, "no splitting" is equivalent to returning the
   /// value which is one less than the size of the function.
   size_t findSplitIndex(const BinaryFunction &BF,
                         const BasicBlockOrder &BlockOrder) {
+    assert(BlockOrder.size() > 2);
     // Find all function calls that can be shortened if we move blocks of the
     // current function to warm/cold
     const std::vector<CallInfo> CoverCalls = extractCoverCalls(BF);
 
-    // Try all possible split indices (blocks with Index <= SplitIndex are in
-    // hot) and find the one maximizing the splitting score.
+    // Find the existing hot-cold splitting index.
+    size_t HotColdIndex = 0;
+    while (HotColdIndex + 1 < BlockOrder.size()) {
+      if (BlockOrder[HotColdIndex + 1]->getFragmentNum() == FragmentNum::cold())
+        break;
+      HotColdIndex++;
+    }
+    assert(HotColdIndex + 1 == BlockOrder.size() ||
+           (BlockOrder[HotColdIndex]->getFragmentNum() == FragmentNum::main() &&
+            BlockOrder[HotColdIndex + 1]->getFragmentNum() ==
+                FragmentNum::cold()));
+
+    // Try all possible split indices up to HotColdIndex (blocks that have
+    // Index <= SplitIndex are in hot) and find the one maximizing the
+    // splitting score.
     SplitScore BestScore;
-    double BestScoreSum = -1.0;
-    SplitScore ReferenceScore;
-    for (size_t Index = 0; Index < BlockOrder.size(); Index++) {
+    for (size_t Index = 0; Index <= HotColdIndex; Index++) {
       const BinaryBasicBlock *LastHotBB = BlockOrder[Index];
-      // No need to keep cold blocks in the hot section.
-      if (LastHotBB->getFragmentNum() == FragmentNum::cold())
-        break;
+      assert(LastHotBB->getFragmentNum() != FragmentNum::cold());
+
+      // Do not break jump to the most likely successor.
+      if (Index + 1 < BlockOrder.size() &&
+          BlockOrder[Index + 1] == getMostLikelySuccessor(LastHotBB))
+        continue;
+
       const SplitScore Score =
-          computeSplitScore(BF, BlockOrder, Index, CoverCalls, ReferenceScore);
-      double ScoreSum = Score.LocalScore + Score.CoverCallScore;
-      if (ScoreSum > BestScoreSum) {
-        BestScoreSum = ScoreSum;
+          computeSplitScore(BF, BlockOrder, Index, CoverCalls);
+      if (Score.sum() > BestScore.sum())
         BestScore = Score;
-      }
-      if (Score.LocalScore > ReferenceScore.LocalScore)
-        ReferenceScore = Score;
     }
 
+    // If we don't find a good splitting point, fallback to the original one.
+    if (BestScore.SplitIndex == size_t(-1))
+      return HotColdIndex;
+
     return BestScore.SplitIndex;
   }
 };

bolt/test/X86/cdsplit-call-scale.s

@@ -2,8 +2,9 @@
 # When -call-scale=0.0, the tested function is 2-way splitted.
 # When -call-scale=1.0, the tested function is 3-way splitted with 5 blocks
 # in warm because of the increased benefit of shortening the call edges.
-# When -call-scale=1000.0, the tested function is 3-way splitted with 7 blocks
-# in warm because of the strong benefit of shortening the call edges.
+# When -call-scale=1000.0, the tested function is still 3-way splitted with
+# 5 blocks in warm because cdsplit does not allow hot-warm splitting to break
+# a fall through branch from a basic block to its most likely successor.
 
 # RUN: llvm-mc --filetype=obj --triple x86_64-unknown-unknown %s -o %t.o
 # RUN: link_fdata %s %t.o %t.fdata
@@ -39,12 +40,10 @@
 # MEDINCENTIVE: {{^\.Ltmp5}}
 
 # HIGHINCENTIVE: Binary Function "chain" after split-functions
-# HIGHINCENTIVE: {{^\.LBB00}}
+# HIGHINCENTIVE: {{^\.Ltmp1}}
 # HIGHINCENTIVE: -------   HOT-COLD SPLIT POINT   -------
 # HIGHINCENTIVE: {{^\.LFT1}}
 # HIGHINCENTIVE: -------   HOT-COLD SPLIT POINT   -------
-# HIGHINCENTIVE: {{^\.LFT0}}
-# HIGHINCENTIVE: {{^\.Ltmp1}}
 # HIGHINCENTIVE: {{^\.Ltmp0}}
 # HIGHINCENTIVE: {{^\.Ltmp2}}
 # HIGHINCENTIVE: {{^\.Ltmp3}}

clang-tools-extra/clang-tidy/bugprone/BugproneTidyModule.cpp

@@ -83,6 +83,7 @@
 #include "UnhandledSelfAssignmentCheck.h"
 #include "UniquePtrArrayMismatchCheck.h"
 #include "UnsafeFunctionsCheck.h"
+#include "UnusedLocalNonTrivialVariableCheck.h"
 #include "UnusedRaiiCheck.h"
 #include "UnusedReturnValueCheck.h"
 #include "UseAfterMoveCheck.h"
@@ -235,6 +236,8 @@ class BugproneModule : public ClangTidyModule {
         "bugprone-unique-ptr-array-mismatch");
     CheckFactories.registerCheck<UnsafeFunctionsCheck>(
         "bugprone-unsafe-functions");
+    CheckFactories.registerCheck<UnusedLocalNonTrivialVariableCheck>(
+        "bugprone-unused-local-non-trivial-variable");
     CheckFactories.registerCheck<UnusedRaiiCheck>("bugprone-unused-raii");
     CheckFactories.registerCheck<UnusedReturnValueCheck>(
         "bugprone-unused-return-value");

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

@@ -79,6 +79,7 @@ add_clang_library(clangTidyBugproneModule
   UnhandledSelfAssignmentCheck.cpp
   UniquePtrArrayMismatchCheck.cpp
   UnsafeFunctionsCheck.cpp
+  UnusedLocalNonTrivialVariableCheck.cpp
   UnusedRaiiCheck.cpp
   UnusedReturnValueCheck.cpp
   UseAfterMoveCheck.cpp

clang-tools-extra/clang-tidy/bugprone/UnusedLocalNonTrivialVariableCheck.cpp

@@ -0,0 +1,91 @@
+//===--- UnusedLocalNonTrivialVariableCheck.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 "UnusedLocalNonTrivialVariableCheck.h"
+#include "../utils/Matchers.h"
+#include "../utils/OptionsUtils.h"
+#include "clang/AST/ASTContext.h"
+#include "clang/AST/ASTTypeTraits.h"
+#include "clang/AST/Type.h"
+#include "clang/ASTMatchers/ASTMatchFinder.h"
+#include "clang/ASTMatchers/ASTMatchers.h"
+#include "clang/ASTMatchers/ASTMatchersMacros.h"
+
+using namespace clang::ast_matchers;
+using namespace clang::tidy::matchers;
+
+namespace clang::tidy::bugprone {
+
+namespace {
+static constexpr StringRef DefaultIncludeTypeRegex =
+    "::std::.*mutex;::std::future;::std::basic_string;::std::basic_regex;"
+    "::std::basic_istringstream;::std::basic_stringstream;::std::bitset;"
+    "::std::filesystem::path";
+
+AST_MATCHER(VarDecl, isLocalVarDecl) { return Node.isLocalVarDecl(); }
+AST_MATCHER(VarDecl, isReferenced) { return Node.isReferenced(); }
+AST_MATCHER(Type, isReferenceType) { return Node.isReferenceType(); }
+AST_MATCHER(QualType, isTrivial) {
+  return Node.isTrivialType(Finder->getASTContext()) ||
+         Node.isTriviallyCopyableType(Finder->getASTContext());
+}
+} // namespace
+
+UnusedLocalNonTrivialVariableCheck::UnusedLocalNonTrivialVariableCheck(
+    StringRef Name, ClangTidyContext *Context)
+    : ClangTidyCheck(Name, Context),
+      IncludeTypes(utils::options::parseStringList(
+          Options.get("IncludeTypes", DefaultIncludeTypeRegex))),
+      ExcludeTypes(
+          utils::options::parseStringList(Options.get("ExcludeTypes", ""))) {}
+
+void UnusedLocalNonTrivialVariableCheck::storeOptions(
+    ClangTidyOptions::OptionMap &Opts) {
+  Options.store(Opts, "IncludeTypes",
+                utils::options::serializeStringList(IncludeTypes));
+  Options.store(Opts, "ExcludeTypes",
+                utils::options::serializeStringList(ExcludeTypes));
+}
+
+void UnusedLocalNonTrivialVariableCheck::registerMatchers(MatchFinder *Finder) {
+  if (IncludeTypes.empty())
+    return;
+
+  Finder->addMatcher(
+      varDecl(isLocalVarDecl(), unless(isReferenced()),
+              unless(isExceptionVariable()), hasLocalStorage(), isDefinition(),
+              unless(hasType(isReferenceType())), unless(hasType(isTrivial())),
+              hasType(hasUnqualifiedDesugaredType(
+                  anyOf(recordType(hasDeclaration(namedDecl(
+                            matchesAnyListedName(IncludeTypes),
+                            unless(matchesAnyListedName(ExcludeTypes))))),
+                        templateSpecializationType(hasDeclaration(namedDecl(
+                            matchesAnyListedName(IncludeTypes),
+                            unless(matchesAnyListedName(ExcludeTypes)))))))))
+          .bind("var"),
+      this);
+}
+
+void UnusedLocalNonTrivialVariableCheck::check(
+    const MatchFinder::MatchResult &Result) {
+  const auto *MatchedDecl = Result.Nodes.getNodeAs<VarDecl>("var");
+  diag(MatchedDecl->getLocation(), "unused local variable %0 of type %1")
+      << MatchedDecl << MatchedDecl->getType();
+}
+
+bool UnusedLocalNonTrivialVariableCheck::isLanguageVersionSupported(
+    const LangOptions &LangOpts) const {
+  return LangOpts.CPlusPlus;
+}
+
+std::optional<TraversalKind>
+UnusedLocalNonTrivialVariableCheck::getCheckTraversalKind() const {
+  return TK_IgnoreUnlessSpelledInSource;
+}
+
+} // namespace clang::tidy::bugprone

clang-tools-extra/clang-tidy/bugprone/UnusedLocalNonTrivialVariableCheck.h

@@ -0,0 +1,44 @@
+//===--- UnusedLocalNonTrivialVariableCheck.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_BUGPRONE_UNUSEDLOCALNONTRIVIALVARIABLECHECK_H
+#define LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_BUGPRONE_UNUSEDLOCALNONTRIVIALVARIABLECHECK_H
+
+#include "../ClangTidyCheck.h"
+
+namespace clang::tidy::bugprone {
+
+/// Warns when a local non trivial variable is unused within a function. By
+/// default std::.*mutex and std::future are included.
+///
+/// The check supports these options:
+///   - 'IncludeTypes': a semicolon-separated list of regular expressions
+///                     matching types to ensure must be used.
+///   - 'ExcludeTypes': a semicolon-separated list of regular expressions
+///                     matching types that are excluded from the
+///                     'IncludeTypes' matches.
+///
+/// For the user-facing documentation see:
+/// http://clang.llvm.org/extra/clang-tidy/checks/bugprone/unused-local-non-trivial-variable.html
+class UnusedLocalNonTrivialVariableCheck : public ClangTidyCheck {
+public:
+  UnusedLocalNonTrivialVariableCheck(StringRef Name, ClangTidyContext *Context);
+  void registerMatchers(ast_matchers::MatchFinder *Finder) override;
+  void check(const ast_matchers::MatchFinder::MatchResult &Result) override;
+  void storeOptions(ClangTidyOptions::OptionMap &Opts) override;
+  bool isLanguageVersionSupported(const LangOptions &LangOpts) const override;
+  std::optional<TraversalKind> getCheckTraversalKind() const override;
+
+private:
+  const std::vector<StringRef> IncludeTypes;
+  const std::vector<StringRef> ExcludeTypes;
+};
+
+} // namespace clang::tidy::bugprone
+
+#endif // LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_BUGPRONE_UNUSEDLOCALNONTRIVIALVARIABLECHECK_H