LLVM and SPIRV-LLVM-Translator pulldown (WW20-21)

clang-tools-extra/clang-tidy/ClangTidyCheck.cpp

@@ -147,7 +147,7 @@ llvm::Optional<int64_t> ClangTidyCheck::OptionsView::getEnumInt(
 
   StringRef Value = Iter->getValue().Value;
   StringRef Closest;
-  unsigned EditDistance = -1;
+  unsigned EditDistance = 3;
   for (const auto &NameAndEnum : Mapping) {
     if (IgnoreCase) {
       if (Value.equals_lower(NameAndEnum.second))
@@ -159,7 +159,8 @@ llvm::Optional<int64_t> ClangTidyCheck::OptionsView::getEnumInt(
       EditDistance = 0;
       continue;
     }
-    unsigned Distance = Value.edit_distance(NameAndEnum.second);
+    unsigned Distance =
+        Value.edit_distance(NameAndEnum.second, true, EditDistance);
     if (Distance < EditDistance) {
       EditDistance = Distance;
       Closest = NameAndEnum.second;

clang-tools-extra/clang-tidy/altera/AlteraTidyModule.cpp

@@ -9,6 +9,7 @@
 #include "../ClangTidy.h"
 #include "../ClangTidyModule.h"
 #include "../ClangTidyModuleRegistry.h"
+#include "IdDependentBackwardBranchCheck.h"
 #include "KernelNameRestrictionCheck.h"
 #include "SingleWorkItemBarrierCheck.h"
 #include "StructPackAlignCheck.h"
@@ -23,6 +24,8 @@ namespace altera {
 class AlteraModule : public ClangTidyModule {
 public:
   void addCheckFactories(ClangTidyCheckFactories &CheckFactories) override {
+    CheckFactories.registerCheck<IdDependentBackwardBranchCheck>(
+        "altera-id-dependent-backward-branch");
     CheckFactories.registerCheck<KernelNameRestrictionCheck>(
         "altera-kernel-name-restriction");
     CheckFactories.registerCheck<SingleWorkItemBarrierCheck>(

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

@@ -5,6 +5,7 @@ set(LLVM_LINK_COMPONENTS
 
 add_clang_library(clangTidyAlteraModule
   AlteraTidyModule.cpp
+  IdDependentBackwardBranchCheck.cpp
   KernelNameRestrictionCheck.cpp
   SingleWorkItemBarrierCheck.cpp
   StructPackAlignCheck.cpp

clang-tools-extra/clang-tidy/altera/IdDependentBackwardBranchCheck.cpp

@@ -0,0 +1,264 @@
+//===--- IdDependentBackwardBranchCheck.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 "IdDependentBackwardBranchCheck.h"
+#include "clang/AST/ASTContext.h"
+#include "clang/ASTMatchers/ASTMatchFinder.h"
+
+using namespace clang::ast_matchers;
+
+namespace clang {
+namespace tidy {
+namespace altera {
+
+void IdDependentBackwardBranchCheck::registerMatchers(MatchFinder *Finder) {
+  // Prototype to identify all variables which hold a thread-variant ID.
+  // First Matcher just finds all the direct assignments of either ID call.
+  const auto ThreadID = expr(hasDescendant(callExpr(callee(functionDecl(
+      anyOf(hasName("get_global_id"), hasName("get_local_id")))))));
+
+  const auto RefVarOrField = forEachDescendant(
+      stmt(anyOf(declRefExpr(to(varDecl())).bind("assign_ref_var"),
+                 memberExpr(member(fieldDecl())).bind("assign_ref_field"))));
+
+  Finder->addMatcher(
+      compoundStmt(
+          // Bind on actual get_local/global_id calls.
+          forEachDescendant(
+              stmt(
+                  anyOf(declStmt(hasDescendant(varDecl(hasInitializer(ThreadID))
+                                                   .bind("tid_dep_var"))),
+                        binaryOperator(allOf(
+                            isAssignmentOperator(), hasRHS(ThreadID),
+                            hasLHS(anyOf(
+                                declRefExpr(to(varDecl().bind("tid_dep_var"))),
+                                memberExpr(member(
+                                    fieldDecl().bind("tid_dep_field")))))))))
+                  .bind("straight_assignment"))),
+      this);
+
+  // Bind all VarDecls that include an initializer with a variable DeclRefExpr
+  // (in case it is ID-dependent).
+  Finder->addMatcher(
+      stmt(forEachDescendant(
+          varDecl(hasInitializer(RefVarOrField)).bind("pot_tid_var"))),
+      this);
+
+  // Bind all VarDecls that are assigned a value with a variable DeclRefExpr (in
+  // case it is ID-dependent).
+  Finder->addMatcher(
+      stmt(forEachDescendant(binaryOperator(
+          allOf(isAssignmentOperator(), hasRHS(RefVarOrField),
+                hasLHS(anyOf(
+                    declRefExpr(to(varDecl().bind("pot_tid_var"))),
+                    memberExpr(member(fieldDecl().bind("pot_tid_field"))))))))),
+      this);
+
+  // Second Matcher looks for branch statements inside of loops and bind on the
+  // condition expression IF it either calls an ID function or has a variable
+  // DeclRefExpr. DeclRefExprs are checked later to confirm whether the variable
+  // is ID-dependent.
+  const auto CondExpr =
+      expr(anyOf(hasDescendant(callExpr(callee(functionDecl(
+                                            anyOf(hasName("get_global_id"),
+                                                  hasName("get_local_id")))))
+                                   .bind("id_call")),
+                 hasDescendant(stmt(anyOf(declRefExpr(to(varDecl())),
+                                          memberExpr(member(fieldDecl())))))))
+          .bind("cond_expr");
+  Finder->addMatcher(stmt(anyOf(forStmt(hasCondition(CondExpr)),
+                                doStmt(hasCondition(CondExpr)),
+                                whileStmt(hasCondition(CondExpr))))
+                         .bind("backward_branch"),
+                     this);
+}
+
+IdDependentBackwardBranchCheck::IdDependencyRecord *
+IdDependentBackwardBranchCheck::hasIdDepVar(const Expr *Expression) {
+  if (const auto *Declaration = dyn_cast<DeclRefExpr>(Expression)) {
+    // It is a DeclRefExpr, so check if it's an ID-dependent variable.
+    const auto *CheckVariable = dyn_cast<VarDecl>(Declaration->getDecl());
+    auto FoundVariable = IdDepVarsMap.find(CheckVariable);
+    if (FoundVariable == IdDepVarsMap.end())
+      return nullptr;
+    return &(FoundVariable->second);
+  }
+  for (const auto *Child : Expression->children())
+    if (const auto *ChildExpression = dyn_cast<Expr>(Child))
+      if (IdDependencyRecord *Result = hasIdDepVar(ChildExpression))
+        return Result;
+  return nullptr;
+}
+
+IdDependentBackwardBranchCheck::IdDependencyRecord *
+IdDependentBackwardBranchCheck::hasIdDepField(const Expr *Expression) {
+  if (const auto *MemberExpression = dyn_cast<MemberExpr>(Expression)) {
+    const auto *CheckField =
+        dyn_cast<FieldDecl>(MemberExpression->getMemberDecl());
+    auto FoundField = IdDepFieldsMap.find(CheckField);
+    if (FoundField == IdDepFieldsMap.end())
+      return nullptr;
+    return &(FoundField->second);
+  }
+  for (const auto *Child : Expression->children())
+    if (const auto *ChildExpression = dyn_cast<Expr>(Child))
+      if (IdDependencyRecord *Result = hasIdDepField(ChildExpression))
+        return Result;
+  return nullptr;
+}
+
+void IdDependentBackwardBranchCheck::saveIdDepVar(const Stmt *Statement,
+                                                  const VarDecl *Variable) {
+  // Record that this variable is thread-dependent.
+  IdDepVarsMap[Variable] =
+      IdDependencyRecord(Variable, Variable->getBeginLoc(),
+                         Twine("assignment of ID-dependent variable ") +
+                             Variable->getNameAsString());
+}
+
+void IdDependentBackwardBranchCheck::saveIdDepField(const Stmt *Statement,
+                                                    const FieldDecl *Field) {
+  // Record that this field is thread-dependent.
+  IdDepFieldsMap[Field] = IdDependencyRecord(
+      Field, Statement->getBeginLoc(),
+      Twine("assignment of ID-dependent field ") + Field->getNameAsString());
+}
+
+void IdDependentBackwardBranchCheck::saveIdDepVarFromReference(
+    const DeclRefExpr *RefExpr, const MemberExpr *MemExpr,
+    const VarDecl *PotentialVar) {
+  // If the variable is already in IdDepVarsMap, ignore it.
+  if (IdDepVarsMap.find(PotentialVar) != IdDepVarsMap.end())
+    return;
+  std::string Message;
+  llvm::raw_string_ostream StringStream(Message);
+  StringStream << "inferred assignment of ID-dependent value from "
+                  "ID-dependent ";
+  if (RefExpr) {
+    const auto *RefVar = dyn_cast<VarDecl>(RefExpr->getDecl());
+    // If variable isn't ID-dependent, but RefVar is.
+    if (IdDepVarsMap.find(RefVar) != IdDepVarsMap.end())
+      StringStream << "variable " << RefVar->getNameAsString();
+  }
+  if (MemExpr) {
+    const auto *RefField = dyn_cast<FieldDecl>(MemExpr->getMemberDecl());
+    // If variable isn't ID-dependent, but RefField is.
+    if (IdDepFieldsMap.find(RefField) != IdDepFieldsMap.end())
+      StringStream << "member " << RefField->getNameAsString();
+  }
+  IdDepVarsMap[PotentialVar] =
+      IdDependencyRecord(PotentialVar, PotentialVar->getBeginLoc(), Message);
+}
+
+void IdDependentBackwardBranchCheck::saveIdDepFieldFromReference(
+    const DeclRefExpr *RefExpr, const MemberExpr *MemExpr,
+    const FieldDecl *PotentialField) {
+  // If the field is already in IdDepFieldsMap, ignore it.
+  if (IdDepFieldsMap.find(PotentialField) != IdDepFieldsMap.end())
+    return;
+  std::string Message;
+  llvm::raw_string_ostream StringStream(Message);
+  StringStream << "inferred assignment of ID-dependent member from "
+                  "ID-dependent ";
+  if (RefExpr) {
+    const auto *RefVar = dyn_cast<VarDecl>(RefExpr->getDecl());
+    // If field isn't ID-dependent, but RefVar is.
+    if (IdDepVarsMap.find(RefVar) != IdDepVarsMap.end())
+      StringStream << "variable " << RefVar->getNameAsString();
+  }
+  if (MemExpr) {
+    const auto *RefField = dyn_cast<FieldDecl>(MemExpr->getMemberDecl());
+    if (IdDepFieldsMap.find(RefField) != IdDepFieldsMap.end())
+      StringStream << "member " << RefField->getNameAsString();
+  }
+  IdDepFieldsMap[PotentialField] = IdDependencyRecord(
+      PotentialField, PotentialField->getBeginLoc(), Message);
+}
+
+IdDependentBackwardBranchCheck::LoopType
+IdDependentBackwardBranchCheck::getLoopType(const Stmt *Loop) {
+  switch (Loop->getStmtClass()) {
+  case Stmt::DoStmtClass:
+    return DoLoop;
+  case Stmt::WhileStmtClass:
+    return WhileLoop;
+  case Stmt::ForStmtClass:
+    return ForLoop;
+  default:
+    return UnknownLoop;
+  }
+}
+
+void IdDependentBackwardBranchCheck::check(
+    const MatchFinder::MatchResult &Result) {
+  // The first half of the callback only deals with identifying and storing
+  // ID-dependency information into the IdDepVars and IdDepFields maps.
+  const auto *Variable = Result.Nodes.getNodeAs<VarDecl>("tid_dep_var");
+  const auto *Field = Result.Nodes.getNodeAs<FieldDecl>("tid_dep_field");
+  const auto *Statement = Result.Nodes.getNodeAs<Stmt>("straight_assignment");
+  const auto *RefExpr = Result.Nodes.getNodeAs<DeclRefExpr>("assign_ref_var");
+  const auto *MemExpr = Result.Nodes.getNodeAs<MemberExpr>("assign_ref_field");
+  const auto *PotentialVar = Result.Nodes.getNodeAs<VarDecl>("pot_tid_var");
+  const auto *PotentialField =
+      Result.Nodes.getNodeAs<FieldDecl>("pot_tid_field");
+
+  // Save variables and fields assigned directly through ID function calls.
+  if (Statement && (Variable || Field)) {
+    if (Variable)
+      saveIdDepVar(Statement, Variable);
+    else if (Field)
+      saveIdDepField(Statement, Field);
+  }
+
+  // Save variables assigned to values of Id-dependent variables and fields.
+  if ((RefExpr || MemExpr) && PotentialVar)
+    saveIdDepVarFromReference(RefExpr, MemExpr, PotentialVar);
+
+  // Save fields assigned to values of ID-dependent variables and fields.
+  if ((RefExpr || MemExpr) && PotentialField)
+    saveIdDepFieldFromReference(RefExpr, MemExpr, PotentialField);
+
+  // The second part of the callback deals with checking if a branch inside a
+  // loop is thread dependent.
+  const auto *CondExpr = Result.Nodes.getNodeAs<Expr>("cond_expr");
+  const auto *IDCall = Result.Nodes.getNodeAs<CallExpr>("id_call");
+  const auto *Loop = Result.Nodes.getNodeAs<Stmt>("backward_branch");
+  if (!Loop)
+    return;
+  LoopType Type = getLoopType(Loop);
+  if (CondExpr) {
+    if (IDCall) { // Conditional expression calls an ID function directly.
+      diag(CondExpr->getBeginLoc(),
+           "backward branch (%select{do|while|for}0 loop) is ID-dependent due "
+           "to ID function call and may cause performance degradation")
+          << Type;
+      return;
+    }
+    // Conditional expression has DeclRefExpr(s), check ID-dependency.
+    IdDependencyRecord *IdDepVar = hasIdDepVar(CondExpr);
+    IdDependencyRecord *IdDepField = hasIdDepField(CondExpr);
+    if (IdDepVar) {
+      // Change one of these to a Note
+      diag(IdDepVar->Location, IdDepVar->Message, DiagnosticIDs::Note);
+      diag(CondExpr->getBeginLoc(),
+           "backward branch (%select{do|while|for}0 loop) is ID-dependent due "
+           "to variable reference to %1 and may cause performance degradation")
+          << Type << IdDepVar->VariableDeclaration;
+    } else if (IdDepField) {
+      diag(IdDepField->Location, IdDepField->Message, DiagnosticIDs::Note);
+      diag(CondExpr->getBeginLoc(),
+           "backward branch (%select{do|while|for}0 loop) is ID-dependent due "
+           "to member reference to %1 and may cause performance degradation")
+          << Type << IdDepField->FieldDeclaration;
+    }
+  }
+}
+
+} // namespace altera
+} // namespace tidy
+} // namespace clang

clang-tools-extra/clang-tidy/altera/IdDependentBackwardBranchCheck.h

@@ -0,0 +1,83 @@
+//===--- IdDependentBackwardBranchCheck.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_ALTERA_IDDEPENDENTBACKWARDBRANCHCHECK_H
+#define LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_ALTERA_IDDEPENDENTBACKWARDBRANCHCHECK_H
+
+#include "../ClangTidyCheck.h"
+
+namespace clang {
+namespace tidy {
+namespace altera {
+
+/// Finds ID-dependent variables and fields used within loops, and warns of
+/// their usage. Using these variables in loops can lead to performance
+/// degradation.
+///
+/// For the user-facing documentation see:
+/// http://clang.llvm.org/extra/clang-tidy/checks/altera-id-dependent-backward-branch.html
+class IdDependentBackwardBranchCheck : public ClangTidyCheck {
+private:
+  enum LoopType { UnknownLoop = -1, DoLoop = 0, WhileLoop = 1, ForLoop = 2 };
+  // Stores information necessary for printing out source of error.
+  struct IdDependencyRecord {
+    IdDependencyRecord(const VarDecl *Declaration, SourceLocation Location,
+                       const llvm::Twine &Message)
+        : VariableDeclaration(Declaration), Location(Location),
+          Message(Message.str()) {}
+    IdDependencyRecord(const FieldDecl *Declaration, SourceLocation Location,
+                       const llvm::Twine &Message)
+        : FieldDeclaration(Declaration), Location(Location),
+          Message(Message.str()) {}
+    IdDependencyRecord() = default;
+    const VarDecl *VariableDeclaration = nullptr;
+    const FieldDecl *FieldDeclaration = nullptr;
+    SourceLocation Location;
+    std::string Message;
+  };
+  // Stores the locations where ID-dependent variables are created.
+  std::map<const VarDecl *, IdDependencyRecord> IdDepVarsMap;
+  // Stores the locations where ID-dependent fields are created.
+  std::map<const FieldDecl *, IdDependencyRecord> IdDepFieldsMap;
+  /// Returns an IdDependencyRecord if the Expression contains an ID-dependent
+  /// variable, returns a nullptr otherwise.
+  IdDependencyRecord *hasIdDepVar(const Expr *Expression);
+  /// Returns an IdDependencyRecord if the Expression contains an ID-dependent
+  /// field, returns a nullptr otherwise.
+  IdDependencyRecord *hasIdDepField(const Expr *Expression);
+  /// Stores the location an ID-dependent variable is created from a call to
+  /// an ID function in IdDepVarsMap.
+  void saveIdDepVar(const Stmt *Statement, const VarDecl *Variable);
+  /// Stores the location an ID-dependent field is created from a call to an ID
+  /// function in IdDepFieldsMap.
+  void saveIdDepField(const Stmt *Statement, const FieldDecl *Field);
+  /// Stores the location an ID-dependent variable is created from a reference
+  /// to another ID-dependent variable or field in IdDepVarsMap.
+  void saveIdDepVarFromReference(const DeclRefExpr *RefExpr,
+                                 const MemberExpr *MemExpr,
+                                 const VarDecl *PotentialVar);
+  /// Stores the location an ID-dependent field is created from a reference to
+  /// another ID-dependent variable or field in IdDepFieldsMap.
+  void saveIdDepFieldFromReference(const DeclRefExpr *RefExpr,
+                                   const MemberExpr *MemExpr,
+                                   const FieldDecl *PotentialField);
+  /// Returns the loop type.
+  LoopType getLoopType(const Stmt *Loop);
+
+public:
+  IdDependentBackwardBranchCheck(StringRef Name, ClangTidyContext *Context)
+      : ClangTidyCheck(Name, Context) {}
+  void registerMatchers(ast_matchers::MatchFinder *Finder) override;
+  void check(const ast_matchers::MatchFinder::MatchResult &Result) override;
+};
+
+} // namespace altera
+} // namespace tidy
+} // namespace clang
+
+#endif // LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_ALTERA_IDDEPENDENTBACKWARDBRANCHCHECK_H