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

   1 //===--- UnrollLoopsCheck.h - clang-tidy ------------------------*- C++ -*-===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8
   9 #ifndef LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_ALTERA_UNROLLLOOPSCHECK_H
  10 #define LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_ALTERA_UNROLLLOOPSCHECK_H
  11
  12 #include "../ClangTidyCheck.h"
  13
  14 namespace clang::tidy::altera {
  15
  16 /// Finds inner loops that have not been unrolled, as well as fully unrolled
  17 /// loops with unknown loop bounds or a large number of iterations.
  18 ///
  19 /// Unrolling inner loops could improve the performance of OpenCL kernels.
  20 /// However, if they have unknown loop bounds or a large number of iterations,
  21 /// they cannot be fully unrolled, and should be partially unrolled.
  22 ///
  23 /// For the user-facing documentation see:
  24 /// http://clang.llvm.org/extra/clang-tidy/checks/altera/unroll-loops.html
  25 class UnrollLoopsCheck : public ClangTidyCheck {
  26 public:
  27   UnrollLoopsCheck(StringRef Name, ClangTidyContext *Context);
  28   void registerMatchers(ast_matchers::MatchFinder *Finder) override;
  29   void check(const ast_matchers::MatchFinder::MatchResult &Result) override;
  30
  31 private:
  32   /// Recommend partial unrolling if number of loop iterations is greater than
  33   /// MaxLoopIterations.
  34   const unsigned MaxLoopIterations;
  35   /// The kind of unrolling, if any, applied to a given loop.
  36   enum UnrollType {
  37     // This loop has no #pragma unroll directive associated with it.
  38     NotUnrolled,
  39     // This loop has a #pragma unroll directive associated with it.
  40     FullyUnrolled,
  41     // This loop has a #pragma unroll <num> directive associated with it.
  42     PartiallyUnrolled
  43   };
  44   /// Attempts to extract an integer value from either side of the
  45   /// BinaryOperator. Returns true and saves the result to &value if successful,
  46   /// returns false otherwise.
  47   bool extractValue(int &Value, const BinaryOperator *Op,
  48                     const ASTContext *Context);
  49   /// Returns true if the given loop statement has a large number of iterations,
  50   /// as determined by the integer value in the loop's condition expression,
  51   /// if one exists.
  52   bool hasLargeNumIterations(const Stmt *Statement,
  53                              const IntegerLiteral *CXXLoopBound,
  54                              const ASTContext *Context);
  55   /// Checks one hand side of the binary operator to ascertain if the upper
  56   /// bound on the number of loops is greater than max_loop_iterations or not.
  57   /// If the expression is not evaluatable or not an integer, returns false.
  58   bool exprHasLargeNumIterations(const Expr *Expression,
  59                                  const ASTContext *Context) const;
  60   /// Returns the type of unrolling, if any, associated with the given
  61   /// statement.
  62   enum UnrollType unrollType(const Stmt *Statement, ASTContext *Context);
  63   /// Returns the condition expression within a given for statement. If there is
  64   /// none, or if the Statement is not a loop, then returns a NULL pointer.
  65   const Expr *getCondExpr(const Stmt *Statement);
  66   /// Returns True if the loop statement has known bounds.
  67   bool hasKnownBounds(const Stmt *Statement, const IntegerLiteral *CXXLoopBound,
  68                       const ASTContext *Context);
  69   void storeOptions(ClangTidyOptions::OptionMap &Opts) override;
  70 };
  71
  72 } // namespace clang::tidy::altera
  73
  74 #endif // LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_ALTERA_UNROLLLOOPSCHECK_H