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  1. //===--- Stack.h - Utilities for dealing with stack space -------*- 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. /// \file
  10. /// Defines utilities for dealing with stack allocation and stack space.
  11. ///
  12. //===----------------------------------------------------------------------===//
  13.  
  14. #ifndef LLVM_CLANG_BASIC_STACK_H
  15. #define LLVM_CLANG_BASIC_STACK_H
  16.  
  17. #include <cstddef>
  18.  
  19. #include "llvm/ADT/STLExtras.h"
  20. #include "llvm/Support/Compiler.h"
  21.  
  22. namespace clang {
  23.   /// The amount of stack space that Clang would like to be provided with.
  24.   /// If less than this much is available, we may be unable to reach our
  25.   /// template instantiation depth limit and other similar limits.
  26.   constexpr size_t DesiredStackSize = 8 << 20;
  27.  
  28.   /// Call this once on each thread, as soon after starting the thread as
  29.   /// feasible, to note the approximate address of the bottom of the stack.
  30.   void noteBottomOfStack();
  31.  
  32.   /// Determine whether the stack is nearly exhausted.
  33.   bool isStackNearlyExhausted();
  34.  
  35.   void runWithSufficientStackSpaceSlow(llvm::function_ref<void()> Diag,
  36.                                        llvm::function_ref<void()> Fn);
  37.  
  38.   /// Run a given function on a stack with "sufficient" space. If stack space
  39.   /// is insufficient, calls Diag to emit a diagnostic before calling Fn.
  40.   inline void runWithSufficientStackSpace(llvm::function_ref<void()> Diag,
  41.                                           llvm::function_ref<void()> Fn) {
  42. #if LLVM_ENABLE_THREADS
  43.     if (LLVM_UNLIKELY(isStackNearlyExhausted()))
  44.       runWithSufficientStackSpaceSlow(Diag, Fn);
  45.     else
  46.       Fn();
  47. #else
  48.     if (LLVM_UNLIKELY(isStackNearlyExhausted()))
  49.       Diag();
  50.     Fn();
  51. #endif
  52.   }
  53. } // end namespace clang
  54.  
  55. #endif // LLVM_CLANG_BASIC_STACK_H
  56.