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
22namespace 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