/Users/buildslave/jenkins/workspace/coverage/llvm-project/clang/lib/Basic/Stack.cpp
Line | Count | Source (jump to first uncovered line) |
1 | | //===--- Stack.cpp - Utilities for dealing with stack space ---------------===// |
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 | | #include "clang/Basic/Stack.h" |
15 | | #include "llvm/ADT/Optional.h" |
16 | | #include "llvm/Support/CrashRecoveryContext.h" |
17 | | |
18 | | #ifdef _MSC_VER |
19 | | #include <intrin.h> // for _AddressOfReturnAddress |
20 | | #endif |
21 | | |
22 | | static LLVM_THREAD_LOCAL void *BottomOfStack = nullptr; |
23 | | |
24 | 15.4M | static void *getStackPointer() { |
25 | 15.4M | #if __GNUC__ || __has_builtin(__builtin_frame_address) |
26 | 15.4M | return __builtin_frame_address(0); |
27 | | #elif defined(_MSC_VER) |
28 | | return _AddressOfReturnAddress(); |
29 | | #else |
30 | | char CharOnStack = 0; |
31 | | // The volatile store here is intended to escape the local variable, to |
32 | | // prevent the compiler from optimizing CharOnStack into anything other |
33 | | // than a char on the stack. |
34 | | // |
35 | | // Tested on: MSVC 2015 - 2019, GCC 4.9 - 9, Clang 3.2 - 9, ICC 13 - 19. |
36 | | char *volatile Ptr = &CharOnStack; |
37 | | return Ptr; |
38 | | #endif |
39 | 15.4M | } |
40 | | |
41 | 115k | void clang::noteBottomOfStack() { |
42 | 115k | if (!BottomOfStack) |
43 | 64.4k | BottomOfStack = getStackPointer(); |
44 | 115k | } |
45 | | |
46 | 15.9M | bool clang::isStackNearlyExhausted() { |
47 | | // We consider 256 KiB to be sufficient for any code that runs between checks |
48 | | // for stack size. |
49 | 15.9M | constexpr size_t SufficientStack = 256 << 10; |
50 | | |
51 | | // If we don't know where the bottom of the stack is, hope for the best. |
52 | 15.9M | if (!BottomOfStack) |
53 | 549k | return false; |
54 | | |
55 | 15.3M | intptr_t StackDiff = (intptr_t)getStackPointer() - (intptr_t)BottomOfStack; |
56 | 15.3M | size_t StackUsage = (size_t)std::abs(StackDiff); |
57 | | |
58 | | // If the stack pointer has a surprising value, we do not understand this |
59 | | // stack usage scheme. (Perhaps the target allocates new stack regions on |
60 | | // demand for us.) Don't try to guess what's going on. |
61 | 15.3M | if (StackUsage > DesiredStackSize) |
62 | 0 | return false; |
63 | | |
64 | 15.3M | return StackUsage >= DesiredStackSize - SufficientStack; |
65 | 15.3M | } |
66 | | |
67 | | void clang::runWithSufficientStackSpaceSlow(llvm::function_ref<void()> Diag, |
68 | 11 | llvm::function_ref<void()> Fn) { |
69 | 11 | llvm::CrashRecoveryContext CRC; |
70 | 11 | CRC.RunSafelyOnThread([&] { |
71 | 11 | noteBottomOfStack(); |
72 | 11 | Diag(); |
73 | 11 | Fn(); |
74 | 11 | }, DesiredStackSize); |
75 | 11 | } |