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Diffstat (limited to 'lib/Basic/Stack.cpp')
-rw-r--r-- | lib/Basic/Stack.cpp | 71 |
1 files changed, 71 insertions, 0 deletions
diff --git a/lib/Basic/Stack.cpp b/lib/Basic/Stack.cpp new file mode 100644 index 0000000000..667db5c51f --- /dev/null +++ b/lib/Basic/Stack.cpp @@ -0,0 +1,71 @@ +//===--- Stack.h - Utilities for dealing with stack space -------*- 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 +// +//===----------------------------------------------------------------------===// +/// +/// \file +/// Defines utilities for dealing with stack allocation and stack space. +/// +//===----------------------------------------------------------------------===// + +#include "clang/Basic/Stack.h" +#include "llvm/ADT/Optional.h" +#include "llvm/Support/CrashRecoveryContext.h" + +static LLVM_THREAD_LOCAL void *BottomOfStack = nullptr; + +static void *getStackPointer() { +#if __GNUC__ || __has_builtin(__builtin_frame_address) + return __builtin_frame_address(0); +#elif defined(_MSC_VER) + return _AddressOfReturnAddress(); +#else + char CharOnStack = 0; + // The volatile store here is intended to escape the local variable, to + // prevent the compiler from optimizing CharOnStack into anything other + // than a char on the stack. + // + // Tested on: MSVC 2015 - 2019, GCC 4.9 - 9, Clang 3.2 - 9, ICC 13 - 19. + char *volatile Ptr = &CharOnStack; + return Ptr; +#endif +} + +void clang::noteBottomOfStack() { + if (!BottomOfStack) + BottomOfStack = getStackPointer(); +} + +bool clang::isStackNearlyExhausted() { + // We consider 256 KiB to be sufficient for any code that runs between checks + // for stack size. + constexpr size_t SufficientStack = 256 << 10; + + // If we don't know where the bottom of the stack is, hope for the best. + if (!BottomOfStack) + return false; + + intptr_t StackDiff = (intptr_t)getStackPointer() - (intptr_t)BottomOfStack; + size_t StackUsage = (size_t)std::abs(StackDiff); + + // If the stack pointer has a surprising value, we do not understand this + // stack usage scheme. (Perhaps the target allocates new stack regions on + // demand for us.) Don't try to guess what's going on. + if (StackUsage > DesiredStackSize) + return false; + + return StackUsage >= DesiredStackSize - SufficientStack; +} + +void clang::runWithSufficientStackSpaceSlow(llvm::function_ref<void()> Diag, + llvm::function_ref<void()> Fn) { + llvm::CrashRecoveryContext CRC; + CRC.RunSafelyOnThread([&] { + noteBottomOfStack(); + Diag(); + Fn(); + }, DesiredStackSize); +} |