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-rw-r--r--lib/Basic/Stack.cpp75
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diff --git a/lib/Basic/Stack.cpp b/lib/Basic/Stack.cpp
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+//===--- Stack.cpp - Utilities for dealing with stack space ---------------===//
+//
+// 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"
+
+#ifdef _MSC_VER
+#include <intrin.h> // for _AddressOfReturnAddress
+#endif
+
+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);
+}