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diff --git a/js/src/jit/ProcessExecutableMemory.h b/js/src/jit/ProcessExecutableMemory.h
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+++ b/js/src/jit/ProcessExecutableMemory.h
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+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef jit_ProcessExecutableMemory_h
+#define jit_ProcessExecutableMemory_h
+
+#include "mozilla/Attributes.h"
+
+namespace js {
+namespace jit {
+
+// Executable code is allocated in 64K chunks. ExecutableAllocator uses pools
+// that are at least this big. Code we allocate does not necessarily have 64K
+// alignment though.
+static const size_t ExecutableCodePageSize = 64 * 1024;
+
+enum class ProtectionSetting {
+    Protected, // Not readable, writable, or executable.
+    Writable,
+    Executable,
+};
+
+extern MOZ_MUST_USE bool ReprotectRegion(void* start, size_t size, ProtectionSetting protection);
+
+// Functions called at process start-up/shutdown to initialize/release the
+// executable memory region.
+extern MOZ_MUST_USE bool InitProcessExecutableMemory();
+extern void ReleaseProcessExecutableMemory();
+
+// Allocate/deallocate executable pages.
+extern void* AllocateExecutableMemory(size_t bytes, ProtectionSetting protection);
+extern void DeallocateExecutableMemory(void* addr, size_t bytes);
+
+// Returns true if we can allocate a few more MB of executable code without
+// hitting our code limit. This function can be used to stop compiling things
+// that are optional (like Baseline and Ion code) when we're about to reach the
+// limit, so we are less likely to OOM or crash. Note that the limit is
+// per-process, so other threads can also allocate code after we call this
+// function.
+extern bool CanLikelyAllocateMoreExecutableMemory();
+
+} // namespace jit
+} // namespace js
+
+#endif // jit_ProcessExecutableMemory_h