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diff --git a/js/src/wasm/WasmSignalHandlers.h b/js/src/wasm/WasmSignalHandlers.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:
+ *
+ * Copyright 2014 Mozilla Foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef wasm_signal_handlers_h
+#define wasm_signal_handlers_h
+
+#include "js/ProfilingFrameIterator.h"
+#include "wasm/WasmProcess.h"
+
+namespace js {
+namespace wasm {
+
+using RegisterState = JS::ProfilingFrameIterator::RegisterState;
+
+// This function performs the low-overhead signal handler initialization that we
+// want to do eagerly to ensure a more-deterministic global process state. This
+// is especially relevant for signal handlers since handler ordering depends on
+// installation order: the wasm signal handler must run *before* the other crash
+// handlers (breakpad) and since POSIX signal handlers work LIFO, this function
+// needs to be called at the end of the startup process, after the other two
+// handlers have been installed. Currently, this is achieved by having
+// JSRuntime() call this function. There can be multiple JSRuntimes per process
+// so this function can thus be called multiple times, having no effect after
+// the first call.
+void EnsureEagerProcessSignalHandlers();
+
+// Assuming EnsureEagerProcessSignalHandlers() has already been called,
+// this function performs the full installation of signal handlers which must
+// be performed per-thread/JSContext. This operation may incur some overhead and
+// so should be done only when needed to use wasm. Currently, this is done in
+// wasm::HasPlatformSupport() which is called when deciding whether to expose
+// the 'WebAssembly' object on the global object.
+bool EnsureFullSignalHandlers(JSContext* cx);
+
+// Return whether, with the given simulator register state, a memory access to
+// 'addr' of size 'numBytes' needs to trap and, if so, where the simulator
+// should redirect pc to.
+bool MemoryAccessTraps(const RegisterState& regs, uint8_t* addr,
+                       uint32_t numBytes, uint8_t** newPC);
+
+// Return whether, with the given simulator register state, an illegal
+// instruction fault is expected and, if so, the value of the next PC.
+bool HandleIllegalInstruction(const RegisterState& regs, uint8_t** newPC);
+
+}  // namespace wasm
+}  // namespace js
+
+#endif  // wasm_signal_handlers_h