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diff --git a/js/public/BuildId.h b/js/public/BuildId.h
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+++ b/js/public/BuildId.h
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+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* 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/. */
+
+/**
+ * Embedding-provided build ID information, used by SpiderMonkey to tag cached
+ * compilation data so that cached data can be reused when possible, or
+ * discarded and regenerated if necessary.
+ */
+
+#ifndef js_BuildId_h
+#define js_BuildId_h
+
+#include "jstypes.h"  // JS_PUBLIC_API
+
+#include "js/Vector.h"  // js::Vector
+
+namespace js {
+
+class SystemAllocPolicy;
+
+}  // namespace js
+
+namespace JS {
+
+/** Vector of characters used for holding build ids. */
+using BuildIdCharVector = js::Vector<char, 0, js::SystemAllocPolicy>;
+
+/**
+ * Return the buildId (represented as a sequence of characters) associated with
+ * the currently-executing build. If the JS engine is embedded such that a
+ * single cache entry can be observed by different compiled versions of the JS
+ * engine, it is critical that the buildId shall change for each new build of
+ * the JS engine.
+ */
+using BuildIdOp = bool (*)(BuildIdCharVector* buildId);
+
+/**
+ * Embedder hook to set the buildId-generating function.
+ */
+extern JS_PUBLIC_API void SetProcessBuildIdOp(BuildIdOp buildIdOp);
+
+/**
+ * Some cached data is, in addition to being build-specific, CPU-specific: the
+ * cached data depends on CPU features like a particular level of SSE support.
+ *
+ * This function produces a buildId that includes:
+ *
+ *   * the buildId defined by the embedder-provided BuildIdOp set by
+ *     JS::SetProcessBuildIdOp, and
+ *   * CPU feature information for the current CPU.
+ *
+ * Embedders may use this function to tag cached data whose validity depends
+ * on having consistent buildId *and* on the CPU supporting features identical
+ * to those in play when the cached data was computed.
+ */
+[[nodiscard]] extern JS_PUBLIC_API bool GetOptimizedEncodingBuildId(
+    BuildIdCharVector* buildId);
+
+/**
+ * Script bytecode is dependent on the buildId and a few other things.
+ *
+ * This function produces a buildId that includes:
+ *
+ *   * The buildId defined by the embedder-provided BuildIdOp set by
+ *     JS::SetProcessBuildIdOp.
+ *   * Additional bytes describing things like endianness, pointer size and
+ *     other state XDR buffers depend on.
+ *
+ * Note: this value may depend on runtime preferences so isn't guaranteed to be
+ * stable across restarts.
+ *
+ * Embedders should use this function to tag transcoded bytecode.
+ * See Transcoding.h.
+ */
+[[nodiscard]] extern JS_PUBLIC_API bool GetScriptTranscodingBuildId(
+    BuildIdCharVector* buildId);
+
+}  // namespace JS
+
+#endif /* js_BuildId_h */