Merge pull request MicrosoftDocs#5153 from MicrosoftDocs/main638726490443165439sync_temp

learn-build-service-prod[bot] · web-flow · commit e1f177fe6b6d · 2025-01-16T18:31:08.000Z
For protected branch, push strategy should use PR and merge to target branch method to work around git push error
diff --git a/docs/cpp/declspec.md b/docs/cpp/declspec.md
@@ -1,15 +1,15 @@
 ---
 description: "Learn more about: `__declspec`"
 title: "__declspec"
-ms.date: 03/01/2022
+ms.date: 1/14/2025
 f1_keywords: ["__declspec_cpp", "__declspec", "_declspec"]
 helpviewer_keywords: ["__declspec keyword [C++]"]
 ---
 # `__declspec`
 
 **Microsoft Specific**
 
-The extended attribute syntax for specifying storage-class information uses the **`__declspec`** keyword, which specifies that an instance of a given type is to be stored with a Microsoft-specific storage-class attribute listed below. Examples of other storage-class modifiers include the **`static`** and **`extern`** keywords. However, these keywords are part of the ANSI specification of the C and C++ languages, and as such aren't covered by extended attribute syntax. The extended attribute syntax simplifies and standardizes Microsoft-specific extensions to the C and C++ languages.
+The extended attribute syntax for specifying storage-class information uses the `__declspec` keyword, which specifies that an instance of a given type is to be stored with a Microsoft-specific storage-class attribute listed below. Examples of other storage-class modifiers include the `static` and `extern` keywords. However, these keywords are part of the ANSI specification of the C and C++ languages, and as such aren't covered by extended attribute syntax. The extended attribute syntax simplifies and standardizes Microsoft-specific extensions to the C and C++ languages.
 
 ## Grammar
 
@@ -30,6 +30,7 @@ The extended attribute syntax for specifying storage-class information uses the
 &emsp;**`dllimport`**\
 &emsp;**`dllexport`**\
 &emsp;**`empty_bases`**\
+&emsp;**`hybrid_patchable`**\
 &emsp;**`jitintrinsic`**\
 &emsp;**`naked`**\
 &emsp;**`noalias`**\
diff --git a/docs/cpp/hybrid-patchable.md b/docs/cpp/hybrid-patchable.md
@@ -0,0 +1,49 @@
+---
+description: "Learn more about: hybrid_patchable (C++)"
+title: "hybrid_patchable (C++)"
+ms.date: 1/15/2025
+f1_keywords: ["hybrid_patchable"]
+helpviewer_keywords: ["__declspec keyword [C++], hybrid_patchable", "hybrid_patchable __declspec keyword"]
+---
+# `hybrid_patchable` (C++)
+
+**Microsoft Specific**
+
+Use `__declspec(hybrid_patchable)` to mark a function as a hybrid patchable function. This attribute generates a fast-forward sequence. Fast-forward sequences are small x64 functions which contain no real logic, and tail-call the real Arm64EC function. Because fast-forward sequences are primarily used for hooking, if they are unaltered, execution is transferred directly to the Arm64EC function.
+
+## Syntax
+
+> `__declspec(hybrid_patchable)`
+
+## Remarks
+
+`__declspec(hybrid_patchable)` is an ARM64EC-only feature.
+
+**Example:**
+
+```cpp
+__declspec(hybrid_patchable) int Example()
+{
+    return 1;
+}
+```
+
+Generates the following fast-forward sequence:
+
+```
+EXP+#Example:
+  00000001400CE000: 48 8B C4           mov         rax,rsp
+  00000001400CE003: 48 89 58 20        mov         qword ptr [rax+20h],rbx
+  00000001400CE007: 55                 push        rbp
+  00000001400CE008: 5D                 pop         rbp
+  00000001400CE009: E9 BA 7A F3 FF     jmp         #Example
+  00000001400CE00E: CC                 int         3
+  00000001400CE00F: CC                 int         3 
+```
+
+**END Microsoft Specific**
+
+## See also
+
+[`__declspec`](../cpp/declspec.md)\
+[Fast-Forward sequences](/windows/arm/arm64ec-abi#fast-forward-sequences)
diff --git a/docs/cpp/toc.yml b/docs/cpp/toc.yml
@@ -696,6 +696,8 @@ items:
                   href: ../cpp/using-dllimport-and-dllexport-in-cpp-classes.md
             - name: empty_bases
               href: ../cpp/empty-bases.md
+            - name: hybrid_patchable
+              href: ../cpp/hybrid-patchable.md
             - name: jitintrinsic
               href: ../cpp/jitintrinsic.md
             - name: naked
