[llvm] [LangRef] Clarify that the pointer after an object must be valid. (PR #127892)

[Florian Hahn via llvm-commits]

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@@ -3280,31 +3281,41 @@ This information is passed along to the backend so that it generates
 code for the proper architecture. It's possible to override this on the
 command line with the ``-mtriple`` command line option.
 
+
+.. _allocatedobjects:
+
+Allocated Objects
+-----------------
+
+An allocated object, memory object, or simply object, is a region of a memory
+space that is reserved by a memory allocation such as :ref:`alloca <i_alloca>`,
+heap allocation calls, and global variable definitions. Once it is allocated,
+the bytes stored in the region can only be read or written through a pointer
+that is :ref:`based on <pointeraliasing>` the allocation value. If a pointer
+that is not based on the object tries to read or write to the object, it is
+undefined behavior.
+
+The following properties hold for all allocated objects:
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fhahn wrote:

Added, thanks

https://github.com/llvm/llvm-project/pull/127892