1 files changed, 53 insertions, 0 deletions
diff --git a/llvm/docs/LangRef.rst b/llvm/docs/LangRef.rst
index bac13cc..5279e69 100644
--- a/llvm/docs/LangRef.rst
+++ b/llvm/docs/LangRef.rst
@@ -12521,6 +12521,59 @@ Example:
       %Y = ptrtoint ptr %P to i64                        ; yields zero extension on 32-bit architecture
       %Z = ptrtoint <4 x ptr> %P to <4 x i64>; yields vector zero extension for a vector of addresses on 32-bit architecture
 
+.. _i_ptrtoaddr:
+
+'``ptrtoaddr .. to``' Instruction
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+Syntax:
+"""""""
+
+::
+
+      <result> = ptrtoaddr <ty> <value> to <ty2>             ; yields ty2
+
+Overview:
+"""""""""
+
+The '``ptrtoaddr``' instruction converts the pointer or a vector of
+pointers ``value`` to the underlying integer address (or vector of integers) of
+type ``ty2``. This is different from :ref:`ptrtoint <i_ptrtoint>` in that it
+only operates on the index bits of the pointer and ignores all other bits.
+``ty2`` must be the integer type (or vector of integers) matching the pointer
+index width of the address space of ``ty``.
+
+Arguments:
+""""""""""
+
+The '``ptrtoaddr``' instruction takes a ``value`` to cast, which must be
+a value of type :ref:`pointer <t_pointer>` or a vector of pointers, and a
+type to cast it to ``ty2``, which must be an :ref:`integer <t_integer>` or
+a vector of integers type.
+
+Semantics:
+""""""""""
+
+The '``ptrtoaddr``' instruction converts ``value`` to integer type ``ty2`` by
+interpreting the lowest index-width pointer representation bits as an integer.
+If the address size and the pointer representation size are the same and
+``value`` and ``ty2`` are the same size, then nothing is done (*no-op cast*)
+other than a type change.
+
+The ``ptrtoaddr`` instruction always :ref:`captures the address but not the provenance <pointercapture>`
+of the pointer argument.
+
+Example:
+""""""""
+This example assumes pointers in address space 1 are 64 bits in size with an
+address width of 32 bits (``p1:64:64:64:32`` :ref:`datalayout string<langref_datalayout>`)
+.. code-block:: llvm
+
+      %X = ptrtoaddr ptr addrspace(1) %P to i8  ; extracts low 32 bits and truncates
+      %Y = ptrtoaddr ptr addrspace(1) %P to i64 ; extracts low 32 bits and zero extends
+      %Z = ptrtoaddr <4 x ptr addrspace(1)> %P to <4 x i64>; yields vector zero extension of low 32 bits for each pointer
+
+
 .. _i_inttoptr:
 
 '``inttoptr .. to``' Instruction