From c6af5ead8696f066fd5ec2978b9fc071ddf88a42 Mon Sep 17 00:00:00 2001
From: Sanjoy Das <sanjoy@playingwithpointers.com>
Date: Thu, 28 Jul 2016 23:43:38 +0000
Subject: [IR] Introduce a non-integral pointer type

Summary:
This change adds a `ni` specifier in the `datalayout` string to denote
pointers in some given address spaces as "non-integral", and adds some
typing rules around these special pointers.

Reviewers: majnemer, chandlerc, atrick, dberlin, eli.friedman, tstellarAMD, arsenm

Subscribers: arsenm, mcrosier, llvm-commits

Differential Revision: https://reviews.llvm.org/D22488

llvm-svn: 277085
---
 llvm/docs/LangRef.rst | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)

(limited to 'llvm/docs/LangRef.rst')

diff --git a/llvm/docs/LangRef.rst b/llvm/docs/LangRef.rst
index d4d0ee325c9..7f69d693294 100644
--- a/llvm/docs/LangRef.rst
+++ b/llvm/docs/LangRef.rst
@@ -546,6 +546,26 @@ An example of an identified structure specification is:
 Prior to the LLVM 3.0 release, identified types were structurally uniqued. Only
 literal types are uniqued in recent versions of LLVM.
 
+.. _nointptrtype:
+
+Non-Integral Pointer Type
+-------------------------
+
+Note: non-integral pointer types are a work in progress, and they should be
+considered experimental at this time.
+
+LLVM IR optionally allows the frontend to denote pointers in certain address
+spaces as "non-integral" via the :ref:```datalayout``
+string<langref_datalayout>`.  Non-integral pointer types represent pointers that
+have an *unspecified* bitwise representation; that is, the integral
+representation may be target dependent or unstable (not backed by a fixed
+integer).
+
+``inttoptr`` instructions converting integers to non-integral pointer types are
+ill-typed, and so are ``ptrtoint`` instructions converting values of
+non-integral pointer types to integers.  Vector versions of said instructions
+are ill-typed as well.
+
 .. _globalvars:
 
 Global Variables
@@ -1831,6 +1851,10 @@ as follows:
     ``n32:64`` for PowerPC 64, or ``n8:16:32:64`` for X86-64. Elements of
     this set are considered to support most general arithmetic operations
     efficiently.
+``ni:<address space0>:<address space1>:<address space2>...``
+    This specifies pointer types with the specified address spaces
+    as :ref:`Non-Integral Pointer Type <nointptrtype>` s.  The ``0``
+    address space cannot be specified as non-integral.
 
 On every specification that takes a ``<abi>:<pref>``, specifying the
 ``<pref>`` alignment is optional. If omitted, the preceding ``:``
-- 
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