From 06914fd8253b8d13818a284c0abd9f2a081d856c Mon Sep 17 00:00:00 2001
From: Momchil Velikov <momchil.velikov@arm.com>
Date: Thu, 19 Oct 2023 11:37:58 +0100
Subject: [PATCH] Describe reinterpret intrinsics for vector and vector tuple
 types

Change-Id: Iba0e37d8b12debe34edae3bb8350bb1ef80a616a
---
 main/acle.md | 65 ++++++++++++++++++++++++++++++++++++++++++----------
 1 file changed, 53 insertions(+), 12 deletions(-)

diff --git a/main/acle.md b/main/acle.md
index de433c98..b5033fd9 100644
--- a/main/acle.md
+++ b/main/acle.md
@@ -5927,18 +5927,6 @@ definition of `bfloat16_t` (see [Scalar types defined by
 `<arm_sve.h>`](#scalar-types-defined-by-arm_sve.h)). The other
 types are available unconditionally.
 
-ACLE provides two sets of intrinsics for converting between vector types:
-
-*   The [`svreinterpret`](https://developer.arm.com/architectures/instruction-sets/intrinsics/#q=svreinterpret)
-    intrinsics simply reinterpret a vector of one type as a vector of another
-    type, without changing any of the bits.
-
-*   The [`svcvt`](https://developer.arm.com/architectures/instruction-sets/intrinsics/#q=svcvt_)
-    intrinsics instead perform numerical conversion from one type to another,
-    such as converting integers to floating-point values.
-
-To avoid any ambiguity between the two operations, ACLE does not allow
-C-style casting from one vector type to another.
 
 [`<arm_sve.h>`](#arm_sve.h) also defines tuples of two, three, and four
 vectors, as follows:
@@ -5998,6 +5986,59 @@ vectors using [`svundef`](https://developer.arm.com/architectures/instruction-se
 [`svundef3`](https://developer.arm.com/architectures/instruction-sets/intrinsics/#q=svundef3) and
 [`svundef4`](https://developer.arm.com/architectures/instruction-sets/intrinsics/#q=svundef4).
 
+ACLE provides two sets of intrinsics for converting between vector types:
+
+*   The [`svreinterpret`](https://developer.arm.com/architectures/instruction-sets/intrinsics/#q=svreinterpret)
+    intrinsics simply reinterpret a vector of one type as a vector of another
+    type, without changing any of the bits.
+
+*   The [`svcvt`](https://developer.arm.com/architectures/instruction-sets/intrinsics/#q=svcvt_)
+    intrinsics instead perform numerical conversion from one type to another,
+    such as converting integers to floating-point values.
+
+To avoid any ambiguity between the two operations, ACLE does not allow
+C-style casting from one vector type to another.
+
+The `svreinterpret` intrinsics for vector types take the form
+
+```
+sv<dst>_t svreinterpret_<dst>_<src>(sv<src>_t op);
+```
+
+where `<src>` denotes the source type and `<dst>` denotes the destination type,
+across all pairs choosen from `{s8, u8, s16, u16, s32, u32, s64, u64, bf16, f16, f32, f64}`
+
+A shorter, overloaded form is also available in which the destintion type is spelled explicitly
+and the source type is deduced from the argument:
+
+```
+sv<dst>_t svreinterpret_<dst>(sv<src>_t op);
+```
+
+The `svreinterpret` intrinsics for vector tuple types take the form
+
+```
+sv<dst>x<N>_t svreinterpret_<dst>_<src>_x<N>(sv<src>x<N>_t op)
+```
+
+where <src> and <dst> is as for above for vector type and `<N>` denotes the number of tuple
+element, 2 or 4.
+
+A shorter, overloaded form is also available in which the destintion type is spelled explicitly
+and the source type is deduced from the argument:
+
+```
+sv<dst>x<N>_t svreinterpret_<dst>(sv<src>x<N>_t op)    
+```
+
+For example:
+``` c
+svuin16_t svreinterpret_u16_s32(svint32_t op);
+svuin16_t svreinterpret_u16(svint32_t op);
+svuin16x2_t svreinterpret_u16_s32_x2(svint32x2_t op);
+svuin16x2_t svreinterpret_u16(svint32x2_t op); 
+```
+
 ### SVE predicate types
 
 [`<arm_sve.h>`](#arm_sve.h) defines a single sizeless predicate type