From: lkcl <lkcl@web>
Date: Tue, 14 Jun 2022 19:23:18 +0000 (+0100)
Subject: (no commit message)
X-Git-Tag: opf_rfc_ls005_v1~1781
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=546b17959f6582e1b3112a1c28d539fd8b32e6ba;p=libreriscv.git

---

diff --git a/openpower/sv/mv.swizzle.mdwn b/openpower/sv/mv.swizzle.mdwn
index d5b3e4287..27b59f8a7 100644
--- a/openpower/sv/mv.swizzle.mdwn
+++ b/openpower/sv/mv.swizzle.mdwn
@@ -206,6 +206,16 @@ Saturation and Predication also left out, for clarity:
              move_operation(RT+dst_idx, RA+src_idx+offs)
 ```
 
+**Vertical-First Mode**
+
+It is important to appreciate that *only* the main loop VL
+is Vertical-First: the SUBVL loop is not.  This makes sense
+from the perspective that the Swizzle Move is a group of
+moves, but is still a single instruction.  Vertical-First
+only performing one of the *sub*-elements at a time would
+break that expectation.  The exceptions to this, explained
+later, are when Pack/Unpack is enabled.
+
 **Effect of Saturation on Vectorised Swizzle**
 
 A useful convenience for pixel data is to be able to insert values