From: lkcl <lkcl@web>
Date: Fri, 20 May 2022 21:57:18 +0000 (+0100)
Subject: (no commit message)
X-Git-Tag: opf_rfc_ls005_v1~2152
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=b4bc2ceb3940414e80b3558371fcaa9a741084bd;p=libreriscv.git

---

diff --git a/openpower/sv/cr_int_predication.mdwn b/openpower/sv/cr_int_predication.mdwn
index 6d3708f68..445083ef7 100644
--- a/openpower/sv/cr_int_predication.mdwn
+++ b/openpower/sv/cr_int_predication.mdwn
@@ -255,7 +255,10 @@ to deriving the Vectorised versions of these instructions.
 Normally the progression of the SV for-loop would move on to the
 next register.  Instead however in the scalar case these instructions
 **remain in the same register** and insert or transfer between **bits**
-of the scalar integer source or destination.
+of the scalar integer source or destination.  The reason is that when
+using CR Fields as predicate masks and there is a need to transfer
+into a GPR, again for use as a predicate mask, the CR Field bits
+need to be efficiently packed into that one GPR (r3, r10 or r31).
 
 Further useful violation of the normal SV Elwidth override rules allows
 for packing (or unpacking) of multiple CR test results into (or out of)