From: lkcl <lkcl@web>
Date: Sun, 3 Apr 2022 15:36:54 +0000 (+0100)
Subject: (no commit message)
X-Git-Tag: opf_rfc_ls005_v1~2894
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=4fe4dad4ea6288a55112a92de7be4d32939c95ae;p=libreriscv.git

---

diff --git a/openpower/sv/normal.mdwn b/openpower/sv/normal.mdwn
index 88db31a4e..f0619fcee 100644
--- a/openpower/sv/normal.mdwn
+++ b/openpower/sv/normal.mdwn
@@ -162,7 +162,7 @@ tests this may be insufficient.  If that is the case, a vectorised crops
 (crand, cror) may be used, and ffirst applied to the crop instead of to
 the arithmetic vector.
 
-One extremely important aspect of ffirst is:
+Two extremely important aspects of ffirst are:
 
 * LDST ffirst may never set VL equal to zero.  This because on the first
   element an exception must be raised "as normal".
@@ -173,7 +173,12 @@ One extremely important aspect of ffirst is:
   vectorised operations are effectively `nops` which is
   *precisely the desired and intended behaviour*.
 
-CR-based data-dependent first on the other hand MUST not truncate VL
+The second crucial aspect, compared to LDST Ffirst:
+
+* LD/ST Failfirst may (beyond the initial first element
+  conditions) truncate VL for any architecturally
+  suitable reason.
+* CR-based data-dependent first on the other hand MUST NOT truncate VL
 arbitrarily to a length decided by the hardware: VL MUST only be
 truncated based explicitly on whether a test fails.
 This because it is a precise test on which algorithms