From: cand@51b69dee28eeccfe0f04790433b843689895c6e3 <cand@web>
Date: Sat, 12 Dec 2020 17:03:40 +0000 (+0000)
Subject: Replace "op is src unless sat" with "op is max(src, dst)"
X-Git-Tag: convert-csv-opcode-to-binary~1385
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=61d1862217f9a8b26a3e13460a26e6261eb1e0e7;p=libreriscv.git

Replace "op is src unless sat" with "op is max(src, dst)"
---

diff --git a/openpower/sv/svp_rewrite/svp64/discussion.mdwn b/openpower/sv/svp_rewrite/svp64/discussion.mdwn
index a99af528f..3b0830295 100644
--- a/openpower/sv/svp_rewrite/svp64/discussion.mdwn
+++ b/openpower/sv/svp_rewrite/svp64/discussion.mdwn
@@ -77,10 +77,8 @@ For 2 op (dest/src1/src2) the tag may be 3 bits: total 9 bits.  for 3 op (dest/s
 
 Note:
 
-* for saturation the operation is done at the **source** width
-  (this is different from normal elwidth overrides which
-   are done at the **dest** width)
-* exceptions: saturated-mul, the operation is done at the **dest** width
+* the operation should always be done at max(srcwidth, dstwidth), unless it can 
+  be proven using the lower will lead to the same result
 * saturation is done on the result at the **dest** elwidth
 
 # Notes about rounding, clamp and saturate