From: Luke Kenneth Casson Leighton <lkcl@lkcl.net>
Date: Mon, 18 Apr 2022 20:58:04 +0000 (+0100)
Subject: split out mul add x into separate instruction
X-Git-Tag: opf_rfc_ls005_v1~2718
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=a8232c8fa455058d8534f76fdbf70c252fe9ff7d;p=libreriscv.git

split out mul add x into separate instruction
or at least looking like it
---

diff --git a/openpower/sv/bitmanip/mulmnu.c b/openpower/sv/bitmanip/mulmnu.c
index 2acdc08ec..a38afc4be 100644
--- a/openpower/sv/bitmanip/mulmnu.c
+++ b/openpower/sv/bitmanip/mulmnu.c
@@ -24,8 +24,15 @@ void mulmnu(unsigned short w[], unsigned short u[],
 
    for (j = 0; j < n; j++) {
       k = 0;
+      unsigned short phi[2000];
+      unsigned short plo[2000];
       for (i = 0; i < m; i++) {
-         t = u[i]*v[j] + w[i + j] + k;
+         unsigned product = u[i]*v[j] + w[i + j];
+         phi[i] = product>>16;
+         plo[i] = product;
+      }
+      for (i = 0; i < m; i++) {
+         t = (phi[i]<<16) | plo[i]  + k;
          w[i + j] = t;          // (I.e., t & 0xFFFF).
          k = t >> 16;
       }