From: Konstantinos Margaritis <konstantinos.margaritis@vectorcamp.gr>
Date: Wed, 19 Jul 2023 13:41:31 +0000 (+0000)
Subject: Fix XLEN != 64 cases where maddsubrs fails
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=72c702d2e144e63f6baf3794bc731a17ae63f4fa;p=openpower-isa.git

Fix XLEN != 64 cases where maddsubrs fails
---

diff --git a/openpower/isa/butterfly.mdwn b/openpower/isa/butterfly.mdwn
index 726151b8..b6b7efe5 100644
--- a/openpower/isa/butterfly.mdwn
+++ b/openpower/isa/butterfly.mdwn
@@ -14,26 +14,43 @@ Pseudo-code:
     sum <- (RT) + (RA)
     diff <- (RT) - (RA)
     prod1 <- MULS(RB, sum)
-    prod1_lo <- prod1[XLEN:(XLEN*2)-1]
     prod2 <- MULS(RB, diff)
-    prod2_lo <- prod2[XLEN:(XLEN*2)-1]
     if n = 0 then
+        prod1_lo <- prod1[XLEN:(XLEN*2)-1]
+        prod2_lo <- prod2[XLEN:(XLEN*2)-1]
         RT <- prod1_lo
         RS <- prod2_lo
     else
-        round <- [0]*XLEN
-        round[XLEN -n] <- 1
-        prod1_lo <- prod1_lo + round
-        prod2_lo <- prod2_lo + round
-        m <- MASK(n, (XLEN-1))
-        res1 <- ROTL64(prod1_lo, XLEN-n) & m
-        res2 <- ROTL64(prod2_lo, XLEN-n) & m
-        signbit1 <- prod1_lo[0]
-        signbit2 <- prod2_lo[0]
-        smask1 <- ([signbit1]*XLEN) & ¬m
-        smask2 <- ([signbit2]*XLEN) & ¬m
-        RT <- (res1 | smask1)
-        RS <- (res2 | smask2)
+        if XLEN = 64 then
+            prod1_lo <- prod1[XLEN:(XLEN*2)-1]
+            prod2_lo <- prod2[XLEN:(XLEN*2)-1]
+            round <- [0]*XLEN
+            round[XLEN -n] <- 1
+            prod1_lo <- prod1_lo + round
+            prod2_lo <- prod2_lo + round
+            m <- MASK(n, (XLEN-1))
+            res1 <- ROTL64(prod1_lo, XLEN-n) & m
+            res2 <- ROTL64(prod2_lo, XLEN-n) & m
+            signbit1 <- prod1_lo[0]
+            signbit2 <- prod2_lo[0]
+            smask1 <- ([signbit1]*XLEN) & ¬m
+            smask2 <- ([signbit2]*XLEN) & ¬m
+            RT <- (res1 | smask1)
+            RS <- (res2 | smask2)
+        else
+            round <- [0]*(XLEN*2)
+            round[XLEN*2 -n] <- 1
+            prod1 <- prod1 + round
+            prod2 <- prod2 + round
+            m <- MASK(XLEN-n, XLEN-1)
+            res1 <- prod1[XLEN-n:XLEN*2 -n -1]
+            res2 <- prod2[XLEN-n:XLEN*2 -n -1]
+            signbit1 <- prod1[0]
+            signbit2 <- prod2[0]
+            smask1 <- ([signbit1]*XLEN) & ¬m
+            smask2 <- ([signbit2]*XLEN) & ¬m
+            RT <- (res1 | smask1)
+            RS <- (res2 | smask2)
 
 Special Registers Altered:
 
@@ -49,26 +66,44 @@ Pseudo-code:
 
     n <- SH
     prod <- MULS(RB, RA)
-    prod_lo <- prod[XLEN:(XLEN*2)-1]
     if n = 0 then
+        prod_lo <- prod[XLEN:(XLEN*2)-1]
         RT <- (RT) + prod_lo
         RS <- (RS) - prod_lo
     else
-        res1 <- (RT) + prod_lo
-        res2 <- (RS) - prod_lo
-        round <- [0]*XLEN
-        round[XLEN -n] <- 1
-        res1 <- res1 + round
-        res2 <- res2 + round
-        signbit1 <- res1[0]
-        signbit2 <- res2[0]
-        m <- MASK(n, (XLEN-1))
-        res1 <- ROTL64(res1, XLEN-n) & m
-        res2 <- ROTL64(res2, XLEN-n) & m
-        smask1 <- ([signbit1]*XLEN) & ¬m
-        smask2 <- ([signbit2]*XLEN) & ¬m
-        RT <- (res1 | smask1)
-        RS <- (res2 | smask2)
+        if XLEN = 64 then
+            prod_lo <- prod[XLEN:(XLEN*2)-1]
+            res1 <- (RT) + prod_lo
+            res2 <- (RS) - prod_lo
+            round <- [0]*XLEN
+            round[XLEN -n] <- 1
+            res1 <- res1 + round
+            res2 <- res2 + round
+            signbit1 <- res1[0]
+            signbit2 <- res2[0]
+            m <- MASK(n, (XLEN-1))
+            res1 <- ROTL64(res1, XLEN-n) & m
+            res2 <- ROTL64(res2, XLEN-n) & m
+            smask1 <- ([signbit1]*XLEN) & ¬m
+            smask2 <- ([signbit2]*XLEN) & ¬m
+            RT <- (res1 | smask1)
+            RS <- (res2 | smask2)
+        else
+            res1 <- (RT) + prod
+            res2 <- (RS) - prod
+            round <- [0]*XLEN*2
+            round[XLEN*2 -n] <- 1
+            res1 <- res1 + round
+            res2 <- res2 + round
+            signbit1 <- res1[0]
+            signbit2 <- res2[0]
+            m <- MASK(XLEN-n, (XLEN-1))
+            res1 <- prod1[XLEN-n:XLEN*2 -n -1]
+            res2 <- prod2[XLEN-n:XLEN*2 -n -1]
+            smask1 <- ([signbit1]*XLEN) & ¬m
+            smask2 <- ([signbit2]*XLEN) & ¬m
+            RT <- (res1 | smask1)
+            RS <- (res2 | smask2)
 
 Special Registers Altered: