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[Qemu-devel] [PULL 8/8] target/s390x: Fix risbg handling


From: Richard Henderson
Subject: [Qemu-devel] [PULL 8/8] target/s390x: Fix risbg handling
Date: Sat, 15 Jul 2017 07:30:50 -1000

The rotation is to the left, but extract shifts to the right.
The computation of the extract parameters needs adjusting.

For the entry condition, simplify

        64 - rot + len <= 64
        -rot + len <= 0
        len <= rot

Reviewed-by: Aurelien Jarno <address@hidden>
Reported-by: David Hildenbrand <address@hidden>
Suggested-by: Aurelien Jarno <address@hidden>
Signed-off-by: Richard Henderson <address@hidden>
---
 target/s390x/translate.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/target/s390x/translate.c b/target/s390x/translate.c
index b46f4c8..1dffcee 100644
--- a/target/s390x/translate.c
+++ b/target/s390x/translate.c
@@ -3479,8 +3479,8 @@ static ExitStatus op_risbg(DisasContext *s, DisasOps *o)
     }
 
     /* In some cases we can implement this with extract.  */
-    if (imask == 0 && pos == 0 && len > 0 && rot + len <= 64) {
-        tcg_gen_extract_i64(o->out, o->in2, rot, len);
+    if (imask == 0 && pos == 0 && len > 0 && len <= rot) {
+        tcg_gen_extract_i64(o->out, o->in2, 64 - rot, len);
         return NO_EXIT;
     }
 
-- 
2.9.4




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