From: Andreas Arnez <arnez@linux.ibm.com>
Date: Fri, 3 Apr 2020 17:16:01 +0000 (+0200)
Subject: s390x: Drop spurious register moves in CDAS instruction selector
X-Git-Tag: VALGRIND_3_16_0~61
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=6a90a15b9c0cbf38b6a9f17e5fa28199e155de73;p=thirdparty%2Fvalgrind.git

s390x: Drop spurious register moves in CDAS instruction selector

The s390x instruction selector for Ist_CAS, in its handling of "compare
double and swap", adds spurious register moves after the CDAS operation
itself.  These moves overwrite registers returned by calls to
s390_isel_int_expr(), potentially causing corruption of temp values.

Delete the spurious move operations after CDAS.
---

diff --git a/VEX/priv/host_s390_isel.c b/VEX/priv/host_s390_isel.c
index 882e72cd6c..2f80dd8504 100644
--- a/VEX/priv/host_s390_isel.c
+++ b/VEX/priv/host_s390_isel.c
@@ -5185,10 +5185,6 @@ no_memcpy_put:
             addInstr(env, s390_insn_cdas(8, r8, r9, op2, r10, r11,
                                          old_high, old_low, r1));
          }
-         addInstr(env, s390_insn_move(8, op1_high, r8));
-         addInstr(env, s390_insn_move(8, op1_low,  r9));
-         addInstr(env, s390_insn_move(8, op3_high, r10));
-         addInstr(env, s390_insn_move(8, op3_low,  r11));
          return;
       }
       break;