From: Andreas Arnez <arnez@linux.ibm.com>
Date: Wed, 18 Mar 2020 11:24:25 +0000 (+0100)
Subject: Bug 417281 - s390x: Fix register usage of conditional moves
X-Git-Tag: VALGRIND_3_16_0~70
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=942a48c1db83ffbcbf1f5781d5607f3b42849b67;p=thirdparty%2Fvalgrind.git

Bug 417281 - s390x: Fix register usage of conditional moves

The s390x register usage callback marks the target register of a
conditional move as HRmWrite only.  It fails to mention the fact that the
target register is also an input to the insn (unless the condition is
"never" or "always").

This was discovered while investigating "grail" failures on s390x and
fixes the majority of them.
---

diff --git a/NEWS b/NEWS
index d7852320e5..52377430ce 100644
--- a/NEWS
+++ b/NEWS
@@ -127,6 +127,7 @@ where XXXXXX is the bug number as listed below.
 417906  clone with CLONE_VFORK and no CLONE_VM fails
 418435  s390x: memcmp test yields extra "Conditional jump or move depends on
         uninitialised value(s)"
+417281  s390x: /bin/true segfaults with "grail" enabled
 n-i-bz  Fix minor one time leaks in dhat.
 n-i-bz  Add --run-cxx-freeres=no in outer args to avoid inner crashes.
 n-i-bz  Add support for the Linux io_uring system calls
diff --git a/VEX/priv/host_s390_defs.c b/VEX/priv/host_s390_defs.c
index 80e56f603a..b9b2158190 100644
--- a/VEX/priv/host_s390_defs.c
+++ b/VEX/priv/host_s390_defs.c
@@ -676,8 +676,18 @@ s390_insn_get_reg_usage(HRegUsage *u, const s390_insn *insn)
       break;
 
    case S390_INSN_COND_MOVE:
-      s390_opnd_RMI_get_reg_usage(u, insn->variant.cond_move.src);
-      addHRegUse(u, HRmWrite, insn->variant.cond_move.dst);
+      switch (insn->variant.cond_move.cond) {
+      case S390_CC_NEVER:
+         break;
+      case S390_CC_ALWAYS:
+         s390_opnd_RMI_get_reg_usage(u, insn->variant.cond_move.src);
+         addHRegUse(u, HRmWrite, insn->variant.cond_move.dst);
+         break;
+      default:
+         s390_opnd_RMI_get_reg_usage(u, insn->variant.cond_move.src);
+         addHRegUse(u, HRmModify, insn->variant.cond_move.dst);
+         break;
+      }
       break;
 
    case S390_INSN_ALU:
diff --git a/docs/internals/3_15_BUGSTATUS.txt b/docs/internals/3_15_BUGSTATUS.txt
index ac4b5f48f5..9509426a04 100644
--- a/docs/internals/3_15_BUGSTATUS.txt
+++ b/docs/internals/3_15_BUGSTATUS.txt
@@ -204,9 +204,6 @@ Uhmm, MUSL
 .417266  Make memcheck/tests/linux/sigqueue usable with musl
 Uhmm, MUSL
 
-.417281  s390x: /bin/true segfaults with "grail" enabled
-Ongoing
-
 .417377  False-positive "uninitialised value(s)" reports from memcheck
 
 .417572  unhandled instruction bytes: 0xC5 0x79 0xD6 0xED 0xC5 0xF9 0x51