From: Philippe Waroquiers <philippe.waroquiers@skynet.be>
Date: Tue, 12 Jul 2016 20:49:05 +0000 (+0000)
Subject: Fix n-i-bz amd64: memcheck false positive with shr %edx
X-Git-Tag: svn/VALGRIND_3_12_0^2~43
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=ebc19f644107772d7fa670589649617570489cff;p=thirdparty%2Fvalgrind.git

Fix n-i-bz amd64: memcheck false positive with shr %edx

False positive analysis and fix by Julian.

Thanks



git-svn-id: svn://svn.valgrind.org/vex/trunk@3223
---

diff --git a/VEX/priv/guest_amd64_helpers.c b/VEX/priv/guest_amd64_helpers.c
index ab53e156b2..3a0a4c606a 100644
--- a/VEX/priv/guest_amd64_helpers.c
+++ b/VEX/priv/guest_amd64_helpers.c
@@ -1604,6 +1604,15 @@ IRExpr* guest_amd64_spechelper ( const HChar* function_name,
                            mkU64(0)));
       }
 
+      /*---------------- SHRL ----------------*/
+
+      if (isU64(cc_op, AMD64G_CC_OP_SHRL) && isU64(cond, AMD64CondZ)) {
+         /* SHRL, then Z --> test dep1 == 0 */
+         return unop(Iop_1Uto64,
+                     binop(Iop_CmpEQ32, unop(Iop_64to32, cc_dep1),
+                           mkU32(0)));
+      }
+
       /*---------------- COPY ----------------*/
       /* This can happen, as a result of amd64 FP compares: "comisd ... ;
          jbe" for example. */