From: Julian Seward <jseward@acm.org>
Date: Fri, 27 Feb 2015 12:51:22 +0000 (+0000)
Subject: fold_Expr: add rules
X-Git-Tag: svn/VALGRIND_3_11_0^2~88
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=3690e33a205b9cd961dffe95f6ab331a7a080e7f;p=thirdparty%2Fvalgrind.git

fold_Expr: add rules
   Xor8/16/32/64(0,t) ==> t
   Xor8/16/32/64(t,0) ==> t


git-svn-id: svn://svn.valgrind.org/vex/trunk@3094
---

diff --git a/VEX/priv/ir_opt.c b/VEX/priv/ir_opt.c
index ffd18f95be..f503bef181 100644
--- a/VEX/priv/ir_opt.c
+++ b/VEX/priv/ir_opt.c
@@ -2292,6 +2292,17 @@ static IRExpr* fold_Expr ( IRExpr** env, IRExpr* e )
                   //   e2 = e->Iex.Binop.arg2;
                   //   break;
                   //}
+               } else {
+                  /* Xor8/16/32/64(0,t) ==> t */
+                  if (isZeroU(e->Iex.Binop.arg1)) {
+                     e2 = e->Iex.Binop.arg2;
+                     break;
+                  }
+                  /* Xor8/16/32/64(t,0) ==> t */
+                  if (isZeroU(e->Iex.Binop.arg2)) {
+                     e2 = e->Iex.Binop.arg1;
+                     break;
+                  }
                }
                break;