From: Julian Seward <jseward@acm.org>
Date: Thu, 26 Aug 2004 12:30:48 +0000 (+0000)
Subject: Fix flags computation for rol/ror instructions in some very obscure
X-Git-Tag: svn/VALGRIND_3_0_1^2~1116
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=d9b35f7b2b9f3139e0bfef1b433429ea8199645c;p=thirdparty%2Fvalgrind.git

Fix flags computation for rol/ror instructions in some very obscure
boundary cases (rotate amount > 0 and an exact multiple of the
word size, in bits.).


git-svn-id: svn://svn.valgrind.org/vex/trunk@218
---

diff --git a/VEX/priv/guest-x86/toIR.c b/VEX/priv/guest-x86/toIR.c
index 5b5eadb3f6..5846eae329 100644
--- a/VEX/priv/guest-x86/toIR.c
+++ b/VEX/priv/guest-x86/toIR.c
@@ -2237,17 +2237,22 @@ UInt dis_Grp2 ( UChar  sorb,
 
    else 
    if (isRotate) {
-      Int    ccOp     = ty==Ity_I8 ? 0 : (ty==Ity_I16 ? 1 : 2);
-      Bool   left     = gregOfRM(modrm) == 0;
-      IRTemp rot_amt  = newTemp(Ity_I8);
-      IRTemp oldFlags = newTemp(Ity_I32);
+      Int    ccOp      = ty==Ity_I8 ? 0 : (ty==Ity_I16 ? 1 : 2);
+      Bool   left      = gregOfRM(modrm) == 0;
+      IRTemp rot_amt   = newTemp(Ity_I8);
+      IRTemp rot_amt32 = newTemp(Ity_I8);
+      IRTemp oldFlags  = newTemp(Ity_I32);
 
       /* rot_amt = shift_expr & mask */
       /* By masking the rotate amount thusly, the IR-level Shl/Shr
          expressions never shift beyond the word size and thus remain
          well defined. */
-      assign(rot_amt, binop(Iop_And8, 
-                            shift_expr, mkU8(8*sz-1)));
+      assign(rot_amt32, binop(Iop_And8, shift_expr, mkU8(31)));
+
+      if (ty == Ity_I32)
+         assign(rot_amt, mkexpr(rot_amt32));
+      else
+         assign(rot_amt, binop(Iop_And8, mkexpr(rot_amt32), mkU8(8*sz-1)));
 
       if (left) {
 
@@ -2293,15 +2298,15 @@ UInt dis_Grp2 ( UChar  sorb,
 
       /* CC_DST is the rotated value.  CC_SRC is flags before. */
       stmt( IRStmt_Put( OFFB_CC_OP,
-                        IRExpr_Mux0X( mkexpr(rot_amt),
+                        IRExpr_Mux0X( mkexpr(rot_amt32),
                                       IRExpr_Get(OFFB_CC_OP,Ity_I32),
                                       mkU32(ccOp))) );
       stmt( IRStmt_Put( OFFB_CC_DST, 
-                        IRExpr_Mux0X( mkexpr(rot_amt),
+                        IRExpr_Mux0X( mkexpr(rot_amt32),
                                       IRExpr_Get(OFFB_CC_DST,Ity_I32),
                                       widenUto32(mkexpr(dst1)))) );
       stmt( IRStmt_Put( OFFB_CC_SRC, 
-                        IRExpr_Mux0X( mkexpr(rot_amt),
+                        IRExpr_Mux0X( mkexpr(rot_amt32),
                                       IRExpr_Get(OFFB_CC_SRC,Ity_I32),
                                       mkexpr(oldFlags))) );
    } /* if (isRotate) */