* Fix flag computation for neg instructions

* Fix flag and result computation for 16/8-bit shl/shr/sar by amounts
  greater than the word size, which inconveniently is a well-defined
  (if useless) operation on x86.  Sigh.  Unfortunately the solution
  depends on IR shifts behaving as per x86, whereas it would be better
  to define IR shifts only to make sense for values in 0 .. 2^word_size-1.
  This needs to be fixed.

* Implement another shrd case.  shrdl doesn't work correctly
  according to the QEMU test suite.  I don't know why.

git-svn-id: svn://svn.valgrind.org/vex/trunk@158

diff --git a/VEX/priv/guest-x86/toIR.c b/VEX/priv/guest-x86/toIR.c
index 97b29ee6bd7e5175fbbb30cf32b20401bcb4ed87..4659c6e0b494ff91b151c89d3ca949dbc0ad90da 100644 (file)
--- a/VEX/priv/guest-x86/toIR.c
+++ b/VEX/priv/guest-x86/toIR.c
@@ -2182,18 +2182,18 @@ UInt dis_Grp2 ( UChar  sorb,
 
       /* shift_amt = shift_expr & mask */
       assign(shift_amt, binop(Iop_And8, 
-                              shift_expr, mkU8(8*sz-1)));
+                              shift_expr, mkU8(31 /* 8*sz-1 */)));
       /* dst1 = dst0 `shift` shift_amt */
       assign(dst1, binop(mkSizedOp(ty,op8), 
                          mkexpr(dst0), mkexpr(shift_amt)));
-      /* subshift = dst0 `shift` (shift_amt - 1) */
+      /* subshift = dst0 `shift` ((shift_amt - 1) & mask) */
       assign(subshift, 
              binop(mkSizedOp(ty,op8), 
                    mkexpr(dst0), 
                    binop(Iop_And8,
                          binop(Iop_Sub8,
                                mkexpr(shift_amt), mkU8(1)),
-                         mkU8(8*sz-1))));
+                         mkU8(31 /* 8*sz-1 */))));
 
       /* Build the flags thunk. */
       setFlags_DSTus_DST1(op8, subshift, dst1, ty, shift_amt);
@@ -2478,9 +2478,9 @@ UInt dis_Grp3 ( UChar sorb, Int sz, UInt delta )
             dst0 = newTemp(ty);
             src  = newTemp(ty);
             dst1 = newTemp(ty);
-            assign(dst0, getIReg(sz,eregOfRM(modrm)));
-           assign(src,  mkU(ty,0));
-           assign(dst1, binop(mkSizedOp(ty,Iop_Sub8),mkexpr(src), mkexpr(dst0)));
+           assign(dst0, mkU(ty,0));
+            assign(src,  getIReg(sz,eregOfRM(modrm)));
+           assign(dst1, binop(mkSizedOp(ty,Iop_Sub8), mkexpr(dst0), mkexpr(src)));
             setFlags_SRC_DST1(Iop_Sub8, src, dst1, ty);
            putIReg(sz, eregOfRM(modrm), mkexpr(dst1));
             DIP("neg%c %s\n", nameISize(sz), nameIReg(sz, eregOfRM(modrm)));
@@ -2539,9 +2539,9 @@ UInt dis_Grp3 ( UChar sorb, Int sz, UInt delta )
             dst0 = newTemp(ty);
             src  = newTemp(ty);
             dst1 = newTemp(ty);
-            assign(dst0, mkexpr(t1));
-           assign(src,  mkU(ty,0));
-           assign(dst1, binop(mkSizedOp(ty,Iop_Sub8),mkexpr(src), mkexpr(dst0)));
+           assign(dst0, mkU(ty,0));
+            assign(src,  mkexpr(t1));
+           assign(dst1, binop(mkSizedOp(ty,Iop_Sub8), mkexpr(dst0), mkexpr(src)));
             setFlags_SRC_DST1(Iop_Sub8, src, dst1, ty);
            storeLE( mkexpr(addr), mkexpr(dst1) );
             DIP("neg%c %s\n", nameISize(sz), dis_buf);
@@ -2583,7 +2583,6 @@ UInt dis_Grp4 ( UChar sorb, UInt delta )
 
    modrm = getIByte(delta);
    if (epartIsReg(modrm)) {
-//--       uInstr2(cb, GET, 1, ArchReg, eregOfRM(modrm), TempReg, t1);
       assign(t1, getIReg(1, eregOfRM(modrm)));
       switch (gregOfRM(modrm)) {
          case 0: /* INC */
@@ -7585,12 +7584,14 @@ static UInt disInstr ( UInt delta, Bool* isEnd )
                     mkU8(getIByte(d32)), True, /* literal */
                     dis_buf, False );
          break;
-//--       case 0xAD: /* SHRDv %cl,Gv,Ev */
-//--          modrm = getUChar(eip);
-//--          eip = dis_SHLRD_Gv_Ev ( 
-//--                   cb, sorb, eip, modrm, sz, ArchReg, R_CL, False );
-//--          break;
-//-- 
+      case 0xAD: /* SHRDv %cl,Gv,Ev */
+         modrm = getIByte(delta);
+         delta = dis_SHLRD_Gv_Ev ( 
+                    sorb, delta, modrm, sz, 
+                    getIReg(1,R_ECX), False, /* not literal */
+                    "%cl", False );
+         break;
+
 //--       /* =-=-=-=-=-=-=-=-=- CMPXCHG -=-=-=-=-=-=-=-=-=-= */
 //-- 
 //--       case 0xC0: /* XADD Gb,Eb */