isel.c

The Valgrind distribution has multiple tools. The most popular is the memory checking tool (called M

         addInstr(env, X86Instr_Alu32R(
                          Xalu_MOV, 
                          X86RMI_Mem(X86AMode_IR(e->Iex.Get.offset,
                                                 hregX86_EBP())),
                          dst));
         return dst;
      }
      if (ty == Ity_I8 || ty == Ity_I16) {
         HReg dst = newVRegI(env);
         addInstr(env, X86Instr_LoadEX(
                          toUChar(ty==Ity_I8 ? 1 : 2),
                          False,
                          X86AMode_IR(e->Iex.Get.offset,hregX86_EBP()),
                          dst));
         return dst;
      }
      break;
   }

   case Iex_GetI: {
      X86AMode* am 
         = genGuestArrayOffset(
              env, e->Iex.GetI.descr, 
                   e->Iex.GetI.ix, e->Iex.GetI.bias );
      HReg dst = newVRegI(env);
      if (ty == Ity_I8) {
         addInstr(env, X86Instr_LoadEX( 1, False, am, dst ));
         return dst;
      }
      if (ty == Ity_I32) {
         addInstr(env, X86Instr_Alu32R(Xalu_MOV, X86RMI_Mem(am), dst));
         return dst;
      }
      break;
   }

   /* --------- CCALL --------- */
   case Iex_CCall: {
      HReg    dst = newVRegI(env);
      vassert(ty == e->Iex.CCall.retty);

      /* be very restrictive for now.  Only 32/64-bit ints allowed
         for args, and 32 bits for return type. */
      if (e->Iex.CCall.retty != Ity_I32)
         goto irreducible;

      /* Marshal args, do the call, clear stack. */
      doHelperCall( env, False, NULL, e->Iex.CCall.cee, e->Iex.CCall.args );

      addInstr(env, mk_iMOVsd_RR(hregX86_EAX(), dst));
      return dst;
   }

   /* --------- LITERAL --------- */
   /* 32/16/8-bit literals */
   case Iex_Const: {
      X86RMI* rmi = iselIntExpr_RMI ( env, e );
      HReg    r   = newVRegI(env);
      addInstr(env, X86Instr_Alu32R(Xalu_MOV, rmi, r));
      return r;
   }

   /* --------- MULTIPLEX --------- */
   case Iex_Mux0X: {
     if ((ty == Ity_I32 || ty == Ity_I16 || ty == Ity_I8)
         && typeOfIRExpr(env->type_env,e->Iex.Mux0X.cond) == Ity_I8) {
        HReg r8;
        HReg rX   = iselIntExpr_R(env, e->Iex.Mux0X.exprX);
        X86RM* r0 = iselIntExpr_RM(env, e->Iex.Mux0X.expr0);
        HReg dst = newVRegI(env);
        addInstr(env, mk_iMOVsd_RR(rX,dst));
        r8 = iselIntExpr_R(env, e->Iex.Mux0X.cond);
        addInstr(env, X86Instr_Test32(0xFF, r8));
        addInstr(env, X86Instr_CMov32(Xcc_Z,r0,dst));
        return dst;
      }
      break;
   }

   default: 
   break;
   } /* switch (e->tag) */

   /* We get here if no pattern matched. */
  irreducible:
   ppIRExpr(e);
   vpanic("iselIntExpr_R: cannot reduce tree");
}


/*---------------------------------------------------------*/
/*--- ISEL: Integer expression auxiliaries              ---*/
/*---------------------------------------------------------*/

/* --------------------- AMODEs --------------------- */

/* Return an AMode which computes the value of the specified
   expression, possibly also adding insns to the code list as a
   result.  The expression may only be a 32-bit one.
*/

static Bool sane_AMode ( X86AMode* am )
{
   switch (am->tag) {
      case Xam_IR:
         return 
            toBool( hregClass(am->Xam.IR.reg) == HRcInt32
                    && (hregIsVirtual(am->Xam.IR.reg)
                        || am->Xam.IR.reg == hregX86_EBP()) );
      case Xam_IRRS:
         return 
            toBool( hregClass(am->Xam.IRRS.base) == HRcInt32
                    && hregIsVirtual(am->Xam.IRRS.base)
                    && hregClass(am->Xam.IRRS.index) == HRcInt32
                    && hregIsVirtual(am->Xam.IRRS.index) );
      default:
        vpanic("sane_AMode: unknown x86 amode tag");
   }
}

static X86AMode* iselIntExpr_AMode ( ISelEnv* env, IRExpr* e )
{
   X86AMode* am = iselIntExpr_AMode_wrk(env, e);
   vassert(sane_AMode(am));
   return am;
}

/* DO NOT CALL THIS DIRECTLY ! */
static X86AMode* iselIntExpr_AMode_wrk ( ISelEnv* env, IRExpr* e )
{
   IRType ty = typeOfIRExpr(env->type_env,e);
   vassert(ty == Ity_I32);

   /* Add32(expr1, Shl32(expr2, imm)) */
   if (e->tag == Iex_Binop
       && e->Iex.Binop.op == Iop_Add32
       && e->Iex.Binop.arg2->tag == Iex_Binop
       && e->Iex.Binop.arg2->Iex.Binop.op == Iop_Shl32
       && e->Iex.Binop.arg2->Iex.Binop.arg2->tag == Iex_Const
       && e->Iex.Binop.arg2->Iex.Binop.arg2->Iex.Const.con->tag == Ico_U8) {
      UInt shift = e->Iex.Binop.arg2->Iex.Binop.arg2->Iex.Const.con->Ico.U8;
      if (shift == 1 || shift == 2 || shift == 3) {
         HReg r1 = iselIntExpr_R(env, e->Iex.Binop.arg1);
         HReg r2 = iselIntExpr_R(env, e->Iex.Binop.arg2->Iex.Binop.arg1 );
         return X86AMode_IRRS(0, r1, r2, shift);
      }
   }

   /* Add32(expr,i) */
   if (e->tag == Iex_Binop 
       && e->Iex.Binop.op == Iop_Add32
       && e->Iex.Binop.arg2->tag == Iex_Const
       && e->Iex.Binop.arg2->Iex.Const.con->tag == Ico_U32) {
      HReg r1 = iselIntExpr_R(env,  e->Iex.Binop.arg1);
      return X86AMode_IR(e->Iex.Binop.arg2->Iex.Const.con->Ico.U32, r1);
   }

   /* Doesn't match anything in particular.  Generate it into
      a register and use that. */
   {
      HReg r1 = iselIntExpr_R(env, e);
      return X86AMode_IR(0, r1);
   }
}


/* --------------------- RMIs --------------------- */

/* Similarly, calculate an expression into an X86RMI operand.  As with
   iselIntExpr_R, the expression can have type 32, 16 or 8 bits.  */

static X86RMI* iselIntExpr_RMI ( ISelEnv* env, IRExpr* e )
{
   X86RMI* rmi = iselIntExpr_RMI_wrk(env, e);
   /* sanity checks ... */
   switch (rmi->tag) {
      case Xrmi_Imm:
         return rmi;
      case Xrmi_Reg:
         vassert(hregClass(rmi->Xrmi.Reg.reg) == HRcInt32);
         vassert(hregIsVirtual(rmi->Xrmi.Reg.reg));
         return rmi;
      case Xrmi_Mem:
         vassert(sane_AMode(rmi->Xrmi.Mem.am));
         return rmi;
      default:
         vpanic("iselIntExpr_RMI: unknown x86 RMI tag");
   }
}

/* DO NOT CALL THIS DIRECTLY ! */
static X86RMI* iselIntExpr_RMI_wrk ( ISelEnv* env, IRExpr* e )
{
   IRType ty = typeOfIRExpr(env->type_env,e);
   vassert(ty == Ity_I32 || ty == Ity_I16 || ty == Ity_I8);

   /* special case: immediate */
   if (e->tag == Iex_Const) {
      UInt u;
      switch (e->Iex.Const.con->tag) {
         case Ico_U32: u = e->Iex.Const.con->Ico.U32; break;
         case Ico_U16: u = 0xFFFF & (e->Iex.Const.con->Ico.U16); break;
         case Ico_U8:  u = 0xFF   & (e->Iex.Const.con->Ico.U8); break;
         default: vpanic("iselIntExpr_RMI.Iex_Const(x86h)");
      }
      return X86RMI_Imm(u);
   }

   /* special case: 32-bit GET */
   if (e->tag == Iex_Get && ty == Ity_I32) {
      return X86RMI_Mem(X86AMode_IR(e->Iex.Get.offset,
                                    hregX86_EBP()));
   }

   /* special case: 32-bit load from memory */
   if (e->tag == Iex_Load && ty == Ity_I32 && e->Iex.Load.end == Iend_LE) {
      X86AMode* am = iselIntExpr_AMode(env, e->Iex.Load.addr);
      return X86RMI_Mem(am);
   }

   /* default case: calculate into a register and return that */
   {
      HReg r = iselIntExpr_R ( env, e );
      return X86RMI_Reg(r);
   }
}


/* --------------------- RIs --------------------- */

/* Calculate an expression into an X86RI operand.  As with
   iselIntExpr_R, the expression can have type 32, 16 or 8 bits. */

static X86RI* iselIntExpr_RI ( ISelEnv* env, IRExpr* e )
{
   X86RI* ri = iselIntExpr_RI_wrk(env, e);
   /* sanity checks ... */
   switch (ri->tag) {
      case Xri_Imm:
         return ri;
      case Xrmi_Reg:
         vassert(hregClass(ri->Xri.Reg.reg) == HRcInt32);
         vassert(hregIsVirtual(ri->Xri.Reg.reg));
         return ri;
      default:
         vpanic("iselIntExpr_RI: unknown x86 RI tag");
   }
}

/* DO NOT CALL THIS DIRECTLY ! */
static X86RI* iselIntExpr_RI_wrk ( ISelEnv* env, IRExpr* e )
{
   IRType ty = typeOfIRExpr(env->type_env,e);
   vassert(ty == Ity_I32 || ty == Ity_I16 || ty == Ity_I8);

   /* special case: immediate */
   if (e->tag == Iex_Const) {
      UInt u;
      switch (e->Iex.Const.con->tag) {
         case Ico_U32: u = e->Iex.Const.con->Ico.U32; break;
         case Ico_U16: u = 0xFFFF & (e->Iex.Const.con->Ico.U16); break;
         case Ico_U8:  u = 0xFF   & (e->Iex.Const.con->Ico.U8); break;
         default: vpanic("iselIntExpr_RMI.Iex_Const(x86h)");
      }
      return X86RI_Imm(u);
   }

   /* default case: calculate into a register and return that */
   {
      HReg r = iselIntExpr_R ( env, e );
      return X86RI_Reg(r);
   }
}


/* --------------------- RMs --------------------- */

/* Similarly, calculate an expression into an X86RM operand.  As with
   iselIntExpr_R, the expression can have type 32, 16 or 8 bits.  */

static X86RM* iselIntExpr_RM ( ISelEnv* env, IRExpr* e )
{
   X86RM* rm = iselIntExpr_RM_wrk(env, e);
   /* sanity checks ... */
   switch (rm->tag) {
      case Xrm_Reg:
         vassert(hregClass(rm->Xrm.Reg.reg) == HRcInt32);
         vassert(hregIsVirtual(rm->Xrm.Reg.reg));
         return rm;
      case Xrm_Mem:
         vassert(sane_AMode(rm->Xrm.Mem.am));
         return rm;
      default:
         vpanic("iselIntExpr_RM: unknown x86 RM tag");
   }
}

/* DO NOT CALL THIS DIRECTLY ! */
static X86RM* iselIntExpr_RM_wrk ( ISelEnv* env, IRExpr* e )
{
   IRType ty = typeOfIRExpr(env->type_env,e);
   vassert(ty == Ity_I32 || ty == Ity_I16 || ty == Ity_I8);

   /* special case: 32-bit GET */
   if (e->tag == Iex_Get && ty == Ity_I32) {
      return X86RM_Mem(X86AMode_IR(e->Iex.Get.offset,
                                   hregX86_EBP()));
   }

   /* special case: load from memory */

   /* default case: calculate into a register and return that */
   {
      HReg r = iselIntExpr_R ( env, e );
      return X86RM_Reg(r);
   }
}


/* --------------------- CONDCODE --------------------- */

/* Generate code to evaluated a bit-typed expression, returning the
   condition code which would correspond when the expression would
   notionally have returned 1. */

static X86CondCode iselCondCode ( ISelEnv* env, IRExpr* e )
{
   /* Uh, there's nothing we can sanity check here, unfortunately. */
   return iselCondCode_wrk(env,e);
}

/* DO NOT CALL THIS DIRECTLY ! */
static X86CondCode iselCondCode_wrk ( ISelEnv* env, IRExpr* e )
{
   MatchInfo mi;
   DECLARE_PATTERN(p_32to1);
   DECLARE_PATTERN(p_1Uto32_then_32to1);
   DECLARE_PATTERN(p_1Sto32_then_32to1);

   vassert(e);
   vassert(typeOfIRExpr(env->type_env,e) == Ity_I1);

   /* var */
   if (e->tag == Iex_Tmp) {
      HReg r32 = lookupIRTemp(env, e->Iex.Tmp.tmp);
      /* Test32 doesn't modify r32; so this is OK. */
      addInstr(env, X86Instr_Test32(1,r32));
      return Xcc_NZ;
   }

   /* Constant 1:Bit */
   if (e->tag == Iex_Const) {
      HReg r;
      vassert(e->Iex.Const.con->tag == Ico_U1);
      vassert(e->Iex.Const.con->Ico.U1 == True 
              || e->Iex.Const.con->Ico.U1 == False);
      r = newVRegI(env);
      addInstr(env, X86Instr_Alu32R(Xalu_MOV,X86RMI_Imm(0),r));
      addInstr(env, X86Instr_Alu32R(Xalu_XOR,X86RMI_Reg(r),r));
      return e->Iex.Const.con->Ico.U1 ? Xcc_Z : Xcc_NZ;
   }

   /* Not1(e) */
   if (e->tag == Iex_Unop && e->Iex.Unop.op == Iop_Not1) {
      /* Generate code for the arg, and negate the test condition */
      return 1 ^ iselCondCode(env, e->Iex.Unop.arg);
   }

   /* --- patterns rooted at: 32to1 --- */

   /* 32to1(1Uto32(e)) ==> e */
   DEFINE_PATTERN(p_1Uto32_then_32to1,
                  unop(Iop_32to1,unop(Iop_1Uto32,bind(0))));
   if (matchIRExpr(&mi,p_1Uto32_then_32to1,e)) {
      IRExpr* expr1 = mi.bindee[0];
      return iselCondCode(env, expr1);
   }

   /* 32to1(1Sto32(e)) ==> e */
   DEFINE_PATTERN(p_1Sto32_then_32to1,
                  unop(Iop_32to1,unop(Iop_1Sto32,bind(0))));
   if (matchIRExpr(&mi,p_1Sto32_then_32to1,e)) {
      IRExpr* expr1 = mi.bindee[0];
      return iselCondCode(env, expr1);
   }

   /* 32to1(expr32) */