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compiler: Rewrite handling of untyped numeric constants.
[pf3gnuchains/gcc-fork.git] / gcc / go / gofrontend / expressions.cc
index 90cf6f3..4c493f8 100644 (file)
@@ -50,57 +50,6 @@ Expression::~Expression()
 {
 }
 
-// If this expression has a constant integer value, return it.
-
-bool
-Expression::integer_constant_value(bool iota_is_constant, mpz_t val,
-                                  Type** ptype) const
-{
-  *ptype = NULL;
-  return this->do_integer_constant_value(iota_is_constant, val, ptype);
-}
-
-// If this expression has a constant floating point value, return it.
-
-bool
-Expression::float_constant_value(mpfr_t val, Type** ptype) const
-{
-  *ptype = NULL;
-  if (this->do_float_constant_value(val, ptype))
-    return true;
-  mpz_t ival;
-  mpz_init(ival);
-  Type* t;
-  bool ret;
-  if (!this->do_integer_constant_value(false, ival, &t))
-    ret = false;
-  else
-    {
-      mpfr_set_z(val, ival, GMP_RNDN);
-      ret = true;
-    }
-  mpz_clear(ival);
-  return ret;
-}
-
-// If this expression has a constant complex value, return it.
-
-bool
-Expression::complex_constant_value(mpfr_t real, mpfr_t imag,
-                                  Type** ptype) const
-{
-  *ptype = NULL;
-  if (this->do_complex_constant_value(real, imag, ptype))
-    return true;
-  Type *t;
-  if (this->float_constant_value(real, &t))
-    {
-      mpfr_set_ui(imag, 0, GMP_RNDN);
-      return true;
-    }
-  return false;
-}
-
 // Traverse the expressions.
 
 int
@@ -824,24 +773,9 @@ class Error_expression : public Expression
   { return true; }
 
   bool
-  do_integer_constant_value(bool, mpz_t val, Type**) const
-  {
-    mpz_set_ui(val, 0);
-    return true;
-  }
-
-  bool
-  do_float_constant_value(mpfr_t val, Type**) const
-  {
-    mpfr_set_ui(val, 0, GMP_RNDN);
-    return true;
-  }
-
-  bool
-  do_complex_constant_value(mpfr_t real, mpfr_t imag, Type**) const
+  do_numeric_constant_value(Numeric_constant* nc) const
   {
-    mpfr_set_ui(real, 0, GMP_RNDN);
-    mpfr_set_ui(imag, 0, GMP_RNDN);
+    nc->set_unsigned_long(NULL, 0);
     return true;
   }
 
@@ -1759,10 +1693,6 @@ class Integer_expression : public Expression
   static Expression*
   do_import(Import*);
 
-  // Return whether VAL fits in the type.
-  static bool
-  check_constant(mpz_t val, Type*, Location);
-
   // Write VAL to string dump.
   static void
   export_integer(String_dump* exp, const mpz_t val);
@@ -1777,7 +1707,7 @@ class Integer_expression : public Expression
   { return true; }
 
   bool
-  do_integer_constant_value(bool, mpz_t val, Type** ptype) const;
+  do_numeric_constant_value(Numeric_constant* nc) const;
 
   Type*
   do_type();
@@ -1817,15 +1747,16 @@ class Integer_expression : public Expression
   bool is_character_constant_;
 };
 
-// Return an integer constant value.
+// Return a numeric constant for this expression.  We have to mark
+// this as a character when appropriate.
 
 bool
-Integer_expression::do_integer_constant_value(bool, mpz_t val,
-                                             Type** ptype) const
+Integer_expression::do_numeric_constant_value(Numeric_constant* nc) const
 {
-  if (this->type_ != NULL)
-    *ptype = this->type_;
-  mpz_set(val, this->val_);
+  if (this->is_character_constant_)
+    nc->set_rune(this->type_, this->val_);
+  else
+    nc->set_int(this->type_, this->val_);
   return true;
 }
 
@@ -1853,10 +1784,7 @@ Integer_expression::do_determine_type(const Type_context* context)
 {
   if (this->type_ != NULL && !this->type_->is_abstract())
     ;
-  else if (context->type != NULL
-          && (context->type->integer_type() != NULL
-              || context->type->float_type() != NULL
-              || context->type->complex_type() != NULL))
+  else if (context->type != NULL && context->type->is_numeric_type())
     this->type_ = context->type;
   else if (!context->may_be_abstract)
     {
@@ -1867,55 +1795,20 @@ Integer_expression::do_determine_type(const Type_context* context)
     }
 }
 
-// Return true if the integer VAL fits in the range of the type TYPE.
-// Otherwise give an error and return false.  TYPE may be NULL.
-
-bool
-Integer_expression::check_constant(mpz_t val, Type* type,
-                                  Location location)
-{
-  if (type == NULL)
-    return true;
-  Integer_type* itype = type->integer_type();
-  if (itype == NULL || itype->is_abstract())
-    return true;
-
-  int bits = mpz_sizeinbase(val, 2);
-
-  if (itype->is_unsigned())
-    {
-      // For an unsigned type we can only accept a nonnegative number,
-      // and we must be able to represent at least BITS.
-      if (mpz_sgn(val) >= 0
-         && bits <= itype->bits())
-       return true;
-    }
-  else
-    {
-      // For a signed type we need an extra bit to indicate the sign.
-      // We have to handle the most negative integer specially.
-      if (bits + 1 <= itype->bits()
-         || (bits <= itype->bits()
-             && mpz_sgn(val) < 0
-             && (mpz_scan1(val, 0)
-                 == static_cast<unsigned long>(itype->bits() - 1))
-             && mpz_scan0(val, itype->bits()) == ULONG_MAX))
-       return true;
-    }
-
-  error_at(location, "integer constant overflow");
-  return false;
-}
-
 // Check the type of an integer constant.
 
 void
 Integer_expression::do_check_types(Gogo*)
 {
-  if (this->type_ == NULL)
+  Type* type = this->type_;
+  if (type == NULL)
     return;
-  if (!Integer_expression::check_constant(this->val_, this->type_,
-                                         this->location()))
+  Numeric_constant nc;
+  if (this->is_character_constant_)
+    nc.set_rune(NULL, this->val_);
+  else
+    nc.set_int(NULL, this->val_);
+  if (!nc.set_type(type, true, this->location()))
     this->set_is_error();
 }
 
@@ -2117,14 +2010,6 @@ class Float_expression : public Expression
     mpfr_init_set(this->val_, *val, GMP_RNDN);
   }
 
-  // Constrain VAL to fit into TYPE.
-  static void
-  constrain_float(mpfr_t val, Type* type);
-
-  // Return whether VAL fits in the type.
-  static bool
-  check_constant(mpfr_t val, Type*, Location);
-
   // Write VAL to export data.
   static void
   export_float(String_dump* exp, const mpfr_t val);
@@ -2139,7 +2024,11 @@ class Float_expression : public Expression
   { return true; }
 
   bool
-  do_float_constant_value(mpfr_t val, Type**) const;
+  do_numeric_constant_value(Numeric_constant* nc) const
+  {
+    nc->set_float(this->type_, this->val_);
+    return true;
+  }
 
   Type*
   do_type();
@@ -2171,27 +2060,6 @@ class Float_expression : public Expression
   Type* type_;
 };
 
-// Constrain VAL to fit into TYPE.
-
-void
-Float_expression::constrain_float(mpfr_t val, Type* type)
-{
-  Float_type* ftype = type->float_type();
-  if (ftype != NULL && !ftype->is_abstract())
-    mpfr_prec_round(val, ftype->bits(), GMP_RNDN);
-}
-
-// Return a floating point constant value.
-
-bool
-Float_expression::do_float_constant_value(mpfr_t val, Type** ptype) const
-{
-  if (this->type_ != NULL)
-    *ptype = this->type_;
-  mpfr_set(val, this->val_, GMP_RNDN);
-  return true;
-}
-
 // Return the current type.  If we haven't set the type yet, we return
 // an abstract float type.
 
@@ -2220,73 +2088,18 @@ Float_expression::do_determine_type(const Type_context* context)
     this->type_ = Type::lookup_float_type("float64");
 }
 
-// Return true if the floating point value VAL fits in the range of
-// the type TYPE.  Otherwise give an error and return false.  TYPE may
-// be NULL.
-
-bool
-Float_expression::check_constant(mpfr_t val, Type* type,
-                                Location location)
-{
-  if (type == NULL)
-    return true;
-  Float_type* ftype = type->float_type();
-  if (ftype == NULL || ftype->is_abstract())
-    return true;
-
-  // A NaN or Infinity always fits in the range of the type.
-  if (mpfr_nan_p(val) || mpfr_inf_p(val) || mpfr_zero_p(val))
-    return true;
-
-  mp_exp_t exp = mpfr_get_exp(val);
-  mp_exp_t max_exp;
-  switch (ftype->bits())
-    {
-    case 32:
-      max_exp = 128;
-      break;
-    case 64:
-      max_exp = 1024;
-      break;
-    default:
-      go_unreachable();
-    }
-  if (exp > max_exp)
-    {
-      error_at(location, "floating point constant overflow");
-      return false;
-    }
-  return true;
-}
-
 // Check the type of a float value.
 
 void
 Float_expression::do_check_types(Gogo*)
 {
-  if (this->type_ == NULL)
+  Type* type = this->type_;
+  if (type == NULL)
     return;
-
-  if (!Float_expression::check_constant(this->val_, this->type_,
-                                       this->location()))
+  Numeric_constant nc;
+  nc.set_float(NULL, this->val_);
+  if (!nc.set_type(this->type_, true, this->location()))
     this->set_is_error();
-
-  Integer_type* integer_type = this->type_->integer_type();
-  if (integer_type != NULL)
-    {
-      if (!mpfr_integer_p(this->val_))
-       this->report_error(_("floating point constant truncated to integer"));
-      else
-       {
-         go_assert(!integer_type->is_abstract());
-         mpz_t ival;
-         mpz_init(ival);
-         mpfr_get_z(ival, this->val_, GMP_RNDN);
-         Integer_expression::check_constant(ival, integer_type,
-                                            this->location());
-         mpz_clear(ival);
-       }
-    }
 }
 
 // Get a tree for a float constant.
@@ -2371,14 +2184,6 @@ class Complex_expression : public Expression
     mpfr_init_set(this->imag_, *imag, GMP_RNDN);
   }
 
-  // Constrain REAL/IMAG to fit into TYPE.
-  static void
-  constrain_complex(mpfr_t real, mpfr_t imag, Type* type);
-
-  // Return whether REAL/IMAG fits in the type.
-  static bool
-  check_constant(mpfr_t real, mpfr_t imag, Type*, Location);
-
   // Write REAL/IMAG to string dump.
   static void
   export_complex(String_dump* exp, const mpfr_t real, const mpfr_t val);
@@ -2394,7 +2199,11 @@ class Complex_expression : public Expression
   { return true; }
 
   bool
-  do_complex_constant_value(mpfr_t real, mpfr_t imag, Type**) const;
+  do_numeric_constant_value(Numeric_constant* nc) const
+  {
+    nc->set_complex(this->type_, this->real_, this->imag_);
+    return true;
+  }
 
   Type*
   do_type();
@@ -2430,32 +2239,6 @@ class Complex_expression : public Expression
   Type* type_;
 };
 
-// Constrain REAL/IMAG to fit into TYPE.
-
-void
-Complex_expression::constrain_complex(mpfr_t real, mpfr_t imag, Type* type)
-{
-  Complex_type* ctype = type->complex_type();
-  if (ctype != NULL && !ctype->is_abstract())
-    {
-      mpfr_prec_round(real, ctype->bits() / 2, GMP_RNDN);
-      mpfr_prec_round(imag, ctype->bits() / 2, GMP_RNDN);
-    }
-}
-
-// Return a complex constant value.
-
-bool
-Complex_expression::do_complex_constant_value(mpfr_t real, mpfr_t imag,
-                                             Type** ptype) const
-{
-  if (this->type_ != NULL)
-    *ptype = this->type_;
-  mpfr_set(real, this->real_, GMP_RNDN);
-  mpfr_set(imag, this->imag_, GMP_RNDN);
-  return true;
-}
-
 // Return the current type.  If we haven't set the type yet, we return
 // an abstract complex type.
 
@@ -2482,65 +2265,17 @@ Complex_expression::do_determine_type(const Type_context* context)
     this->type_ = Type::lookup_complex_type("complex128");
 }
 
-// Return true if the complex value REAL/IMAG fits in the range of the
-// type TYPE.  Otherwise give an error and return false.  TYPE may be
-// NULL.
-
-bool
-Complex_expression::check_constant(mpfr_t real, mpfr_t imag, Type* type,
-                                  Location location)
-{
-  if (type == NULL)
-    return true;
-  Complex_type* ctype = type->complex_type();
-  if (ctype == NULL || ctype->is_abstract())
-    return true;
-
-  mp_exp_t max_exp;
-  switch (ctype->bits())
-    {
-    case 64:
-      max_exp = 128;
-      break;
-    case 128:
-      max_exp = 1024;
-      break;
-    default:
-      go_unreachable();
-    }
-
-  // A NaN or Infinity always fits in the range of the type.
-  if (!mpfr_nan_p(real) && !mpfr_inf_p(real) && !mpfr_zero_p(real))
-    {
-      if (mpfr_get_exp(real) > max_exp)
-       {
-         error_at(location, "complex real part constant overflow");
-         return false;
-       }
-    }
-
-  if (!mpfr_nan_p(imag) && !mpfr_inf_p(imag) && !mpfr_zero_p(imag))
-    {
-      if (mpfr_get_exp(imag) > max_exp)
-       {
-         error_at(location, "complex imaginary part constant overflow");
-         return false;
-       }
-    }
-
-  return true;
-}
-
 // Check the type of a complex value.
 
 void
 Complex_expression::do_check_types(Gogo*)
 {
-  if (this->type_ == NULL)
+  Type* type = this->type_;
+  if (type == NULL)
     return;
-
-  if (!Complex_expression::check_constant(this->real_, this->imag_,
-                                         this->type_, this->location()))
+  Numeric_constant nc;
+  nc.set_complex(NULL, this->real_, this->imag_);
+  if (!nc.set_type(this->type_, true, this->location()))
     this->set_is_error();
 }
 
@@ -2665,13 +2400,7 @@ class Const_expression : public Expression
   { return true; }
 
   bool
-  do_integer_constant_value(bool, mpz_t val, Type**) const;
-
-  bool
-  do_float_constant_value(mpfr_t val, Type**) const;
-
-  bool
-  do_complex_constant_value(mpfr_t real, mpfr_t imag, Type**) const;
+  do_numeric_constant_value(Numeric_constant* nc) const;
 
   bool
   do_string_constant_value(std::string* val) const
@@ -2755,109 +2484,33 @@ Const_expression::do_lower(Gogo* gogo, Named_object*,
   return this;
 }
 
-// Return an integer constant value.
+// Return a numeric constant value.
 
 bool
-Const_expression::do_integer_constant_value(bool iota_is_constant, mpz_t val,
-                                           Type** ptype) const
+Const_expression::do_numeric_constant_value(Numeric_constant* nc) const
 {
   if (this->seen_)
     return false;
 
-  Type* ctype;
-  if (this->type_ != NULL)
-    ctype = this->type_;
-  else
-    ctype = this->constant_->const_value()->type();
-  if (ctype != NULL && ctype->integer_type() == NULL)
-    return false;
-
   Expression* e = this->constant_->const_value()->expr();
-
+  
   this->seen_ = true;
 
-  Type* t;
-  bool r = e->integer_constant_value(iota_is_constant, val, &t);
+  bool r = e->numeric_constant_value(nc);
 
   this->seen_ = false;
 
-  if (r
-      && ctype != NULL
-      && !Integer_expression::check_constant(val, ctype, this->location()))
-    return false;
-
-  *ptype = ctype != NULL ? ctype : t;
-  return r;
-}
-
-// Return a floating point constant value.
-
-bool
-Const_expression::do_float_constant_value(mpfr_t val, Type** ptype) const
-{
-  if (this->seen_)
-    return false;
-
   Type* ctype;
   if (this->type_ != NULL)
     ctype = this->type_;
   else
     ctype = this->constant_->const_value()->type();
-  if (ctype != NULL && ctype->float_type() == NULL)
-    return false;
-
-  this->seen_ = true;
-
-  Type* t;
-  bool r = this->constant_->const_value()->expr()->float_constant_value(val,
-                                                                       &t);
-
-  this->seen_ = false;
-
   if (r && ctype != NULL)
     {
-      if (!Float_expression::check_constant(val, ctype, this->location()))
+      if (!nc->set_type(ctype, false, this->location()))
        return false;
-      Float_expression::constrain_float(val, ctype);
     }
-  *ptype = ctype != NULL ? ctype : t;
-  return r;
-}
-
-// Return a complex constant value.
 
-bool
-Const_expression::do_complex_constant_value(mpfr_t real, mpfr_t imag,
-                                           Type **ptype) const
-{
-  if (this->seen_)
-    return false;
-
-  Type* ctype;
-  if (this->type_ != NULL)
-    ctype = this->type_;
-  else
-    ctype = this->constant_->const_value()->type();
-  if (ctype != NULL && ctype->complex_type() == NULL)
-    return false;
-
-  this->seen_ = true;
-
-  Type *t;
-  bool r = this->constant_->const_value()->expr()->complex_constant_value(real,
-                                                                         imag,
-                                                                         &t);
-
-  this->seen_ = false;
-
-  if (r && ctype != NULL)
-    {
-      if (!Complex_expression::check_constant(real, imag, ctype,
-                                             this->location()))
-       return false;
-      Complex_expression::constrain_complex(real, imag, ctype);
-    }
-  *ptype = ctype != NULL ? ctype : t;
   return r;
 }
 
@@ -2909,12 +2562,8 @@ Const_expression::do_determine_type(const Type_context* context)
   if (ctype != NULL && !ctype->is_abstract())
     ;
   else if (context->type != NULL
-          && (context->type->integer_type() != NULL
-              || context->type->float_type() != NULL
-              || context->type->complex_type() != NULL)
-          && (cetype->integer_type() != NULL
-              || cetype->float_type() != NULL
-              || cetype->complex_type() != NULL))
+          && context->type->is_numeric_type()
+          && cetype->is_numeric_type())
     this->type_ = context->type;
   else if (context->type != NULL
           && context->type->is_string_type()
@@ -2976,35 +2625,15 @@ Const_expression::do_check_types(Gogo*)
 
   this->check_for_init_loop();
 
-  if (this->type_ == NULL || this->type_->is_abstract())
-    return;
-
-  // Check for integer overflow.
-  if (this->type_->integer_type() != NULL)
+  // Check that numeric constant fits in type.
+  if (this->type_ != NULL && this->type_->is_numeric_type())
     {
-      mpz_t ival;
-      mpz_init(ival);
-      Type* dummy;
-      if (!this->integer_constant_value(true, ival, &dummy))
+      Numeric_constant nc;
+      if (this->constant_->const_value()->expr()->numeric_constant_value(&nc))
        {
-         mpfr_t fval;
-         mpfr_init(fval);
-         Expression* cexpr = this->constant_->const_value()->expr();
-         if (cexpr->float_constant_value(fval, &dummy))
-           {
-             if (!mpfr_integer_p(fval))
-               this->report_error(_("floating point constant "
-                                    "truncated to integer"));
-             else
-               {
-                 mpfr_get_z(ival, fval, GMP_RNDN);
-                 Integer_expression::check_constant(ival, this->type_,
-                                                    this->location());
-               }
-           }
-         mpfr_clear(fval);
+         if (!nc.set_type(this->type_, true, this->location()))
+           this->set_is_error();
        }
-      mpz_clear(ival);
     }
 }
 
@@ -3028,41 +2657,18 @@ Const_expression::do_get_tree(Translate_context* context)
   // object is an abstract int or float, we try to get the abstract
   // value.  Otherwise we may lose something in the conversion.
   if (this->type_ != NULL
+      && this->type_->is_numeric_type()
       && (this->constant_->const_value()->type() == NULL
          || this->constant_->const_value()->type()->is_abstract()))
     {
       Expression* expr = this->constant_->const_value()->expr();
-      mpz_t ival;
-      mpz_init(ival);
-      Type* t;
-      if (expr->integer_constant_value(true, ival, &t))
-       {
-         tree ret = Expression::integer_constant_tree(ival, type_tree);
-         mpz_clear(ival);
-         return ret;
-       }
-      mpz_clear(ival);
-
-      mpfr_t fval;
-      mpfr_init(fval);
-      if (expr->float_constant_value(fval, &t))
-       {
-         tree ret = Expression::float_constant_tree(fval, type_tree);
-         mpfr_clear(fval);
-         return ret;
-       }
-
-      mpfr_t imag;
-      mpfr_init(imag);
-      if (expr->complex_constant_value(fval, imag, &t))
+      Numeric_constant nc;
+      if (expr->numeric_constant_value(&nc)
+         && nc.set_type(this->type_, false, this->location()))
        {
-         tree ret = Expression::complex_constant_tree(fval, imag, type_tree);
-         mpfr_clear(fval);
-         mpfr_clear(imag);
-         return ret;
+         Expression* e = nc.expression(this->location());
+         return e->get_tree(context);
        }
-      mpfr_clear(imag);
-      mpfr_clear(fval);
     }
 
   tree const_tree = this->constant_->get_tree(gogo, context->function());
@@ -3279,13 +2885,7 @@ class Type_conversion_expression : public Expression
   { return this->expr_->is_constant(); }
 
   bool
-  do_integer_constant_value(bool, mpz_t, Type**) const;
-
-  bool
-  do_float_constant_value(mpfr_t, Type**) const;
-
-  bool
-  do_complex_constant_value(mpfr_t, mpfr_t, Type**) const;
+  do_numeric_constant_value(Numeric_constant*) const;
 
   bool
   do_string_constant_value(std::string*) const;
@@ -3351,82 +2951,15 @@ Type_conversion_expression::do_lower(Gogo*, Named_object*,
   Expression* val = this->expr_;
   Location location = this->location();
 
-  if (type->integer_type() != NULL)
-    {
-      mpz_t ival;
-      mpz_init(ival);
-      Type* dummy;
-      if (val->integer_constant_value(false, ival, &dummy))
-       {
-         if (!Integer_expression::check_constant(ival, type, location))
-           mpz_set_ui(ival, 0);
-         Expression* ret = Expression::make_integer(&ival, type, location);
-         mpz_clear(ival);
-         return ret;
-       }
-
-      mpfr_t fval;
-      mpfr_init(fval);
-      if (val->float_constant_value(fval, &dummy))
-       {
-         if (!mpfr_integer_p(fval))
-           {
-             error_at(location,
-                      "floating point constant truncated to integer");
-             return Expression::make_error(location);
-           }
-         mpfr_get_z(ival, fval, GMP_RNDN);
-         if (!Integer_expression::check_constant(ival, type, location))
-           mpz_set_ui(ival, 0);
-         Expression* ret = Expression::make_integer(&ival, type, location);
-         mpfr_clear(fval);
-         mpz_clear(ival);
-         return ret;
-       }
-      mpfr_clear(fval);
-      mpz_clear(ival);
-    }
-
-  if (type->float_type() != NULL)
-    {
-      mpfr_t fval;
-      mpfr_init(fval);
-      Type* dummy;
-      if (val->float_constant_value(fval, &dummy))
-       {
-         if (!Float_expression::check_constant(fval, type, location))
-           mpfr_set_ui(fval, 0, GMP_RNDN);
-         Float_expression::constrain_float(fval, type);
-         Expression *ret = Expression::make_float(&fval, type, location);
-         mpfr_clear(fval);
-         return ret;
-       }
-      mpfr_clear(fval);
-    }
-
-  if (type->complex_type() != NULL)
+  if (type->is_numeric_type())
     {
-      mpfr_t real;
-      mpfr_t imag;
-      mpfr_init(real);
-      mpfr_init(imag);
-      Type* dummy;
-      if (val->complex_constant_value(real, imag, &dummy))
+      Numeric_constant nc;
+      if (val->numeric_constant_value(&nc))
        {
-         if (!Complex_expression::check_constant(real, imag, type, location))
-           {
-             mpfr_set_ui(real, 0, GMP_RNDN);
-             mpfr_set_ui(imag, 0, GMP_RNDN);
-           }
-         Complex_expression::constrain_complex(real, imag, type);
-         Expression* ret = Expression::make_complex(&real, &imag, type,
-                                                    location);
-         mpfr_clear(real);
-         mpfr_clear(imag);
-         return ret;
+         if (!nc.set_type(type, true, location))
+           return Expression::make_error(location);
+         return nc.expression(location);
        }
-      mpfr_clear(real);
-      mpfr_clear(imag);
     }
 
   if (type->is_slice_type())
@@ -3491,118 +3024,17 @@ Type_conversion_expression::do_lower(Gogo*, Named_object*,
   return this;
 }
 
-// Return the constant integer value if there is one.
-
-bool
-Type_conversion_expression::do_integer_constant_value(bool iota_is_constant,
-                                                     mpz_t val,
-                                                     Type** ptype) const
-{
-  if (this->type_->integer_type() == NULL)
-    return false;
-
-  mpz_t ival;
-  mpz_init(ival);
-  Type* dummy;
-  if (this->expr_->integer_constant_value(iota_is_constant, ival, &dummy))
-    {
-      if (!Integer_expression::check_constant(ival, this->type_,
-                                             this->location()))
-       {
-         mpz_clear(ival);
-         return false;
-       }
-      mpz_set(val, ival);
-      mpz_clear(ival);
-      *ptype = this->type_;
-      return true;
-    }
-  mpz_clear(ival);
-
-  mpfr_t fval;
-  mpfr_init(fval);
-  if (this->expr_->float_constant_value(fval, &dummy))
-    {
-      mpfr_get_z(val, fval, GMP_RNDN);
-      mpfr_clear(fval);
-      if (!Integer_expression::check_constant(val, this->type_,
-                                             this->location()))
-       return false;
-      *ptype = this->type_;
-      return true;
-    }
-  mpfr_clear(fval);
-
-  return false;
-}
-
-// Return the constant floating point value if there is one.
+// Return the constant numeric value if there is one.
 
 bool
-Type_conversion_expression::do_float_constant_value(mpfr_t val,
-                                                   Type** ptype) const
+Type_conversion_expression::do_numeric_constant_value(
+    Numeric_constant* nc) const
 {
-  if (this->type_->float_type() == NULL)
+  if (!this->type_->is_numeric_type())
     return false;
-
-  mpfr_t fval;
-  mpfr_init(fval);
-  Type* dummy;
-  if (this->expr_->float_constant_value(fval, &dummy))
-    {
-      if (!Float_expression::check_constant(fval, this->type_,
-                                           this->location()))
-       {
-         mpfr_clear(fval);
-         return false;
-       }
-      mpfr_set(val, fval, GMP_RNDN);
-      mpfr_clear(fval);
-      Float_expression::constrain_float(val, this->type_);
-      *ptype = this->type_;
-      return true;
-    }
-  mpfr_clear(fval);
-
-  return false;
-}
-
-// Return the constant complex value if there is one.
-
-bool
-Type_conversion_expression::do_complex_constant_value(mpfr_t real,
-                                                     mpfr_t imag,
-                                                     Type **ptype) const
-{
-  if (this->type_->complex_type() == NULL)
+  if (!this->expr_->numeric_constant_value(nc))
     return false;
-
-  mpfr_t rval;
-  mpfr_t ival;
-  mpfr_init(rval);
-  mpfr_init(ival);
-  Type* dummy;
-  if (this->expr_->complex_constant_value(rval, ival, &dummy))
-    {
-      if (!Complex_expression::check_constant(rval, ival, this->type_,
-                                             this->location()))
-       {
-         mpfr_clear(rval);
-         mpfr_clear(ival);
-         return false;
-       }
-      mpfr_set(real, rval, GMP_RNDN);
-      mpfr_set(imag, ival, GMP_RNDN);
-      mpfr_clear(rval);
-      mpfr_clear(ival);
-      Complex_expression::constrain_complex(real, imag, this->type_);
-      *ptype = this->type_;
-      return true;
-    }
-  mpfr_clear(rval);
-  mpfr_clear(ival);
-
-  return false;  
+  return nc->set_type(this->type_, false, this->location());
 }
 
 // Return the constant string value if there is one.
@@ -3613,20 +3045,17 @@ Type_conversion_expression::do_string_constant_value(std::string* val) const
   if (this->type_->is_string_type()
       && this->expr_->type()->integer_type() != NULL)
     {
-      mpz_t ival;
-      mpz_init(ival);
-      Type* dummy;
-      if (this->expr_->integer_constant_value(false, ival, &dummy))
+      Numeric_constant nc;
+      if (this->expr_->numeric_constant_value(&nc))
        {
-         unsigned long ulval = mpz_get_ui(ival);
-         if (mpz_cmp_ui(ival, ulval) == 0)
+         unsigned long ival;
+         if (nc.to_unsigned_long(&ival) == Numeric_constant::NC_UL_VALID)
            {
-             Lex::append_char(ulval, true, val, this->location());
-             mpz_clear(ival);
+             val->clear();
+             Lex::append_char(ival, true, val, this->location());
              return true;
            }
        }
-      mpz_clear(ival);
     }
 
   // FIXME: Could handle conversion from const []int here.
@@ -4041,22 +3470,11 @@ class Unary_expression : public Expression
     this->create_temp_ = true;
   }
 
-  // Apply unary opcode OP to UVAL, setting VAL.  Return true if this
-  // could be done, false if not.
+  // Apply unary opcode OP to UNC, setting NC.  Return true if this
+  // could be done, false if not.  Issue errors for overflow.
   static bool
-  eval_integer(Operator op, Type* utype, mpz_t uval, mpz_t val,
-              Location);
-
-  // Apply unary opcode OP to UVAL, setting VAL.  Return true if this
-  // could be done, false if not.
-  static bool
-  eval_float(Operator op, mpfr_t uval, mpfr_t val);
-
-  // Apply unary opcode OP to UREAL/UIMAG, setting REAL/IMAG.  Return
-  // true if this could be done, false if not.
-  static bool
-  eval_complex(Operator op, mpfr_t ureal, mpfr_t uimag, mpfr_t real,
-              mpfr_t imag);
+  eval_constant(Operator op, const Numeric_constant* unc,
+               Location, Numeric_constant* nc);
 
   static Expression*
   do_import(Import*);
@@ -4073,13 +3491,7 @@ class Unary_expression : public Expression
   do_is_constant() const;
 
   bool
-  do_integer_constant_value(bool, mpz_t, Type**) const;
-
-  bool
-  do_float_constant_value(mpfr_t, Type**) const;
-
-  bool
-  do_complex_constant_value(mpfr_t, mpfr_t, Type**) const;
+  do_numeric_constant_value(Numeric_constant*) const;
 
   Type*
   do_type();
@@ -4181,59 +3593,12 @@ Unary_expression::do_lower(Gogo*, Named_object*, Statement_inserter*, int)
   if (op == OPERATOR_PLUS || op == OPERATOR_MINUS
       || op == OPERATOR_NOT || op == OPERATOR_XOR)
     {
-      Expression* ret = NULL;
-
-      mpz_t eval;
-      mpz_init(eval);
-      Type* etype;
-      if (expr->integer_constant_value(false, eval, &etype))
-       {
-         mpz_t val;
-         mpz_init(val);
-         if (Unary_expression::eval_integer(op, etype, eval, val, loc))
-           ret = Expression::make_integer(&val, etype, loc);
-         mpz_clear(val);
-       }
-      mpz_clear(eval);
-      if (ret != NULL)
-       return ret;
-
-      if (op == OPERATOR_PLUS || op == OPERATOR_MINUS)
+      Numeric_constant nc;
+      if (expr->numeric_constant_value(&nc))
        {
-         mpfr_t fval;
-         mpfr_init(fval);
-         Type* ftype;
-         if (expr->float_constant_value(fval, &ftype))
-           {
-             mpfr_t val;
-             mpfr_init(val);
-             if (Unary_expression::eval_float(op, fval, val))
-               ret = Expression::make_float(&val, ftype, loc);
-             mpfr_clear(val);
-           }
-         if (ret != NULL)
-           {
-             mpfr_clear(fval);
-             return ret;
-           }
-
-         mpfr_t ival;
-         mpfr_init(ival);
-         if (expr->complex_constant_value(fval, ival, &ftype))
-           {
-             mpfr_t real;
-             mpfr_t imag;
-             mpfr_init(real);
-             mpfr_init(imag);
-             if (Unary_expression::eval_complex(op, fval, ival, real, imag))
-               ret = Expression::make_complex(&real, &imag, ftype, loc);
-             mpfr_clear(real);
-             mpfr_clear(imag);
-           }
-         mpfr_clear(ival);
-         mpfr_clear(fval);
-         if (ret != NULL)
-           return ret;
+         Numeric_constant result;
+         if (Unary_expression::eval_constant(op, &nc, loc, &result))
+           return result.expression(loc);
        }
     }
 
@@ -4269,199 +3634,171 @@ Unary_expression::do_is_constant() const
     return this->expr_->is_constant();
 }
 
-// Apply unary opcode OP to UVAL, setting VAL.  UTYPE is the type of
-// UVAL, if known; it may be NULL.  Return true if this could be done,
-// false if not.
+// Apply unary opcode OP to UNC, setting NC.  Return true if this
+// could be done, false if not.  Issue errors for overflow.
 
 bool
-Unary_expression::eval_integer(Operator op, Type* utype, mpz_t uval, mpz_t val,
-                              Location location)
+Unary_expression::eval_constant(Operator op, const Numeric_constant* unc,
+                               Location location, Numeric_constant* nc)
 {
   switch (op)
     {
     case OPERATOR_PLUS:
-      mpz_set(val, uval);
+      *nc = *unc;
       return true;
+
     case OPERATOR_MINUS:
-      mpz_neg(val, uval);
-      return Integer_expression::check_constant(val, utype, location);
-    case OPERATOR_NOT:
-      mpz_set_ui(val, mpz_cmp_si(uval, 0) == 0 ? 1 : 0);
-      return true;
-    case OPERATOR_XOR:
-      if (utype == NULL
-         || utype->integer_type() == NULL
-         || utype->integer_type()->is_abstract())
-       mpz_com(val, uval);
+      if (unc->is_int() || unc->is_rune())
+       break;
+      else if (unc->is_float())
+       {
+         mpfr_t uval;
+         unc->get_float(&uval);
+         mpfr_t val;
+         mpfr_init(val);
+         mpfr_neg(val, uval, GMP_RNDN);
+         nc->set_float(unc->type(), val);
+         mpfr_clear(uval);
+         mpfr_clear(val);
+         return true;
+       }
+      else if (unc->is_complex())
+       {
+         mpfr_t ureal, uimag;
+         unc->get_complex(&ureal, &uimag);
+         mpfr_t real, imag;
+         mpfr_init(real);
+         mpfr_init(imag);
+         mpfr_neg(real, ureal, GMP_RNDN);
+         mpfr_neg(imag, uimag, GMP_RNDN);
+         nc->set_complex(unc->type(), real, imag);
+         mpfr_clear(ureal);
+         mpfr_clear(uimag);
+         mpfr_clear(real);
+         mpfr_clear(imag);
+         return true;
+       }
       else
-       {
-         // The number of HOST_WIDE_INTs that it takes to represent
-         // UVAL.
-         size_t count = ((mpz_sizeinbase(uval, 2)
-                          + HOST_BITS_PER_WIDE_INT
-                          - 1)
-                         / HOST_BITS_PER_WIDE_INT);
-
-         unsigned HOST_WIDE_INT* phwi = new unsigned HOST_WIDE_INT[count];
-         memset(phwi, 0, count * sizeof(HOST_WIDE_INT));
-
-         size_t obits = utype->integer_type()->bits();
-
-         if (!utype->integer_type()->is_unsigned()
-             && mpz_sgn(uval) < 0)
-           {
-             mpz_t adj;
-             mpz_init_set_ui(adj, 1);
-             mpz_mul_2exp(adj, adj, obits);
-             mpz_add(uval, uval, adj);
-             mpz_clear(adj);
-           }
-
-         size_t ecount;
-         mpz_export(phwi, &ecount, -1, sizeof(HOST_WIDE_INT), 0, 0, uval);
-         go_assert(ecount <= count);
-
-         // Trim down to the number of words required by the type.
-         size_t ocount = ((obits + HOST_BITS_PER_WIDE_INT - 1)
-                          / HOST_BITS_PER_WIDE_INT);
-         go_assert(ocount <= count);
-
-         for (size_t i = 0; i < ocount; ++i)
-           phwi[i] = ~phwi[i];
-
-         size_t clearbits = ocount * HOST_BITS_PER_WIDE_INT - obits;
-         if (clearbits != 0)
-           phwi[ocount - 1] &= (((unsigned HOST_WIDE_INT) (HOST_WIDE_INT) -1)
-                                >> clearbits);
-
-         mpz_import(val, ocount, -1, sizeof(HOST_WIDE_INT), 0, 0, phwi);
+       go_unreachable();
 
-         if (!utype->integer_type()->is_unsigned()
-             && mpz_tstbit(val, obits - 1))
-           {
-             mpz_t adj;
-             mpz_init_set_ui(adj, 1);
-             mpz_mul_2exp(adj, adj, obits);
-             mpz_sub(val, val, adj);
-             mpz_clear(adj);
-           }
+    case OPERATOR_NOT:
+    case OPERATOR_XOR:
+      break;
 
-         delete[] phwi;
-       }
-      return Integer_expression::check_constant(val, utype, location);
     case OPERATOR_AND:
     case OPERATOR_MULT:
       return false;
+
     default:
       go_unreachable();
     }
-}
 
-// Apply unary opcode OP to UVAL, setting VAL.  Return true if this
-// could be done, false if not.
+  if (!unc->is_int() && !unc->is_rune())
+    return false;
+
+  mpz_t uval;
+  unc->get_int(&uval);
+  mpz_t val;
+  mpz_init(val);
 
-bool
-Unary_expression::eval_float(Operator op, mpfr_t uval, mpfr_t val)
-{
   switch (op)
     {
-    case OPERATOR_PLUS:
-      mpfr_set(val, uval, GMP_RNDN);
-      return true;
     case OPERATOR_MINUS:
-      mpfr_neg(val, uval, GMP_RNDN);
-      return true;
+      mpz_neg(val, uval);
+      break;
+
     case OPERATOR_NOT:
+      mpz_set_ui(val, mpz_cmp_si(uval, 0) == 0 ? 1 : 0);
+      break;
+
     case OPERATOR_XOR:
-    case OPERATOR_AND:
-    case OPERATOR_MULT:
-      return false;
-    default:
-      go_unreachable();
-    }
-}
+      {
+       Type* utype = unc->type();
+       if (utype->integer_type() == NULL
+           || utype->integer_type()->is_abstract())
+         mpz_com(val, uval);
+       else
+         {
+           // The number of HOST_WIDE_INTs that it takes to represent
+           // UVAL.
+           size_t count = ((mpz_sizeinbase(uval, 2)
+                            + HOST_BITS_PER_WIDE_INT
+                            - 1)
+                           / HOST_BITS_PER_WIDE_INT);
 
-// Apply unary opcode OP to RVAL/IVAL, setting REAL/IMAG.  Return true
-// if this could be done, false if not.
+           unsigned HOST_WIDE_INT* phwi = new unsigned HOST_WIDE_INT[count];
+           memset(phwi, 0, count * sizeof(HOST_WIDE_INT));
+
+           size_t obits = utype->integer_type()->bits();
+
+           if (!utype->integer_type()->is_unsigned() && mpz_sgn(uval) < 0)
+             {
+               mpz_t adj;
+               mpz_init_set_ui(adj, 1);
+               mpz_mul_2exp(adj, adj, obits);
+               mpz_add(uval, uval, adj);
+               mpz_clear(adj);
+             }
+
+           size_t ecount;
+           mpz_export(phwi, &ecount, -1, sizeof(HOST_WIDE_INT), 0, 0, uval);
+           go_assert(ecount <= count);
+
+           // Trim down to the number of words required by the type.
+           size_t ocount = ((obits + HOST_BITS_PER_WIDE_INT - 1)
+                            / HOST_BITS_PER_WIDE_INT);
+           go_assert(ocount <= count);
+
+           for (size_t i = 0; i < ocount; ++i)
+             phwi[i] = ~phwi[i];
+
+           size_t clearbits = ocount * HOST_BITS_PER_WIDE_INT - obits;
+           if (clearbits != 0)
+             phwi[ocount - 1] &= (((unsigned HOST_WIDE_INT) (HOST_WIDE_INT) -1)
+                                  >> clearbits);
+
+           mpz_import(val, ocount, -1, sizeof(HOST_WIDE_INT), 0, 0, phwi);
+
+           if (!utype->integer_type()->is_unsigned()
+               && mpz_tstbit(val, obits - 1))
+             {
+               mpz_t adj;
+               mpz_init_set_ui(adj, 1);
+               mpz_mul_2exp(adj, adj, obits);
+               mpz_sub(val, val, adj);
+               mpz_clear(adj);
+             }
+
+           delete[] phwi;
+         }
+      }
+      break;
 
-bool
-Unary_expression::eval_complex(Operator op, mpfr_t rval, mpfr_t ival,
-                              mpfr_t real, mpfr_t imag)
-{
-  switch (op)
-    {
-    case OPERATOR_PLUS:
-      mpfr_set(real, rval, GMP_RNDN);
-      mpfr_set(imag, ival, GMP_RNDN);
-      return true;
-    case OPERATOR_MINUS:
-      mpfr_neg(real, rval, GMP_RNDN);
-      mpfr_neg(imag, ival, GMP_RNDN);
-      return true;
-    case OPERATOR_NOT:
-    case OPERATOR_XOR:
-    case OPERATOR_AND:
-    case OPERATOR_MULT:
-      return false;
     default:
       go_unreachable();
     }
-}
-
-// Return the integral constant value of a unary expression, if it has one.
 
-bool
-Unary_expression::do_integer_constant_value(bool iota_is_constant, mpz_t val,
-                                           Type** ptype) const
-{
-  mpz_t uval;
-  mpz_init(uval);
-  bool ret;
-  if (!this->expr_->integer_constant_value(iota_is_constant, uval, ptype))
-    ret = false;
+  if (unc->is_rune())
+    nc->set_rune(NULL, val);
   else
-    ret = Unary_expression::eval_integer(this->op_, *ptype, uval, val,
-                                        this->location());
-  mpz_clear(uval);
-  return ret;
-}
+    nc->set_int(NULL, val);
 
-// Return the floating point constant value of a unary expression, if
-// it has one.
+  mpz_clear(uval);
+  mpz_clear(val);
 
-bool
-Unary_expression::do_float_constant_value(mpfr_t val, Type** ptype) const
-{
-  mpfr_t uval;
-  mpfr_init(uval);
-  bool ret;
-  if (!this->expr_->float_constant_value(uval, ptype))
-    ret = false;
-  else
-    ret = Unary_expression::eval_float(this->op_, uval, val);
-  mpfr_clear(uval);
-  return ret;
+  return nc->set_type(unc->type(), true, location);
 }
 
-// Return the complex constant value of a unary expression, if it has
-// one.
+// Return the integral constant value of a unary expression, if it has one.
 
 bool
-Unary_expression::do_complex_constant_value(mpfr_t real, mpfr_t imag,
-                                           Type** ptype) const
+Unary_expression::do_numeric_constant_value(Numeric_constant* nc) const
 {
-  mpfr_t rval;
-  mpfr_t ival;
-  mpfr_init(rval);
-  mpfr_init(ival);
-  bool ret;
-  if (!this->expr_->complex_constant_value(rval, ival, ptype))
-    ret = false;
-  else
-    ret = Unary_expression::eval_complex(this->op_, rval, ival, real, imag);
-  mpfr_clear(rval);
-  mpfr_clear(ival);
-  return ret;
+  Numeric_constant unc;
+  if (!this->expr_->numeric_constant_value(&unc))
+    return false;
+  return Unary_expression::eval_constant(this->op_, &unc, this->location(),
+                                        nc);
 }
 
 // Return the type of a unary expression.
@@ -4854,124 +4191,239 @@ Binary_expression::do_traverse(Traverse* traverse)
   return Expression::traverse(&this->right_, traverse);
 }
 
-// Compare integer constants according to OP.
+// Return the type to use for a binary operation on operands of
+// LEFT_TYPE and RIGHT_TYPE.  These are the types of constants and as
+// such may be NULL or abstract.
+
+bool
+Binary_expression::operation_type(Operator op, Type* left_type,
+                                 Type* right_type, Type** result_type)
+{
+  if (left_type != right_type
+      && !left_type->is_abstract()
+      && !right_type->is_abstract()
+      && left_type->base() != right_type->base()
+      && op != OPERATOR_LSHIFT
+      && op != OPERATOR_RSHIFT)
+    {
+      // May be a type error--let it be diagnosed elsewhere.
+      return false;
+    }
+
+  if (op == OPERATOR_LSHIFT || op == OPERATOR_RSHIFT)
+    {
+      if (left_type->integer_type() != NULL)
+       *result_type = left_type;
+      else
+       *result_type = Type::make_abstract_integer_type();
+    }
+  else if (!left_type->is_abstract() && left_type->named_type() != NULL)
+    *result_type = left_type;
+  else if (!right_type->is_abstract() && right_type->named_type() != NULL)
+    *result_type = right_type;
+  else if (!left_type->is_abstract())
+    *result_type = left_type;
+  else if (!right_type->is_abstract())
+    *result_type = right_type;
+  else if (left_type->complex_type() != NULL)
+    *result_type = left_type;
+  else if (right_type->complex_type() != NULL)
+    *result_type = right_type;
+  else if (left_type->float_type() != NULL)
+    *result_type = left_type;
+  else if (right_type->float_type() != NULL)
+    *result_type = right_type;
+  else if (left_type->integer_type() != NULL
+          && left_type->integer_type()->is_rune())
+    *result_type = left_type;
+  else if (right_type->integer_type() != NULL
+          && right_type->integer_type()->is_rune())
+    *result_type = right_type;
+  else
+    *result_type = left_type;
+
+  return true;
+}
+
+// Convert an integer comparison code and an operator to a boolean
+// value.
 
 bool
-Binary_expression::compare_integer(Operator op, mpz_t left_val,
-                                  mpz_t right_val)
+Binary_expression::cmp_to_bool(Operator op, int cmp)
 {
-  int i = mpz_cmp(left_val, right_val);
   switch (op)
     {
     case OPERATOR_EQEQ:
-      return i == 0;
+      return cmp == 0;
+      break;
     case OPERATOR_NOTEQ:
-      return i != 0;
+      return cmp != 0;
+      break;
     case OPERATOR_LT:
-      return i < 0;
+      return cmp < 0;
+      break;
     case OPERATOR_LE:
-      return i <= 0;
+      return cmp <= 0;
     case OPERATOR_GT:
-      return i > 0;
+      return cmp > 0;
     case OPERATOR_GE:
-      return i >= 0;
+      return cmp >= 0;
     default:
       go_unreachable();
     }
 }
 
-// Compare floating point constants according to OP.
+// Compare constants according to OP.
 
 bool
-Binary_expression::compare_float(Operator op, Type* type, mpfr_t left_val,
-                                mpfr_t right_val)
+Binary_expression::compare_constant(Operator op, Numeric_constant* left_nc,
+                                   Numeric_constant* right_nc,
+                                   Location location, bool* result)
 {
-  int i;
-  if (type == NULL)
-    i = mpfr_cmp(left_val, right_val);
+  Type* left_type = left_nc->type();
+  Type* right_type = right_nc->type();
+
+  Type* type;
+  if (!Binary_expression::operation_type(op, left_type, right_type, &type))
+    return false;
+
+  // When comparing an untyped operand to a typed operand, we are
+  // effectively coercing the untyped operand to the other operand's
+  // type, so make sure that is valid.
+  if (!left_nc->set_type(type, true, location)
+      || !right_nc->set_type(type, true, location))
+    return false;
+
+  bool ret;
+  int cmp;
+  if (type->complex_type() != NULL)
+    {
+      if (op != OPERATOR_EQEQ && op != OPERATOR_NOTEQ)
+       return false;
+      ret = Binary_expression::compare_complex(left_nc, right_nc, &cmp);
+    }
+  else if (type->float_type() != NULL)
+    ret = Binary_expression::compare_float(left_nc, right_nc, &cmp);
   else
+    ret = Binary_expression::compare_integer(left_nc, right_nc, &cmp);
+
+  if (ret)
+    *result = Binary_expression::cmp_to_bool(op, cmp);
+
+  return ret;
+}
+
+// Compare integer constants.
+
+bool
+Binary_expression::compare_integer(const Numeric_constant* left_nc,
+                                  const Numeric_constant* right_nc,
+                                  int* cmp)
+{
+  mpz_t left_val;
+  if (!left_nc->to_int(&left_val))
+    return false;
+  mpz_t right_val;
+  if (!right_nc->to_int(&right_val))
     {
-      mpfr_t lv;
-      mpfr_init_set(lv, left_val, GMP_RNDN);
-      mpfr_t rv;
-      mpfr_init_set(rv, right_val, GMP_RNDN);
-      Float_expression::constrain_float(lv, type);
-      Float_expression::constrain_float(rv, type);
-      i = mpfr_cmp(lv, rv);
-      mpfr_clear(lv);
-      mpfr_clear(rv);
+      mpz_clear(left_val);
+      return false;
     }
-  switch (op)
+
+  *cmp = mpz_cmp(left_val, right_val);
+
+  mpz_clear(left_val);
+  mpz_clear(right_val);
+
+  return true;
+}
+
+// Compare floating point constants.
+
+bool
+Binary_expression::compare_float(const Numeric_constant* left_nc,
+                                const Numeric_constant* right_nc,
+                                int* cmp)
+{
+  mpfr_t left_val;
+  if (!left_nc->to_float(&left_val))
+    return false;
+  mpfr_t right_val;
+  if (!right_nc->to_float(&right_val))
     {
-    case OPERATOR_EQEQ:
-      return i == 0;
-    case OPERATOR_NOTEQ:
-      return i != 0;
-    case OPERATOR_LT:
-      return i < 0;
-    case OPERATOR_LE:
-      return i <= 0;
-    case OPERATOR_GT:
-      return i > 0;
-    case OPERATOR_GE:
-      return i >= 0;
-    default:
-      go_unreachable();
+      mpfr_clear(left_val);
+      return false;
+    }
+
+  // We already coerced both operands to the same type.  If that type
+  // is not an abstract type, we need to round the values accordingly.
+  Type* type = left_nc->type();
+  if (!type->is_abstract() && type->float_type() != NULL)
+    {
+      int bits = type->float_type()->bits();
+      mpfr_prec_round(left_val, bits, GMP_RNDN);
+      mpfr_prec_round(right_val, bits, GMP_RNDN);
     }
+
+  *cmp = mpfr_cmp(left_val, right_val);
+
+  mpfr_clear(left_val);
+  mpfr_clear(right_val);
+
+  return true;
 }
 
-// Compare complex constants according to OP.  Complex numbers may
-// only be compared for equality.
+// Compare complex constants.  Complex numbers may only be compared
+// for equality.
 
 bool
-Binary_expression::compare_complex(Operator op, Type* type,
-                                  mpfr_t left_real, mpfr_t left_imag,
-                                  mpfr_t right_real, mpfr_t right_imag)
+Binary_expression::compare_complex(const Numeric_constant* left_nc,
+                                  const Numeric_constant* right_nc,
+                                  int* cmp)
 {
-  bool is_equal;
-  if (type == NULL)
-    is_equal = (mpfr_cmp(left_real, right_real) == 0
-               && mpfr_cmp(left_imag, right_imag) == 0);
-  else
+  mpfr_t left_real, left_imag;
+  if (!left_nc->to_complex(&left_real, &left_imag))
+    return false;
+  mpfr_t right_real, right_imag;
+  if (!right_nc->to_complex(&right_real, &right_imag))
     {
-      mpfr_t lr;
-      mpfr_t li;
-      mpfr_init_set(lr, left_real, GMP_RNDN);
-      mpfr_init_set(li, left_imag, GMP_RNDN);
-      mpfr_t rr;
-      mpfr_t ri;
-      mpfr_init_set(rr, right_real, GMP_RNDN);
-      mpfr_init_set(ri, right_imag, GMP_RNDN);
-      Complex_expression::constrain_complex(lr, li, type);
-      Complex_expression::constrain_complex(rr, ri, type);
-      is_equal = mpfr_cmp(lr, rr) == 0 && mpfr_cmp(li, ri) == 0;
-      mpfr_clear(lr);
-      mpfr_clear(li);
-      mpfr_clear(rr);
-      mpfr_clear(ri);
+      mpfr_clear(left_real);
+      mpfr_clear(left_imag);
+      return false;
     }
-  switch (op)
+
+  // We already coerced both operands to the same type.  If that type
+  // is not an abstract type, we need to round the values accordingly.
+  Type* type = left_nc->type();
+  if (!type->is_abstract() && type->complex_type() != NULL)
     {
-    case OPERATOR_EQEQ:
-      return is_equal;
-    case OPERATOR_NOTEQ:
-      return !is_equal;
-    default:
-      go_unreachable();
+      int bits = type->complex_type()->bits();
+      mpfr_prec_round(left_real, bits / 2, GMP_RNDN);
+      mpfr_prec_round(left_imag, bits / 2, GMP_RNDN);
+      mpfr_prec_round(right_real, bits / 2, GMP_RNDN);
+      mpfr_prec_round(right_imag, bits / 2, GMP_RNDN);
     }
+
+  *cmp = (mpfr_cmp(left_real, right_real) != 0
+         || mpfr_cmp(left_imag, right_imag) != 0);
+
+  mpfr_clear(left_real);
+  mpfr_clear(left_imag);
+  mpfr_clear(right_real);
+  mpfr_clear(right_imag);
+
+  return true;
 }
 
-// Apply binary opcode OP to LEFT_VAL and RIGHT_VAL, setting VAL.
-// LEFT_TYPE is the type of LEFT_VAL, RIGHT_TYPE is the type of
-// RIGHT_VAL; LEFT_TYPE and/or RIGHT_TYPE may be NULL.  Return true if
-// this could be done, false if not.
+// Apply binary opcode OP to LEFT_NC and RIGHT_NC, setting NC.  Return
+// true if this could be done, false if not.  Issue errors at LOCATION
+// as appropriate.
 
 bool
-Binary_expression::eval_integer(Operator op, Type* left_type, mpz_t left_val,
-                               Type* right_type, mpz_t right_val,
-                               Location location, mpz_t val)
+Binary_expression::eval_constant(Operator op, Numeric_constant* left_nc,
+                                Numeric_constant* right_nc,
+                                Location location, Numeric_constant* nc)
 {
-  bool is_shift_op = false;
   switch (op)
     {
     case OPERATOR_OROR:
@@ -4982,9 +4434,68 @@ Binary_expression::eval_integer(Operator op, Type* left_type, mpz_t left_val,
     case OPERATOR_LE:
     case OPERATOR_GT:
     case OPERATOR_GE:
-      // These return boolean values.  We should probably handle them
-      // anyhow in case a type conversion is used on the result.
+      // These return boolean values and as such must be handled
+      // elsewhere.
+      go_unreachable();
+    default:
+      break;
+    }
+
+  Type* left_type = left_nc->type();
+  Type* right_type = right_nc->type();
+
+  Type* type;
+  if (!Binary_expression::operation_type(op, left_type, right_type, &type))
+    return false;
+
+  bool is_shift = op == OPERATOR_LSHIFT || op == OPERATOR_RSHIFT;
+
+  // When combining an untyped operand with a typed operand, we are
+  // effectively coercing the untyped operand to the other operand's
+  // type, so make sure that is valid.
+  if (!left_nc->set_type(type, true, location))
+    return false;
+  if (!is_shift && !right_nc->set_type(type, true, location))
+    return false;
+
+  bool r;
+  if (type->complex_type() != NULL)
+    r = Binary_expression::eval_complex(op, left_nc, right_nc, location, nc);
+  else if (type->float_type() != NULL)
+    r = Binary_expression::eval_float(op, left_nc, right_nc, location, nc);
+  else
+    r = Binary_expression::eval_integer(op, left_nc, right_nc, location, nc);
+
+  if (r)
+    r = nc->set_type(type, true, location);
+
+  return r;
+}
+
+// Apply binary opcode OP to LEFT_NC and RIGHT_NC, setting NC, using
+// integer operations.  Return true if this could be done, false if
+// not.
+
+bool
+Binary_expression::eval_integer(Operator op, const Numeric_constant* left_nc,
+                               const Numeric_constant* right_nc,
+                               Location location, Numeric_constant* nc)
+{
+  mpz_t left_val;
+  if (!left_nc->to_int(&left_val))
+    return false;
+  mpz_t right_val;
+  if (!right_nc->to_int(&right_val))
+    {
+      mpz_clear(left_val);
       return false;
+    }
+
+  mpz_t val;
+  mpz_init(val);
+
+  switch (op)
+    {
     case OPERATOR_PLUS:
       mpz_add(val, left_val, right_val);
       break;
@@ -5007,7 +4518,6 @@ Binary_expression::eval_integer(Operator op, Type* left_type, mpz_t left_val,
        {
          error_at(location, "division by zero");
          mpz_set_ui(val, 0);
-         return true;
        }
       break;
     case OPERATOR_MOD:
@@ -5017,20 +4527,18 @@ Binary_expression::eval_integer(Operator op, Type* left_type, mpz_t left_val,
        {
          error_at(location, "division by zero");
          mpz_set_ui(val, 0);
-         return true;
        }
       break;
     case OPERATOR_LSHIFT:
       {
        unsigned long shift = mpz_get_ui(right_val);
-       if (mpz_cmp_ui(right_val, shift) != 0 || shift > 0x100000)
+       if (mpz_cmp_ui(right_val, shift) == 0 && shift <= 0x100000)
+         mpz_mul_2exp(val, left_val, shift);
+       else
          {
            error_at(location, "shift count overflow");
            mpz_set_ui(val, 0);
-           return true;
          }
-       mpz_mul_2exp(val, left_val, shift);
-       is_shift_op = true;
        break;
       }
       break;
@@ -5041,13 +4549,14 @@ Binary_expression::eval_integer(Operator op, Type* left_type, mpz_t left_val,
          {
            error_at(location, "shift count overflow");
            mpz_set_ui(val, 0);
-           return true;
          }
-       if (mpz_cmp_ui(left_val, 0) >= 0)
-         mpz_tdiv_q_2exp(val, left_val, shift);
        else
-         mpz_fdiv_q_2exp(val, left_val, shift);
-       is_shift_op = true;
+         {
+           if (mpz_cmp_ui(left_val, 0) >= 0)
+             mpz_tdiv_q_2exp(val, left_val, shift);
+           else
+             mpz_fdiv_q_2exp(val, left_val, shift);
+         }
        break;
       }
       break;
@@ -5067,63 +4576,47 @@ Binary_expression::eval_integer(Operator op, Type* left_type, mpz_t left_val,
       go_unreachable();
     }
 
-  Type* type = left_type;
-  if (!is_shift_op)
-    {
-      if (type == NULL)
-       type = right_type;
-      else if (type != right_type && right_type != NULL)
-       {
-         if (type->is_abstract())
-           type = right_type;
-         else if (!right_type->is_abstract())
-           {
-             // This look like a type error which should be diagnosed
-             // elsewhere.  Don't do anything here, to avoid an
-             // unhelpful chain of error messages.
-             return true;
-           }
-       }
-    }
+  mpz_clear(left_val);
+  mpz_clear(right_val);
 
-  if (type != NULL && !type->is_abstract())
-    {
-      // We have to check the operands too, as we have implicitly
-      // coerced them to TYPE.
-      if ((type != left_type
-          && !Integer_expression::check_constant(left_val, type, location))
-         || (!is_shift_op
-             && type != right_type
-             && !Integer_expression::check_constant(right_val, type,
-                                                    location))
-         || !Integer_expression::check_constant(val, type, location))
-       mpz_set_ui(val, 0);
-    }
+  if (left_nc->is_rune()
+      || (op != OPERATOR_LSHIFT
+         && op != OPERATOR_RSHIFT
+         && right_nc->is_rune()))
+    nc->set_rune(NULL, val);
+  else
+    nc->set_int(NULL, val);
+
+  mpz_clear(val);
 
   return true;
 }
 
-// Apply binary opcode OP to LEFT_VAL and RIGHT_VAL, setting VAL.
-// Return true if this could be done, false if not.
+// Apply binary opcode OP to LEFT_NC and RIGHT_NC, setting NC, using
+// floating point operations.  Return true if this could be done,
+// false if not.
 
 bool
-Binary_expression::eval_float(Operator op, Type* left_type, mpfr_t left_val,
-                             Type* right_type, mpfr_t right_val,
-                             mpfr_t val, Location location)
+Binary_expression::eval_float(Operator op, const Numeric_constant* left_nc,
+                             const Numeric_constant* right_nc,
+                             Location location, Numeric_constant* nc)
 {
-  switch (op)
+  mpfr_t left_val;
+  if (!left_nc->to_float(&left_val))
+    return false;
+  mpfr_t right_val;
+  if (!right_nc->to_float(&right_val))
     {
-    case OPERATOR_OROR:
-    case OPERATOR_ANDAND:
-    case OPERATOR_EQEQ:
-    case OPERATOR_NOTEQ:
-    case OPERATOR_LT:
-    case OPERATOR_LE:
-    case OPERATOR_GT:
-    case OPERATOR_GE:
-      // These return boolean values.  We should probably handle them
-      // anyhow in case a type conversion is used on the result.
+      mpfr_clear(left_val);
       return false;
+    }
+
+  mpfr_t val;
+  mpfr_init(val);
+
+  bool ret = true;
+  switch (op)
+    {
     case OPERATOR_PLUS:
       mpfr_add(val, left_val, right_val, GMP_RNDN);
       break;
@@ -5134,78 +4627,64 @@ Binary_expression::eval_float(Operator op, Type* left_type, mpfr_t left_val,
     case OPERATOR_XOR:
     case OPERATOR_AND:
     case OPERATOR_BITCLEAR:
-      return false;
+    case OPERATOR_MOD:
+    case OPERATOR_LSHIFT:
+    case OPERATOR_RSHIFT:
+      mpfr_set_ui(val, 0, GMP_RNDN);
+      ret = false;
+      break;
     case OPERATOR_MULT:
       mpfr_mul(val, left_val, right_val, GMP_RNDN);
       break;
     case OPERATOR_DIV:
-      if (mpfr_zero_p(right_val))
-       error_at(location, "division by zero");
-      mpfr_div(val, left_val, right_val, GMP_RNDN);
+      if (!mpfr_zero_p(right_val))
+       mpfr_div(val, left_val, right_val, GMP_RNDN);
+      else
+       {
+         error_at(location, "division by zero");
+         mpfr_set_ui(val, 0, GMP_RNDN);
+       }
       break;
-    case OPERATOR_MOD:
-      return false;
-    case OPERATOR_LSHIFT:
-    case OPERATOR_RSHIFT:
-      return false;
     default:
       go_unreachable();
     }
 
-  Type* type = left_type;
-  if (type == NULL)
-    type = right_type;
-  else if (type != right_type && right_type != NULL)
-    {
-      if (type->is_abstract())
-       type = right_type;
-      else if (!right_type->is_abstract())
-       {
-         // This looks like a type error which should be diagnosed
-         // elsewhere.  Don't do anything here, to avoid an unhelpful
-         // chain of error messages.
-         return true;
-       }
-    }
+  mpfr_clear(left_val);
+  mpfr_clear(right_val);
 
-  if (type != NULL && !type->is_abstract())
-    {
-      if ((type != left_type
-          && !Float_expression::check_constant(left_val, type, location))
-         || (type != right_type
-             && !Float_expression::check_constant(right_val, type,
-                                                  location))
-         || !Float_expression::check_constant(val, type, location))
-       mpfr_set_ui(val, 0, GMP_RNDN);
-    }
+  nc->set_float(NULL, val);
+  mpfr_clear(val);
 
-  return true;
+  return ret;
 }
 
-// Apply binary opcode OP to LEFT_REAL/LEFT_IMAG and
-// RIGHT_REAL/RIGHT_IMAG, setting REAL/IMAG.  Return true if this
-// could be done, false if not.
+// Apply binary opcode OP to LEFT_NC and RIGHT_NC, setting NC, using
+// complex operations.  Return true if this could be done, false if
+// not.
 
 bool
-Binary_expression::eval_complex(Operator op, Type* left_type,
-                               mpfr_t left_real, mpfr_t left_imag,
-                               Type *right_type,
-                               mpfr_t right_real, mpfr_t right_imag,
-                               mpfr_t real, mpfr_t imag,
-                               Location location)
+Binary_expression::eval_complex(Operator op, const Numeric_constant* left_nc,
+                               const Numeric_constant* right_nc,
+                               Location location, Numeric_constant* nc)
 {
-  switch (op)
+  mpfr_t left_real, left_imag;
+  if (!left_nc->to_complex(&left_real, &left_imag))
+    return false;
+  mpfr_t right_real, right_imag;
+  if (!right_nc->to_complex(&right_real, &right_imag))
     {
-    case OPERATOR_OROR:
-    case OPERATOR_ANDAND:
-    case OPERATOR_EQEQ:
-    case OPERATOR_NOTEQ:
-    case OPERATOR_LT:
-    case OPERATOR_LE:
-    case OPERATOR_GT:
-    case OPERATOR_GE:
-      // These return boolean values and must be handled differently.
+      mpfr_clear(left_real);
+      mpfr_clear(left_imag);
       return false;
+    }
+
+  mpfr_t real, imag;
+  mpfr_init(real);
+  mpfr_init(imag);
+
+  bool ret = true;
+  switch (op)
+    {
     case OPERATOR_PLUS:
       mpfr_add(real, left_real, right_real, GMP_RNDN);
       mpfr_add(imag, left_imag, right_imag, GMP_RNDN);
@@ -5218,7 +4697,13 @@ Binary_expression::eval_complex(Operator op, Type* left_type,
     case OPERATOR_XOR:
     case OPERATOR_AND:
     case OPERATOR_BITCLEAR:
-      return false;
+    case OPERATOR_MOD:
+    case OPERATOR_LSHIFT:
+    case OPERATOR_RSHIFT:
+      mpfr_set_ui(real, 0, GMP_RNDN);
+      mpfr_set_ui(imag, 0, GMP_RNDN);
+      ret = false;
+      break;
     case OPERATOR_MULT:
       {
        // You might think that multiplying two complex numbers would
@@ -5371,7 +4856,12 @@ Binary_expression::eval_complex(Operator op, Type* left_type,
        // scale the values to try to avoid this.
 
        if (mpfr_zero_p(right_real) && mpfr_zero_p(right_imag))
-         error_at(location, "division by zero");
+         {
+           error_at(location, "division by zero");
+           mpfr_set_ui(real, 0, GMP_RNDN);
+           mpfr_set_ui(imag, 0, GMP_RNDN);
+           break;
+         }
 
        mpfr_t rra;
        mpfr_t ria;
@@ -5502,48 +4992,20 @@ Binary_expression::eval_complex(Operator op, Type* left_type,
        mpfr_clear(ria);
       }
       break;
-    case OPERATOR_MOD:
-      return false;
-    case OPERATOR_LSHIFT:
-    case OPERATOR_RSHIFT:
-      return false;
     default:
       go_unreachable();
     }
 
-  Type* type = left_type;
-  if (type == NULL)
-    type = right_type;
-  else if (type != right_type && right_type != NULL)
-    {
-      if (type->is_abstract())
-       type = right_type;
-      else if (!right_type->is_abstract())
-       {
-         // This looks like a type error which should be diagnosed
-         // elsewhere.  Don't do anything here, to avoid an unhelpful
-         // chain of error messages.
-         return true;
-       }
-    }
+  mpfr_clear(left_real);
+  mpfr_clear(left_imag);
+  mpfr_clear(right_real);
+  mpfr_clear(right_imag);
 
-  if (type != NULL && !type->is_abstract())
-    {
-      if ((type != left_type
-          && !Complex_expression::check_constant(left_real, left_imag,
-                                                 type, location))
-         || (type != right_type
-             && !Complex_expression::check_constant(right_real, right_imag,
-                                                    type, location))
-         || !Complex_expression::check_constant(real, imag, type,
-                                                location))
-       {
-         mpfr_set_ui(real, 0, GMP_RNDN);
-         mpfr_set_ui(imag, 0, GMP_RNDN);
-       }
-    }
+  nc->set_complex(NULL, real, imag);
+  mpfr_clear(real);
+  mpfr_clear(imag);
 
-  return true;
+  return ret;
 }
 
 // Lower a binary expression.  We have to evaluate constant
@@ -5566,288 +5028,34 @@ Binary_expression::do_lower(Gogo* gogo, Named_object*,
                              || op == OPERATOR_GT
                              || op == OPERATOR_GE);
 
-  // Integer constant expressions.
+  // Numeric constant expressions.
   {
-    mpz_t left_val;
-    mpz_init(left_val);
-    Type* left_type;
-    mpz_t right_val;
-    mpz_init(right_val);
-    Type* right_type;
-    if (left->integer_constant_value(false, left_val, &left_type)
-       && right->integer_constant_value(false, right_val, &right_type))
+    Numeric_constant left_nc;
+    Numeric_constant right_nc;
+    if (left->numeric_constant_value(&left_nc)
+       && right->numeric_constant_value(&right_nc))
       {
-       Expression* ret = NULL;
-       if (left_type != right_type
-           && left_type != NULL
-           && !left_type->is_abstract()
-           && right_type != NULL
-           && !right_type->is_abstract()
-           && left_type->base() != right_type->base()
-           && op != OPERATOR_LSHIFT
-           && op != OPERATOR_RSHIFT)
-         {
-           // May be a type error--let it be diagnosed later.
-           return this;
-         }
-       else if (is_comparison)
+       if (is_comparison)
          {
-           bool b = Binary_expression::compare_integer(op, left_val,
-                                                       right_val);
-           ret = Expression::make_cast(Type::lookup_bool_type(),
-                                       Expression::make_boolean(b, location),
-                                       location);
+           bool result;
+           if (!Binary_expression::compare_constant(op, &left_nc,
+                                                    &right_nc, location,
+                                                    &result))
+             return this;
+           return Expression::make_cast(Type::lookup_bool_type(),
+                                        Expression::make_boolean(result,
+                                                                 location),
+                                        location);
          }
        else
          {
-           mpz_t val;
-           mpz_init(val);
-
-           if (Binary_expression::eval_integer(op, left_type, left_val,
-                                               right_type, right_val,
-                                               location, val))
-             {
-               go_assert(op != OPERATOR_OROR && op != OPERATOR_ANDAND);
-               Type* type;
-               if (op == OPERATOR_LSHIFT || op == OPERATOR_RSHIFT)
-                 type = left_type;
-               else if (left_type == NULL)
-                 type = right_type;
-               else if (right_type == NULL)
-                 type = left_type;
-               else if (!left_type->is_abstract()
-                        && left_type->named_type() != NULL)
-                 type = left_type;
-               else if (!right_type->is_abstract()
-                        && right_type->named_type() != NULL)
-                 type = right_type;
-               else if (!left_type->is_abstract())
-                 type = left_type;
-               else if (!right_type->is_abstract())
-                 type = right_type;
-               else if (left_type->float_type() != NULL)
-                 type = left_type;
-               else if (right_type->float_type() != NULL)
-                 type = right_type;
-               else if (left_type->complex_type() != NULL)
-                 type = left_type;
-               else if (right_type->complex_type() != NULL)
-                 type = right_type;
-               else
-                 type = left_type;
-
-               bool is_character = false;
-               if (type == NULL)
-                 {
-                   Type* t = this->left_->type();
-                   if (t->integer_type() != NULL
-                       && t->integer_type()->is_rune())
-                     is_character = true;
-                   else if (op != OPERATOR_LSHIFT && op != OPERATOR_RSHIFT)
-                     {
-                       t = this->right_->type();
-                       if (t->integer_type() != NULL
-                           && t->integer_type()->is_rune())
-                         is_character = true;
-                     }
-                 }
-
-               if (is_character)
-                 ret = Expression::make_character(&val, type, location);
-               else
-                 ret = Expression::make_integer(&val, type, location);
-             }
-
-           mpz_clear(val);
-         }
-
-       if (ret != NULL)
-         {
-           mpz_clear(right_val);
-           mpz_clear(left_val);
-           return ret;
+           Numeric_constant nc;
+           if (!Binary_expression::eval_constant(op, &left_nc, &right_nc,
+                                                 location, &nc))
+             return this;
+           return nc.expression(location);
          }
       }
-    mpz_clear(right_val);
-    mpz_clear(left_val);
-  }
-
-  // Floating point constant expressions.
-  {
-    mpfr_t left_val;
-    mpfr_init(left_val);
-    Type* left_type;
-    mpfr_t right_val;
-    mpfr_init(right_val);
-    Type* right_type;
-    if (left->float_constant_value(left_val, &left_type)
-       && right->float_constant_value(right_val, &right_type))
-      {
-       Expression* ret = NULL;
-       if (left_type != right_type
-           && left_type != NULL
-           && right_type != NULL
-           && left_type->base() != right_type->base()
-           && op != OPERATOR_LSHIFT
-           && op != OPERATOR_RSHIFT)
-         {
-           // May be a type error--let it be diagnosed later.
-           return this;
-         }
-       else if (is_comparison)
-         {
-           bool b = Binary_expression::compare_float(op,
-                                                     (left_type != NULL
-                                                      ? left_type
-                                                      : right_type),
-                                                     left_val, right_val);
-           ret = Expression::make_boolean(b, location);
-         }
-       else
-         {
-           mpfr_t val;
-           mpfr_init(val);
-
-           if (Binary_expression::eval_float(op, left_type, left_val,
-                                             right_type, right_val, val,
-                                             location))
-             {
-               go_assert(op != OPERATOR_OROR && op != OPERATOR_ANDAND
-                          && op != OPERATOR_LSHIFT && op != OPERATOR_RSHIFT);
-               Type* type;
-               if (left_type == NULL)
-                 type = right_type;
-               else if (right_type == NULL)
-                 type = left_type;
-               else if (!left_type->is_abstract()
-                        && left_type->named_type() != NULL)
-                 type = left_type;
-               else if (!right_type->is_abstract()
-                        && right_type->named_type() != NULL)
-                 type = right_type;
-               else if (!left_type->is_abstract())
-                 type = left_type;
-               else if (!right_type->is_abstract())
-                 type = right_type;
-               else if (left_type->float_type() != NULL)
-                 type = left_type;
-               else if (right_type->float_type() != NULL)
-                 type = right_type;
-               else
-                 type = left_type;
-               ret = Expression::make_float(&val, type, location);
-             }
-
-           mpfr_clear(val);
-         }
-
-       if (ret != NULL)
-         {
-           mpfr_clear(right_val);
-           mpfr_clear(left_val);
-           return ret;
-         }
-      }
-    mpfr_clear(right_val);
-    mpfr_clear(left_val);
-  }
-
-  // Complex constant expressions.
-  {
-    mpfr_t left_real;
-    mpfr_t left_imag;
-    mpfr_init(left_real);
-    mpfr_init(left_imag);
-    Type* left_type;
-
-    mpfr_t right_real;
-    mpfr_t right_imag;
-    mpfr_init(right_real);
-    mpfr_init(right_imag);
-    Type* right_type;
-
-    if (left->complex_constant_value(left_real, left_imag, &left_type)
-       && right->complex_constant_value(right_real, right_imag, &right_type))
-      {
-       Expression* ret = NULL;
-       if (left_type != right_type
-           && left_type != NULL
-           && right_type != NULL
-           && left_type->base() != right_type->base())
-         {
-           // May be a type error--let it be diagnosed later.
-           return this;
-         }
-       else if (op == OPERATOR_EQEQ || op == OPERATOR_NOTEQ)
-         {
-           bool b = Binary_expression::compare_complex(op,
-                                                       (left_type != NULL
-                                                        ? left_type
-                                                        : right_type),
-                                                       left_real,
-                                                       left_imag,
-                                                       right_real,
-                                                       right_imag);
-           ret = Expression::make_boolean(b, location);
-         }
-       else
-         {
-           mpfr_t real;
-           mpfr_t imag;
-           mpfr_init(real);
-           mpfr_init(imag);
-
-           if (Binary_expression::eval_complex(op, left_type,
-                                               left_real, left_imag,
-                                               right_type,
-                                               right_real, right_imag,
-                                               real, imag,
-                                               location))
-             {
-               go_assert(op != OPERATOR_OROR && op != OPERATOR_ANDAND
-                          && op != OPERATOR_LSHIFT && op != OPERATOR_RSHIFT);
-               Type* type;
-               if (left_type == NULL)
-                 type = right_type;
-               else if (right_type == NULL)
-                 type = left_type;
-               else if (!left_type->is_abstract()
-                        && left_type->named_type() != NULL)
-                 type = left_type;
-               else if (!right_type->is_abstract()
-                        && right_type->named_type() != NULL)
-                 type = right_type;
-               else if (!left_type->is_abstract())
-                 type = left_type;
-               else if (!right_type->is_abstract())
-                 type = right_type;
-               else if (left_type->complex_type() != NULL)
-                 type = left_type;
-               else if (right_type->complex_type() != NULL)
-                 type = right_type;
-               else
-                 type = left_type;
-               ret = Expression::make_complex(&real, &imag, type,
-                                              location);
-             }
-           mpfr_clear(real);
-           mpfr_clear(imag);
-         }
-
-       if (ret != NULL)
-         {
-           mpfr_clear(left_real);
-           mpfr_clear(left_imag);
-           mpfr_clear(right_real);
-           mpfr_clear(right_imag);
-           return ret;
-         }
-      }
-
-    mpfr_clear(left_real);
-    mpfr_clear(left_imag);
-    mpfr_clear(right_real);
-    mpfr_clear(right_imag);
   }
 
   // String constant expressions.
@@ -5864,77 +5072,13 @@ Binary_expression::do_lower(Gogo* gogo, Named_object*,
          else if (is_comparison)
            {
              int cmp = left_string.compare(right_string);
-             bool r;
-             switch (op)
-               {
-               case OPERATOR_EQEQ:
-                 r = cmp == 0;
-                 break;
-               case OPERATOR_NOTEQ:
-                 r = cmp != 0;
-                 break;
-               case OPERATOR_LT:
-                 r = cmp < 0;
-                 break;
-               case OPERATOR_LE:
-                 r = cmp <= 0;
-                 break;
-               case OPERATOR_GT:
-                 r = cmp > 0;
-                 break;
-               case OPERATOR_GE:
-                 r = cmp >= 0;
-                 break;
-               default:
-                 go_unreachable();
-               }
-             return Expression::make_boolean(r, location);
-           }
-       }
-    }
-
-  // Special case for shift of a floating point constant.
-  if (op == OPERATOR_LSHIFT || op == OPERATOR_RSHIFT)
-    {
-      mpfr_t left_val;
-      mpfr_init(left_val);
-      Type* left_type;
-      mpz_t right_val;
-      mpz_init(right_val);
-      Type* right_type;
-      if (left->float_constant_value(left_val, &left_type)
-         && right->integer_constant_value(false, right_val, &right_type)
-         && mpfr_integer_p(left_val)
-         && (left_type == NULL
-             || left_type->is_abstract()
-             || left_type->integer_type() != NULL))
-       {
-         mpz_t left_int;
-         mpz_init(left_int);
-         mpfr_get_z(left_int, left_val, GMP_RNDN);
-
-         mpz_t val;
-         mpz_init(val);
-
-         Expression* ret = NULL;
-         if (Binary_expression::eval_integer(op, left_type, left_int,
-                                             right_type, right_val,
-                                             location, val))
-           ret = Expression::make_integer(&val, left_type, location);
-
-         mpz_clear(left_int);
-         mpz_clear(val);
-
-         if (ret != NULL)
-           {
-             mpfr_clear(left_val);
-             mpz_clear(right_val);
-             return ret;
+             bool r = Binary_expression::cmp_to_bool(op, cmp);
+             return Expression::make_cast(Type::lookup_bool_type(),
+                                          Expression::make_boolean(r,
+                                                                   location),
+                                          location);
            }
        }
-
-      mpfr_clear(left_val);
-      mpz_clear(right_val);
     }
 
   // Lower struct and array comparisons.
@@ -6114,154 +5258,30 @@ Binary_expression::operand_address(Statement_inserter* inserter,
   return Expression::make_cast(unsafe_pointer_type, expr, loc);
 }
 
-// Return the integer constant value, if it has one.
-
-bool
-Binary_expression::do_integer_constant_value(bool iota_is_constant, mpz_t val,
-                                            Type** ptype) const
-{
-  mpz_t left_val;
-  mpz_init(left_val);
-  Type* left_type;
-  if (!this->left_->integer_constant_value(iota_is_constant, left_val,
-                                          &left_type))
-    {
-      mpz_clear(left_val);
-      return false;
-    }
-
-  mpz_t right_val;
-  mpz_init(right_val);
-  Type* right_type;
-  if (!this->right_->integer_constant_value(iota_is_constant, right_val,
-                                           &right_type))
-    {
-      mpz_clear(right_val);
-      mpz_clear(left_val);
-      return false;
-    }
-
-  bool ret;
-  if (left_type != right_type
-      && left_type != NULL
-      && right_type != NULL
-      && left_type->base() != right_type->base()
-      && this->op_ != OPERATOR_RSHIFT
-      && this->op_ != OPERATOR_LSHIFT)
-    ret = false;
-  else
-    ret = Binary_expression::eval_integer(this->op_, left_type, left_val,
-                                         right_type, right_val,
-                                         this->location(), val);
-
-  mpz_clear(right_val);
-  mpz_clear(left_val);
-
-  if (ret)
-    *ptype = left_type;
-
-  return ret;
-}
-
-// Return the floating point constant value, if it has one.
-
-bool
-Binary_expression::do_float_constant_value(mpfr_t val, Type** ptype) const
-{
-  mpfr_t left_val;
-  mpfr_init(left_val);
-  Type* left_type;
-  if (!this->left_->float_constant_value(left_val, &left_type))
-    {
-      mpfr_clear(left_val);
-      return false;
-    }
-
-  mpfr_t right_val;
-  mpfr_init(right_val);
-  Type* right_type;
-  if (!this->right_->float_constant_value(right_val, &right_type))
-    {
-      mpfr_clear(right_val);
-      mpfr_clear(left_val);
-      return false;
-    }
-
-  bool ret;
-  if (left_type != right_type
-      && left_type != NULL
-      && right_type != NULL
-      && left_type->base() != right_type->base())
-    ret = false;
-  else
-    ret = Binary_expression::eval_float(this->op_, left_type, left_val,
-                                       right_type, right_val,
-                                       val, this->location());
-
-  mpfr_clear(left_val);
-  mpfr_clear(right_val);
-
-  if (ret)
-    *ptype = left_type;
-
-  return ret;
-}
-
-// Return the complex constant value, if it has one.
+// Return the numeric constant value, if it has one.
 
 bool
-Binary_expression::do_complex_constant_value(mpfr_t real, mpfr_t imag,
-                                            Type** ptype) const
+Binary_expression::do_numeric_constant_value(Numeric_constant* nc) const
 {
-  mpfr_t left_real;
-  mpfr_t left_imag;
-  mpfr_init(left_real);
-  mpfr_init(left_imag);
-  Type* left_type;
-  if (!this->left_->complex_constant_value(left_real, left_imag, &left_type))
-    {
-      mpfr_clear(left_real);
-      mpfr_clear(left_imag);
-      return false;
-    }
-
-  mpfr_t right_real;
-  mpfr_t right_imag;
-  mpfr_init(right_real);
-  mpfr_init(right_imag);
-  Type* right_type;
-  if (!this->right_->complex_constant_value(right_real, right_imag,
-                                           &right_type))
-    {
-      mpfr_clear(left_real);
-      mpfr_clear(left_imag);
-      mpfr_clear(right_real);
-      mpfr_clear(right_imag);
-      return false;
-    }
+  Operator op = this->op_;
 
-  bool ret;
-  if (left_type != right_type
-      && left_type != NULL
-      && right_type != NULL
-      && left_type->base() != right_type->base())
-    ret = false;
-  else
-    ret = Binary_expression::eval_complex(this->op_, left_type,
-                                         left_real, left_imag,
-                                         right_type,
-                                         right_real, right_imag,
-                                         real, imag,
-                                         this->location());
-  mpfr_clear(left_real);
-  mpfr_clear(left_imag);
-  mpfr_clear(right_real);
-  mpfr_clear(right_imag);
+  if (op == OPERATOR_EQEQ
+      || op == OPERATOR_NOTEQ
+      || op == OPERATOR_LT
+      || op == OPERATOR_LE
+      || op == OPERATOR_GT
+      || op == OPERATOR_GE)
+    return false;
 
-  if (ret)
-    *ptype = left_type;
+  Numeric_constant left_nc;
+  if (!this->left_->numeric_constant_value(&left_nc))
+    return false;
+  Numeric_constant right_nc;
+  if (!this->right_->numeric_constant_value(&right_nc))
+    return false;
 
-  return ret;
+  return Binary_expression::eval_constant(op, &left_nc, &right_nc,
+                                         this->location(), nc);
 }
 
 // Note that the value is being discarded.
@@ -6305,41 +5325,13 @@ Binary_expression::do_type()
     case OPERATOR_AND:
     case OPERATOR_BITCLEAR:
       {
-       Type* left_type = this->left_->type();
-       Type* right_type = this->right_->type();
-       if (left_type->is_error())
-         return left_type;
-       else if (right_type->is_error())
-         return right_type;
-       else if (!Type::are_compatible_for_binop(left_type, right_type))
-         {
-           this->report_error(_("incompatible types in binary expression"));
-           return Type::make_error_type();
-         }
-       else if (!left_type->is_abstract() && left_type->named_type() != NULL)
-         return left_type;
-       else if (!right_type->is_abstract() && right_type->named_type() != NULL)
-         return right_type;
-       else if (!left_type->is_abstract())
-         return left_type;
-       else if (!right_type->is_abstract())
-         return right_type;
-       else if (left_type->complex_type() != NULL)
-         return left_type;
-       else if (right_type->complex_type() != NULL)
-         return right_type;
-       else if (left_type->float_type() != NULL)
-         return left_type;
-       else if (right_type->float_type() != NULL)
-         return right_type;
-       else if (left_type->integer_type() != NULL
-                && left_type->integer_type()->is_rune())
-         return left_type;
-       else if (right_type->integer_type() != NULL
-                && right_type->integer_type()->is_rune())
-         return right_type;
-       else
-         return left_type;
+       Type* type;
+       if (!Binary_expression::operation_type(this->op_,
+                                              this->left_->type(),
+                                              this->right_->type(),
+                                              &type))
+         return Type::make_error_type();
+       return type;
       }
 
     case OPERATOR_LSHIFT:
@@ -6604,21 +5596,25 @@ Binary_expression::do_check_types(Gogo*)
        this->report_error(_("shift count not unsigned integer"));
       else
        {
-         mpz_t val;
-         mpz_init(val);
-         Type* type;
-         if (this->right_->integer_constant_value(true, val, &type))
+         Numeric_constant nc;
+         if (this->right_->numeric_constant_value(&nc))
            {
-             if (mpz_sgn(val) < 0)
+             mpz_t val;
+             if (!nc.to_int(&val))
+               this->report_error(_("shift count not unsigned integer"));
+             else
                {
-                 this->report_error(_("negative shift count"));
-                 mpz_set_ui(val, 0);
-                 Location rloc = this->right_->location();
-                 this->right_ = Expression::make_integer(&val, right_type,
-                                                         rloc);
+                 if (mpz_sgn(val) < 0)
+                   {
+                     this->report_error(_("negative shift count"));
+                     mpz_set_ui(val, 0);
+                     Location rloc = this->right_->location();
+                     this->right_ = Expression::make_integer(&val, right_type,
+                                                             rloc);
+                   }
+                 mpz_clear(val);
                }
            }
-         mpz_clear(val);
        }
     }
 }
@@ -7390,13 +6386,7 @@ class Builtin_call_expression : public Call_expression
   do_is_constant() const;
 
   bool
-  do_integer_constant_value(bool, mpz_t, Type**) const;
-
-  bool
-  do_float_constant_value(mpfr_t, Type**) const;
-
-  bool
-  do_complex_constant_value(mpfr_t, mpfr_t, Type**) const;
+  do_numeric_constant_value(Numeric_constant*) const;
 
   void
   do_discarding_value();
@@ -7628,37 +6618,9 @@ Builtin_call_expression::do_lower(Gogo* gogo, Named_object* function,
            }
        }
 
-      mpz_t ival;
-      mpz_init(ival);
-      Type* type;
-      if (this->integer_constant_value(true, ival, &type))
-       {
-         Expression* ret = Expression::make_integer(&ival, type, loc);
-         mpz_clear(ival);
-         return ret;
-       }
-      mpz_clear(ival);
-
-      mpfr_t rval;
-      mpfr_init(rval);
-      if (this->float_constant_value(rval, &type))
-       {
-         Expression* ret = Expression::make_float(&rval, type, loc);
-         mpfr_clear(rval);
-         return ret;
-       }
-
-      mpfr_t imag;
-      mpfr_init(imag);
-      if (this->complex_constant_value(rval, imag, &type))
-       {
-         Expression* ret = Expression::make_complex(&rval, &imag, type, loc);
-         mpfr_clear(rval);
-         mpfr_clear(imag);
-         return ret;
-       }
-      mpfr_clear(rval);
-      mpfr_clear(imag);
+      Numeric_constant nc;
+      if (this->numeric_constant_value(&nc))
+       return nc.expression(loc);
     }
 
   switch (this->code_)
@@ -7906,43 +6868,14 @@ Builtin_call_expression::check_int_value(Expression* e)
     return true;
 
   // Check for a floating point constant with integer value.
-  mpfr_t fval;
-  mpfr_init(fval);
-
-  Type* dummy;
-  if (e->float_constant_value(fval, &dummy) && mpfr_integer_p(fval))
+  Numeric_constant nc;
+  mpz_t ival;
+  if (e->numeric_constant_value(&nc) && nc.to_int(&ival))
     {
-      mpz_t ival;
-      mpz_init(ival);
-
-      bool ok = false;
-
-      mpfr_clear_overflow();
-      mpfr_clear_erangeflag();
-      mpfr_get_z(ival, fval, GMP_RNDN);
-      if (!mpfr_overflow_p()
-         && !mpfr_erangeflag_p()
-         && mpz_sgn(ival) >= 0)
-       {
-         Named_type* ntype = Type::lookup_integer_type("int");
-         Integer_type* inttype = ntype->integer_type();
-         mpz_t max;
-         mpz_init_set_ui(max, 1);
-         mpz_mul_2exp(max, max, inttype->bits() - 1);
-         ok = mpz_cmp(ival, max) < 0;
-         mpz_clear(max);
-       }
       mpz_clear(ival);
-
-      if (ok)
-       {
-         mpfr_clear(fval);
-         return true;
-       }
+      return true;
     }
 
-  mpfr_clear(fval);
-
   return false;
 }
 
@@ -8073,12 +7006,10 @@ Builtin_call_expression::do_is_constant() const
   return false;
 }
 
-// Return an integer constant value if possible.
+// Return a numeric constant if possible.
 
 bool
-Builtin_call_expression::do_integer_constant_value(bool iota_is_constant,
-                                                  mpz_t val,
-                                                  Type** ptype) const
+Builtin_call_expression::do_numeric_constant_value(Numeric_constant* nc) const
 {
   if (this->code_ == BUILTIN_LEN
       || this->code_ == BUILTIN_CAP)
@@ -8093,8 +7024,8 @@ Builtin_call_expression::do_integer_constant_value(bool iota_is_constant,
          std::string sval;
          if (arg->string_constant_value(&sval))
            {
-             mpz_set_ui(val, sval.length());
-             *ptype = Type::lookup_integer_type("int");
+             nc->set_unsigned_long(Type::lookup_integer_type("int"),
+                                   sval.length());
              return true;
            }
        }
@@ -8111,13 +7042,15 @@ Builtin_call_expression::do_integer_constant_value(bool iota_is_constant,
            return false;
          Expression* e = arg_type->array_type()->length();
          this->seen_ = true;
-         bool r = e->integer_constant_value(iota_is_constant, val, ptype);
+         bool r = e->numeric_constant_value(nc);
          this->seen_ = false;
          if (r)
            {
-             *ptype = Type::lookup_integer_type("int");
-             return true;
+             if (!nc->set_type(Type::lookup_integer_type("int"), false,
+                               this->location()))
+               r = false;
            }
+         return r;
        }
     }
   else if (this->code_ == BUILTIN_SIZEOF
@@ -8158,8 +7091,7 @@ Builtin_call_expression::do_integer_constant_value(bool iota_is_constant,
       else
        go_unreachable();
 
-      mpz_set_ui(val, ret);
-      *ptype = NULL;
+      nc->set_unsigned_long(NULL, static_cast<unsigned long>(ret));
       return true;
     }
   else if (this->code_ == BUILTIN_OFFSETOF)
@@ -8181,88 +7113,72 @@ Builtin_call_expression::do_integer_constant_value(bool iota_is_constant,
                                                   farg->field_index(),
                                                   &offset))
        return false;
-      mpz_set_ui(val, offset);
+      nc->set_unsigned_long(NULL, static_cast<unsigned long>(offset));
       return true;
     }
-  return false;
-}
-
-// Return a floating point constant value if possible.
-
-bool
-Builtin_call_expression::do_float_constant_value(mpfr_t val,
-                                                Type** ptype) const
-{
-  if (this->code_ == BUILTIN_REAL || this->code_ == BUILTIN_IMAG)
+  else if (this->code_ == BUILTIN_REAL || this->code_ == BUILTIN_IMAG)
     {
       Expression* arg = this->one_arg();
       if (arg == NULL)
        return false;
 
+      Numeric_constant argnc;
+      if (!arg->numeric_constant_value(&argnc))
+       return false;
+
       mpfr_t real;
       mpfr_t imag;
-      mpfr_init(real);
-      mpfr_init(imag);
-
-      bool ret = false;
-      Type* type;
-      if (arg->complex_constant_value(real, imag, &type))
-       {
-         if (this->code_ == BUILTIN_REAL)
-           mpfr_set(val, real, GMP_RNDN);
-         else
-           mpfr_set(val, imag, GMP_RNDN);
-         *ptype = Builtin_call_expression::real_imag_type(type);
-         ret = true;
-       }
+      if (!argnc.to_complex(&real, &imag))
+       return false;
 
-      mpfr_clear(real);
-      mpfr_clear(imag);
-      return ret;
+      Type* type = Builtin_call_expression::real_imag_type(argnc.type());
+      if (this->code_ == BUILTIN_REAL)
+       nc->set_float(type, real);
+      else
+       nc->set_float(type, imag);
+      return true;
     }
-
-  return false;
-}
-
-// Return a complex constant value if possible.
-
-bool
-Builtin_call_expression::do_complex_constant_value(mpfr_t real, mpfr_t imag,
-                                                  Type** ptype) const
-{
-  if (this->code_ == BUILTIN_COMPLEX)
+  else if (this->code_ == BUILTIN_COMPLEX)
     {
       const Expression_list* args = this->args();
       if (args == NULL || args->size() != 2)
        return false;
 
+      Numeric_constant rnc;
+      if (!args->front()->numeric_constant_value(&rnc))
+       return false;
+      Numeric_constant inc;
+      if (!args->back()->numeric_constant_value(&inc))
+       return false;
+
+      if (rnc.type() != NULL
+         && !rnc.type()->is_abstract()
+         && inc.type() != NULL
+         && !inc.type()->is_abstract()
+         && !Type::are_identical(rnc.type(), inc.type(), false, NULL))
+       return false;
+
       mpfr_t r;
-      mpfr_init(r);
-      Type* rtype;
-      if (!args->front()->float_constant_value(r, &rtype))
+      if (!rnc.to_float(&r))
+       return false;
+      mpfr_t i;
+      if (!inc.to_float(&i))
        {
          mpfr_clear(r);
          return false;
        }
 
-      mpfr_t i;
-      mpfr_init(i);
+      Type* arg_type = rnc.type();
+      if (arg_type == NULL || arg_type->is_abstract())
+       arg_type = inc.type();
 
-      bool ret = false;
-      Type* itype;
-      if (args->back()->float_constant_value(i, &itype)
-         && Type::are_identical(rtype, itype, false, NULL))
-       {
-         mpfr_set(real, r, GMP_RNDN);
-         mpfr_set(imag, i, GMP_RNDN);
-         *ptype = Builtin_call_expression::complex_type(rtype);
-         ret = true;
-       }
+      Type* type = Builtin_call_expression::complex_type(arg_type);
+      nc->set_complex(type, r, i);
 
       mpfr_clear(r);
       mpfr_clear(i);
 
-      return ret;
+      return true;
     }
 
   return false;
@@ -8461,15 +7377,19 @@ Builtin_call_expression::do_determine_type(const Type_context* context)
                {
                  if (atype->integer_type() != NULL)
                    {
-                     mpz_t val;
-                     mpz_init(val);
-                     Type* dummy;
-                     if (this->integer_constant_value(true, val, &dummy)
-                         && mpz_sgn(val) >= 0)
-                       want_type = Type::lookup_integer_type("uint64");
-                     else
+                     Numeric_constant nc;
+                     if (this->numeric_constant_value(&nc))
+                       {
+                         mpz_t val;
+                         if (nc.to_int(&val))
+                           {
+                             if (mpz_sgn(val) >= 0)
+                               want_type = Type::lookup_integer_type("uint64");
+                             mpz_clear(val);
+                           }
+                       }
+                     if (want_type == NULL)
                        want_type = Type::lookup_integer_type("int64");
-                     mpz_clear(val);
                    }
                  else if (atype->float_type() != NULL)
                    want_type = Type::lookup_float_type("float64");
@@ -9148,20 +8068,17 @@ Builtin_call_expression::do_get_tree(Translate_context* context)
     case BUILTIN_OFFSETOF:
     case BUILTIN_ALIGNOF:
       {
-       mpz_t val;
-       mpz_init(val);
-       Type* dummy;
-       bool b = this->integer_constant_value(true, val, &dummy);
-       if (!b)
+       Numeric_constant nc;
+       unsigned long val;
+       if (!this->numeric_constant_value(&nc)
+           || nc.to_unsigned_long(&val) != Numeric_constant::NC_UL_VALID)
          {
            go_assert(saw_errors());
            return error_mark_node;
          }
        Type* int_type = Type::lookup_integer_type("int");
        tree type = type_to_tree(int_type->get_backend(gogo));
-       tree ret = Expression::integer_constant_tree(val, type);
-       mpz_clear(val);
-       return ret;
+       return build_int_cst(type, val);
       }
 
     case BUILTIN_COPY:
@@ -9376,50 +8293,37 @@ Builtin_call_expression::do_get_tree(Translate_context* context)
 void
 Builtin_call_expression::do_export(Export* exp) const
 {
-  bool ok = false;
+  Numeric_constant nc;
+  if (!this->numeric_constant_value(&nc))
+    {
+      error_at(this->location(), "value is not constant");
+      return;
+    }
 
-  mpz_t val;
-  mpz_init(val);
-  Type* dummy;
-  if (this->integer_constant_value(true, val, &dummy))
+  if (nc.is_int())
     {
+      mpz_t val;
+      nc.get_int(&val);
       Integer_expression::export_integer(exp, val);
-      ok = true;
+      mpz_clear(val);
     }
-  mpz_clear(val);
-
-  if (!ok)
+  else if (nc.is_float())
     {
       mpfr_t fval;
-      mpfr_init(fval);
-      if (this->float_constant_value(fval, &dummy))
-       {
-         Float_expression::export_float(exp, fval);
-         ok = true;
-       }
+      nc.get_float(&fval);
+      Float_expression::export_float(exp, fval);
       mpfr_clear(fval);
     }
-
-  if (!ok)
+  else if (nc.is_complex())
     {
       mpfr_t real;
       mpfr_t imag;
-      mpfr_init(real);
-      mpfr_init(imag);
-      if (this->complex_constant_value(real, imag, &dummy))
-       {
-         Complex_expression::export_complex(exp, real, imag);
-         ok = true;
-       }
+      Complex_expression::export_complex(exp, real, imag);
       mpfr_clear(real);
       mpfr_clear(imag);
     }
-
-  if (!ok)
-    {
-      error_at(this->location(), "value is not constant");
-      return;
-    }
+  else
+    go_unreachable();
 
   // A trailing space lets us reliably identify the end of the number.
   exp->write_c_string(" ");
@@ -10660,16 +9564,14 @@ Array_index_expression::do_check_types(Gogo*)
   unsigned int int_bits =
     Type::lookup_integer_type("int")->integer_type()->bits();
 
-  Type* dummy;
+  Numeric_constant lvalnc;
   mpz_t lval;
-  mpz_init(lval);
   bool lval_valid = (array_type->length() != NULL
-                    && array_type->length()->integer_constant_value(true,
-                                                                    lval,
-                                                                    &dummy));
+                    && array_type->length()->numeric_constant_value(&lvalnc)
+                    && lvalnc.to_int(&lval));
+  Numeric_constant inc;
   mpz_t ival;
-  mpz_init(ival);
-  if (this->start_->integer_constant_value(true, ival, &dummy))
+  if (this->start_->numeric_constant_value(&inc) && inc.to_int(&ival))
     {
       if (mpz_sgn(ival) < 0
          || mpz_sizeinbase(ival, 2) >= int_bits
@@ -10681,22 +9583,26 @@ Array_index_expression::do_check_types(Gogo*)
          error_at(this->start_->location(), "array index out of bounds");
          this->set_is_error();
        }
+      mpz_clear(ival);
     }
   if (this->end_ != NULL && !this->end_->is_nil_expression())
     {
-      if (this->end_->integer_constant_value(true, ival, &dummy))
+      Numeric_constant enc;
+      mpz_t eval;
+      if (this->end_->numeric_constant_value(&enc) && enc.to_int(&eval))
        {
-         if (mpz_sgn(ival) < 0
-             || mpz_sizeinbase(ival, 2) >= int_bits
-             || (lval_valid && mpz_cmp(ival, lval) > 0))
+         if (mpz_sgn(eval) < 0
+             || mpz_sizeinbase(eval, 2) >= int_bits
+             || (lval_valid && mpz_cmp(eval, lval) > 0))
            {
              error_at(this->end_->location(), "array index out of bounds");
              this->set_is_error();
            }
+         mpz_clear(eval);
        }
     }
-  mpz_clear(ival);
-  mpz_clear(lval);
+  if (lval_valid)
+    mpz_clear(lval);
 
   // A slice of an array requires an addressable array.  A slice of a
   // slice is always possible.
@@ -11071,10 +9977,9 @@ String_index_expression::do_check_types(Gogo*)
   std::string sval;
   bool sval_valid = this->string_->string_constant_value(&sval);
 
+  Numeric_constant inc;
   mpz_t ival;
-  mpz_init(ival);
-  Type* dummy;
-  if (this->start_->integer_constant_value(true, ival, &dummy))
+  if (this->start_->numeric_constant_value(&inc) && inc.to_int(&ival))
     {
       if (mpz_sgn(ival) < 0
          || (sval_valid && mpz_cmp_ui(ival, sval.length()) >= 0))
@@ -11082,20 +9987,23 @@ String_index_expression::do_check_types(Gogo*)
          error_at(this->start_->location(), "string index out of bounds");
          this->set_is_error();
        }
+      mpz_clear(ival);
     }
   if (this->end_ != NULL && !this->end_->is_nil_expression())
     {
-      if (this->end_->integer_constant_value(true, ival, &dummy))
+      Numeric_constant enc;
+      mpz_t eval;
+      if (this->end_->numeric_constant_value(&enc) && enc.to_int(&eval))
        {
-         if (mpz_sgn(ival) < 0
-             || (sval_valid && mpz_cmp_ui(ival, sval.length()) > 0))
+         if (mpz_sgn(eval) < 0
+             || (sval_valid && mpz_cmp_ui(eval, sval.length()) > 0))
            {
              error_at(this->end_->location(), "string index out of bounds");
              this->set_is_error();
            }
+         mpz_clear(eval);
        }
     }
-  mpz_clear(ival);
 }
 
 // Get a tree for a string index.
@@ -12464,17 +11372,15 @@ Array_construction_expression::do_check_types(Gogo*)
     }
 
   Expression* length = at->length();
-  if (length != NULL && !length->is_error_expression())
+  Numeric_constant nc;
+  unsigned long val;
+  if (length != NULL
+      && !length->is_error_expression()
+      && length->numeric_constant_value(&nc)
+      && nc.to_unsigned_long(&val) == Numeric_constant::NC_UL_VALID)
     {
-      mpz_t val;
-      mpz_init(val);
-      Type* type;
-      if (at->length()->integer_constant_value(true, val, &type))
-       {
-         if (this->vals_->size() > mpz_get_ui(val))
-           this->report_error(_("too many elements in composite literal"));
-       }
-      mpz_clear(val);
+      if (this->vals_->size() > val)
+       this->report_error(_("too many elements in composite literal"));
     }
 }
 
@@ -13472,49 +12378,41 @@ Composite_literal_expression::lower_array(Type* type)
 
       if (index_expr != NULL)
        {
-         mpz_t ival;
-         mpz_init(ival);
-
-         Type* dummy;
-         if (!index_expr->integer_constant_value(true, ival, &dummy))
+         Numeric_constant nc;
+         if (!index_expr->numeric_constant_value(&nc))
            {
-             mpz_clear(ival);
              error_at(index_expr->location(),
                       "index expression is not integer constant");
              return Expression::make_error(location);
            }
 
-         if (mpz_sgn(ival) < 0)
+         switch (nc.to_unsigned_long(&index))
            {
-             mpz_clear(ival);
+           case Numeric_constant::NC_UL_VALID:
+             break;
+           case Numeric_constant::NC_UL_NOTINT:
+             error_at(index_expr->location(),
+                      "index expression is not integer constant");
+             return Expression::make_error(location);
+           case Numeric_constant::NC_UL_NEGATIVE:
              error_at(index_expr->location(), "index expression is negative");
              return Expression::make_error(location);
-           }
-
-         index = mpz_get_ui(ival);
-         if (mpz_cmp_ui(ival, index) != 0)
-           {
-             mpz_clear(ival);
+           case Numeric_constant::NC_UL_BIG:
              error_at(index_expr->location(), "index value overflow");
              return Expression::make_error(location);
+           default:
+             go_unreachable();
            }
 
          Named_type* ntype = Type::lookup_integer_type("int");
          Integer_type* inttype = ntype->integer_type();
-         mpz_t max;
-         mpz_init_set_ui(max, 1);
-         mpz_mul_2exp(max, max, inttype->bits() - 1);
-         bool ok = mpz_cmp(ival, max) < 0;
-         mpz_clear(max);
-         if (!ok)
+         if (sizeof(index) <= static_cast<size_t>(inttype->bits() * 8)
+             && index >> (inttype->bits() - 1) != 0)
            {
-             mpz_clear(ival);
              error_at(index_expr->location(), "index value overflow");
              return Expression::make_error(location);
            }
 
-         mpz_clear(ival);
-
          // FIXME: Our representation isn't very good; this avoids
          // thrashing.
          if (index > 0x1000000)
@@ -14449,3 +13347,594 @@ Expression_list::contains_error() const
       return true;
   return false;
 }
+
+// Class Numeric_constant.
+
+// Destructor.
+
+Numeric_constant::~Numeric_constant()
+{
+  this->clear();
+}
+
+// Copy constructor.
+
+Numeric_constant::Numeric_constant(const Numeric_constant& a)
+  : classification_(a.classification_), type_(a.type_)
+{
+  switch (a.classification_)
+    {
+    case NC_INVALID:
+      break;
+    case NC_INT:
+    case NC_RUNE:
+      mpz_init_set(this->u_.int_val, a.u_.int_val);
+      break;
+    case NC_FLOAT:
+      mpfr_init_set(this->u_.float_val, a.u_.float_val, GMP_RNDN);
+      break;
+    case NC_COMPLEX:
+      mpfr_init_set(this->u_.complex_val.real, a.u_.complex_val.real,
+                   GMP_RNDN);
+      mpfr_init_set(this->u_.complex_val.imag, a.u_.complex_val.imag,
+                   GMP_RNDN);
+      break;
+    default:
+      go_unreachable();
+    }
+}
+
+// Assignment operator.
+
+Numeric_constant&
+Numeric_constant::operator=(const Numeric_constant& a)
+{
+  this->clear();
+  this->classification_ = a.classification_;
+  this->type_ = a.type_;
+  switch (a.classification_)
+    {
+    case NC_INVALID:
+      break;
+    case NC_INT:
+    case NC_RUNE:
+      mpz_init_set(this->u_.int_val, a.u_.int_val);
+      break;
+    case NC_FLOAT:
+      mpfr_init_set(this->u_.float_val, a.u_.float_val, GMP_RNDN);
+      break;
+    case NC_COMPLEX:
+      mpfr_init_set(this->u_.complex_val.real, a.u_.complex_val.real,
+                   GMP_RNDN);
+      mpfr_init_set(this->u_.complex_val.imag, a.u_.complex_val.imag,
+                   GMP_RNDN);
+      break;
+    default:
+      go_unreachable();
+    }
+  return *this;
+}
+
+// Clear the contents.
+
+void
+Numeric_constant::clear()
+{
+  switch (this->classification_)
+    {
+    case NC_INVALID:
+      break;
+    case NC_INT:
+    case NC_RUNE:
+      mpz_clear(this->u_.int_val);
+      break;
+    case NC_FLOAT:
+      mpfr_clear(this->u_.float_val);
+      break;
+    case NC_COMPLEX:
+      mpfr_clear(this->u_.complex_val.real);
+      mpfr_clear(this->u_.complex_val.imag);
+      break;
+    default:
+      go_unreachable();
+    }
+  this->classification_ = NC_INVALID;
+}
+
+// Set to an unsigned long value.
+
+void
+Numeric_constant::set_unsigned_long(Type* type, unsigned long val)
+{
+  this->clear();
+  this->classification_ = NC_INT;
+  this->type_ = type;
+  mpz_init_set_ui(this->u_.int_val, val);
+}
+
+// Set to an integer value.
+
+void
+Numeric_constant::set_int(Type* type, const mpz_t val)
+{
+  this->clear();
+  this->classification_ = NC_INT;
+  this->type_ = type;
+  mpz_init_set(this->u_.int_val, val);
+}
+
+// Set to a rune value.
+
+void
+Numeric_constant::set_rune(Type* type, const mpz_t val)
+{
+  this->clear();
+  this->classification_ = NC_RUNE;
+  this->type_ = type;
+  mpz_init_set(this->u_.int_val, val);
+}
+
+// Set to a floating point value.
+
+void
+Numeric_constant::set_float(Type* type, const mpfr_t val)
+{
+  this->clear();
+  this->classification_ = NC_FLOAT;
+  this->type_ = type;
+  mpfr_init_set(this->u_.float_val, val, GMP_RNDN);
+}
+
+// Set to a complex value.
+
+void
+Numeric_constant::set_complex(Type* type, const mpfr_t real, const mpfr_t imag)
+{
+  this->clear();
+  this->classification_ = NC_COMPLEX;
+  this->type_ = type;
+  mpfr_init_set(this->u_.complex_val.real, real, GMP_RNDN);
+  mpfr_init_set(this->u_.complex_val.imag, imag, GMP_RNDN);
+}
+
+// Get an int value.
+
+void
+Numeric_constant::get_int(mpz_t* val) const
+{
+  go_assert(this->is_int());
+  mpz_init_set(*val, this->u_.int_val);
+}
+
+// Get a rune value.
+
+void
+Numeric_constant::get_rune(mpz_t* val) const
+{
+  go_assert(this->is_rune());
+  mpz_init_set(*val, this->u_.int_val);
+}
+
+// Get a floating point value.
+
+void
+Numeric_constant::get_float(mpfr_t* val) const
+{
+  go_assert(this->is_float());
+  mpfr_init_set(*val, this->u_.float_val, GMP_RNDN);
+}
+
+// Get a complex value.
+
+void
+Numeric_constant::get_complex(mpfr_t* real, mpfr_t* imag) const
+{
+  go_assert(this->is_complex());
+  mpfr_init_set(*real, this->u_.complex_val.real, GMP_RNDN);
+  mpfr_init_set(*imag, this->u_.complex_val.imag, GMP_RNDN);
+}
+
+// Express value as unsigned long if possible.
+
+Numeric_constant::To_unsigned_long
+Numeric_constant::to_unsigned_long(unsigned long* val) const
+{
+  switch (this->classification_)
+    {
+    case NC_INT:
+    case NC_RUNE:
+      return this->mpz_to_unsigned_long(this->u_.int_val, val);
+    case NC_FLOAT:
+      return this->mpfr_to_unsigned_long(this->u_.float_val, val);
+    case NC_COMPLEX:
+      if (!mpfr_zero_p(this->u_.complex_val.imag))
+       return NC_UL_NOTINT;
+      return this->mpfr_to_unsigned_long(this->u_.complex_val.real, val);
+    default:
+      go_unreachable();
+    }
+}
+
+// Express integer value as unsigned long if possible.
+
+Numeric_constant::To_unsigned_long
+Numeric_constant::mpz_to_unsigned_long(const mpz_t ival,
+                                      unsigned long *val) const
+{
+  if (mpz_sgn(ival) < 0)
+    return NC_UL_NEGATIVE;
+  unsigned long ui = mpz_get_ui(ival);
+  if (mpz_cmp_ui(ival, ui) != 0)
+    return NC_UL_BIG;
+  *val = ui;
+  return NC_UL_VALID;
+}
+
+// Express floating point value as unsigned long if possible.
+
+Numeric_constant::To_unsigned_long
+Numeric_constant::mpfr_to_unsigned_long(const mpfr_t fval,
+                                       unsigned long *val) const
+{
+  if (!mpfr_integer_p(fval))
+    return NC_UL_NOTINT;
+  mpz_t ival;
+  mpz_init(ival);
+  mpfr_get_z(ival, fval, GMP_RNDN);
+  To_unsigned_long ret = this->mpz_to_unsigned_long(ival, val);
+  mpz_clear(ival);
+  return ret;
+}
+
+// Convert value to integer if possible.
+
+bool
+Numeric_constant::to_int(mpz_t* val) const
+{
+  switch (this->classification_)
+    {
+    case NC_INT:
+    case NC_RUNE:
+      mpz_init_set(*val, this->u_.int_val);
+      return true;
+    case NC_FLOAT:
+      if (!mpfr_integer_p(this->u_.float_val))
+       return false;
+      mpz_init(*val);
+      mpfr_get_z(*val, this->u_.float_val, GMP_RNDN);
+      return true;
+    case NC_COMPLEX:
+      if (!mpfr_zero_p(this->u_.complex_val.imag)
+         || !mpfr_integer_p(this->u_.complex_val.real))
+       return false;
+      mpz_init(*val);
+      mpfr_get_z(*val, this->u_.complex_val.real, GMP_RNDN);
+      return true;
+    default:
+      go_unreachable();
+    }
+}
+
+// Convert value to floating point if possible.
+
+bool
+Numeric_constant::to_float(mpfr_t* val) const
+{
+  switch (this->classification_)
+    {
+    case NC_INT:
+    case NC_RUNE:
+      mpfr_init_set_z(*val, this->u_.int_val, GMP_RNDN);
+      return true;
+    case NC_FLOAT:
+      mpfr_init_set(*val, this->u_.float_val, GMP_RNDN);
+      return true;
+    case NC_COMPLEX:
+      if (!mpfr_zero_p(this->u_.complex_val.imag))
+       return false;
+      mpfr_init_set(*val, this->u_.complex_val.real, GMP_RNDN);
+      return true;
+    default:
+      go_unreachable();
+    }
+}
+
+// Convert value to complex.
+
+bool
+Numeric_constant::to_complex(mpfr_t* vr, mpfr_t* vi) const
+{
+  switch (this->classification_)
+    {
+    case NC_INT:
+    case NC_RUNE:
+      mpfr_init_set_z(*vr, this->u_.int_val, GMP_RNDN);
+      mpfr_init_set_ui(*vi, 0, GMP_RNDN);
+      return true;
+    case NC_FLOAT:
+      mpfr_init_set(*vr, this->u_.float_val, GMP_RNDN);
+      mpfr_init_set_ui(*vi, 0, GMP_RNDN);
+      return true;
+    case NC_COMPLEX:
+      mpfr_init_set(*vr, this->u_.complex_val.real, GMP_RNDN);
+      mpfr_init_set(*vi, this->u_.complex_val.imag, GMP_RNDN);
+      return true;
+    default:
+      go_unreachable();
+    }
+}
+
+// Get the type.
+
+Type*
+Numeric_constant::type() const
+{
+  if (this->type_ != NULL)
+    return this->type_;
+  switch (this->classification_)
+    {
+    case NC_INT:
+      return Type::make_abstract_integer_type();
+    case NC_RUNE:
+      return Type::make_abstract_character_type();
+    case NC_FLOAT:
+      return Type::make_abstract_float_type();
+    case NC_COMPLEX:
+      return Type::make_abstract_complex_type();
+    default:
+      go_unreachable();
+    }
+}
+
+// If the constant can be expressed in TYPE, then set the type of the
+// constant to TYPE and return true.  Otherwise return false, and, if
+// ISSUE_ERROR is true, report an appropriate error message.
+
+bool
+Numeric_constant::set_type(Type* type, bool issue_error, Location loc)
+{
+  bool ret;
+  if (type == NULL)
+    ret = true;
+  else if (type->integer_type() != NULL)
+    ret = this->check_int_type(type->integer_type(), issue_error, loc);
+  else if (type->float_type() != NULL)
+    ret = this->check_float_type(type->float_type(), issue_error, loc);
+  else if (type->complex_type() != NULL)
+    ret = this->check_complex_type(type->complex_type(), issue_error, loc);
+  else
+    go_unreachable();
+  if (ret)
+    this->type_ = type;
+  return ret;
+}
+
+// Check whether the constant can be expressed in an integer type.
+
+bool
+Numeric_constant::check_int_type(Integer_type* type, bool issue_error,
+                                Location location) const
+{
+  mpz_t val;
+  switch (this->classification_)
+    {
+    case NC_INT:
+    case NC_RUNE:
+      mpz_init_set(val, this->u_.int_val);
+      break;
+
+    case NC_FLOAT:
+      if (!mpfr_integer_p(this->u_.float_val))
+       {
+         if (issue_error)
+           error_at(location, "floating point constant truncated to integer");
+         return false;
+       }
+      mpz_init(val);
+      mpfr_get_z(val, this->u_.float_val, GMP_RNDN);
+      break;
+
+    case NC_COMPLEX:
+      if (!mpfr_integer_p(this->u_.complex_val.real)
+         || !mpfr_zero_p(this->u_.complex_val.imag))
+       {
+         if (issue_error)
+           error_at(location, "complex constant truncated to integer");
+         return false;
+       }
+      mpz_init(val);
+      mpfr_get_z(val, this->u_.complex_val.real, GMP_RNDN);
+      break;
+
+    default:
+      go_unreachable();
+    }
+
+  bool ret;
+  if (type->is_abstract())
+    ret = true;
+  else
+    {
+      int bits = mpz_sizeinbase(val, 2);
+      if (type->is_unsigned())
+       {
+         // For an unsigned type we can only accept a nonnegative
+         // number, and we must be able to represents at least BITS.
+         ret = mpz_sgn(val) >= 0 && bits <= type->bits();
+       }
+      else
+       {
+         // For a signed type we need an extra bit to indicate the
+         // sign.  We have to handle the most negative integer
+         // specially.
+         ret = (bits + 1 <= type->bits()
+                || (bits <= type->bits()
+                    && mpz_sgn(val) < 0
+                    && (mpz_scan1(val, 0)
+                        == static_cast<unsigned long>(type->bits() - 1))
+                    && mpz_scan0(val, type->bits()) == ULONG_MAX));
+       }
+    }
+
+  if (!ret && issue_error)
+    error_at(location, "integer constant overflow");
+
+  return ret;
+}
+
+// Check whether the constant can be expressed in a floating point
+// type.
+
+bool
+Numeric_constant::check_float_type(Float_type* type, bool issue_error,
+                                  Location location) const
+{
+  mpfr_t val;
+  switch (this->classification_)
+    {
+    case NC_INT:
+    case NC_RUNE:
+      mpfr_init_set_z(val, this->u_.int_val, GMP_RNDN);
+      break;
+
+    case NC_FLOAT:
+      mpfr_init_set(val, this->u_.float_val, GMP_RNDN);
+      break;
+
+    case NC_COMPLEX:
+      if (!mpfr_zero_p(this->u_.complex_val.imag))
+       {
+         if (issue_error)
+           error_at(location, "complex constant truncated to float");
+         return false;
+       }
+      mpfr_init_set(val, this->u_.complex_val.real, GMP_RNDN);
+      break;
+
+    default:
+      go_unreachable();
+    }
+
+  bool ret;
+  if (type->is_abstract())
+    ret = true;
+  else if (mpfr_nan_p(val) || mpfr_inf_p(val) || mpfr_zero_p(val))
+    {
+      // A NaN or Infinity always fits in the range of the type.
+      ret = true;
+    }
+  else
+    {
+      mp_exp_t exp = mpfr_get_exp(val);
+      mp_exp_t max_exp;
+      switch (type->bits())
+       {
+       case 32:
+         max_exp = 128;
+         break;
+       case 64:
+         max_exp = 1024;
+         break;
+       default:
+         go_unreachable();
+       }
+
+      ret = exp <= max_exp;
+    }
+
+  mpfr_clear(val);
+
+  if (!ret && issue_error)
+    error_at(location, "floating point constant overflow");
+
+  return ret;
+} 
+
+// Check whether the constant can be expressed in a complex type.
+
+bool
+Numeric_constant::check_complex_type(Complex_type* type, bool issue_error,
+                                    Location location) const
+{
+  if (type->is_abstract())
+    return true;
+
+  mp_exp_t max_exp;
+  switch (type->bits())
+    {
+    case 64:
+      max_exp = 128;
+      break;
+    case 128:
+      max_exp = 1024;
+      break;
+    default:
+      go_unreachable();
+    }
+
+  mpfr_t real;
+  switch (this->classification_)
+    {
+    case NC_INT:
+    case NC_RUNE:
+      mpfr_init_set_z(real, this->u_.int_val, GMP_RNDN);
+      break;
+
+    case NC_FLOAT:
+      mpfr_init_set(real, this->u_.float_val, GMP_RNDN);
+      break;
+
+    case NC_COMPLEX:
+      if (!mpfr_nan_p(this->u_.complex_val.imag)
+         && !mpfr_inf_p(this->u_.complex_val.imag)
+         && !mpfr_zero_p(this->u_.complex_val.imag))
+       {
+         if (mpfr_get_exp(this->u_.complex_val.imag) > max_exp)
+           {
+             if (issue_error)
+               error_at(location, "complex imaginary part overflow");
+             return false;
+           }
+       }
+      mpfr_init_set(real, this->u_.complex_val.real, GMP_RNDN);
+      break;
+
+    default:
+      go_unreachable();
+    }
+
+  bool ret;
+  if (mpfr_nan_p(real) || mpfr_inf_p(real) || mpfr_zero_p(real))
+    ret = true;
+  else
+    ret = mpfr_get_exp(real) <= max_exp;
+
+  mpfr_clear(real);
+
+  if (!ret && issue_error)
+    error_at(location, "complex real part overflow");
+
+  return ret;
+}
+
+// Return an Expression for this value.
+
+Expression*
+Numeric_constant::expression(Location loc) const
+{
+  switch (this->classification_)
+    {
+    case NC_INT:
+      return Expression::make_integer(&this->u_.int_val, this->type_, loc);
+    case NC_RUNE:
+      return Expression::make_character(&this->u_.int_val, this->type_, loc);
+    case NC_FLOAT:
+      return Expression::make_float(&this->u_.float_val, this->type_, loc);
+    case NC_COMPLEX:
+      return Expression::make_complex(&this->u_.complex_val.real,
+                                     &this->u_.complex_val.imag,
+                                     this->type_, loc);
+    default:
+      go_unreachable();
+    }
+}