Additions to gdb_mpz

In preparation for adding more 128-bit support to gdb, a few additions
to gdb_mpz are needed.

First, this adds a new 'as_integer_truncate' method.  This method
works like 'as_integer' but does not require the value to fit in the
target type -- it just truncates.

Second, gdb_mpz::export_bits is changed to handle the somewhat unusual
situation of zero-length types.  This can happen for a Rust '()' type;
but I think other languages have zero-bit integer types as well.

Finally, this adds some operator== overloads.

1 files changed, 46 insertions, 2 deletions

diff --git a/gdb/gmp-utils.h b/gdb/gmp-utils.h
index f294ab6..d05c11e 100644
--- a/gdb/gmp-utils.h
+++ b/gdb/gmp-utils.h
@@ -119,11 +119,17 @@ struct gdb_mpz
     return result;
   }
 
-  /* Convert VAL to an integer of the given type.
+  /* Convert this value to an integer of the given type.
 
      The return type can signed or unsigned, with no size restriction.  */
   template<typename T> T as_integer () const;
 
+  /* Convert this value to an integer of the given type.  If this
+     value is too large, it is truncated.
+
+     The return type can signed or unsigned, with no size restriction.  */
+  template<typename T> T as_integer_truncate () const;
+
   /* Set VAL by importing the number stored in the byte array (BUF),
      using the given BYTE_ORDER.  The size of the data to read is
      the byte array's size.
@@ -312,7 +318,7 @@ struct gdb_mpz
     return mpz_cmp (m_val, other.m_val) <= 0;
   }
 
-  bool operator< (int other) const
+  bool operator< (long other) const
   {
     return mpz_cmp_si (m_val, other) < 0;
   }
@@ -322,6 +328,28 @@ struct gdb_mpz
     return mpz_cmp_si (m_val, other) == 0;
   }
 
+  bool operator== (long other) const
+  {
+    return mpz_cmp_si (m_val, other) == 0;
+  }
+
+  bool operator== (unsigned long other) const
+  {
+    return mpz_cmp_ui (m_val, other) == 0;
+  }
+
+  template<typename T,
+	   typename = gdb::Requires<
+	     gdb::And<std::is_integral<T>,
+		      std::integral_constant<bool,
+					     (sizeof (T) > sizeof (long))>>
+	     >
+	   >
+  bool operator== (T src)
+  {
+    return *this == gdb_mpz (src);
+  }
+
   bool operator== (const gdb_mpz &other) const
   {
     return mpz_cmp (m_val, other.m_val) == 0;
@@ -612,4 +640,20 @@ gdb_mpz::as_integer () const
   return result;
 }
 
+/* See declaration above.  */
+
+template<typename T>
+T
+gdb_mpz::as_integer_truncate () const
+{
+  T result;
+
+  this->export_bits ({(gdb_byte *) &result, sizeof (result)},
+		     0 /* endian (0 = native) */,
+		     !std::is_signed<T>::value /* unsigned_p */,
+		     false /* safe */);
+
+  return result;
+}
+
 #endif