On 02/26/2018 12:45 PM, Richard Sandiford wrote:
Martin Sebor <mse...@gmail.com> writes:
Richard,
If you agree, I'd like to update the conversion section of
the poly_int manual to make the conversion to make it clearer
that the to_constant() function can be used even with class
types like offset_int besides scalars.
Also, when testing this I also tried converting poly64_int
into wide_int but that doesn't work. Is there a way to do
that?
Not in one go, because you have to specify the intended precision
of the wide_int when constructing it from something like HOST_WIDE_INT.
(That's deliberate.)
Thanks
Martin
gcc/ChangeLog:
* doc/poly-int.texi (is_constant): Expand.
Index: gcc/doc/poly-int.texi
===================================================================
--- gcc/doc/poly-int.texi (revision 258004)
+++ gcc/doc/poly-int.texi (working copy)
@@ -836,9 +836,24 @@ Return true if @code{poly_int} @var{value} is a co
@item @var{value}.is_constant (&@var{c1})
Return true if @code{poly_int} @var{value} is a compile-time constant,
-storing it in @var{c1} if so. @var{c1} must be able to hold all
-constant values of @var{value} without loss of precision.
+storing it in @var{c1} if so. @var{c1} may be a scalar or a wide int
+class type capable of holding all constant values of @var{value} without
Not sure about "a scalar or a wide int", since that implies that wide ints
aren't scalar. Even more pedantic, sorry, but c1 is an object rather than
a type.
At a higher level, I'm a bit nervous about singling this out as a special
case, since all the poly_int stuff allows HOST_WIDE_INT, offset_int and
wide_int to be combined in the (hopefully) natural way. E.g. you can
add offset_ints to poly_int64s, assign HOST_WIDE_INTs to poly_offset_ints,
and so on.
But if we do keep it like this, how about:
@var{c1} must be some form of integer object that can hold all constant
values of @var{value} without loss of precision; it can be either a normal
C++ integer or a wide-int class like @code{offset_int}.
?
Sure. Attached is an update with your change.
Martin
gcc/ChangeLog:
* doc/poly-int.texi (is_constant): Expand.
Index: gcc/doc/poly-int.texi
===================================================================
--- gcc/doc/poly-int.texi (revision 258004)
+++ gcc/doc/poly-int.texi (working copy)
@@ -836,8 +836,23 @@ Return true if @code{poly_int} @var{value} is a co
@item @var{value}.is_constant (&@var{c1})
Return true if @code{poly_int} @var{value} is a compile-time constant,
-storing it in @var{c1} if so. @var{c1} must be able to hold all
-constant values of @var{value} without loss of precision.
+storing it in @var{c1} if so. @var{c1} must be some form of integer
+object that can hold all constant values of @var{value} without loss
+of precision; it can be either a normal C++ integer or a wide-int class
+like @code{offset_int}. The following example illustrates using
+the function to convert a @code{poly_int64} to @code{HOST_WIDE_INT}
+and to @code{offset_int}.
+@smallexample
+void f (poly_int64 pi)
+@{
+ HOST_WIDE_INT hwi;
+ if (pi.is_constant (&hwi))
+ ; // Use hwi...
+ offset_int off;
+ if (pi.is_constant (&off))
+ ; // Use off...
+@}
+@end smallexample
@item @var{value}.to_constant ()
Assert that @var{value} is a compile-time constant and return its value.