[cfe-commits] [Patch] PR11179 - Update StmtPrinter to not complain on some IntegerLiteral types

[Richard Trieu]

On Wed, Nov 2, 2011 at 3:51 PM, Abramo Bagnara <abramo.bagnara at gmail.com>wrote:

> Il 02/11/2011 03:21, Richard Trieu ha scritto:
> > On Mon, Oct 24, 2011 at 7:30 AM, Douglas Gregor <dgregor at apple.com
> > <mailto:dgregor at apple.com>> wrote:
> >
> >
> >     On Oct 20, 2011, at 5:36 PM, Chandler Carruth wrote:
> >
> >>     On Thu, Oct 20, 2011 at 5:12 PM, Richard Trieu <rtrieu at google.com
> >>     <mailto:rtrieu at google.com>> wrote:
> >>
> >>         Should Clang be printing suffixes that are accepted only with
> >>         certain flags?
> >>
> >>
> >>     I think this is an interesting policy decision. I'd love to hear
> >>     Doug's thoughts on it.
> >>
> >>     It seems fine to me for Clang, when running with -fms-extensions,
> >>     to suggest fixes even if only valid for -fms-extensions. Clearly
> >>     if there is a generic suggestion that could be made, that would be
> >>     a preferred alternative. For example, '__asm__' should be
> >>     suggested before 'asm'.
> >
> >     I think it's fine for Clang to print suffixes that are only accepted
> >     with certain flags. Presumably, you should never get an
> >     IntegerLiteral of type __int128_t unless you're in a dialect that
> >     supports parsing it.
> >
> >     … except that we cheat when we're building template arguments,
> >     because it was convenient. That cheating could be eliminated by
> >     encoding integer literal values directly within
> >     SubstNonTypeTemplateParmExpr.
> >
> >     - Doug
> >
> >
> > New patch.  Changes as follows:
> > Add int128 and uint128 suffixes (i128 and Ui128) to StmtPrinter.  short
> > and unsigned short will get to llvm_unreachable
> > Add assert to IntergerLiteral to prevent creation with type short or
> > unsigned short
> > Fix comment in IntegerLiteral to say that int128 and uint128 are
> > acceptable types
> > Change BuildExpressFromIntegralTemplateArgument to give a proper Expr.
> >  For negative numbers, use UnaryOperator of IntegerLiteral.  For short
> > and unsigned short, ImplicitCastExpr from int.
>
> Following this path have you considered how to represent an int
> parameter with value INT_MIN?
>
> I think there is no way you can represent it in standard conformant way
> except to use -INT_MAX - 1 (i.e. -2147483647 - 1 if int has 32 bits).
>
> You cannot use -214783648 because no integer literal of type int with
> value 214783648 can exists.
>

Richard Smith brought up a similar point in the code review comments.  I am
putting in an integer type selector which will move up to larger types
until a large enough type can be found.  For instance, for int_min, use the
negation of a long with a cast back to int.
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