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

[Richard Trieu]

On Wed, Nov 2, 2011 at 4:21 PM, Abramo Bagnara <abramo.bagnara at gmail.com>wrote:

> Il 03/11/2011 00:16, Richard Trieu ha scritto:
> > On Wed, Nov 2, 2011 at 3:51 PM, Abramo Bagnara <abramo.bagnara at gmail.com
> > <mailto: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>
> >     > <mailto: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>
> >     >>     <mailto: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 <tel: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.
>
> What about when you don't have a larger type? (i.e. the minimum negative
> number of larger signed integral type)
>

I'm thinking of switching to the unsigned version of that signed type.  And
if that is still not large enough, assert, because there's nothing left
Clang can do.
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