On Jan 31, 2008 9:26 PM, DJ Delorie <[EMAIL PROTECTED]> wrote:
>
> > It's correct to always sign-extend the offset to the pointer mode
> > width (or simply truncate it, if the offset width is larger than
> > pointer mode width).
>
> I'd argue against that if you're dereferencing a large structure
>
> It's correct to always sign-extend the offset to the pointer mode
> width (or simply truncate it, if the offset width is larger than
> pointer mode width).
I'd argue against that if you're dereferencing a large structure
pointer. P->foo would always be an unsigned offset. Similarly for
arrays
On Jan 31, 2008 9:11 PM, DJ Delorie <[EMAIL PROTECTED]> wrote:
>
> > case POINTER_PLUS_EXPR:
> > /* Even though the sizetype mode and the pointer's mode can be
> > different
> > expand is able to handle this correctly and get the correct result
> > out
> > of the PLUS_
> case POINTER_PLUS_EXPR:
> /* Even though the sizetype mode and the pointer's mode can be different
> expand is able to handle this correctly and get the correct result
> out
> of the PLUS_EXPR code. */
Me thinks that comment now needs some rethinking ;-)
On Jan 31, 2008 12:00 PM, DJ Delorie <[EMAIL PROTECTED]> wrote:
> Which file would that be in? It wasn't obvious from a simple grep.
> Or is that sprinkled all over the place?
The expansion is in expr.c with a comment of:
case POINTER_PLUS_EXPR:
/* Even though the sizetype mode and the
> Can you represent all pointer offsets (well, those you actually
> support) within sizetype?
Yes. It's a limit, but we live with it. It would be nice if the
offsets were extended according to their own sign, which gives us 1.5x
the range of choosing a single signedness.
> If so you probably o
On Jan 31, 2008 8:40 PM, DJ Delorie <[EMAIL PROTECTED]> wrote:
>
> > The problem you are running into is that sizeof(sizetype) !=
> > sizeof(void *). In the middle-end the type used as offset
> > (sizetype) doesn't have a defined signedness (it's unsigned for C,
> > signed for Ada for example), so
> The problem you are running into is that sizeof(sizetype) !=
> sizeof(void *). In the middle-end the type used as offset
> (sizetype) doesn't have a defined signedness (it's unsigned for C,
> signed for Ada for example), so we rely on the fact that its size
> should match that of pointers (as t
On Jan 31, 2008 12:45 AM, DJ Delorie <[EMAIL PROTECTED]> wrote:
>
> I'm debugging an EH failure on m32c-elf (-mcpu=m32c). The test case
> is this:
>
> extern int U();
>
> void *ra;
>
> main()
> {
> foo((ra + U()) - 1);
> }
>
> In the context of the bug, sizeof(void *) is 32 (well, PSImode = 24
>
DJ Delorie writes:
>extern int U();
>void *ra;
...
> foo((ra + U()) - 1)
...
>1. What are the language rules controlling this expression, and do they
>have any say about signed vs unsigned wrt the int->pointer promotion?
There is no integer to pointer promotion. You're adding an integer to a
poi
I'm debugging an EH failure on m32c-elf (-mcpu=m32c). The test case
is this:
extern int U();
void *ra;
main()
{
foo((ra + U()) - 1);
}
In the context of the bug, sizeof(void *) is 32 (well, PSImode = 24
bit) and sizeof(int) == 16. U() returns zero in this example.
So, the call is this:
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