> So, if you have int16 target, where unsigned int is 16-bit and UINT_MAX
> 65535, then shift count must be >= 0 and < 16, therefore, 2U << 31 is
> undefined behavior.
Well, if the shift count is masked by the target, if will be masked according
to the width of the register and the result will ne
> I believe Jakub is referring to the following in the C standard:
>
> "Bitwise shift operators
> ...
> Semantics
> ... If the value of the right operand ... is greater than or equal to the
> width of the promoted left operand, the behavior is undefined."
>
> So on 16-bit int systems you can't p
On Sat, Apr 26, 2014 at 03:30:25PM +0200, Eric Botcazou wrote:
> > > Not clear to me, (2U << i) should be zero if the shift count is masked.
> >
> > 2U << 31 is undefined behavior on those targets.
>
> Precisely not, or else we are not talking about the same notion of masking.
Eh, C99, 6.5.7/3:
Eric Botcazou writes:
> > > Not clear to me, (2U << i) should be zero if the shift count is masked.
> >
> > 2U << 31 is undefined behavior on those targets.
>
> Precisely not, or else we are not talking about the same notion of masking.
I believe Jakub is referring to the following in the C
> > Not clear to me, (2U << i) should be zero if the shift count is masked.
>
> 2U << 31 is undefined behavior on those targets.
Precisely not, or else we are not talking about the same notion of masking.
--
Eric Botcazou
On Fri, Apr 25, 2014 at 01:24:13PM +0200, Eric Botcazou wrote:
> > I'm afraid the testcase will fail on int16 targets, so perhaps
> > you should guard the body of main other than return 0; with
> > #if __INT_MAX__ >= 2147483647ULL
> > or
> > #if __SIZEOF_INT__ >= 4
> > or similar (or require int32p
> I'm afraid the testcase will fail on int16 targets, so perhaps
> you should guard the body of main other than return 0; with
> #if __INT_MAX__ >= 2147483647ULL
> or
> #if __SIZEOF_INT__ >= 4
> or similar (or require int32plus target, but gcc.c-torture/execute/
> is not a good place for that and *
On Fri, Apr 25, 2014 at 12:47:32PM +0200, Eric Botcazou wrote:
> /* PR target/60941 */
> /* Reported by Martin Husemann */
>
> extern void abort (void);
>
> static void __attribute__((noinline))
> set (unsigned long *l)
> {
> *l = 31;
> }
>
> int main (void)
> {
> unsigned long l;
> int i
This is a regression present on all active branches. The first pattern added
by http://gcc.gnu.org/ml/gcc-patches/2011-10/msg00060.html is wrong since, as
counter-intuitive as it may seem, "sll" also does a full 64-bit shift.
Tested on SPARC/Solaris, applied on all active branches.
2014-04-25
