On Wed, Nov 21, 2012 at 9:38 PM, Jakub Jelinek <ja...@redhat.com> wrote:
> Hi!
>
> If a type has 2 * HWI precision, sizem1 is maximum double_int (all ones)
> and thus size = sizem1 + double_int_one overflows into 0. If either min0
> or min1 is also zero, we might wrongly canonicalize the range into a signed
> one. Fixed thusly, bootstrapped/regtested on x86_64-linux and i686-linux,
> ok for trunk?
Ok.
Thanks,
Richard.
> 2012-11-21 Jakub Jelinek <ja...@redhat.com>
>
> PR tree-optimization/54471
> * tree-vrp.c (extract_range_from_binary_expr_1): For MULT_EXPR,
> don't canonicalize range if min2 is zero.
>
> * gcc.dg/tree-ssa/vrp86.c: New test.
> * gcc.c-torture/execute/pr54471.c: New test.
>
> --- gcc/tree-vrp.c.jj 2012-11-21 16:00:05.000085079 +0100
> +++ gcc/tree-vrp.c 2012-11-21 18:24:58.385290035 +0100
> @@ -2653,7 +2653,7 @@ extract_range_from_binary_expr_1 (value_
> if (TYPE_UNSIGNED (expr_type))
> {
> double_int min2 = size - min0;
> - if (min2.cmp (max0, true) < 0)
> + if (!min2.is_zero () && min2.cmp (max0, true) < 0)
> {
> min0 = -min2;
> max0 -= size;
> @@ -2661,7 +2661,7 @@ extract_range_from_binary_expr_1 (value_
> }
>
> min2 = size - min1;
> - if (min2.cmp (max1, true) < 0)
> + if (!min2.is_zero () && min2.cmp (max1, true) < 0)
> {
> min1 = -min2;
> max1 -= size;
> --- gcc/testsuite/gcc.dg/tree-ssa/vrp86.c.jj 2012-11-21 18:27:53.389280736
> +0100
> +++ gcc/testsuite/gcc.dg/tree-ssa/vrp86.c 2012-11-21 18:27:47.000000000
> +0100
> @@ -0,0 +1,28 @@
> +/* PR tree-optimization/54471 */
> +/* { dg-do compile } */
> +/* { dg-options "-O2 -fdump-tree-vrp1" } */
> +
> +#ifdef __SIZEOF_INT128__
> +#define T __int128
> +#else
> +#define T long long
> +#endif
> +
> +void fn1call (void);
> +void fn2call (void);
> +
> +void
> +foo (unsigned T x)
> +{
> + if (x > (unsigned T) -3)
> + return;
> + unsigned T y = 2 * x;
> + if (y == 42)
> + fn1call ();
> + else
> + fn2call ();
> +}
> +
> +/* { dg-final { scan-tree-dump "fn1call" "vrp1"} } */
> +/* { dg-final { scan-tree-dump "fn2call" "vrp1"} } */
> +/* { dg-final { cleanup-tree-dump "vrp1" } } */
> --- gcc/testsuite/gcc.c-torture/execute/pr54471.c.jj 2012-11-21
> 18:24:58.386289954 +0100
> +++ gcc/testsuite/gcc.c-torture/execute/pr54471.c 2012-11-21
> 18:24:58.386289954 +0100
> @@ -0,0 +1,36 @@
> +/* PR tree-optimization/54471 */
> +
> +#ifdef __SIZEOF_INT128__
> +#define T __int128
> +#else
> +#define T long long
> +#endif
> +
> +extern void abort (void);
> +
> +__attribute__ ((noinline))
> +unsigned T
> +foo (T ixi, unsigned ctr)
> +{
> + unsigned T irslt = 1;
> + T ix = ixi;
> +
> + for (; ctr; ctr--)
> + {
> + irslt *= ix;
> + ix *= ix;
> + }
> +
> + if (irslt != 14348907)
> + abort ();
> + return irslt;
> +}
> +
> +int
> +main ()
> +{
> + unsigned T res;
> +
> + res = foo (3, 4);
> + return 0;
> +}
>
> Jakub
