On Mon, Aug 20, 2012 at 8:27 AM, Jakub Jelinek <ja...@redhat.com> wrote:
> Hi!
>
> The middle-end argument of memset is signed (int), so simplify_builtin_call
> correctly checks host_integerp (val2, 0), but later on used tree_low_cst
> (val2, 1), so for negative values it would ICE. Fixed thusly, the memset
> is supposed to cast the int to unsigned char internally anyway.
>
> Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
Yes, sorry for the mixup.
Thanks,
Richard.
> 2012-08-20 Jakub Jelinek <ja...@redhat.com>
>
> PR tree-optimization/54321
> * tree-ssa-forwprop.c (simplify_builtin_call): Pass 0 instead of 1
> as second argument to tree_low_cst call on val2.
>
> * gcc.c-torture/compile/pr54321.c: New test.
>
> --- gcc/tree-ssa-forwprop.c.jj 2012-08-14 08:45:00.000000000 +0200
> +++ gcc/tree-ssa-forwprop.c 2012-08-20 08:11:06.247936035 +0200
> @@ -1554,7 +1554,7 @@ simplify_builtin_call (gimple_stmt_itera
> else
> src_buf[0] = tree_low_cst (src1, 0);
> memset (src_buf + tree_low_cst (diff, 1),
> - tree_low_cst (val2, 1), tree_low_cst (len2, 1));
> + tree_low_cst (val2, 0), tree_low_cst (len2, 1));
> src_buf[src_len] = '\0';
> /* Neither builtin_strncpy_read_str nor builtin_memcpy_read_str
> handle embedded '\0's. */
> --- gcc/testsuite/gcc.c-torture/compile/pr54321.c.jj 2012-08-20
> 08:12:10.955630873 +0200
> +++ gcc/testsuite/gcc.c-torture/compile/pr54321.c 2012-08-20
> 08:13:27.963398948 +0200
> @@ -0,0 +1,12 @@
> +/* PR tree-optimization/54321 */
> +struct S { char s[0]; } *a;
> +
> +void
> +foo (void)
> +{
> + char *b = a->s;
> + int c = 0;
> + b[0] = 0;
> + while (++c < 9)
> + b[c] = 255;
> +}
>
> Jakub
