On Thu, 14 Dec 2017, Jakub Jelinek wrote:
> On Wed, Dec 13, 2017 at 03:55:13PM -0700, Martin Sebor wrote:
> > For the second part, can you please also add a compile-time test
> > to verify that the result isn't constrained to the same range as
> > with a real argument? Checking that the abort below isn't
> > eliminated would do it for %f:
> >
> > void f (char *d)
> > {
> > int n = __builtin_sprintf (d, "%f", 1.0Q);
> > if (n < 8 || 13 < n)
> > __builtin_abort ();
> > }
> >
> > A test that has a convenient setup for this is tree-ssa/builtin-
> > sprintf-2.c in case you want to add to it.
>
> Can't use that test, because I need __float128, add options for it etc.
>
> Anyway, here is the same patch with added extra test, tested on x86_64-linux
> and powerpc64-linux. The tree-ssa test FAILs without the patch on both
> targets.
Ok
> 2017-12-14 Jakub Jelinek <ja...@redhat.com>
>
> PR tree-optimization/83198
> * gimple-ssa-sprintf.c (format_floating): Set type solely based on
> dir.modifier, regardless of TREE_TYPE (arg). Assume non-REAL_CST
> value if arg is a REAL_CST with incompatible type.
>
> * gcc.dg/pr83198.c: New test.
> * gcc.dg/tree-ssa/pr83198.c: New test.
>
> --- gcc/gimple-ssa-sprintf.c.jj 2017-11-03 15:37:04.000000000 +0100
> +++ gcc/gimple-ssa-sprintf.c 2017-12-13 13:37:59.289435623 +0100
> @@ -1885,6 +1885,8 @@ static fmtresult
> format_floating (const directive &dir, tree arg)
> {
> HOST_WIDE_INT prec[] = { dir.prec[0], dir.prec[1] };
> + tree type = (dir.modifier == FMT_LEN_L || dir.modifier == FMT_LEN_ll
> + ? long_double_type_node : double_type_node);
>
> /* For an indeterminate precision the lower bound must be assumed
> to be zero. */
> @@ -1892,10 +1894,6 @@ format_floating (const directive &dir, t
> {
> /* Get the number of fractional decimal digits needed to represent
> the argument without a loss of accuracy. */
> - tree type = arg ? TREE_TYPE (arg) :
> - (dir.modifier == FMT_LEN_L || dir.modifier == FMT_LEN_ll
> - ? long_double_type_node : double_type_node);
> -
> unsigned fmtprec
> = REAL_MODE_FORMAT (TYPE_MODE (type))->p;
>
> @@ -1946,7 +1944,9 @@ format_floating (const directive &dir, t
> }
> }
>
> - if (!arg || TREE_CODE (arg) != REAL_CST)
> + if (!arg
> + || TREE_CODE (arg) != REAL_CST
> + || !useless_type_conversion_p (type, TREE_TYPE (arg)))
> return format_floating (dir, prec);
>
> /* The minimum and maximum number of bytes produced by the directive. */
> --- gcc/testsuite/gcc.dg/pr83198.c.jj 2017-12-13 13:43:36.056192309 +0100
> +++ gcc/testsuite/gcc.dg/pr83198.c 2017-12-13 13:47:11.716474956 +0100
> @@ -0,0 +1,18 @@
> +/* PR tree-optimization/83198 */
> +/* { dg-do compile } */
> +/* { dg-options "-Wall -Wno-format" } */
> +
> +int
> +foo (char *d[6], int x)
> +{
> + int r = 0;
> + r += __builtin_sprintf (d[0], "%f", x);
> + r += __builtin_sprintf (d[1], "%a", x);
> + r += __builtin_sprintf (d[2], "%f", "foo");
> + r += __builtin_sprintf (d[3], "%a", "bar");
> +#ifdef __SIZEOF_FLOAT128__
> + r += __builtin_sprintf (d[4], "%a", 1.0Q);
> + r += __builtin_sprintf (d[5], "%Lf", 1.0Q);
> +#endif
> + return r;
> +}
> --- gcc/testsuite/gcc.dg/tree-ssa/pr83198.c.jj 2017-12-14
> 09:43:07.534102549 +0100
> +++ gcc/testsuite/gcc.dg/tree-ssa/pr83198.c 2017-12-14 09:52:39.772964559
> +0100
> @@ -0,0 +1,23 @@
> +/* PR tree-optimization/83198 */
> +/* { dg-do compile { target __float128 } } */
> +/* { dg-options "-O2 -fprintf-return-value -Wno-format
> -fdump-tree-optimized" } */
> +/* { dg-add-options __float128 } */
> +
> +void bar (void);
> +void link_error (void);
> +
> +void
> +foo (char *x)
> +{
> + int a = __builtin_sprintf (x, "%f", 1.0Q);
> + if (a < 8)
> + link_error ();
> + if (a > 13)
> + bar ();
> + if (a > 322)
> + link_error ();
> +}
> +
> +/* Verify we don't optimize return value to [8, 13]. */
> +/* { dg-final { scan-tree-dump-not "link_error \\(\\);" "optimized" } } */
> +/* { dg-final { scan-tree-dump "bar \\(\\);" "optimized" } } */
>
>
> Jakub
>
>
--
Richard Biener <rguent...@suse.de>
SUSE LINUX GmbH, GF: Felix Imendoerffer, Jane Smithard, Graham Norton, HRB
21284 (AG Nuernberg)
