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.
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
