[gcc r16-9506] testsuite: Fix up gcc.dg/pr126464.c test [PR126464]

https://gcc.gnu.org/g:0b0209ca1aff9f7cd28150b5714cb6dd7514b313

commit r16-9506-g0b0209ca1aff9f7cd28150b5714cb6dd7514b313
Author: Jakub Jelinek <[email protected]>
Date:   Tue Aug 4 21:42:49 2026 +0200

    testsuite: Fix up gcc.dg/pr126464.c test [PR126464]
    
    On Tue, Aug 04, 2026 at 02:13:19PM +0200, Torbjorn SVENSSON wrote:
    > This causes regression on most (all?) arm-none-eabi targets.
    > /build/gcc_src/gcc/testsuite/gcc.dg/pr126464.c:56:3: warning: floating constant exceeds range of 'long double' [-Woverflow]
    
    This patch guards it with preprocessor tests whether such floating point
    constants are representable.
    
    2026-08-04  Jakub Jelinek  <[email protected]>
    
            PR tree-optimization/126464
            * gcc.dg/pr126464.c: Guard uses of 1e300 with
            __DBL_MAX_10_EXP__ >= 301 and uses of 1e4000L with
            __LDBL_MAX_10_EXP__ >= 4001.
    
    Reviewed-by: Andrea Pinski <[email protected]>
    (cherry picked from commit b5b0203b8c3b7cee4e65a09e4443f948dee434b4)

Diff:
---
 gcc/testsuite/gcc.dg/pr126464.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/gcc/testsuite/gcc.dg/pr126464.c b/gcc/testsuite/gcc.dg/pr126464.c
index b6eb1320dec5..620b9b42f62c 100644
--- a/gcc/testsuite/gcc.dg/pr126464.c
+++ b/gcc/testsuite/gcc.dg/pr126464.c
@@ -47,15 +47,19 @@ qux (long double x)
 int
 main ()
 {
+#if __DBL_MAX_10_EXP__ >= 301
   if (!__builtin_isinf ((double) 1e300)
       && __builtin_isinf ((float) 1e300)
       && (foo (-1e300) != -5e299
 	  || baz (1e300) != 5e299))
     __builtin_abort ();
+#endif
 
+#if __LDBL_MAX_10_EXP__ >= 4001
   if (!__builtin_isinf ((long double) 1e4000L)
       && __builtin_isinf ((double) 1e4000L)
       && (bar (1e4000L) != 5e3999L
 	  || qux (-1e4000L) != -5e3999L))
     __builtin_abort ();
+#endif
 }