[gcc r16-1449] ada: Fix rounding test with odd bases

[Marc Poulhies]

https://gcc.gnu.org/g:fa6a71aac7eee3ad1597759724992ee1f65ee87f

commit r16-1449-gfa6a71aac7eee3ad1597759724992ee1f65ee87f
Author: Eric Botcazou <ebotcazou@adacore.com>
Date:   Wed Apr 2 13:13:33 2025 +0200

    ada: Fix rounding test with odd bases
    
    The test as currently written is incorrect for odd bases.
    
    gcc/ada/ChangeLog:
    
            * libgnat/s-valuer.adb (Round_Extra): Use multiplicative test.

Diff:
---
 gcc/ada/libgnat/s-valuer.adb | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/gcc/ada/libgnat/s-valuer.adb b/gcc/ada/libgnat/s-valuer.adb
index 6f557e932079..93e292cc34f4 100644
--- a/gcc/ada/libgnat/s-valuer.adb
+++ b/gcc/ada/libgnat/s-valuer.adb
@@ -135,7 +135,9 @@ package body System.Value_R is
       B : constant Uns := Uns (Base);
 
    begin
-      if Digit >= Base / 2 then
+      --  Beware that Base may be odd
+
+      if 2 * Unsigned (Digit) >= Base then
 
          --  If Extra is maximum, round Value