[PR103437] Use long long multiplication as backup for overflow processing

__builtin_smul_overflow can be unavailable for some C++ compilers.
Add long long multiplication as backup for overflow processing.

gcc/ChangeLog:
	PR rtl-optimization/103437
	* ira-color.c (setup_allocno_priorities): Use long long
	multiplication as backup for overflow processing.

diff --git a/gcc/ira-color.c b/gcc/ira-color.c
index 1f80cbea0e2fc4975efeb5343547be7ae81969ac..3b19a58e1f0660ac98ddb45821c43ca4de5e1ae8 100644 (file)
--- a/gcc/ira-color.c
+++ b/gcc/ira-color.c
@@ -2797,6 +2797,7 @@ static void
 setup_allocno_priorities (ira_allocno_t *consideration_allocnos, int n)
 {
   int i, length, nrefs, priority, max_priority, mult, diff;
+  bool overflow_backup_p = true;
   ira_allocno_t a;
 
   max_priority = 0;
@@ -2811,9 +2812,25 @@ setup_allocno_priorities (ira_allocno_t *consideration_allocnos, int n)
       diff = ALLOCNO_MEMORY_COST (a) - ALLOCNO_CLASS_COST (a);
       /* Multiplication can overflow for very large functions.
         Check the overflow and constrain the result if necessary: */
+#ifdef __has_builtin
+#if __has_builtin(__builtin_smul_overflow)
+      overflow_backup_p = false;
       if (__builtin_smul_overflow (mult, diff, &priority)
          || priority <= -INT_MAX)
        priority = diff >= 0 ? INT_MAX : -INT_MAX;
+#endif
+#endif
+      if (overflow_backup_p)
+       {
+         static_assert
+           (sizeof (long long) >= 2 * sizeof (int),
+            "overflow code does not work for such int and long long sizes");
+         long long priorityll = (long long) mult * diff;
+         if (priorityll < -INT_MAX || priorityll > INT_MAX)
+           priority = diff >= 0 ? INT_MAX : -INT_MAX;
+         else
+           priority = priorityll;
+       }
       allocno_priorities[ALLOCNO_NUM (a)] = priority;
       if (priority < 0)
        priority = -priority;