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[PR103437] Make backup code for overflow conditional

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Switch off long long variant overflow code by preprocessor if the
build compiler has __builtin_smul_overflow.

gcc/ChangeLog:
	PR rtl-optimization/103437
	* ira-color.c (setup_allocno_priorities): Switch off backup code
	for overflow if compiler has __builtin_smul_overflow.  Use <
	for comparison with -INT_MAX.
This commit is contained in:
Vladimir N. Makarov 2021-12-02 12:31:28 -05:00
parent acf4fe96f1
commit cd47cd4b5e
1 changed files with 16 additions and 17 deletions
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33
gcc/ira-color.c
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@ -2797,7 +2797,6 @@ 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;
@ -2810,27 +2809,27 @@ setup_allocno_priorities (ira_allocno_t *consideration_allocnos, int n)
ira_assert (mult >= 0);
mult *= ira_reg_class_max_nregs[ALLOCNO_CLASS (a)][ALLOCNO_MODE (a)];
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;
#define HAS_SMUL_OVERFLOW
#endif
#endif
/* Multiplication can overflow for very large functions.
Check the overflow and constrain the result if necessary: */
#ifdef HAS_SMUL_OVERFLOW
if (__builtin_smul_overflow (mult, diff, &priority)
|| priority <= -INT_MAX)
|| priority < -INT_MAX)
priority = diff >= 0 ? INT_MAX : -INT_MAX;
#else
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;
#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;