Put in some more safeguards against executing a division-by-zero.

Add dummy returns before every potential division-by-zero in int8.c,
because apparently further "improvements" in gcc's optimizer have
enabled it to break functions that weren't broken before.

Aurelien Jarno, via Martin Pitt

diff --git a/src/backend/utils/adt/int8.c b/src/backend/utils/adt/int8.c
index 903d415327fc8629c2e9cf57cab0fac3254b9cda..5901d407de1e755dc910d0360ad70e42071b543c 100644 (file)
--- a/src/backend/utils/adt/int8.c
+++ b/src/backend/utils/adt/int8.c
@@ -595,9 +595,13 @@ int8div(PG_FUNCTION_ARGS)
    int64       result;
 
    if (arg2 == 0)
+   {
        ereport(ERROR,
                (errcode(ERRCODE_DIVISION_BY_ZERO),
                 errmsg("division by zero")));
+       /* ensure compiler realizes we mustn't reach the division (gcc bug) */
+       PG_RETURN_NULL();
+   }
 
    result = arg1 / arg2;
 
@@ -641,9 +645,14 @@ int8mod(PG_FUNCTION_ARGS)
    int64       arg2 = PG_GETARG_INT64(1);
 
    if (arg2 == 0)
+   {
        ereport(ERROR,
                (errcode(ERRCODE_DIVISION_BY_ZERO),
                 errmsg("division by zero")));
+       /* ensure compiler realizes we mustn't reach the division (gcc bug) */
+       PG_RETURN_NULL();
+   }
+
    /* No overflow is possible */
 
    PG_RETURN_INT64(arg1 % arg2);
@@ -817,9 +826,13 @@ int84div(PG_FUNCTION_ARGS)
    int64       result;
 
    if (arg2 == 0)
+   {
        ereport(ERROR,
                (errcode(ERRCODE_DIVISION_BY_ZERO),
                 errmsg("division by zero")));
+       /* ensure compiler realizes we mustn't reach the division (gcc bug) */
+       PG_RETURN_NULL();
+   }
 
    result = arg1 / arg2;
 
@@ -911,10 +924,16 @@ int48div(PG_FUNCTION_ARGS)
    int64       arg2 = PG_GETARG_INT64(1);
 
    if (arg2 == 0)
+   {
        ereport(ERROR,
                (errcode(ERRCODE_DIVISION_BY_ZERO),
                 errmsg("division by zero")));
+       /* ensure compiler realizes we mustn't reach the division (gcc bug) */
+       PG_RETURN_NULL();
+   }
+
    /* No overflow is possible */
+
    PG_RETURN_INT64((int64) arg1 / arg2);
 }