Install a workaround for a longstanding gcc bug that allows SIGFPE traps

to occur for division by zero, even though the code is carefully avoiding
that.  All available evidence is that the only functions affected are
int24div, int48div, and int28div, so patch just those three functions to
include a "return" after the ereport() call.

Backpatch to 8.4 so that the fix can be tested in production builds.
For older branches our recommendation will continue to be to use -O1
on affected platforms (which are mostly non-mainstream anyway).

diff --git a/src/backend/utils/adt/int.c b/src/backend/utils/adt/int.c
index 5214e29..ad4df06 100644 (file)
--- a/src/backend/utils/adt/int.c
+++ b/src/backend/utils/adt/int.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *       $PostgreSQL: pgsql/src/backend/utils/adt/int.c,v 1.84 2009/01/01 17:23:49 momjian Exp $
+ *       $PostgreSQL: pgsql/src/backend/utils/adt/int.c,v 1.85 2009/09/03 18:48:14 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -950,9 +950,14 @@ int24div(PG_FUNCTION_ARGS)
        int32           arg2 = PG_GETARG_INT32(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_INT32((int32) arg1 / arg2);
 }

diff --git a/src/backend/utils/adt/int8.c b/src/backend/utils/adt/int8.c
index 89162f0..54a134d 100644 (file)
--- a/src/backend/utils/adt/int8.c
+++ b/src/backend/utils/adt/int8.c
@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  * IDENTIFICATION
- *       $PostgreSQL: pgsql/src/backend/utils/adt/int8.c,v 1.74 2009/06/11 14:49:03 momjian Exp $
+ *       $PostgreSQL: pgsql/src/backend/utils/adt/int8.c,v 1.75 2009/09/03 18:48:14 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -919,9 +919,14 @@ 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);
 }
@@ -1098,9 +1103,14 @@ int28div(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);
 }