------- Comment #2 from ebotcazou at gcc dot gnu dot org 2008-09-09 19:17
-------
Several files are miscompiled by the stage1 compiler, starting with c-decl.c.
Now if you take the preprocessed file c-decl.i and compile it with a cross on
Linux, the resulting code is OK (the differences are in offsets against FP).
The discrepancy comes from the second qsort in ira_sort_regnos_for_alter_reg:
/* Sort regnos according the slot numbers. */
regno_max_ref_width = reg_max_ref_width;
qsort (pseudo_regnos, n, sizeof (int), coalesced_pseudo_reg_slot_compare);
It is not stable and this is quite obvious by looking at the compare function:
/* Sort pseudos according their slot numbers (putting ones with
smaller numbers first, or last when the frame pointer is not
needed). */
static int
coalesced_pseudo_reg_slot_compare (const void *v1p, const void *v2p)
{
const int regno1 = *(const int *) v1p;
const int regno2 = *(const int *) v2p;
ira_allocno_t a1 = ira_regno_allocno_map[regno1];
ira_allocno_t a2 = ira_regno_allocno_map[regno2];
int diff, slot_num1, slot_num2;
int total_size1, total_size2;
if (a1 == NULL || ALLOCNO_HARD_REGNO (a1) >= 0)
{
if (a2 == NULL || ALLOCNO_HARD_REGNO (a2) >= 0)
return (const int *) v1p - (const int *) v2p; /* Save the order. */
return 1;
}
else if (a2 == NULL || ALLOCNO_HARD_REGNO (a2) >= 0)
return -1;
slot_num1 = -ALLOCNO_HARD_REGNO (a1);
slot_num2 = -ALLOCNO_HARD_REGNO (a2);
if ((diff = slot_num1 - slot_num2) != 0)
return (frame_pointer_needed
|| !FRAME_GROWS_DOWNWARD == STACK_GROWS_DOWNWARD ? diff : -diff);
total_size1 = MAX (PSEUDO_REGNO_BYTES (regno1), regno_max_ref_width[regno1]);
total_size2 = MAX (PSEUDO_REGNO_BYTES (regno2), regno_max_ref_width[regno2]);
if ((diff = total_size2 - total_size1) != 0)
return diff;
return (const int *) v1p - (const int *) v2p; /* Save the order. */
}
The following patchlet stabilizes the sort:
Index: ira-color.c
===================================================================
--- ira-color.c (revision 140145)
+++ ira-color.c (working copy)
@@ -2169,7 +2169,7 @@ coalesced_pseudo_reg_slot_compare (const
if (a1 == NULL || ALLOCNO_HARD_REGNO (a1) >= 0)
{
if (a2 == NULL || ALLOCNO_HARD_REGNO (a2) >= 0)
- return (const int *) v1p - (const int *) v2p; /* Save the order. */
+ return regno1 - regno2;
return 1;
}
else if (a2 == NULL || ALLOCNO_HARD_REGNO (a2) >= 0)
@@ -2183,7 +2183,7 @@ coalesced_pseudo_reg_slot_compare (const
total_size2 = MAX (PSEUDO_REGNO_BYTES (regno2),
regno_max_ref_width[regno2]);
if ((diff = total_size2 - total_size1) != 0)
return diff;
- return (const int *) v1p - (const int *) v2p; /* Save the order. */
+ return regno1 - regno2;
}
/* Setup REGNO_COALESCED_ALLOCNO_COST and REGNO_COALESCED_ALLOCNO_NUM
and the resulting code is the same (and correct) on both Linux and Solaris.
Bootstrap is still running, we'll see how far it goes after that.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37424
