https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102147
--- Comment #7 from Vladimir Makarov <vmakarov at gcc dot gnu.org> ---
I've been thinking about ways to fix this problem but only come to the
following patch. The patch results in working mostly the same for 64-bit
targets and different for 32-bit targets. In any case the profitability is only
an estimation so I think the patch is ok. Avoiding 4 stage bootstrap is more
important than a bit slower RA on 32-bit targets (which is questionable) on few
border cases.
I am going to commit the patch this Friday.
--- a/gcc/ira-build.c
+++ b/gcc/ira-build.c
@@ -629,7 +629,7 @@ ior_hard_reg_conflicts (ira_allocno_t a, const_hard_reg_set
set)
bool
ira_conflict_vector_profitable_p (ira_object_t obj, int num)
{
- int nw;
+ int nbytes;
int max = OBJECT_MAX (obj);
int min = OBJECT_MIN (obj);
@@ -638,9 +638,14 @@ ira_conflict_vector_profitable_p (ira_object_t obj, int
num)
in allocation. */
return false;
- nw = (max - min + IRA_INT_BITS) / IRA_INT_BITS;
- return (2 * sizeof (ira_object_t) * (num + 1)
- < 3 * nw * sizeof (IRA_INT_TYPE));
+ nbytes = (max - min) / 8 + 1;
+ STATIC_ASSERT (sizeof (ira_object_t) <= 8);
+ /* Don't use sizeof (ira_object_t), use constant 8. Size of ira_object_t (a
+ pointer) is different on 32-bit and 64-bit targets. Usage sizeof
+ (ira_object_t) can result in different code generation by GCC built as
32-
+ and 64-bit program. In any case the profitability is just an estimation
+ and border cases are rare. */
+ return (2 * 8 /* sizeof (ira_object_t) */ * (num + 1) < 3 * nbytes);
}
/* Allocates and initialize the conflict vector of OBJ for NUM
