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