Make profitability calculation of RA conflict presentations independent of host compi...

gcc/ChangeLog:

2021-09-24  Vladimir Makarov  <vmakarov@redhat.com>

	PR rtl-optimization/102147
	* ira-build.c (ira_conflict_vector_profitable_p): Make
	profitability calculation independent of host compiler pointer and
	IRA_INT_BITS sizes.

diff --git a/gcc/ira-build.c b/gcc/ira-build.c
index 42120656366416d56f81dec01d38e097fefaf16d..2a30efc4f2f1033600d573b1e50e7aff8d4ac5fc 100644 (file)
--- 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