ira: Add ira_subloop_allocnos_can_differ_p

color_pass has two instances of the same code for propagating non-cap
assignments from parent loops to subloops.  This patch adds a helper
function for testing when such propagations are required for correctness
and uses it to remove the duplicated code.

A later patch will use this in ira-build.c too, which is why the
function is exported to ira-int.h.

No functional change intended.

gcc/
	PR rtl-optimization/98782
	* ira-int.h (ira_subloop_allocnos_can_differ_p): New function,
	extracted from...
	* ira-color.c (color_pass): ...here.

1 files changed, 28 insertions, 0 deletions

diff --git a/gcc/ira-int.h b/gcc/ira-int.h
index b32c80d..c5b1a13 100644
--- a/gcc/ira-int.h
+++ b/gcc/ira-int.h
@@ -1595,4 +1595,32 @@ ira_loop_border_costs::move_between_loops_cost () const
   return move_cost * (m_entry_freq + m_exit_freq);
 }
 
+/* Return true if subloops that contain allocnos for A's register can
+   use a different assignment from A.  ALLOCATED_P is true for the case
+   in which allocation succeeded for A.  */
+inline bool
+ira_subloop_allocnos_can_differ_p (ira_allocno_t a, bool allocated_p = true)
+{
+  auto regno = ALLOCNO_REGNO (a);
+
+  if (pic_offset_table_rtx != NULL
+      && regno == (int) REGNO (pic_offset_table_rtx))
+    return false;
+
+  ira_assert (regno < ira_reg_equiv_len);
+  if (ira_equiv_no_lvalue_p (regno))
+    return false;
+
+  /* Avoid overlapping multi-registers.  Moves between them might result
+     in wrong code generation.  */
+  if (allocated_p)
+    {
+      auto pclass = ira_pressure_class_translate[ALLOCNO_CLASS (a)];
+      if (ira_reg_class_max_nregs[pclass][ALLOCNO_MODE (a)] > 1)
+	return false;
+    }
+
+  return true;
+}
+
 #endif /* GCC_IRA_INT_H */