[PATCH 2/2] cprop_hardreg: Enable propagation of the stack pointer if possible.

[Manolis Tsamis <manolis.tsamis@vrull.eu>]

Propagation of the stack pointer in cprop_hardreg is currenty forbidden
in all cases, due to maybe_mode_change returning NULL. Relax this
restriction and allow propagation when no mode change is requested.

gcc/ChangeLog:

        * regcprop.cc (maybe_mode_change): Enable stack pointer propagation.

Signed-off-by: Manolis Tsamis <manolis.tsamis@vrull.eu>
---

 gcc/regcprop.cc | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/gcc/regcprop.cc b/gcc/regcprop.cc
index f426f4fedcd..6cbfadb181f 100644
--- a/gcc/regcprop.cc
+++ b/gcc/regcprop.cc
@@ -422,7 +422,12 @@ maybe_mode_change (machine_mode orig_mode, machine_mode copy_mode,
 
      It's unclear if we need to do the same for other special registers.  */
   if (regno == STACK_POINTER_REGNUM)
-    return NULL_RTX;
+    {
+      if (orig_mode == new_mode)
+	return stack_pointer_rtx;
+      else
+	return NULL_RTX;
+    }
 
   if (orig_mode == new_mode)
     return gen_raw_REG (new_mode, regno);
-- 
2.34.1