+https://bugs.launchpad.net/gcc-linaro/+bug/728315
+https://lists.openwrt.org/pipermail/openwrt-devel/2011-March/009847.html
+
+--- a/gcc/ee.c
++++ b/gcc/ee.c
+@@ -209,7 +209,11 @@
+
+ *regno = REGNO (reg);
+
+- if (paradoxical_subreg_p (use))
++ /* Non-paradoxical SUBREGs of promoted vars guarantee that the
++ upper (elided) bits of the inner register have a particular value.
++ For our purposes, such SUBREGs act as a full reference to the
++ inner register. */
++ if (paradoxical_subreg_p (use) || SUBREG_PROMOTED_VAR_P (use))
+ *size = GET_MODE_BITSIZE (GET_MODE (reg));
+ else
+ *size = subreg_lsb (use) + GET_MODE_BITSIZE (GET_MODE (use));