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));