A colleague at ARM found this a couple of days back. With trunk as of a few days back configured for arm-none-eabi for cortex-a8
typedef unsigned short ushort; typedef unsigned char uchar; ushort foo(uchar data, uchar data1, uchar data2) { uchar x = (uchar)(data); x ^= (x + 5); x ^= (x << 2); x ^= (x << 1); return x; } foo: @ args = 0, pretend = 0, frame = 0 @ frame_needed = 0, uses_anonymous_args = 0 @ link register save eliminated. add r3, r0, #5 eor r0, r3, r0 uxtb r0, r0 //redundant eor r0, r0, r0, lsl #2 uxtb r0, r0 // redundant eor r0, r0, r0, lsl #1 uxtb r0, r0 bx lr -- Summary: Extra zero extensions produced for ARM. Product: gcc Version: 4.5.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: target AssignedTo: unassigned at gcc dot gnu dot org ReportedBy: ramana at gcc dot gnu dot org GCC build triplet: x86_64-linux GCC host triplet: x86_64-linux GCC target triplet: arm-eabi http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40487