[Bug target/43550] New: arm missing rev16

[astrange at ithinksw dot com]

typedef unsigned short uint16_t;
typedef unsigned int   uint32_t;

uint16_t s16(uint16_t v)
{
        return v>>8|v<<8;
}

uint32_t s32(uint32_t v)
{
        return __builtin_bswap32(v);
}

> gcc -O3 -mcpu=cortex-a8 -S bswap.c
s16:
        @ args = 0, pretend = 0, frame = 0
        @ frame_needed = 0, uses_anonymous_args = 0
        @ link register save eliminated.
        mov     r3, r0, lsr #8
        orr     r0, r3, r0, asl #8
        uxth    r0, r0
        bx      lr

s32:
        @ args = 0, pretend = 0, frame = 0
        @ frame_needed = 0, uses_anonymous_args = 0
        @ link register save eliminated.
        rev     r0, r0
        bx      lr

It generates 32-bit bswap using rev but not 16-bit using rev16. x86 can do
both.


-- 
           Summary: arm missing rev16
           Product: gcc
           Version: 4.5.0
            Status: UNCONFIRMED
          Severity: enhancement
          Priority: P3
         Component: target
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: astrange at ithinksw dot com
GCC target triplet: arm-*-*


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=43550