Why won't gcc-arm allow "eorc" in assembly?

[Ted Krovetz]

Hello,

I'm writing a small low-level routine using inline ARM assembly. The  
following gives me trouble:

#include <stdint.h>
uint64_t foo(uint64_t a)
{
     asm ("adds %0,%0,%0\n\t"
          "adcs %H0,%H0,%H0\n\t"
          "eorc %0,#0x51\n\t"
          "eorcs %H0,#0x80000000"
     : "+r"(a) : : "cc");
     return a;
}

thecus> gcc-4.4 test.c -march=armv5te -O2 -c
/tmp/cc1CraGk.s: Assembler messages:
/tmp/cc1CraGk.s:28: Error: bad instruction `eorc r3,#0x51'

If I use eorcs or eor instead of eorc then there is no complier  
complaint, but I need both eor's to be conditional on the same carry  
flag (from adcs) so cannot use 's' in the first eor case.

Why won't gcc (or is it gas) let me use eorc? It is a legitimate  
opcode for ARM, as far as I can tell.

This happens on both gcc 4.3 and 4.4.

Thank you,
Ted Krovetz