> On Wed, 4 Dec 2013, Ian Bolton wrote: > > > The main update, other than cosmetic differences, is that we've > chosen > > the same ARM encoding as LLVM for practical purposes. (The Thumb > > encoding in Mark's patch already matched LLVM.) > > Do the encodings match what plain "udf" does in recent-enough gas (too > recent for us to assume it in GCC or glibc for now), or is it something > else?
Hi Joseph, Yes, these encodings match the UDF instruction that is defined in the most recent edition of the ARM architecture reference manual. Thumb: 0xde00 | imm8 (we chose 0xff for the imm8) ARM: 0xe7f000f0 | (imm12 << 8) | imm4 (we chose to use 0 for both imms) So as not to break old versions of gas that don't recognise UDF, the encoding is output directly. Apologies if I have over-explained there! Cheers, Ian
