[LLVMdev] [PATCH] x86/asm: avoid mnemonics without type suffix

H. Peter Anvin hpa at zytor.com
Mon Jul 15 11:40:52 PDT 2013

On 07/14/2013 12:23 PM, Jeremy Fitzhardinge wrote:
> The SDM entry for BT mentions that the instruction may touch 2 or 4
> bytes depending on the operand size, but doesn't specifically mention
> that a 64 bit operation size touches 8 bytes - and it doesn't mention
> anything at all about operand size and access size in BTR/BTS/BTC
> (unless it's implied as part of the discussion about encoding the MSBs
> of a constant bit offset in the offset of the addressing mode). Is that
> an oversight?

Most likely.  I'll check with the people responsible for the SDM here at


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