[LLVMdev] [PATCH] x86: disambiguate unqualified btr, bts

Stephen Checkoway s at pahtak.org
Wed Jul 10 18:54:58 PDT 2013

On Jul 10, 2013, at 17:44, Jim Grosbach <grosbach at apple.com> wrote:
> The length specifier is, as I understand it, required when the instruction references memory but is optional (and inferred from the registers) for the register variants.
> The best reference I know of for the AT&T syntax is: http://docs.oracle.com/cd/E19253-01/817-5477/817-5477.pdf

I'm not sure I'd use the documentation for the Solaris assembler as authoritative for AT&T syntax, but page 17 does say that if the suffix is omitted it defaults to long.

However, that isn't my experience with gas which uses register operands to disambiguate, if possible (although I'm on a phone and can't check right now).

Stephen Checkoway

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