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    SubjectRe: Intel vs AMD x86-64

    H. Peter Anvin wrote:
    > Followup to: <>
    > By author: Timothy Miller <>
    > In newsgroup:
    >>Nakajima, Jun wrote:
    >>>No, it's not a problem. Branches with 16-bit operand size are not useful
    >>>for compilers.
    >> From AMD's documentation, I got the impression that 66H caused near
    >>branches to be 32 bits in long mode (default is 64).
    >>So, Intel makes it 16 bits, and AMD makes it 32 bits?
    >>Either way, I don't see much use for either one.
    > Both claims are pretty bogus. Shorter branches are quite nice for
    > intraprocedural jumps; it reduces the cache footprint.

    I think we were talking about absolute branches when referring to "near
    branches". For absolute branches, having a 32-bit address restricts you
    to the lower 4G of the address space.

    For long mode on AMD64, default operand size for _relative_ branch is 32
    bits. I get the impression that the size of the relative branch operand
    is handled differently from the "segment default word size".

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