[fpc-devel] x86_64.inc CompareByte

[Markus Beth]

It did some changes to CompareByte in rtl/x86_64/x86_64.inc to reduce 
the code size and make it run faster (see attached path). I was 
successful with the code size deduction (47 bytes vs. 62 bytes) and also 
with the speed (according to a micro benchmark [1] run on an Ivy Bridge 
desktop).

To achieve this I used movzbl twice. But then I came across the comment 
in FillChar (also in rtl/x86_64/x86_64.inc) about movzbl breaking 
targets using external GAS (Mantis #19188). As this Mantis issue is 
dated back in 2011 my question is: Is this still valid? And what would 
be the preferred way to overcome this issue?
{$ifdef oldbinutils}
    .byte 0x0F,0xb6,0x01
{$else}
    movzbl (%rcx),%eax
{$endif}


Markus

[1] the benchmark compares a 10 MB memory block with itself 10000 times
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