And apologies for my horrendous grammar in that last e-mail! What I
meant to say is that an option could be that x86-64 can favour MOVZX, since
the oldest processors are guaranteed to have been first released no earlier
than the early 2000s, while i386 and i8086 can favour MOV + AND, unless
more
In that case, I would argue that it should optimise for more modern
processors - that is, favour MOVZX, especially as the first few Pentium
processors were released in the 90s. If backwards-compatibility is more
of a concern, well, if compiling for x86-64, when it's certain that the
processor was
> I'm a tad confused in regards to the best course
of action regarding MOVZX. Many of the peephole
optimisations seek to change them to MOV followed
by AND (e.g. "movzbl (mem), %eax" to "mov (mem),
%al; and $0xff, %eax"). Does MOVZX have a
well-documented performance penalty in modern
processors
Hi everyone,
I'm a tad confused in regards to the best course of action regarding
MOVZX. Many of the peephole optimisations seek to change them to MOV
followed by AND (e.g. "movzbl (mem), %eax" to "mov (mem), %al; and $0xff,
%eax"). Does MOVZX have a well-documented performance penalty in moder
