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Re: remarks about g++ 4.3 and some comparison to msvc & icc on ia32
Jan Hubicka wrote:
> I though the comment was more reffering to fact that we will happily
> generate
> movl $0x0, place1
> movl $0x0, place2
> ...
> movl $0x0, placeMillion
>
> rather than shorter
> xor %eax, %eax
> movl %eax, ...
Yes, that would be an improvement, but, as you say, at some point we
want to call memset.
> With the repeated mov issue unforutnately I don't know what would be the
> best place: we obviously don't want to constrain register allocation too
> much and after regalloc I guess only machine dependent pass
I would hope that we could notice this much earlier than that. Wouldn't
this be evident even at the tree level or at least after
stack-allocation in the RTL layer? I wouldn't expect the zeroing to be
coming from machine-dependent code.
One possibility is that we're doing something dumb with arrays. Another
possibility is that we're SRA-ing a lot of small structures, which add
up to a ton of stack space.
I realize that we need a full bug report to be sure, though.
--
Mark Mitchell
CodeSourcery
mark@codesourcery.com
(650) 331-3385 x713