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    SubjectRe: [PATCH] trivial: the memset operation on a automatic array variable should be optimized out by data initialization
    On Mon, Jun 18, 2007 at 10:07:21AM -0700, Jeremy Fitzhardinge wrote:
    > Denis Cheng wrote:
    > > From: Denis Cheng <crquan@gmail.com>
    > >
    > > the explicit memset call could be optimized out by data initialization,
    > > thus all the fill working can be done by the compiler implicitly.
    >
    > How does the generated code change? Does gcc do something stupid like
    > statically allocate a prototype structure full of zeros, and then memcpy
    > it in? Or does it generate a series of explicit assignments for each
    > member? Or does it generate a memset anyway?
    >
    > Seems to me that this gives gcc the opportunity to be more stupid, and
    > the only right answer is what we're doing anyway.

    I checked with gcc 4.2, and gcc is quite clever:

    If an array is big, gcc uses memset.
    If an array is small, gcc does it directly in assembler.

    > J

    cu
    Adrian

    --

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