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References: <bug-19431-6528@http.gcc.gnu.org/bugzilla/>
Subject: [Bug tree-optimization/19431] missed optimization with ifs and deferencing
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From: "pluto at agmk dot net" <gcc-bugzilla@gcc.gnu.org>
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------- Comment #10 from pluto at agmk dot net  2007-02-25 19:00 -------
one more testcase:

#include <tr1/functional>
#include <algorithm>
extern void assign( long* variable, long v )
{
        std::transform( variable, variable + 1, variable,
                std::tr1::bind( std::plus< long >(), 0L, v ) );
}
extern void assign( long& variable, long v )
{
        std::transform( &variable, &variable + 1, &variable,
                std::tr1::bind( std::plus< long >(), 0L, v ) );
}

at -O3 gcc 4.2 produces:

assign(long&, long):
        movq    -40(%rsp), %rax
        movq    %rsi, -24(%rsp)
        movq    $0, -32(%rsp)
        movq    $0, -64(%rsp)
        movq    %rsi, -56(%rsp)
        movq    %rsi, (%rdi)
        movq    %rax, -72(%rsp)
        ret

assign(long*, long):
        movq    %rsi, (%rdi)
        ret


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=19431