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From: "tnfchris at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
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Subject: [Bug tree-optimization/94294] [missed optimization] new+delete of
 unused local string not removed
Date: Mon, 14 Feb 2022 15:38:15 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D94294

Tamar Christina <tnfchris at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |tnfchris at gcc dot gnu.org

--- Comment #5 from Tamar Christina <tnfchris at gcc dot gnu.org> ---
(In reply to Marc Glisse from comment #4)
> I don't believe there is a "new/delete" issue.

I wonder.. , looking at

#include <cstdint>
#include <cstdlib>
#include <vector>

struct param {
  uint32_t k;
  std::vector<uint8_t> src;
  std::vector<uint8_t> ref0;
};

size_t foo() {
    param test[] =3D {
    {48, {255, 0, 0, 0, 0, 0}
    }};
    return sizeof(test);
}

I had expected the answer to simply be

        mov     w0, #56
        ret

since the new and delete can be elided.
...but GCC generates some pretty bad code here...=20
https://godbolt.org/z/EPoYYohPa

In this case nothing of the structure is used at all yet we keep all the
construction code.=