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From: "zhongyunde at huawei dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug c/107316] New: [aarch64] Init big const value should be improved compare to llvm
Date: Wed, 19 Oct 2022 11:26:27 +0000	[thread overview]
Message-ID: <bug-107316-4@http.gcc.gnu.org/bugzilla/> (raw)

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107316

            Bug ID: 107316
           Summary: [aarch64] Init big const value should be improved
                    compare to llvm
           Product: gcc
           Version: 13.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
          Assignee: unassigned at gcc dot gnu.org
          Reporter: zhongyunde at huawei dot com
  Target Milestone: ---

test case: https://godbolt.org/z/ahreYnahE
```
int main (int argc, char** argv)
{
  if (lshift_1 (0xaaaa5555aaaa5555ull) != 0ll)
    abort();

  return 0;
}
```
* gcc use 4 instructions
```
        mov     x0, 21845
        movk    x0, 0xaaaa, lsl 16
        movk    x0, 0x5555, lsl 32
        movk    x0, 0xaaaa, lsl 48
```

* while llvm use 3 instructions:
```
        mov     x0, #6148914691236517205
        movk    x0, #43690, lsl #16
        movk    x0, #43690, lsl #48
```

             reply	other threads:[~2022-10-19 11:26 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-10-19 11:26 zhongyunde at huawei dot com [this message]
2022-10-19 16:15 ` [Bug target/107316] " pinskia at gcc dot gnu.org
2022-10-23  5:55 ` zhongyunde at huawei dot com
2022-10-25 12:05 ` wilco at gcc dot gnu.org
2022-10-25 12:14 ` wilco at gcc dot gnu.org
2022-11-28 22:42 ` pinskia at gcc dot gnu.org

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