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From: "xxs_chy at outlook dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug tree-optimization/114712] New: Missed optimization: simplify
 if-else basic blocks that share common destinations
Date: Sat, 13 Apr 2024 18:19:24 +0000
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X-Bugzilla-Type: new
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X-Bugzilla-Product: gcc
X-Bugzilla-Component: tree-optimization
X-Bugzilla-Version: 14.0
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X-Bugzilla-Severity: normal
X-Bugzilla-Who: xxs_chy at outlook dot com
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D114712

            Bug ID: 114712
           Summary: Missed optimization: simplify if-else basic blocks
                    that share common destinations
           Product: gcc
           Version: 14.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: xxs_chy at outlook dot com
  Target Milestone: ---

Godbolt link: https://godbolt.org/z/hY6Eaj8fj

```
void dummy();
void dummy1();

void src(bool c1, bool c2){
    if(c1) {
        if(c2)
            goto bb1;
        else
            goto bb2;
    } else {
        if(c2)
            goto bb2;
        else
            goto bb1;
    }

bb1:
    dummy();
    return;
bb2:
    dummy1();
    return;
}
```

can be folded to:

```
void tgt(bool c1, bool c2){
    if (c1 ^ c2) {
        dummy1();
    } else {
        dummy();
    }
}
```
It saves unnecessary branches.=