[llvm-bugs] [Bug 39510] New: Incorrect optimization in InstSimplify

[via llvm-bugs]

https://bugs.llvm.org/show_bug.cgi?id=39510

            Bug ID: 39510
           Summary: Incorrect optimization in InstSimplify
           Product: libraries
           Version: trunk
          Hardware: PC
                OS: Linux
            Status: NEW
          Severity: enhancement
          Priority: P
         Component: Transformation Utilities
          Assignee: unassignedbugs at nondot.org
          Reporter: sbc at chromium.org
                CC: llvm-bugs at lists.llvm.org

The following C code is (I believe) incorrectly being reduces to a constant
value:

```
int f (int a) {
  a = a > 0 ? a : -a;
  if (a == 2)
    return 0;
  else
    return 1;
}
```

$ clang vrp-2.c -O1 -c -emit-llvm -S  -o -
...

define dso_local i32 @f(i32 %a) local_unnamed_addr #0 {
entry:
  ret i32 1
}
...

I tracked it down to this recent change:
https://reviews.llvm.org/D53844

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