[Bug tree-optimization/95769] New: Constant expression in inline function not optimized

[gcc at mailinator dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95769

            Bug ID: 95769
           Summary: Constant expression in inline function not optimized
           Product: gcc
           Version: 10.1.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: gcc at mailinator dot com
  Target Milestone: ---

Godbolt link: https://godbolt.org/z/Kimna8

Code:

```
int constexpr expensive_function(int x){
    int result{};
    while(x!=1){
        x=x%2!=0 ? x*3+1 : x/2;
        result++;
    }
    return result;
}

int constexpr other_function(int a, int b){
    return a*expensive_function(b);
}

int f_(int x){
    return other_function(x, 1000);
}

int g(int x){
    return x*expensive_function(1000);
}
```

The function `g` is optimized so `expensive_function(1000)` is evaluated at
compile time. The function `f` isn't.