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From: "pinskia at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug ipa/114215] GCC makes wrong decision for inline with -Os or -Oz
 to deal with trivial functions
Date: Sun, 03 Mar 2024 03:18:33 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D114215

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
     Ever confirmed|0                           |1
             Status|UNCONFIRMED                 |WAITING
   Last reconfirmed|                            |2024-03-03

--- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
    checkedvector::value_type& checkedvector::operator[](size_type)/167 cal=
l is
unlikely and code size would grow
      freq:1.00 loop depth: 0 size: 4 time: 13 callee size: 6 stack: 0
       op1 is compile time invariant



If I had:
```
void test_demovector(checkedvector& vec, int x) noexcept
{
  for(int i =3D 0; i < y; i++)
    vec[i]=3D5;
}
```

Then GCC will inling operator[]:
    checkedvector::value_type& checkedvector::operator[](size_type)/167 inl=
ined
      freq:8.09
      Stack frame offset 0, callee self size 0
      void __builtin_trap()/205 function body not available
        freq:0.00 loop depth: 1 size: 1 time:  1

I am suspecting this is the right heurstic. Do you have real code where the
inlining does not happen at -Os/-Oz or you just looking at the code generat=
ion
with code that might be benchmarking things?=