[Bug tree-optimization/121762] pass_fold_builtins and pass_optimize_widening_mul and pass_gimple_isel should be merged or moved other places

[pinskia at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=121762

--- Comment #10 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Just some notes on optimize_stack_restore.
The comment in front says:
```
   ... Optimize it out 
   if there is another __builtin_stack_restore in the same basic
   block and no calls or ASM_EXPRs are in between, or if this block's
   only outgoing edge is to EXIT_BLOCK and there are no calls or
   ASM_EXPRs after this __builtin_stack_restore.
```

But the loop does something different.
It checks if there are calls but allows normal builtins too. So it could allow
__atomic_*. It does not allow internal functions nor target builtins.

I think the check should allow pure/const functions but not all normal
builtins.
PR 43220 happened because of the comment was not the same as the code.