[Bug tree-optimization/83518] [8/9 Regression] Missing optimization: useless instructions should be dropped

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83518

--- Comment #20 from Richard Biener <rguenth at gcc dot gnu.org> ---
(In reply to Steve Ellcey from comment #19)
> Should this defect be reopened?  One of the tests that was added is failing
> for me on aarch64.
> 
> FAIL: g++.dg/tree-ssa/pr83518.C  -std=gnu++98  scan-tree-dump optimized
> "return 15;"
> FAIL: g++.dg/tree-ssa/pr83518.C  -std=gnu++14  scan-tree-dump optimized
> "return 15;"
> FAIL: g++.dg/tree-ssa/pr83518.C  -std=gnu++17  scan-tree-dump optimized
> "return 15;"

It should have been fixed by r273732 (checked with a cc1 cross to aarch64,
albeit on a not clean tree...)