[Bug rtl-optimization/91865] Combine misses opportunity to remove (sign_extend (zero_extend)) before searching for insn patterns

[jozefl.gcc at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91865

--- Comment #5 from Jozef Lawrynowicz <jozefl.gcc at gmail dot com> ---
(In reply to Segher Boessenkool from comment #4)
> Created attachment 47550 [details]
> simplify-rtx patch for extends of AND of hard reg
> 
> So I did a patch to make this work (in simplify-rtx) also for hard registers
> (see attachment).

Confirmed that I can remove the unnamed RTL insns labelled under "BZ 91865" in
msp430.md and optimal code is generated for the first testcase when the patch
is applied.