https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81423
--- Comment #5 from Segher Boessenkool <segher at gcc dot gnu.org> ---
There are a few issues here.
1) I cannot reproduce it: a trunk x86_64-linux compiler stores to
memory in that insn 20 (the testcase from comment 3).
2) 17, 18 -> 19 should already match. Instead we get
Trying 17, 18 -> 19:
Failed to match this instruction:
(parallel [
(set (reg:SI 114)
(lshiftrt:SI (subreg:SI (reg:DI 109) 0)
(plus:QI (subreg:QI (ior:SI (subreg:SI (reg:DI 111 [ ull2 ]) 0)
(const_int -8651009 [0xffffffffff7bfeff])) 0)
(const_int 5 [0x5]))))
(clobber (reg:CC 17 flags))
])
If the subreg:QI there was simplified properly (to just 0xff) the
plus:QI could be simplified as well.
3) The reported issue. Confirmed.
