https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112398
Andrew Pinski <pinskia at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|WAITING |UNCONFIRMED
Component|target |rtl-optimization
Ever confirmed|1 |0
--- Comment #4 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Expand does:
;; _1 = *src_5(D);
(insn 7 6 0 (set (reg:SI 134 [ _1 ])
(zero_extend:SI (mem:QI (reg/v/f:SI 138 [ srcD.2336 ]) [0 MEM[(const
uint8_tD.2311 *)src_5(D) clique 1 base 1]+0 S1 A8]))) "/app/example.cpp":5:21
-1
(nil))
;; work_6 = ~_1;
(insn 8 7 9 (set (reg:SI 139)
(not:SI (reg:SI 134 [ _1 ]))) "/app/example.cpp":5:13 -1
(nil))
(insn 9 8 0 (set (reg/v:SI 136 [ workD.2339 ])
(zero_extend:SI (subreg:QI (reg:SI 139) 0))) "/app/example.cpp":5:13 -1
(nil))
The bigger issue we don't take into track of nonzerobits as much as we could.
Though the other issue when combine does the combining here:
Trying 7, 8 -> 9:
7: r134:SI=zero_extend([r148:SI])
REG_DEAD r148:SI
8: r139:SI=~r134:SI
REG_DEAD r134:SI
9: r136:SI=zero_extend(r139:SI#0)
REG_DEAD r139:SI
Failed to match this instruction:
(set (reg/v:SI 136 [ workD.2339 ])
(zero_extend:SI (subreg:QI (not:SI (subreg:SI (mem:QI (reg:SI 148) [0
MEM[(const uint8_tD.2311 *)src_5(D) clique 1 base 1]+0 S1 A8]) 0)) 0)))
that could be just (xor (zero_extend:SI (mem:QI (reg:SI 148) [0 MEM[(const
uint8_tD.2311 *)src_5(D) clique 1 base 1]+0 S1 A8]) 0))) 255)
But I am not so sure combine knows how to simplify that ...
