https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115102
Oleg Endo <olegendo at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Ever confirmed|0 |1
Last reconfirmed| |2024-05-15
Status|UNCONFIRMED |NEW
--- Comment #2 from Oleg Endo <olegendo at gcc dot gnu.org> ---
(In reply to Richard Biener from comment #1)
> I believe this might be the middle-end using bswap32 (you can try to confirm
> for SH by looking at the dump generated by -fdump-tree-optimized).
>
Haven't checked the tree dump, but combine log shows patterns with
'bswap-something' in it. And the patterns that it tries to match are some sort
of partial bswaps.
On SH there is already a pattern:
(define_insn "swapbsi2"
[(set (match_operand:SI 0 "arith_reg_dest" "=r")
(ior:SI (and:SI (match_operand:SI 1 "arith_reg_operand" "r")
(const_int -65536)) ;; 0xFFFF0000
(ior:SI (and:SI (ashift:SI (match_dup 1) (const_int 8))
(const_int 65280))
(and:SI (ashiftrt:SI (match_dup 1) (const_int 8))
(const_int 255)))))]
But combine doesn't arrive there and it stops at the intermediate combine
bridge pattern
(define_insn_and_split "*swapbisi2_and_shl8"
[(set (match_operand:SI 0 "arith_reg_dest" "=r")
(ior:SI (and:SI (ashift:SI (match_operand:SI 1 "arith_reg_operand" "r")
(const_int 8))
(const_int 65280))
(match_operand:SI 2 "arith_reg_operand" "r")))]
Adding another variant of the existing pattern, which combine is looking for,
helps in this case:
(define_insn "*swapbisi2"
[(set (match_operand:SI 0 "arith_reg_dest" "=r")
(ior:SI (ior:SI (and:SI (ashift:SI
(match_operatnd:SI 1 "arith_reg_operand"
"r")
(const_int 8))
(const_int 65280))
(and:SI (lshiftrt:SI (match_dup 1) (const_int 8))
(const_int 255)))
(and:SI (match_dup 1)
(const_int -65536))))]
I haven't checked if the original pattern is still used in other cases or not.
