https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109040
--- Comment #5 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
The insn with HImode subreg comes from RTL DSE, before DSE we have:
(insn 36 35 39 2 (set (mem/c:SI (plus:SI (reg/f:SI 65 frame)
(const_int -64 [0xffffffffffffffc0])) [2 S4 A128])
(reg:SI 166)) "pr109040.c":9:11 178 {*movsi_internal}
(expr_list:REG_DEAD (reg:SI 166)
(nil)))
(insn 39 36 40 2 (set (reg:SI 171)
(zero_extend:SI (mem/c:HI (plus:SI (reg/f:SI 65 frame)
(const_int -64 [0xffffffffffffffc0])) [0 S2 A128])))
"pr109040.c":9:11 111 {*zero_extendhisi2}
(nil))
and DSE makes:
(insn 47 35 39 2 (set (reg:HI 175)
(subreg:HI (reg:SI 166) 0)) "pr109040.c":9:11 179 {*movhi_internal}
(expr_list:REG_DEAD (reg:SI 166)
(nil)))
(insn 39 47 40 2 (set (reg:SI 171)
(zero_extend:SI (reg:HI 175))) "pr109040.c":9:11 111
{*zero_extendhisi2}
(expr_list:REG_DEAD (reg:HI 175)
(nil)))
out of it. Does it for WORD_REGISTER_OPERATIONS need to create a single
instruction?
