https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93997
--- Comment #1 from Uroš Bizjak <ubizjak at gmail dot com> ---
Before my patch, the compiler generated this IR:
#(insn 42 291 43 2 (set (strict_low_part (mem/c:HI (plus:SI (reg/f:SI 6 bp)
# (const_int -40 [0xffffffffffffffd8])) [5 %sfp+-16 S2
A128]))
# (reg:HI 1 dx [orig:91 _14 ] [91])) "vector-scalar.c":9:17 83
{*movstricthi_1}
# (nil))
movw %dx, -40(%ebp) # 42 [c=4 l=4] *movstricthi_1/0
This is strict_low_part of a memory operand, which isn't valid according to
docs:
'(strict_low_part (subreg:M (reg:N R) 0))'
This expression code is used in only one context: as the
destination operand of a 'set' expression. In addition, the
operand of this expression must be a non-paradoxical 'subreg'
expression.
The presence of 'strict_low_part' says that the part of the
register which is meaningful in mode N, but is not part of mode M,
is not to be altered. Normally, an assignment to such a subreg is
allowed to have undefined effects on the rest of the register when
M is smaller than 'REGMODE_NATURAL_SIZE (N)'.
After the patch, we have:
(insn 42 41 43 2 (set (strict_low_part (subreg:HI (reg:TI 135) 0))
(reg:HI 91 [ _14 ])) "vector-scalar.c":9:17 83 {*movstricthi_1}
(nil))
but TImode is not valid for general regs.
Probably we have to reject TImode in case of 32bit targets from the expander.
