https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82356
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |NEW
Last reconfirmed| |2017-09-29
Component|tree-optimization |rtl-optimization
Ever confirmed|0 |1
--- Comment #1 from Richard Biener <rguenth at gcc dot gnu.org> ---
The vectorizer itself just emits
<bb 13> [81.00%]:
# ivtmp.30_143 = PHI <0(12), ivtmp.30_144(13)>
# ivtmp.35_145 = PHI <0(12), ivtmp.35_146(13)>
vect__1.15_75 = MEM[base: vectp_src.14_71, index: ivtmp.35_145, step: 2,
offset: 0B];
vect__1.16_77 = MEM[base: vectp_src.14_71, index: ivtmp.35_145, step: 2,
offset: 16B];
vect__2.17_78 = vect__1.15_75 >> 8;
vect__2.17_79 = vect__1.16_77 >> 8;
vect__3.18_80 = VEC_PACK_TRUNC_EXPR <vect__2.17_78, vect__2.17_79>;
MEM[base: vectp_dst.20_81, index: ivtmp.35_145, offset: 0B] = vect__3.18_80;
ivtmp.30_144 = ivtmp.30_143 + 1;
ivtmp.35_146 = ivtmp.35_145 + 16;
if (bnd.9_65 > ivtmp.30_144)
goto <bb 13>; [83.34%]
it seems the ands come from VEC_PAC_TRUNC_EXPR expansion somehow.
(insn 150 149 151 (set (reg:V8HI 219)
(and:V8HI (reg:V8HI 221)
(reg:V8HI 214 [ vect__2.17 ]))) "t.c":5 -1
(nil))
(insn 151 150 152 (set (reg:V8HI 220)
(and:V8HI (reg:V8HI 221)
(reg:V8HI 216 [ vect__2.17 ]))) "t.c":5 -1
(nil))
(insn 152 151 153 (set (reg:V16QI 218 [ vect__3.18 ])
(vec_concat:V16QI (us_truncate:V8QI (reg:V8HI 219))
(us_truncate:V8QI (reg:V8HI 220)))) "t.c":5 -1
(nil))
and combine / simplify-rtx are not able to remove them again (no wonders,
simplify-rtx is notoriously unaware of vectors).
