https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99767
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Target Milestone|--- |9.4
Status|UNCONFIRMED |NEW
Ever confirmed|0 |1
Last reconfirmed| |2021-03-25
--- Comment #1 from Richard Biener <rguenth at gcc dot gnu.org> ---
OMP lowering makes the dead division conditional and we produce and want to
expand
;; basic block 2, loop depth 0
;; pred: ENTRY
MEM <vector(2) int> [(int *)&mask.4] = mask.5_9(D);
vect__5.21_31 = .MASK_LOAD (&mask.4, 32B, { -1, -1, 0, 0, ... });
_5 = mask.4[0];
mask__26.22_33 = vect__5.21_31 != { 0, ... };
_26 = _5 != 0;
v_1 = .COND_DIV (_26, 1, 0, 1);
vec_mask_and_37 = mask__26.22_33 & { -1, -1, 0, 0, ... };
.MASK_STORE (&retval.3, 32B, vec_mask_and_37, { 0, ... });
vectp_mask.19_29 = &mask.4 + POLY_INT_CST [16, 16];
vectp_retval.23_36 = &retval.3 + POLY_INT_CST [16, 16];
_6 = VIEW_CONVERT_EXPR<vector(2) int>(retval.3);
return _6;
;; succ: EXIT
but that's still scalar, so sth forgot to "vectorize" it? Indeed when
returning 'v' we instead get
_26 = _5 != 0;
vec_mask_and_37 = mask__26.34_33 & { -1, -1, -1, -1, 0, 0, 0, 0, ... };
vect_v_1.35_38 = .COND_DIV (vec_mask_and_37, { 1, ... }, { 0, ... }, { 1, ...
});
.MASK_STORE (&retval.9, 32B, vec_mask_and_37, vect_v_1.35_38);
The .COND_DIV is generated by if-conversion which supposedly expects we
will vectorize it (or throw it away) but it doesn't ignore (as the vectorizer)
obviously dead stmts. So the bug is this disconnect between if-conversion
and vectorization.
