https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87105
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |jamborm at gcc dot gnu.org,
| |marxin at gcc dot gnu.org
--- Comment #9 from Richard Biener <rguenth at gcc dot gnu.org> ---
For the original testcase there's also the issue that the bez[] accesses end up
as
_68 = MEM[(double *)bez_27(D) + 16B];
_69 = MEM[(double *)bez_27(D) + 24B];
and thus they possibly alias with the earlier stores
bBox_33(D)->x0 = iftmp.1_190;
bBox_33(D)->y0 = iftmp.1_193;
bBox_33(D)->x1 = iftmp.0_196;
bBox_33(D)->y1 = iftmp.0_199;
which we subsequently fail to eliminate against the final ones
iftmp.1_49 = MIN_EXPR <_119, iftmp.1_190>;
bBox_33(D)->x0 = iftmp.1_49;
iftmp.1_31 = MIN_EXPR <_118, iftmp.1_193>;
bBox_33(D)->y0 = iftmp.1_31;
iftmp.0_102 = MAX_EXPR <_119, iftmp.0_196>;
bBox_33(D)->x1 = iftmp.0_102;
iftmp.0_105 = MAX_EXPR <_118, iftmp.0_199>;
bBox_33(D)->y1 = iftmp.0_105;
if we'd eliminate the earlier ones then vectorization would have had a chance
here. That's from
// Linear interpolation, works with points as well.
template<typename V, typename T = double>
inline V lerp(const V& a, const V& b, const T& t) noexcept {
return (a * (1.0 - t)) + (b * t);
}
and
// Min/Max - different semantics compared to std.
template<typename T> constexpr T myMin(const T& a, const T& b) noexcept
{ return b < a ? b : a; }
template<typename T> constexpr T myMax(const T& a, const T& b) noexcept
{ return a < b ? b : a; }
taking references to double.
Plus it is because IPA SRA decomposing the by reference Point passing
to
_17 = MEM[(double *)b_2(D)];
_18 = MEM[(double *)b_2(D) + 8B];
_19 = MEM[(double *)&t];
_20 = MEM[(double *)&t + 8B];
D.19260 = _ZmlRK5PointS1_.isra.5 (_17, _18, _19, _20);
that's quite bad for TBAA ... the function uses b->x, etc. to access the
memory.
