https://gcc.gnu.org/bugzilla/show_bug.cgi?id=116338
--- Comment #5 from kugan at gcc dot gnu.org ---
(In reply to Richard Biener from comment #4)
> You can try to see whether adding a SSA copy would make this supported, it
> seems not allowing a PHI is simply a missed feature.
We now fail in
/* If this isn't a nested cycle or if the nested cycle reduction value
is used ouside of the inner loop we cannot handle uses of the reduction
value. */
if (nlatch_def_loop_uses > 1 || nphi_def_loop_uses > 1)
Even if I comment this, I see:
t1.c:16:25: note: worklist: examine stmt: _22 = x_18 + y_19;
t1.c:16:25: note: vect_is_simple_use: operand x_18 = PHI <_1(5), x_10(2)>,
type of def: unknown
t1.c:16:25: missed: Unsupported pattern.
t1.c:10:6: missed: not vectorized: unsupported use in stmt.
t1.c:16:25: missed: unexpected pattern.
t1.c:16:25: note: ***** Analysis failed with vector mode V4SF
Do we need to somehow mark both the PHI stents as part of the first order
reduction?
<bb 3> [local count: 1063004408]:
# x_18 = PHI <_1(5), x_10(2)>
# y_19 = PHI <x_18(5), y_11(2)>
# i_20 = PHI <i_13(5), 0(2)>
# ivtmp_17 = PHI <ivtmp_16(5), 32000(2)>
_1 = b[i_20];
_22 = x_18 + y_19;
_3 = _1 + _22;
_4 = _3 * 3.33000004291534423828125e-1;
a[i_20] = _4;
i_13 = i_20 + 1;
ivtmp_16 = ivtmp_17 - 1;
if (ivtmp_16 != 0)
goto <bb 5>; [98.99%]
else
goto <bb 4>; [1.01%]
<bb 5> [local count: 1052266995]:
goto <bb 3>; [100.00%]
