https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111125
--- Comment #3 from Richard Biener <rguenth at gcc dot gnu.org> ---
gcc.dg/vect/pr53773.c is interesting - we vectorize the function to
<bb 2> [local count: 118111600]:
_20 = {integral_4(D), decimal_5(D)};
if (power_ten_6(D) > 0)
goto <bb 3>; [89.00%]
else
goto <bb 4>; [11.00%]
<bb 3> [local count: 955630224]:
# power_ten_19 = PHI <power_ten_11(3), power_ten_6(D)(2)>
# vect_integral_15.4_1 = PHI <vect_integral_9.5_12(3), _20(2)>
vect_integral_9.5_12 = vect_integral_15.4_1 * { 10, 10 };
power_ten_11 = power_ten_19 + -1;
if (power_ten_11 != 0)
goto <bb 3>; [89.00%]
else
goto <bb 4>; [11.00%]
<bb 4> [local count: 118111600]:
# vect_integral_16.7_21 = PHI <vect_integral_9.5_12(3), _20(2)>
_22 = VIEW_CONVERT_EXPR<vector(2) unsigned int>(vect_integral_16.7_21);
_23 = .REDUC_PLUS (_22); [tail call]
_24 = (int) _23;
return _24;
where loop vectorization fails because
/space/rguenther/src/gcc/gcc/testsuite/gcc.dg/vect/pr53773.c:9:20: note:
Analyze phi: integral_15 = PHI <integral_9(6), integral_4(D)(5)>
/space/rguenther/src/gcc/gcc/testsuite/gcc.dg/vect/pr53773.c:9:20: missed:
Peeling for epilogue is not supported for nonlinear induction except neg when
iteration count is unknown.
/space/rguenther/src/gcc/gcc/testsuite/gcc.dg/vect/pr53773.c:9:20: missed: not
vectorized: can't create required epilog loop
loop vectorization doesn't try SLP here because we only SLP reduction groups,
not induction groups.
So I think this vectorization is quite nice, possibly even better than
the loop vectorization we expect. generated code:
foo:
.LFB0:
.cfi_startproc
fmov s31, w0
ins v31.s[1], w1
cmp w2, 0
ble .L2
movi v30.2s, 0xa
.p2align 3,,7
.L3:
mul v31.2s, v31.2s, v30.2s
subs w2, w2, #1
bne .L3
.L2:
addp v31.2s, v31.2s, v31.2s
fmov w0, s31
ret
the path for power_ten == 0 is of course sub-optimal. Note it's again
determined not profitable with costing (we do not try to weight stmts
based on profile, thus in-loop stmts cost the same as out-of-loop stmts).
I'm going to adjust the testcase, disabling BB vectorization.
