https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102756
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
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CC| |rsandifo at gcc dot gnu.org
--- Comment #6 from Richard Biener <rguenth at gcc dot gnu.org> ---
Btw, the same happens on x86-64. With -O2 and vectorization we end up with
<bb 3> [local count: 858993457]:
# ivtmp.14_11 = PHI <ivtmp.14_12(5), ivtmp.14_13(2)>
_14 = (void *) ivtmp.14_11;
_1 = MEM <int> [(vector(4) int *)_14];
if (_1 != -3)
goto <bb 4>; [0.00%]
else
goto <bb 5>; [100.00%]
<bb 4> [count: 0]:
__builtin_abort ();
<bb 5> [local count: 858993457]:
ivtmp.14_12 = ivtmp.14_11 + 4;
if (ivtmp.14_12 != _16)
goto <bb 3>; [80.00%]
else
goto <bb 6>; [20.00%]
<bb 6> [local count: 214748368]:
r ={v} {CLOBBER};
while everything is optimized away with -O2 -fno-tree-vectorize.
Let's keep this open as a regression since -O2 now enables vectorization. In
principle we could preserve the previous behavior for the very-cheap
vectorizer cost model or adjust the heuristic for that case to only cover
loops with a single BB.
The real issue here is of course the unroller not considering the true
size after simplification.
