https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88676
Jakub Jelinek <jakub at gcc dot gnu.org> changed:
What |Removed |Added
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CC| |jakub at gcc dot gnu.org
--- Comment #1 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
We have:
# RANGE [0, 1] NONZERO 1
unsigned int b_2(D) = b;
int r;
<bb 2> [local count: 1073741824]:
if (b_2(D) == 1)
goto <bb 3>; [21.72%]
else
goto <bb 4>; [78.28%]
<bb 3> [local count: 233216728]:
<bb 4> [local count: 1073741824]:
# RANGE [1, 2] NONZERO 3
# r_1 = PHI <1(2), 2(3)>
So, we'd need in some suitable pass (phiopt) figure out that a) the SSA_NAME in
the comparison has a value range of 2 values only, compared against one of them
b) that the PHI values can be expressed by cheap arithmetics from that.
