[Bug tree-optimization/67121] [6 Regression] wrong code at -O3 on x86_64-linux-gnu
rguenth at gcc dot gnu.org
gcc-bugzilla@gcc.gnu.org
Wed Aug 5 10:43:00 GMT 2015
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67121
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Keywords| |wrong-code
Status|NEW |ASSIGNED
Assignee|unassigned at gcc dot gnu.org |rguenth at gcc dot gnu.org
--- Comment #3 from Richard Biener <rguenth at gcc dot gnu.org> ---
Hmm.
Visiting statement:
h_38 = (char) pretmp_48;
Found new range for h_38: VARYING
...
Visiting statement:
_42 = (int) h_38;
Intersecting
[-128, 127]
and
[0, 127]
to
[0, 127]
Found new range for _42: [0, 127]
so it seems that the old value-range for _42 is bad:
# RANGE [0, 127] NONZERO 127
_42 = (int) h_38;
Before if-conversion we have
<bb 2>:
a[0] = 1;
f = 0;
pretmp_48 = c;
<bb 3>:
# f.4_36 = PHI <0(2), _19(6)>
# ivtmp_59 = PHI <9(2), ivtmp_28(6)>
h_9 = (char) pretmp_48;
if (h_9 >= 0)
goto <bb 4>;
else
goto <bb 10>;
<bb 4>:
# RANGE [0, 127] NONZERO 127
_10 = (int) h_9;
while after:
<bb 2>:
a[0] = 1;
f = 0;
pretmp_48 = c;
<bb 3>:
# f.4_36 = PHI <0(2), _19(4)>
# ivtmp_59 = PHI <9(2), ivtmp_28(4)>
h_9 = (char) pretmp_48;
# RANGE [0, 127] NONZERO 127
_10 = (int) h_9;
...
prephitmp_3 = h_9 >= 0 ? _14 : _38;
so if-conversion has to reset value-range info on stmts previously
conditionally
executed.
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