http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59999
--- Comment #7 from Paulo J. Matos <pa...@matos-sorge.com> ---
(In reply to Richard Biener from comment #5)
> Apart from expand there is the redundant-extension-elimination, ree.c.
In expand we get the following gimple for the loop:
;; basic block 4, loop depth 0
;; pred: 2
;; 4
# i_15 = PHI <0(2), i_12(4)>
# _18 = PHI <0(2), _4(4)>
_6 = arr[_18];
_7 = _6 + 1;
arr[_18] = _7;
_17 = (unsigned short) i_15;
_13 = _17 + 1;
i_12 = (short int) _13;
_4 = (int) i_12;
if (_4 < limit_5(D))
goto <bb 4>;
else
goto <bb 3>;
;; succ: 4
;; 3
Where _13 is an unsigned short and what we want to eliminate is this sign
extend:
_4 = (int) i_12;
This doesn't seem trivial in the expand phase because to eliminate the sign
expand, you promote i_12 to int and have then to promote a bunch of other
variables, whose insn have been already emitted when you get here. Shouldn't
this be ivopts noticing that if it generates an int IV, it saves a sign extend
and therefore is better?
