https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66002
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |NEW
Last reconfirmed| |2015-05-04
Blocks| |53947
Ever confirmed|0 |1
--- Comment #4 from Richard Biener <rguenth at gcc dot gnu.org> ---
prephitmp_61 = _53 <= 65535 ? pretmp_60 : -32768;
is
unsigned int <= 65535 ? short int : short int;
pushing the condition to a separate stmt might get us to support this
"narrowing" conversion.
Of course ifcvt does a pretty poor job on this as well...
We do vectorize
for (int i=0; i<n; ++i) {
int wt=w[i]+((t[i]*err*2>>16)+1>>1);
if (wt<-32768) wt=-32768;
// if (wt>32767) wt=32767;
w[i]=wt;
}
as if (wt<-32768) wt=-32768; becomes a MAX_EXPR. Also if I change it to
for (int i=0; i<n; ++i) {
int wt=w[i]+((t[i]*err*2>>16)+1>>1);
if (wt<-32768) wt=-32768;
else if (wt>32767) wt=32767;
w[i]=wt;
}
we vectorize it as MIN/MAX_EXPRs.
Maybe you can perform this source change manually and see what it does
to performance.
Referenced Bugs:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=53947
[Bug 53947] [meta-bug] vectorizer missed-optimizations
