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[Bug middle-end/31531] A microoptimization of isnegative of signed integer
- From: "pinskia at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: Sun, 12 Feb 2012 04:35:53 +0000
- Subject: [Bug middle-end/31531] A microoptimization of isnegative of signed integer
- Auto-submitted: auto-generated
- References: <bug-31531-4@http.gcc.gnu.org/bugzilla/>
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=31531
--- Comment #6 from Andrew Pinski <pinskia at gcc dot gnu.org> 2012-02-12 04:35:53 UTC ---
The shortest testcase for the problem function:
int isnegative_optimized_4(unsigned int X) {
int result; // Y is the conditional expression of if-else.
if ((~X) >> 31) result = 0;
else result = 1;
return result;
}
We need to combine the following gimple:
D.2293_3 = ~X_2(D);
D.2294_4 = (int) D.2293_3;
D.2424_9 = D.2294_4 >= 0;