This is the mail archive of the
gcc-bugs@gcc.gnu.org
mailing list for the GCC project.
[Bug middle-end/69526] ivopts candidate strangeness
- From: "rdapp at linux dot vnet.ibm.com" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: Thu, 28 Jan 2016 09:31:25 +0000
- Subject: [Bug middle-end/69526] ivopts candidate strangeness
- Auto-submitted: auto-generated
- References: <bug-69526-4 at http dot gcc dot gnu dot org/bugzilla/>
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69526
--- Comment #2 from rdapp at linux dot vnet.ibm.com ---
Ok, that's sensible but why is the - 1 necessary in the first place?
n_5 - 1 can only underflow if n_5 == 0 which is checked by
testl %edx, %edx
before. This is in a previous basic block, unfortunately, and will not be
regarded by ivopts then (because strictly speaking, it has no influence on the
induction variable)?