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[Bug tree-optimization/77283] [7 Regression] Revision 238005 disables loop unrolling
- From: "rguenth at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: Thu, 18 Aug 2016 09:33:47 +0000
- Subject: [Bug tree-optimization/77283] [7 Regression] Revision 238005 disables loop unrolling
- Authentication-results: sourceware.org; auth=none
- Auto-submitted: auto-generated
- References: <bug-77283-4@http.gcc.gnu.org/bugzilla/>
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=77283
--- Comment #6 from Richard Biener <rguenth at gcc dot gnu.org> ---
I'm reasonably happy with the PHI logic so I am going to test it. It's quite
on the do-more-duplicating side for memory references (just uses the virtual
operand PHI to see if there are any loads/stores in the joiner).
For the case of
if (a)
i = i + 1;
else
...;
j = i + 1;
thus CSE opportunities on one/both paths this is something that PRE catches
already. So we're not actually looking for CSE opportunities but opportunities
for simplification or DCE/DSE.