This is the mail archive of the
gcc@gcc.gnu.org
mailing list for the GCC project.
Re: loop_latch_edge is NULL during jump threading
- From: Jeff Law <law at redhat dot com>
- To: Kugan <kugan dot vivekanandarajah at linaro dot org>, gcc at gcc dot gnu dot org
- Date: Sun, 01 Mar 2015 21:29:27 -0700
- Subject: Re: loop_latch_edge is NULL during jump threading
- Authentication-results: sourceware.org; auth=none
- References: <54F3A189 dot 2050102 at linaro dot org>
On 03/01/15 16:32, Kugan wrote:
In linaro-4.9-branch, with the following (reduced) test case, I run into
a situation where loop_latch_edge is NULL during jump threading. I am
wondering if this a possible during jump threading or the error lies
some where else? I can't reproduce it with the trunk.
There's really no way to tell without a lot more information. If you
can't reproduce on the 4.9 branch or the trunk, then you're likely going
to have to do the real digging.
THe first thing I tend to do with these things is to draw the CFG and
annotate it with all the jump threading paths. Then I look at how the
jump threading paths interact with each other and the loop structure,
then reconcile that with the constraints placed on threading in
tree-ssa-threadupdate.c.
If I apply the following patch, segfault goes away. Is this aright approach?
No way to know for sure without further analysis.
jeff