On Tue, Aug 22, 2017 at 4:11 PM Jeff Law <l...@redhat.com> wrote: > > On 08/22/2017 03:03 AM, Richard Biener wrote: > > > > The following patch makes sure to not grow the number of incoming > > edges in the destination when doing split_edge on GIMPLE. That's > > easy by first redirecting the existing edge to the destination > > to the new block rather than creating the new fallthru from the > > new block to the destination. > > > > Bootstrapped and tested on x86_64-unknown-linux-gnu, applied to trunk. > > > > Richard. > > > > 2017-08-22 Richard Biener <rguent...@suse.de> > > > > * tree-cfg.c (gimple_split_edge): Avoid reallocating target > > PHI nodes. > Definitely a good thing. Having PHIs get reallocated has led to some > subtle bugs. I realize this isn't a complete solution to that problem, > but every bit helps.
So this causes PHI args to be swapped which I need to avoid now.
Thus the following followup, bootstrapped on x86_64-unknown-linux-gnu,
testing in progress.
Richard.
>From b17d1ec8ef94f1ab87fcfedf7c947815e60e42e7 Mon Sep 17 00:00:00 2001
From: Richard Biener <rguent...@suse.de>
Date: Tue, 20 Oct 2020 12:52:31 +0200
Subject: [PATCH] Avoid changing PHIs in GIMPLE split_edge
To: gcc-patches@gcc.gnu.org
Previously I've changed gimple_split_edge to avoid PHI node
re-allocation, but this introduced swapping of PHI arguments
due to the way edge redirection works. This is now a problem
for me and which can be solved with the following approach
reducing the overhead of split_edge even more. We can simply
pretend there are no PHI nodes if we can make sure the
new fallthru will have the same dest_idx as the old edge
into the destination.
2020-10-20 Richard Biener <rguent...@suse.de>
* tree-cfg.c (reinstall_phi_args): Remove.
(gimple_split_edge): Remove PHIs around the edge redirection
to avoid touching them at all.
p
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