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RE: [PATCH 4/7] [ARC] [LRA] Avoid emitting COND_EXEC during expand.
- From: Claudiu Zissulescu <Claudiu dot Zissulescu at synopsys dot com>
- To: Andrew Burgess <andrew dot burgess at embecosm dot com>
- Cc: "gcc-patches at gcc dot gnu dot org" <gcc-patches at gcc dot gnu dot org>, "Francois dot Bedard at synopsys dot com" <Francois dot Bedard at synopsys dot com>
- Date: Thu, 13 Jul 2017 12:54:50 +0000
- Subject: RE: [PATCH 4/7] [ARC] [LRA] Avoid emitting COND_EXEC during expand.
- Authentication-results: sourceware.org; auth=none
- References: <1496324097-21221-1-git-send-email-claziss@synopsys.com> <1496324097-21221-5-git-send-email-claziss@synopsys.com> <20170713113819.GD27353@embecosm.com>
> This seems fine, your description "....does not always work." is a bit
> of a tease :) it would be nice to know _why_ it doesn't work, or at
> least a description of what problem you're seeing.
>
As far as I can see, LRA doesn't handle very well the conditional execution patterns, as it expects conditional execution to happen after this step. Thus, some of those instructions are marked dead and removed later on.
> Also we seem to be missing a test, would it be possible to find one?
> If not then I guess we live without, but we should note that in the
> commit message.
This error is found by executing dg.exp testsuite with our port and -mlra option on. As we speak, I am on the last 100m of testing our port having the LRA on. This bug being found like that.
I'll add this discussion to the commit message body.
Thank you,
Claudiu