[PATCH] testsuite: add -fno-tree-fre in gcc.dg/guality

Hu, Jiangping hujiangping@cn.fujitsu.com
Sat Aug 29 11:43:16 GMT 2020

Hi, Jakub

Thank you for your detailed explanation. 
I will try to compare the results of rtl expand as Richard have
suggested, to see if I can find anything. May be I can make
another patch.

Thanks again.


> On Thu, Aug 27, 2020 at 11:13:50AM +0000, Hu, Jiangping wrote:
> > I'm not sure about if the case should fail.
> > So, I add Jakub who committed this testcase.
> >
> > I thought the case should success, but for changes of gcc of
> > years, now it failed. So I think that may be some optimization
> > are unnecessary for this testcase, and I found the FRE.
> The intent of the guality testsuite is to track regressions in debug info
> quality.  Because the testing matrix is huge
> (different targets x different -O* options x different gdb versions),
> it isn't really feasible to keep xfails for them accurately, so all we
> care
> about is whether we don't regress compared to older gcc releases for the
> same target, same -O* options and same gdb version.
> If we do regress e.g. because of some added optimization, the intent is
> that it is analyzed why it regressed and if possible some improvements
> in the debug info generation are added to deal with the optimization if
> possible.
> So adding -fno-tree-* is not the right solution, the majority of people
> will
> not use such options in their codes and so they will observe the debug
> info
> quality degradation there.
> 	Jakub

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