<div dir="ltr">On 7 January 2013 15:32, Michael Gottesman <span dir="ltr"><<a href="mailto:mgottesman@apple.com" target="_blank">mgottesman@apple.com</a>></span> wrote:<br><div class="gmail_extra"><div class="gmail_quote">
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="auto"><div>We are testing LTO internally and have not run into this issue IIRC. But on the other hand, we are doing a straight compilation (I.e. not doing it in parts as you said you were). Even so, you are right, we should have public lnt LTO testers.</div>
</div></blockquote><div><br></div><div><br></div><div style>My opinion is that tests should be intentional. If you spot a difference between two calls, you either start testing both explicitly or ignore one of them. Relying on side-effects for testing, in the majority of cases, increase the perceived importance of small matters and takes away time to fix real bugs.</div>
<div style><br></div><div style>If LTO is important (I think it is), then we should have explicit LTO tests. If testing the order of passes is important, we should consistently test it on all important configurations we have (ex. using bugpoint). Keeping an old testing style *just* to have the side-effect of testing LTO leads to confusion and noise which is worse in the end.</div>
<div style><br></div><div style>Random tests are one way of achieving a huge vector space in a fair way. The hard bits is to know what to ignore (ie. it'll never happen in real world) against the real bugs, that need fixing, or the real bugs that have very little importance, etc. But all that should only be pursued when all the other proper tests are set up and giving meaningful results.</div>
<div style><br></div><div style>cheers,</div><div style>--renato</div></div></div></div>