<div dir="ltr"><br><div class="gmail_extra"><br><div class="gmail_quote">On Fri, Jul 10, 2015 at 9:00 PM, escha <span dir="ltr"><<a href="mailto:escha@apple.com" target="_blank">escha@apple.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div style="word-wrap:break-word"><br><div><span class=""><div><blockquote type="cite"><div><div class="gmail_quote" style="font-family:Helvetica;font-size:12px;font-style:normal;font-variant:normal;font-weight:normal;letter-spacing:normal;line-height:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px"><div><br></div><div>What's up with this giant immediate we're now generating instead of an imm8? Seems worse.</div></div></div></blockquote><br></div></span><div>It’s a known issue: <a href="https://urldefense.proofpoint.com/v2/url?u=https-3A__llvm.org_bugs_show-5Fbug.cgi-3Fid-3D24085&d=AwMFaQ&c=8hUWFZcy2Z-Za5rBPlktOQ&r=mQ4LZ2PUj9hpadE3cDHZnIdEwhEBrbAstXeMaFoB9tg&m=H9B0c2krm6lZo8LaBpZ_qKvgpyEuMUSWEFfjgRI_i30&s=0A6OSwQEwrsm9pyFQrnKve5JDi3odlWcNU61dJtRkLc&e=" target="_blank">https://llvm.org/bugs/show_bug.cgi?id=24085</a>. It’s likely a backend problem; computeKnownBits decides that the constant can be shrunk (which we already do in a lot of places, this just adds one more), so sometimes enhancing computeKnownBits can cause de-optimizations if the backend doesn’t know how to optimize the constant appropriately.</div><div><br></div><div>The reviewers on Phab decided we should commit it and file a bug report about the deoptimization, since better KnownBits tracking *should* always be better.</div></div></div></blockquote><div><br></div><div>Totally reasonable. Glad that's on the radar.</div><div><br></div><div>-- Sean Silva</div><div> </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div style="word-wrap:break-word"><div><div><div><br></div><div>—escha</div></div><br></div></div></blockquote></div><br></div></div>