<div dir="ltr"><br><div class="gmail_extra"><br><div class="gmail_quote">On Mon, Jun 20, 2016 at 8:55 PM, Reid Kleckner <span dir="ltr"><<a href="mailto:rnk@google.com" target="_blank">rnk@google.com</a>></span> wrote:</div><div class="gmail_quote">Hello Reid,</div><div class="gmail_quote">Yes actually idea to identify local function is taken from GlobalOpt : )<br><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex"><div dir="ltr">GlobalOpt already does this with fastcc, use it as a guide if you want to do this:<div><a href="https://github.com/llvm-mirror/llvm/blob/63b34cdf342b8265d98357008765b2563dd04e6c/lib/Transforms/IPO/GlobalOpt.cpp#L2023" target="_blank">https://github.com/llvm-mirror/llvm/blob/63b34cdf342b8265d98357008765b2563dd04e6c/lib/Transforms/IPO/GlobalOpt.cpp#L2023</a><br></div><div><br></div><div>You can't just change the convention of F, you need to update the convention used at F's call sites.</div></div></blockquote><div> Thanks for pointing this out , and looking at RemoveNestAttribute() in GlobalOpt I think even if I add new Function attribute then also it needs to be updated at every call sites.</div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex"><div dir="ltr"><div>Unfortunately, while LLVM has PreserveMost and PreservesAll calling conventions, it does not appear to have an equivalent PreservesNone/Least.</div></div></blockquote><div>Actually we are in favor of adding new CC like No_CSR but what I want to discuss is how much minimal changes are required and also as I mentioned for the purpose of IPRA we don't really have any new rules for parameter passing or return value etc So will it be good to have new CC for this purpose and if new CC is added is it ok to keep parameter passing and other rules same as common CC?</div><div><br></div><div>I hope my question is clear.</div><div><br></div><div>Sincerely,</div><div>Vivek</div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex"><div class="gmail_extra"><br><div class="gmail_quote"><div><div class="h5">On Mon, Jun 20, 2016 at 7:39 AM, vivek pandya via llvm-dev <span dir="ltr"><<a href="mailto:llvm-dev@lists.llvm.org" target="_blank">llvm-dev@lists.llvm.org</a>></span> wrote:<br></div></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex"><div><div class="h5"><div dir="ltr">Dear Community,<div><br></div><div>To improve current interprocedural register allocation (IPRA) , we have planned to set callee saved registers to none for local functions, currently I am doing it in following way:</div><div><br></div><div><font face="monospace, monospace">if (F->hasLocalLinkage() <span style="font-size:12.499999046325684px"> </span><span style="font-size:12.499999046325684px">&& !F->hasAddressTaken()</span>) {</font></div><div><font face="monospace, monospace"> DEBUG(dbgs() << "Function has LocalLinkage \n");</font></div><div><font face="monospace, monospace">F->setCallingConv(CallingConv::GHC); </font></div><div><font face="monospace, monospace"> }</font></div><div><br></div><div>but we think threre should be clean and properway to do this perhaps like:</div><div><br></div><div><div><div style="font-size:12.499999046325684px"><font face="monospace, monospace">if (F->hasLocalLinkage() && !F->hasAddressTaken()) {</font></div><span style="font-size:12.499999046325684px"><font face="monospace, monospace"> DEBUG(dbgs() << "Function has LocalLinkage \n");</font></span><div style="font-size:12.499999046325684px"><font face="monospace, monospace"> F->setCallingConv(CallingConv::NO_Callee_Saved);</font></div><div style="font-size:12.499999046325684px"><font face="monospace, monospace"> }</font></div><div style="font-size:12.499999046325684px"><font face="monospace, monospace"><br></font></div><div><font face="arial, helvetica, sans-serif"><span style="font-size:12.499999046325684px">So I would like to know any better suggestions and if it is better to add a new CC for this purpose then what aspects should be considered while defining a new CC. Actually in this case the new CC does not really required to define how parameters should be passed or any special rule for return value etc , it just required to set callee saved registers to be none. So what are the minimal things required to define such a CC?</span></font></div></div></div><div><font face="arial, helvetica, sans-serif"><span style="font-size:12.499999046325684px"><br></span></font></div><div><font face="arial, helvetica, sans-serif"><span style="font-size:12.499999046325684px">Other alternative that I have thought was to add new attribute for function and use it like following in TargetFrameLowering::determineCalleeSaves()</span></font></div><div><font face="arial, helvetica, sans-serif"><span style="font-size:12.499999046325684px"><br></span></font></div><div><div style="font-size:12.499999046325684px"> <font face="monospace, monospace">// In Naked functions we aren't going to save any registers.</font></div><div style="font-size:12.499999046325684px"><font face="monospace, monospace"> if (MF.getFunction()->hasFnAttribute(Attribute::Naked))</font></div><div style="font-size:12.499999046325684px"><font face="monospace, monospace"> return;</font></div></div><div style="font-size:12.499999046325684px"><font face="monospace, monospace"><br></font></div><div style="font-size:12.499999046325684px"><font face="arial, helvetica, sans-serif">Any suggestions / thoughts are welcomed !</font></div><div style="font-size:12.499999046325684px"><font face="arial, helvetica, sans-serif"><br></font></div><div style="font-size:12.499999046325684px"><font face="arial, helvetica, sans-serif">Sincerely,</font></div><div style="font-size:12.499999046325684px"><font face="arial, helvetica, sans-serif">Vivek</font></div></div>
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