<html><head><meta http-equiv="Content-Type" content="text/html charset=utf-8"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;"><br><div><div>On Oct 22, 2013, at 5:03 AM, 罗勇刚(Yonggang Luo) <<a href="mailto:luoyonggang@gmail.com">luoyonggang@gmail.com</a>> wrote:</div><br class="Apple-interchange-newline"><blockquote type="cite"><p dir="ltr">Forward to llvmdev</p>
<div class="gmail_quote">---------- 转发的邮件 ----------<br>发件人："Chris Lattner" <<a href="mailto:clattner@apple.com">clattner@apple.com</a>><br>日期：2013年10月22日 下午7:33<br>主题：Re: [lldb-dev] Has Fast register allocation been finished in 3.3 version?<br>
收件人： <<a href="mailto:wansheg@gmail.com">wansheg@gmail.com</a>><br>抄送： <<a href="mailto:lldb-dev@cs.uiuc.edu">lldb-dev@cs.uiuc.edu</a>><br><br type="attribution"><div style="word-wrap:break-word"><br><div><div>
On Oct 21, 2013, at 7:43 PM, <a href="mailto:wansheg@gmail.com" target="_blank">wansheg@gmail.com</a> wrote:</div><br><blockquote type="cite"><div style="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">
<br>When I use llc command with --regalloc=fast , get error<span> </span><br></div></blockquote></div></div></div></blockquote><div><br></div><div>And I presume the error is:</div>LLVM ERROR: regalloc=... not currently supported with -O0</div><div><br></div><div>-regalloc=fast is not a very useful flag because it requires “-O0” and is also implied by -O0.</div><div><br></div><div>However, if you still want all the other llc optimizations you can use an internal option instead of -O0:</div><div><br></div><div>-optimize-regalloc=false -regalloc=fast</div><div><br></div><div>Register allocation is not just the allocation algorithm. It’s a set of passes that cooperate. The ‘fast’ allocator uses a different pipeline than the optimizing global allocators.</div><div><br><blockquote type="cite"><div class="gmail_quote"><div style="word-wrap:break-word"><div><blockquote type="cite"><div style="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">In addition, is lli use fast register allocation?<br></div></blockquote></div></div></div></blockquote><br></div><div>AFAIK, the -O levels are the same, with -O0 using fast regalloc.</div><div><br></div><div>-Andy</div><br></body></html>