<html><head><meta http-equiv="Content-Type" content="text/html charset=windows-1252"><base href="x-msg://7279/"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><br><div><div>On Feb 26, 2013, at 4:01 PM, Mark Schimmel <<a href="mailto:Mark.Schimmel@synopsys.com">Mark.Schimmel@synopsys.com</a>> wrote:</div><br class="Apple-interchange-newline"><blockquote type="cite"><div lang="EN-US" link="blue" vlink="purple" style="font-family: Helvetica; font-size: medium; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-align: -webkit-auto; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; "><div class="WordSection1" style="page: WordSection1; "><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif; ">I found myself wanting a “scheduling barrier” in LLVM. In my specific circumstances I only want it to mean that TargetInstrInfoImpl::isSchedulingBoundary() would return true.<o:p></o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif; "><o:p> </o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif; ">I added SchedulingBarrier to MCID in MCInstrDesc.h and pushed it through TD attributes down to isSchedulingBoundary(). Is this something of general interest, or is there another mechanism for implementing barriers that I missed?</div></div></div></blockquote><br></div><div> I don't think you need both a SchedulingBarrier MCID and a special TargetInstrInfo hook. isSchedulingBoundary is a currently target hook because it's fairly specific to a CodeGen pass, we want to make general queries here like isTerminator and isCall, and the answer may vary depending on some attribute of the function. You can always add a target specific barrier opcode and check for it within the target hook without changing the MC API.</div><div><br></div><div>-Andy</div></body></html>