<html><head><meta http-equiv="Content-Type" content="text/html charset=windows-1252"><base href="x-msg://1984/"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; ">Applied in r157215.<div><br></div><div>--Owen</div><div><br><div><div>On May 21, 2012, at 11:21 AM, "Villmow, Micah" <<a href="mailto:Micah.Villmow@amd.com">Micah.Villmow@amd.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 a bug in the expansion code for SUB going back to at least LLVM 2.6 and still shows up in trunk.<o:p></o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif; "><span style="font-size: 10pt; font-family: 'Courier New'; ">case ISD::SUB: {<o:p></o:p></span></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif; "><span style="font-size: 10pt; font-family: 'Courier New'; "> EVT VT = Node->getValueType(0);<o:p></o:p></span></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif; "><span style="font-size: 10pt; font-family: 'Courier New'; "> assert(TLI.isOperationLegalOrCustom(ISD::ADD, VT) &&<o:p></o:p></span></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif; "><span style="font-size: 10pt; font-family: 'Courier New'; "> TLI.isOperationLegalOrCustom(ISD::XOR, VT) &&<o:p></o:p></span></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif; "><span style="font-size: 10pt; font-family: 'Courier New'; "> "Don't know how to expand this subtraction!");<o:p></o:p></span></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif; "><span style="font-size: 10pt; font-family: 'Courier New'; "> Tmp1 = DAG.getNode(ISD::XOR, dl, VT, Node->getOperand(1),<o:p></o:p></span></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif; "><span style="font-size: 10pt; font-family: 'Courier New'; "> DAG.getConstant(APInt::getAllOnesValue(VT.getSizeInBits()), VT));<o:p></o:p></span></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif; "><span style="font-size: 10pt; font-family: 'Courier New'; "> Tmp1 = DAG.getNode(ISD::ADD, dl, VT, Tmp2, DAG.getConstant(1, VT));<o:p></o:p></span></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif; "><span style="font-size: 10pt; font-family: 'Courier New'; "> Results.push_back(DAG.getNode(ISD::ADD, dl, VT, Node->getOperand(0), Tmp1));<o:p></o:p></span></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif; "><span style="font-size: 10pt; font-family: 'Courier New'; "> break;<o:p></o:p></span></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif; "><span style="font-size: 10pt; font-family: 'Courier New'; "> }<o:p></o:p></span></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; "><o:p> </o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif; ">The problem is Tmp2 is not initialized and should be Tmp1 instead. This code only is hit if the architecture does not support ‘SUB’ and you need to expand it.<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; ">Patch is attached, please commit if good.<o:p></o:p></div></div><span><isd_sub_expand.diff></span>_______________________________________________<br>LLVM Developers mailing list<br><a href="mailto:LLVMdev@cs.uiuc.edu" style="color: purple; text-decoration: underline; ">LLVMdev@cs.uiuc.edu</a><span class="Apple-converted-space"> </span> <a href="http://llvm.cs.uiuc.edu" style="color: purple; text-decoration: underline; ">http://llvm.cs.uiuc.edu</a><br><a href="http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev" style="color: purple; text-decoration: underline; ">http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev</a></div></blockquote></div><br></div></body></html>