<html><head></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><div><div>On May 21, 2012, at 11:21 AM, Villmow, Micah wrote:</div><br class="Apple-interchange-newline"><blockquote type="cite"><span class="Apple-style-span" style="border-collapse: separate; font-family: 'Lucida Grande'; 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-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; font-size: medium; "><div lang="EN-US" link="blue" vlink="purple"><div class="WordSection1" style="page: WordSection1; "><div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 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-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif; "><span style="font-size: 10pt; font-family: 'Courier New'; color: black; ">case ISD::SUB: {<o:p></o:p></span></div><div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif; "><span style="font-size: 10pt; font-family: 'Courier New'; color: black; "> EVT VT = Node->getValueType(0);<o:p></o:p></span></div><div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif; "><span style="font-size: 10pt; font-family: 'Courier New'; color: black; "> assert(TLI.isOperationLegalOrCustom(ISD::ADD, VT) &&<o:p></o:p></span></div><div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif; "><span style="font-size: 10pt; font-family: 'Courier New'; color: black; "> TLI.isOperationLegalOrCustom(ISD::XOR, VT) &&<o:p></o:p></span></div><div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif; "><span style="font-size: 10pt; font-family: 'Courier New'; color: black; "> "Don't know how to expand this subtraction!");<o:p></o:p></span></div><div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif; "><span style="font-size: 10pt; font-family: 'Courier New'; color: black; "> Tmp1 = DAG.getNode(ISD::XOR, dl, VT, Node->getOperand(1),<o:p></o:p></span></div><div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif; "><span style="font-size: 10pt; font-family: 'Courier New'; color: black; "> DAG.getConstant(APInt::getAllOnesValue(VT.getSizeInBits()), VT));<o:p></o:p></span></div><div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif; "><span style="font-size: 10pt; font-family: 'Courier New'; color: black; "> Tmp1 = DAG.getNode(ISD::ADD, dl, VT, Tmp2, DAG.getConstant(1, VT));<o:p></o:p></span></div><div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif; "><span style="font-size: 10pt; font-family: 'Courier New'; color: black; "> Results.push_back(DAG.getNode(ISD::ADD, dl, VT, Node->getOperand(0), Tmp1));<o:p></o:p></span></div><div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif; "><span style="font-size: 10pt; font-family: 'Courier New'; color: black; "> break;<o:p></o:p></span></div><div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif; "><span style="font-size: 10pt; font-family: 'Courier New'; color: black; "> }<o:p></o:p></span></div><div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif; "><o:p> </o:p></div><div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif; "><o:p> </o:p></div><div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 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-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif; "><o:p> </o:p></div><div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif; ">Patch is attached, please commit if good.</div></div></div></span></blockquote><br></div><div>It seems to me that a test case demonstrating bad code would be helpful here.</div><div>[ Not that I'm suggesting that the current code is correct… ]</div><br><div apple-content-edited="true">
<span class="Apple-style-span" style="border-collapse: separate; color: rgb(0, 0, 0); font-family: 'Lucida Grande'; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-align: auto; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; font-size: medium; ">-- Marshall<br><br>Marshall Clow Idio Software <<a href="mailto:mclow.lists@gmail.com">mailto:mclow.lists@gmail.com</a>><br><br>A.D. 1517: Martin Luther nails his 95 Theses to the church door and is promptly moderated down to (-1, Flamebait).<br> -- Yu Suzuki</span>
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