<html xmlns:v="urn:schemas-microsoft-com:vml" xmlns:o="urn:schemas-microsoft-com:office:office" xmlns:w="urn:schemas-microsoft-com:office:word" xmlns:x="urn:schemas-microsoft-com:office:excel" xmlns:p="urn:schemas-microsoft-com:office:powerpoint" xmlns:a="urn:schemas-microsoft-com:office:access" xmlns:dt="uuid:C2F41010-65B3-11d1-A29F-00AA00C14882" xmlns:s="uuid:BDC6E3F0-6DA3-11d1-A2A3-00AA00C14882" xmlns:rs="urn:schemas-microsoft-com:rowset" xmlns:z="#RowsetSchema" xmlns:b="urn:schemas-microsoft-com:office:publisher" xmlns:ss="urn:schemas-microsoft-com:office:spreadsheet" xmlns:c="urn:schemas-microsoft-com:office:component:spreadsheet" xmlns:odc="urn:schemas-microsoft-com:office:odc" xmlns:oa="urn:schemas-microsoft-com:office:activation" xmlns:html="http://www.w3.org/TR/REC-html40" xmlns:q="http://schemas.xmlsoap.org/soap/envelope/" xmlns:rtc="http://microsoft.com/officenet/conferencing" xmlns:D="DAV:" xmlns:Repl="http://schemas.microsoft.com/repl/" xmlns:mt="http://schemas.microsoft.com/sharepoint/soap/meetings/" xmlns:x2="http://schemas.microsoft.com/office/excel/2003/xml" xmlns:ppda="http://www.passport.com/NameSpace.xsd" xmlns:ois="http://schemas.microsoft.com/sharepoint/soap/ois/" xmlns:dir="http://schemas.microsoft.com/sharepoint/soap/directory/" xmlns:ds="http://www.w3.org/2000/09/xmldsig#" xmlns:dsp="http://schemas.microsoft.com/sharepoint/dsp" xmlns:udc="http://schemas.microsoft.com/data/udc" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:sub="http://schemas.microsoft.com/sharepoint/soap/2002/1/alerts/" xmlns:ec="http://www.w3.org/2001/04/xmlenc#" xmlns:sp="http://schemas.microsoft.com/sharepoint/" xmlns:sps="http://schemas.microsoft.com/sharepoint/soap/" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:udcs="http://schemas.microsoft.com/data/udc/soap" xmlns:udcxf="http://schemas.microsoft.com/data/udc/xmlfile" xmlns:udcp2p="http://schemas.microsoft.com/data/udc/parttopart" xmlns:wf="http://schemas.microsoft.com/sharepoint/soap/workflow/" xmlns:dsss="http://schemas.microsoft.com/office/2006/digsig-setup" xmlns:dssi="http://schemas.microsoft.com/office/2006/digsig" xmlns:mdssi="http://schemas.openxmlformats.org/package/2006/digital-signature" xmlns:mver="http://schemas.openxmlformats.org/markup-compatibility/2006" xmlns:m="http://schemas.microsoft.com/office/2004/12/omml" xmlns:mrels="http://schemas.openxmlformats.org/package/2006/relationships" xmlns:spwp="http://microsoft.com/sharepoint/webpartpages" xmlns:ex12t="http://schemas.microsoft.com/exchange/services/2006/types" xmlns:ex12m="http://schemas.microsoft.com/exchange/services/2006/messages" xmlns:pptsl="http://schemas.microsoft.com/sharepoint/soap/SlideLibrary/" xmlns:spsl="http://microsoft.com/webservices/SharePointPortalServer/PublishedLinksService" xmlns:Z="urn:schemas-microsoft-com:" xmlns:st="" xmlns="http://www.w3.org/TR/REC-html40"><head><meta http-equiv=Content-Type content="text/html; charset=us-ascii"><meta name=Generator content="Microsoft Word 12 (filtered medium)"><style><!--
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</o:shapelayout></xml><![endif]--></head><body lang=EN-US link=blue vlink=purple><div class=WordSection1><p class=MsoNormal>Hi All,<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>I have a question on ConstantExpressions and llvm intrinsic memcpy/memset/memmove. I am using llvm-2.8 release. In one of the C programs that I am compiling using clang frontend, the call to memcpy instrinsic looks like the following<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>call void @llvm.memcpy.p0i8.p0i8.i64(i8* %tmp2, i8* bitcast (%struct.ta* @tret to i8*), i64 4, i32 4, i1 false), !dbg !19<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>The second argument to memcpy is of type “struct ta” and global variable “tret” is defined as follows in the code.<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>struct ta {<o:p></o:p></p><p class=MsoNormal> int a;<o:p></o:p></p><p class=MsoNormal>};<o:p></o:p></p><p class=MsoNormal>struct ta tret;<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Since memcpy takes i8* as its argument, the struct.ta* is bitcasted to i8* in the call to llvm.memcpy. For a pass that I am working on, I would like to know the original type of this pointer. In this example, I would like to know that the second argument is a pointer to type struct.ta, and hence the size of memory allocated to that pointer is 4 bytes. <o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>I understand that the second argument to memcpy intrinsic namely i8* bitcast (%struct.ta* @t1 to i8*) is a ConstantExpression (CE). When I dump CE->getArgument(0), I get the following. <o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>@t1 = global %struct.ta zeroinitializer, align 4<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>But from here, I am not able to find the relevant class/API to extract the type of CE->getArgument(0) and hence the size of it. When I tried CE->getArgument(0)->getType(), I am getting the type as Pointer and hence the size to be 8 bytes. I would like to get the type as StructTy and size to be 4 bytes. I searched through the llvm code <o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Any help is appreciated. <o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Thanks<o:p></o:p></p><p class=MsoNormal>Sreekumar<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p></div></body></html>