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</o:shapelayout></xml><![endif]--></head><body lang=EN-US link=blue vlink=purple><div class=WordSection1><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>We cannot use bitcast because bitcast is a value preserving operation, but the address space conversion operation we have is a bit-changing operation. <o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Where will the bulk of work be? Can we make a ConstantExpr which has a new Opcode (or reuse call) and a list of operands? The first operand is a string. <o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><div><div style='border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0in 0in 0in'><p class=MsoNormal><b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'>From:</span></b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'> Chris Lattner [mailto:clattner@apple.com] <br><b>Sent:</b> Monday, December 17, 2012 4:39 PM<br><b>To:</b> Yuan Lin<br><b>Cc:</b> llvmdev@cs.uiuc.edu<br><b>Subject:</b> Re: [LLVMdev] target specific ways to extend ConstantExpr<o:p></o:p></span></p></div></div><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal><o:p> </o:p></p><div><div><p class=MsoNormal>On Dec 17, 2012, at 4:23 PM, Yuan Lin <<a href="mailto:yulin@nvidia.com">yulin@nvidia.com</a>> wrote:<o:p></o:p></p></div><p class=MsoNormal><br><br><o:p></o:p></p><div><div><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>The particular case we are looking at is converting a pointer from one address space to another address space. There is one operand and one output, both are the same pointer type, except for their address space. The pointers are of the same size. The operation is a bit-changing operation.</span><o:p></o:p></p></div></div><div><blockquote style='margin-top:5.0pt;margin-bottom:5.0pt'><div><div><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'> We are using intrinsic functions for the instructions. We need a solution for the ConstantExpr.</span><o:p></o:p></p></div></div></blockquote><div><div><div><p class=MsoNormal><o:p> </o:p></p></div></div></div></div><div><p class=MsoNormal>Sounds like a bitcast to me. Is there a reason the bitcast constexpr isn't working for you?<o:p></o:p></p></div><p class=MsoNormal><br><br><o:p></o:p></p><div><div><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Instead of adding one target specific expression, it would be better to have a more generic scheme in LLVM.</span><o:p></o:p></p></div></div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>I agree! However, fixing this is also a lot of work.<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>-Chris<o:p></o:p></p></div><p class=MsoNormal><o:p> </o:p></p></div>
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