<html><head><meta http-equiv="Content-Type" content="text/html charset=utf-8"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class="">Hi Ethan,<div class=""><br class=""><div><blockquote type="cite" class=""><div class="">On Aug 11, 2015, at 3:36 PM, Ethan J. Johnson via llvm-dev <<a href="mailto:llvm-dev@lists.llvm.org" class="">llvm-dev@lists.llvm.org</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><div class="WordSection1" style="page: WordSection1; font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;"><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class="">Hi all,<o:p class=""></o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><o:p class=""> </o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class="">I am attempting to implement the “reaching definitions” data-flow algorithm on (X86) MachineBasicBlocks for an analysis pass. To do this, I need to compute gen/kill sets for machine basic blocks. To start with, I am only considering the general-purpose registers, RAX-R15 and their sub-registers. Thus, I need to examine each MachineInstr to determine which register(s) it defines and/or uses.<o:p class=""></o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""></div></div></div></blockquote><div><br class=""></div>There is an implementation of such algorithm in AArch64CollectLOH.cpp. I suggest you have a look there.</div><div>If the algorithm is of general use, we may want to move it into some generic place.</div><div><br class=""></div><div>Let me know if you need more information.</div><div><br class=""></div><div>Cheers,</div><div>-Quentin<br class=""><blockquote type="cite" class=""><div class=""><div class="WordSection1" style="page: WordSection1; font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;"><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><o:p class=""> </o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class="">I see in the Doxygen that for a MachineOperand, I can call<span class="Apple-converted-space"> </span><span style="font-family: 'Courier New';" class="">isReg()</span><span class="Apple-converted-space"> </span>and<span style="font-family: 'Courier New';" class=""><span class="Apple-converted-space"> </span>getReg()</span><span class="Apple-converted-space"> </span>to figure out which X86 register the operand corresponds to. These return an unsigned int “register number”; but I’m not sure how to identify which register actually corresponds to that number.<o:p class=""></o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><o:p class=""> </o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class="">Also, I will need to identify definitions and uses of registers in instructions. I see that MachineOperand has methods such as<span class="Apple-converted-space"> </span><span style="font-family: 'Courier New';" class="">isUse()</span>,<span class="Apple-converted-space"> </span><span style="font-family: 'Courier New';" class="">isDef()</span>, and<span class="Apple-converted-space"> </span><span style="font-family: 'Courier New';" class="">isKill()</span>, which sound like they might be relevant to what I’m doing; but neither the Doxygen nor the source are particularly helpful as to what they actually do. From the MachineInstr documentation, I gathered that instructions which define a value are always written so that the value being defined is the first operand; but since X86 has instructions that use more than one register as output (multiplication, for instance), I would need to manually account for the semantics of each instruction. Since X86 has a great many instructions to account for, many of them obscure, I would very much prefer not to go this route if LLVM already provides it! :-)<o:p class=""></o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><o:p class=""> </o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class="">To summarize, my questions are as follows:<o:p class=""></o:p></div><div style="margin: 0in 0in 0.0001pt 38.25pt; font-size: 11pt; font-family: Calibri, sans-serif; text-indent: -0.25in;" class=""><span class="">1.<span style="font-style: normal; font-variant: normal; font-weight: normal; font-size: 7pt; line-height: normal; font-family: 'Times New Roman';" class=""> <span class="Apple-converted-space"> </span></span></span>How can I determine the actual X86 register that a MachineOperand corresponds to?<o:p class=""></o:p></div><div style="margin: 0in 0in 0.0001pt 38.25pt; font-size: 11pt; font-family: Calibri, sans-serif; text-indent: -0.25in;" class=""><span class="">2.<span style="font-style: normal; font-variant: normal; font-weight: normal; font-size: 7pt; line-height: normal; font-family: 'Times New Roman';" class=""> <span class="Apple-converted-space"> </span></span></span>What is the best/most straightforward way to determine whether a MachineInstr defines and/or uses a particular register?<o:p class=""></o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><o:p class=""> </o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class="">Thanks,<o:p class=""></o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class="">Ethan Johnson<o:p class=""></o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><o:p class=""> </o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><i class="">Ethan J. Johnson<o:p class=""></o:p></i></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><i class="">Computer Science PhD student, Systems group, University of Rochester<o:p class=""></o:p></i></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><a href="mailto:ejohns48@cs.rochester.edu" style="color: rgb(149, 79, 114); text-decoration: underline;" class=""><i class=""><span style="color: rgb(5, 99, 193);" class="">ejohns48@cs.rochester.edu</span></i></a><i class=""><o:p class=""></o:p></i></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><a href="mailto:ethanjohnson@acm.org" style="color: rgb(149, 79, 114); text-decoration: underline;" class=""><i class=""><span style="color: rgb(5, 99, 193);" class="">ethanjohnson@acm.org</span></i></a><i class=""><o:p class=""></o:p></i></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><i class="">PGP pubkey available from public directory or on request<o:p class=""></o:p></i></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><o:p class=""> </o:p></div></div><span style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; float: none; display: inline !important;" class="">_______________________________________________</span><br style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;" class=""><span style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; float: none; display: inline !important;" class="">LLVM Developers mailing list</span><br style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;" class=""><a href="mailto:llvm-dev@lists.llvm.org" style="color: rgb(149, 79, 114); text-decoration: underline; font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;" class="">llvm-dev@lists.llvm.org</a><span style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; float: none; display: inline !important;" class=""><span class="Apple-converted-space"> </span> </span><a href="http://llvm.cs.uiuc.edu/" style="color: rgb(149, 79, 114); text-decoration: underline; font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;" class="">http://llvm.cs.uiuc.edu</a><br style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;" class=""><a href="http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev" style="color: rgb(149, 79, 114); text-decoration: underline; font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;" class="">http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev</a></div></blockquote></div><br class=""></div></body></html>