<html><head><meta http-equiv="Content-Type" content="text/html charset=windows-1252"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;"><br><div><div>On Sep 11, 2014, at 2:15 PM, Sean Silva <<a href="mailto:chisophugis@gmail.com">chisophugis@gmail.com</a>> wrote:</div><br class="Apple-interchange-newline"><blockquote type="cite"><div dir="ltr"><br><div class="gmail_extra"><br><div class="gmail_quote">On Thu, Sep 11, 2014 at 1:30 PM, Kevin Enderby <span dir="ltr"><<a href="mailto:enderby@apple.com" target="_blank">enderby@apple.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex"><div style="word-wrap:break-word"><br><div><span class=""><div>On Sep 11, 2014, at 1:09 PM, Sean Silva <<a href="mailto:chisophugis@gmail.com" target="_blank">chisophugis@gmail.com</a>> wrote:</div><br><blockquote type="cite"><div dir="ltr"><br><div class="gmail_extra"><br><div class="gmail_quote">On Thu, Sep 11, 2014 at 11:59 AM, Kevin Enderby <span dir="ltr"><<a href="mailto:enderby@apple.com" target="_blank">enderby@apple.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex"><div style="word-wrap:break-word"><br><div><span><div>On Sep 11, 2014, at 12:11 AM, Steve King <<a href="mailto:steve@metrokings.com" target="_blank">steve@metrokings.com</a>> wrote:</div><br><blockquote type="cite"><span style="font-family:Helvetica;font-size:12px;font-style:normal;font-variant:normal;font-weight:normal;letter-spacing:normal;line-height:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px;float:none;display:inline!important">On Wed, Sep 10, 2014 at 8:29 PM, Sean Silva <</span><a href="mailto:chisophugis@gmail.com" style="font-family:Helvetica;font-size:12px;font-style:normal;font-variant:normal;font-weight:normal;letter-spacing:normal;line-height:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px" target="_blank">chisophugis@gmail.com</a><span style="font-family:Helvetica;font-size:12px;font-style:normal;font-variant:normal;font-weight:normal;letter-spacing:normal;line-height:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px;float:none;display:inline!important">> wrote:</span><br style="font-family:Helvetica;font-size:12px;font-style:normal;font-variant:normal;font-weight:normal;letter-spacing:normal;line-height:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px"><blockquote type="cite" style="font-family:Helvetica;font-size:12px;font-style:normal;font-variant:normal;font-weight:normal;letter-spacing:normal;line-height:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px"><br>Right, you mean like otool's -d (" Display the contents of the<br>(__DATA,__data) section") or -t ("Display the contents of the<br>(__TEXT,__text) section. With the -v flag, this disassembles the text.")?<br>;)<br><br></blockquote><br style="font-family:Helvetica;font-size:12px;font-style:normal;font-variant:normal;font-weight:normal;letter-spacing:normal;line-height:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px"><span style="font-family:Helvetica;font-size:12px;font-style:normal;font-variant:normal;font-weight:normal;letter-spacing:normal;line-height:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px;float:none;display:inline!important">I've never used otools, but presumably Kevin has some idea here.</span><br style="font-family:Helvetica;font-size:12px;font-style:normal;font-variant:normal;font-weight:normal;letter-spacing:normal;line-height:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px"></blockquote><div><br></div></span><div>I’ll try to explain my ideas. I think what we are talking about is how detailed the disassembly is, that is not printing just the raw bytes of a section and no disassembly. That is we are not talking about otool(1)’s printing of the text section without the -v flag.</div><div><br></div><div>Disassembly for otool(1) requires -v to get the disassembly of sections with instructions in them. In this mode (without -V) it will disassembly the instructions but will not try to symbolicate the operands. For example:</div><div><br></div><div>% otool -tv hello.o</div><div>…</div><div>0000000000000026<span style="white-space:pre-wrap"> </span>callq<span style="white-space:pre-wrap"> </span>0x2b</div><div><br></div><div>With -V then it will attempt to symbolicate the operands (using all the information it has, relocation entries, symbol tables, etc):</div><div><br></div><div>% otool -tV hello.o</div><div>…</div><div>0000000000000026<span style="white-space:pre-wrap"> </span>callq<span style="white-space:pre-wrap"> </span>_printf</div><div><br></div><div>my goal is by default this:</div><div><br></div><div>% llvm-objdump -m -d hello.o</div><div><br></div><div>will do the same as otool(1)’s -tV and produce the best disassembly (or maybe even better).</div><div><br></div><div>But I do want have the option of getting just the disassembly without symbolicating operands. So I’m thinking that these would would produce the same results:</div><div><br></div><div>% llvm-objdump -m -d hello.o -bare</div><div>% otool -tv hello.o</div><div><br></div><div>with both producing disassembly but not symbolicating operands. But I’m open to other ways to get this functionality. One note if your carefully reading non-symbolic operand to the callq instruction above, I want to see the the target address, in this case 0x2b, not the displacement.</div></div></div></blockquote><div><br></div><div>So what is your use case?</div></div></div></div></blockquote><div><br></div></span>My use case for -v without -V is for developers like myself that have to debug broken binaries. The use case for using a target address not a displacement is one can actually follow the flow control if the disassembly without knowing how each instruction works and doing the math to see where branches and calls go.</div></div></blockquote><div><br></div><div>Sorry, what I mean was: what is your use case that is motivating you to ship this tool to users? Did you literally get a user request "I want llvm-objdump”? </div></div></div></div></blockquote><div><br></div>Sort of literally my boss, Jim Grosbach, asked me to work on llvm-objdump and make it as good as otool(1) :)</div><div><br><blockquote type="cite"><div dir="ltr"><div class="gmail_extra"><div class="gmail_quote"><div> </div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex"><div style="word-wrap:break-word"><span class=""><br><blockquote type="cite"><div dir="ltr"><div class="gmail_extra"><div class="gmail_quote"> Are you shipping this tool to users?</div></div></div></blockquote><div><br></div></span>Yes otool(1) has always been shipped to users with the developer tools. The hope is to ship llvm-objdump to users at some point too.</div></blockquote><div><br></div><div>Shipping llvm-objdump to users puts it under a much stronger compatibility contract than any of the other tools (except obviously the clang driver). That along I think is enough to motivate splitting it out into a separate tool.</div><div> </div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex"><div style="word-wrap:break-word"><span class=""><br><blockquote type="cite"><div dir="ltr"><div class="gmail_extra"><div class="gmail_quote"> If you're explicitly trying to replicate otool's behavior, it seems much better to just make a separate tool, or look at argv[0].</div></div></div></blockquote><div><br></div></span>With the -m (or -macho) option for llvm-objdump to "Use MachO specific object file parser” I’m hoping to replicate otool(1)’s behavior but in the clang tree so all can use and improve it.</div></blockquote><div><br></div><div>I think it would make more sense to make a separate tool that does exactly what you want, so that you don't have to bother users with -m or anything. </div></div></div></div></blockquote><div><br></div>I don’t think that is much of a bother. There are lots of Mach-O bits that Nick, Tim and myself are adding under the -m flag.</div><div><br><blockquote type="cite"><div dir="ltr"><div class="gmail_extra"><div class="gmail_quote"><div> What code, if any, are you sharing with the rest of llvm-objdump?<br></div></div></div></div></blockquote><div><br></div>Right now I’m doing this work inside tools/llvm-objdump/MachODump.cpp . But I suspect when I have the Symbolizer hooked up it will be a good model for other targets version’s of the call backs for GetOpInfo() and SymbolLookUp(). And will figure out how to share this with the rest of llvm-objdump in the future. For now it is nice to work inside MachODump.cpp to get things working for Mach-O for others to see and we’ll figure out how to share things as they become more full functional.</div><div><br><blockquote type="cite"><div dir="ltr"><div class="gmail_extra"><div class="gmail_quote"><div><br></div><div>-- Sean Silva</div><div> </div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex"><div style="word-wrap:break-word"><span class=""><div><br><blockquote type="cite"><div dir="ltr"><div class="gmail_extra"><div class="gmail_quote"><div><br></div><div>-- Sean Silva</div><div><br></div><div> </div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex"><div style="word-wrap:break-word"><div><span><div><br></div><blockquote type="cite"><br style="font-family:Helvetica;font-size:12px;font-style:normal;font-variant:normal;font-weight:normal;letter-spacing:normal;line-height:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px"><blockquote type="cite" style="font-family:Helvetica;font-size:12px;font-style:normal;font-variant:normal;font-weight:normal;letter-spacing:normal;line-height:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px">What is your goal?<br></blockquote><br style="font-family:Helvetica;font-size:12px;font-style:normal;font-variant:normal;font-weight:normal;letter-spacing:normal;line-height:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px"><span style="font-family:Helvetica;font-size:12px;font-style:normal;font-variant:normal;font-weight:normal;letter-spacing:normal;line-height:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px;float:none;display:inline!important">A symbolizing disassembler with at least the possibility to tune</span><br style="font-family:Helvetica;font-size:12px;font-style:normal;font-variant:normal;font-weight:normal;letter-spacing:normal;line-height:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px"><span style="font-family:Helvetica;font-size:12px;font-style:normal;font-variant:normal;font-weight:normal;letter-spacing:normal;line-height:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px;float:none;display:inline!important">output to match existing norms per host platform.</span><br style="font-family:Helvetica;font-size:12px;font-style:normal;font-variant:normal;font-weight:normal;letter-spacing:normal;line-height:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px"><br style="font-family:Helvetica;font-size:12px;font-style:normal;font-variant:normal;font-weight:normal;letter-spacing:normal;line-height:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px"><br style="font-family:Helvetica;font-size:12px;font-style:normal;font-variant:normal;font-weight:normal;letter-spacing:normal;line-height:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px"><blockquote type="cite" style="font-family:Helvetica;font-size:12px;font-style:normal;font-variant:normal;font-weight:normal;letter-spacing:normal;line-height:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px">From what I can gather, it seems like you just want to<br>make llvm-objdump's default behavior match GNU objdump, which doesn't seem<br>like a very good direction (how deep is the rabbit hole? why GNU objdump and<br>not tool or the windows one?).<br></blockquote><br style="font-family:Helvetica;font-size:12px;font-style:normal;font-variant:normal;font-weight:normal;letter-spacing:normal;line-height:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px"><span style="font-family:Helvetica;font-size:12px;font-style:normal;font-variant:normal;font-weight:normal;letter-spacing:normal;line-height:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px;float:none;display:inline!important">What I personally need is a just symbolizing disassembler. What my</span><br style="font-family:Helvetica;font-size:12px;font-style:normal;font-variant:normal;font-weight:normal;letter-spacing:normal;line-height:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px"><span style="font-family:Helvetica;font-size:12px;font-style:normal;font-variant:normal;font-weight:normal;letter-spacing:normal;line-height:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px;float:none;display:inline!important">colleagues will expect is a fair approximation of GNU objdump because</span><br style="font-family:Helvetica;font-size:12px;font-style:normal;font-variant:normal;font-weight:normal;letter-spacing:normal;line-height:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px"><span style="font-family:Helvetica;font-size:12px;font-style:normal;font-variant:normal;font-weight:normal;letter-spacing:normal;line-height:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px;float:none;display:inline!important">that's what they already know. Kevin piped up early that he wanted</span><br style="font-family:Helvetica;font-size:12px;font-style:normal;font-variant:normal;font-weight:normal;letter-spacing:normal;line-height:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px"><span style="font-family:Helvetica;font-size:12px;font-style:normal;font-variant:normal;font-weight:normal;letter-spacing:normal;line-height:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px;float:none;display:inline!important">otools style output, so we ended up at the goal above.</span></blockquote></span></div><br><div>Yep my goal would be the best symbolic disassembly by default. With switches to turn off the symbolic operands for test cases or the power user who is likely the guy hunting down bugs and needs to see the operands raw. Basically it would be nice to have a less verbose option for those that need these things.</div><div><br></div><div>For example, the code I added for the Mach-O printing of private headers has a boolean verbose and will do this today. The call right now is passing in true for verbose but if there was a -bare or some other option I’d wire it up to that parameter. I don’t really care what we call it and I can live with what ever develops over time. If nothing does I’ll eventually create a Mach-O specific option to wire this up.</div><div><br></div><div>My thoughts,</div><div>Kev</div></div></blockquote></div><br></div></div>
</blockquote></div><br></span></div></blockquote></div><br></div></div>
</blockquote></div><br></body></html>