<div dir="ltr">I've always just hacked support for this in to the various JITs (for JuliaLang, in our debuginfo.cpp file), by setting the no-frame-pointer-optim flag in the IR, then creating and populating a dummy unwind description object in the .text section, and registering that dynamically. Some day I hope to actually just register the .pdata/.xdata sections with the unwinder.<div><br></div><div>PDBs are a bit different though, since the above steps work well for gdb, but generally I find that WinDbg is less willing or able to be given JIT-frame information from LLVM. (I assume somehow it can be done, for dotNET. I just don't know how.)</div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Sat, Feb 29, 2020 at 11:07 PM Reid Kleckner via llvm-dev <<a href="mailto:llvm-dev@lists.llvm.org">llvm-dev@lists.llvm.org</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-style:solid;border-left-color:rgb(204,204,204);padding-left:1ex"><div dir="ltr">Yes, I think <a href="https://bugs.llvm.org/show_bug.cgi?id=24233" target="_blank">https://bugs.llvm.org/show_bug.cgi?id=24233</a> needs to be implemented to fix this.<div><br></div><div>The Windows x64 unwinder doesn't generally look at frame pointers. We would need to register unwind info to make this work. What you see is fairly typical of attempting to unwind the stack when unwind info is missing.</div><div><br></div><div>PDBs shouldn't generally enter into the picture.</div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Sat, Feb 29, 2020 at 8:14 AM Vivien Millet via llvm-dev <<a href="mailto:llvm-dev@lists.llvm.org" target="_blank">llvm-dev@lists.llvm.org</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-style:solid;border-left-color:rgb(204,204,204);padding-left:1ex"><div dir="ltr"><p style="margin:0px 0px 1em;padding:0px;border:0px;font-variant-numeric:inherit;font-variant-east-asian:inherit;font-stretch:inherit;line-height:inherit;font-family:Arial,"Helvetica Neue",Helvetica,sans-serif;font-size:15px;vertical-align:baseline;box-sizing:inherit;clear:both;color:rgb(36,39,41)">Hi,<br><br>I'm using IR and MCJIT to compile a script language. I debug it with on the fly generated .pdb files. During debugging, almost each time I step into a function, I loose information about calling function inside the visual studio callstack view or I have a bunch of pure addresses in the callstack in between the current function and the calling function, for example :</p><pre style="margin-top:0px;margin-bottom:1em;padding:12px 8px;border:0px;font-variant-numeric:inherit;font-variant-east-asian:inherit;font-stretch:inherit;line-height:inherit;font-family:Consolas,Menlo,Monaco,"Lucida Console","Liberation Mono","DejaVu Sans Mono","Bitstream Vera Sans Mono","Courier New",monospace,sans-serif;font-size:13px;vertical-align:baseline;box-sizing:inherit;width:auto;max-height:600px;overflow:auto;border-top-left-radius:3px;border-top-right-radius:3px;border-bottom-right-radius:3px;border-bottom-left-radius:3px;color:rgb(36,39,41)"><code style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant-ligatures:inherit;font-variant-caps:inherit;font-variant-numeric:inherit;font-variant-alternates:inherit;font-variant-east-asian:inherit;font-weight:inherit;font-stretch:inherit;line-height:inherit;font-family:Consolas,Menlo,Monaco,"Lucida Console","Liberation Mono","DejaVu Sans Mono","Bitstream Vera Sans Mono","Courier New",monospace,sans-serif;vertical-align:baseline;box-sizing:inherit;white-space:inherit">MyJit.dll!MyCurrentFunction()
[0x1234567887654321]
[0x8765432112345678]
MyJit.dll!MyCallingFunction()
...
</code></pre><p style="margin:0px 0px 1em;padding:0px;border:0px;font-variant-numeric:inherit;font-variant-east-asian:inherit;font-stretch:inherit;line-height:inherit;font-family:Arial,"Helvetica Neue",Helvetica,sans-serif;font-size:15px;vertical-align:baseline;box-sizing:inherit;clear:both;color:rgb(36,39,41)">It looks like visual studio get lost while walking up stack.<br>Does anyone know where it could come from ?   <br></p><p style="margin:0px 0px 1em;padding:0px;border:0px;font-variant-numeric:inherit;font-variant-east-asian:inherit;font-stretch:inherit;line-height:inherit;font-family:Arial,"Helvetica Neue",Helvetica,sans-serif;font-size:15px;vertical-align:baseline;box-sizing:inherit;clear:both;color:rgb(36,39,41)">I have disabled all optimisations (among them is the omit-frame-pointer).</p><p style="margin:0px 0px 1em;padding:0px;border:0px;font-variant-numeric:inherit;font-variant-east-asian:inherit;font-stretch:inherit;line-height:inherit;font-family:Arial,"Helvetica Neue",Helvetica,sans-serif;font-size:15px;vertical-align:baseline;box-sizing:inherit;clear:both;color:rgb(36,39,41)">I have seen this bug here : <a href="https://bugs.llvm.org/show_bug.cgi?id=24233" style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant-ligatures:inherit;font-variant-caps:inherit;font-variant-numeric:inherit;font-variant-alternates:inherit;font-variant-east-asian:inherit;font-weight:inherit;font-stretch:inherit;line-height:inherit;font-family:inherit;vertical-align:baseline;box-sizing:inherit" target="_blank">https://bugs.llvm.org/show_bug.cgi?id=24233</a> which is quite similar but it is quite old now, and since the proposed patch has been posted, the code in RuntimeDyldCOFFX86_64.h has changed and it is difficult for me to know if it has really been fixed since or not.</p><p style="margin:0px 0px 1em;padding:0px;border:0px;font-variant-numeric:inherit;font-variant-east-asian:inherit;font-stretch:inherit;line-height:inherit;font-family:Arial,"Helvetica Neue",Helvetica,sans-serif;font-size:15px;vertical-align:baseline;box-sizing:inherit;clear:both;color:rgb(36,39,41)">Could it be related to the way IR CreateAlloca are used to build local variables ? Could it be related to missing informations inside the PDB ? (I don't know if there is stack related information inside PDB files to ensure good stack walking).<br><br>Thanks.<br><br>Vivien</p></div>
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