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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">I would like to check in code sometime soon that allows LLVM to support pointers of different sizes. One of the complaints about this was that bitcast between
pointers of different address spaces then breaks if bitcast between the pointers has different sizes. There was a thread about this discussing the various pro’s and con’s and it was decided to just make bitcast between pointers of different sizes illegal and
require the user to use PtrToInt/IntToPtr instead. In order to handle this case, I had to make modifications to the verifier to start failing if it detects the bitcasts and to auto-upgrade older bitcode files to the correct behavior. Then while developing
the patches for that, I ran into the problem where TargetData only exists in the Target module and as it relies on VMCore, and VMCore now would rely on Target, there is a circular dependency. This was seen as a bad thing, so I’m proposing moving TargetData
into Support, so there is no longer a circular dependency.<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">So, I can’t check in the variable sized pointers until I can check in the bitcast changes. Those changes are dependent on removing the circular dependency.
After these three patches are in, I have about 5 more patches fixing the optimizers, clang and tools to do the right things.<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">So, I’d prefer not to hold off on the changes as I have a lot of them and re-integrating every week is getting burdensome, but I really don’t have a choice
until I can get approval. If I can get approval for submitting patches that are being conditionally acceptable if another set of changes is done first to be allowed without those changes, that would fix my issue. No one should hit the cases I am hitting unless
you explicitly utilize the variable pointer sizes. It shouldn’t affect anyone to postpone the bitcast changes, but allow the variable pointer sizes.<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">Thanks,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Micah<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>
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<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""> Evan Cheng [mailto:evan.cheng@apple.com]
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<b>Sent:</b> Tuesday, September 25, 2012 4:16 PM<br>
<b>To:</b> Villmow, Micah<br>
<b>Cc:</b> llvm-commits@cs.uiuc.edu LLVM; cfe-commits@cs.uiuc.edu cfe; Nadav Rotem<br>
<b>Subject:</b> Re: [llvm-commits] [Patch] Move TargetData from Target to Support/VMCore<o:p></o:p></span></p>
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<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Sorry, I understand why you are requesting this but I thinking moving TargetData to support is conceptually dirty. Nadav is going to propose a BOF at the DevMeeting to talk about designing an abstraction to expose target information to
LLVM ir. Can we hold off this kind of change for now?<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Losing the ability to verify isn't a strong enough argument for an immediate change. I don't follow the auto-upgrade argument. Can you elaborate?<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Thanks,<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Evan<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">On Sep 21, 2012, at 4:08 PM, "Villmow, Micah" <<a href="mailto:Micah.Villmow@amd.com">Micah.Villmow@amd.com</a>> wrote:<o:p></o:p></p>
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<o:p></o:p></p>
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif"">This time with the actual patch<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif""> <o:p></o:p></span></p>
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<p class="MsoNormal"><b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif"">From:</span></b><span class="apple-converted-space"><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif""> </span></span><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif"">Villmow,
Micah<span class="apple-converted-space"> </span><br>
<b>Sent:</b><span class="apple-converted-space"> </span>Friday, September 21, 2012 4:08 PM<br>
<b>To:</b><span class="apple-converted-space"> </span><a href="mailto:llvm-commits@cs.uiuc.edu"><span style="color:purple">llvm-commits@cs.uiuc.edu</span></a>;<span class="apple-converted-space"> </span><a href="mailto:cfe-commits@cs.uiuc.edu"><span style="color:purple">cfe-commits@cs.uiuc.edu</span></a><br>
<b>Subject:</b><span class="apple-converted-space"> </span>[Patch] Move TargetData from Target to Support/VMCore</span><span style="font-size:11.0pt;font-family:"Calibri","sans-serif""><o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif""> <o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif"">I have attached a patch which moves TargetData from Target to Support/VMCore.<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif"">The reason why I would like to have this change can be read about in more detail in message [1][2], which in turn is required for [3].<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif""> <o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif"">In short, I need the capability of querying, if available, target specific information in the bitcode during verifier and the auto-upgrade mechanism.<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif"">Because TargetData is in the target directory, a circular dependency is created when the verifier and auto-upgrade mechanism utilize the information.<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif""> <o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif""> <o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif"">Please let me know what you think and if this approach isn't good, possible alternate solutions,<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif"">Micah<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif""> <o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif""> <o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif"">[1]<span class="apple-converted-space"> </span><a href="http://lists.cs.uiuc.edu/pipermail/llvmdev/2012-September/053277.html"><span style="color:purple">http://lists.cs.uiuc.edu/pipermail/llvmdev/2012-September/053277.html</span></a><o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif"">[2]<span class="apple-converted-space"> </span><a href="http://lists.cs.uiuc.edu/pipermail/llvmdev/2012-September/053166.html"><span style="color:purple">http://lists.cs.uiuc.edu/pipermail/llvmdev/2012-September/053166.html</span></a><o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif"">[3]<span class="apple-converted-space"> </span><a href="http://lists.cs.uiuc.edu/pipermail/llvmdev/2012-August/052639.html"><span style="color:purple">http://lists.cs.uiuc.edu/pipermail/llvmdev/2012-August/052639.html</span></a><o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:13.5pt;font-family:"Helvetica","sans-serif""><move_target_data_to_support_vmcore.txt>_______________________________________________<br>
llvm-commits mailing list<br>
<a href="mailto:llvm-commits@cs.uiuc.edu"><span style="color:purple">llvm-commits@cs.uiuc.edu</span></a><br>
<a href="http://lists.cs.uiuc.edu/mailman/listinfo/llvm-commits"><span style="color:purple">http://lists.cs.uiuc.edu/mailman/listinfo/llvm-commits</span></a><o:p></o:p></span></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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