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<p class="MsoNormal"><span style="color:#1F497D">Hi,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">Any help in pushing this change through would be greatly appreciated. As I mentioned in my previous email, this bug causes breakage of VLIW bundles and results in incorrect schedules when debug info gets generated
and is hence an important one to fix. My previous post had a small patch with the fix.
<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">Best regards<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">Saurabh Verma<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
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<p class="MsoNormal"><a name="_____replyseparator"></a><b>From:</b> Verma, Saurabh
<br>
<b>Sent:</b> Friday, December 22, 2017 2:28 PM<br>
<b>To:</b> 'llvm-dev@lists.llvm.org' <llvm-dev@lists.llvm.org><br>
<b>Subject:</b> RE: DBG_VALUE insertion for spills breaks bundles<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><span style="color:#1F497D">Hi again,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">Here is a small patch to fix this issue. Please note that since the problem results in broken bundles, it can result in invalid schedules for any VLIW back-ends using bundling to group instructions.
<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">Best regards<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">Saurabh Verma<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
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<p class="MsoNormal"><b>From:</b> Verma, Saurabh <br>
<b>Sent:</b> Tuesday, December 19, 2017 4:14 PM<br>
<b>To:</b> <a href="mailto:llvm-dev@lists.llvm.org">llvm-dev@lists.llvm.org</a><br>
<b>Subject:</b> DBG_VALUE insertion for spills breaks bundles<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Hi,<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">The insertion of DBG_VALUE instructions for spills does not seem to be handling insert locations inside bundles well. If the spill instruction is part of a bundle, the new DBG_VALUE is inserted after it, but does not have the bundling flags
set. This essentially means that if we start with a set of bundled instructions:<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">MI1 [BundledSucc=true, BundledPred=false]<o:p></o:p></p>
<p class="MsoNormal">MI2 [BundledSucc=false, BundledPred=true]<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Where MI1 is a spill, and MI2 is a different instruction, after ExtendRanges we end up with<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">MI1 [BundledSucc=true, BundledPred=false]<o:p></o:p></p>
<p class="MsoNormal">DBG_VALUE MI [BundledSucc=false, BundledPred=false]<o:p></o:p></p>
<p class="MsoNormal">MI2 [BundledSucc=false, BundledPred=true]<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Since this happens after the final instruction scheduling, it results in broken schedules. I believe setting the bundling flags before invoking MBB->insertAfter in ExtendRanges should fix this.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Best regards<o:p></o:p></p>
<p class="MsoNormal">Saurabh Verma<o:p></o:p></p>
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