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<p class="MsoNormal">Well, I found out the reason why this assert is here, and this is problematic.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">CondCodeActions only supports up to 32 different value types. Since we are past 32, what LLVM has is broken.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Currently the 4 different Legalize states are stored in successive bits and packed into a uin64_t, see TargetLowering.h.<o:p></o:p></p>
<p class="MsoNormal">/// CondCodeActions - For each condition code (ISD::CondCode) keep a<o:p></o:p></p>
<p class="MsoNormal"> /// LegalizeAction that indicates how instruction selection should<o:p></o:p></p>
<p class="MsoNormal"> /// deal with the condition code.<o:p></o:p></p>
<p class="MsoNormal"> uint64_t CondCodeActions[ISD::SETCC_INVALID];<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">What I suggest is the following: <o:p></o:p></p>
<p class="MsoNormal">Change the definition of CondCodeAction to:<o:p></o:p></p>
<p class="MsoNormal"> uint64_t CondCodeActions[ISD::SETCC_INVALID][2];<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">setCondCodeAction then becomes:<o:p></o:p></p>
<p class="MsoNormal">void setCondCodeAction(ISD::CondCode CC, MVT VT,<o:p></o:p></p>
<p class="MsoNormal"> LegalizeAction Action) {<o:p></o:p></p>
<p class="MsoNormal"> assert(VT < MVT::LAST_VALUETYPE &&<o:p></o:p></p>
<p class="MsoNormal"> (unsigned)CC < array_lengthof(CondCodeActions) &&<o:p></o:p></p>
<p class="MsoNormal"> "Table isn't big enough!");<o:p></o:p></p>
<p class="MsoNormal"> CondCodeActions[(unsigned)CC][VT.SimplyTy >> 5] &= ~(uint64_t(3UL) << (VT.SimpleTy - 32)*2);<o:p></o:p></p>
<p class="MsoNormal"> CondCodeActions[(unsigned)CC][VT.SimpleTy >> 5] |= (uint64_t)Action << (VT.SimpleTy - 32)*2;<o:p></o:p></p>
<p class="MsoNormal"> }<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">getCondCodeAction then becomes:<o:p></o:p></p>
<p class="MsoNormal">LegalizeAction<o:p></o:p></p>
<p class="MsoNormal"> getCondCodeAction(ISD::CondCode CC, EVT VT) const {<o:p></o:p></p>
<p class="MsoNormal"> assert((unsigned)CC < array_lengthof(CondCodeActions) &&<o:p></o:p></p>
<p class="MsoNormal"> (unsigned)VT.getSimpleVT().SimpleTy < MVT::LAST_VECTOR_VALUETYPE &&<o:p></o:p></p>
<p class="MsoNormal"> "Table isn't big enough!");<o:p></o:p></p>
<p class="MsoNormal"> LegalizeAction Action = (LegalizeAction)<o:p></o:p></p>
<p class="MsoNormal"> ((CondCodeActions[CC][VT.getSimpleVT().SimpleTy >> 5] >> (2*(VT.getSimpleVT().SimpleTy - 32))) & 3);<o:p></o:p></p>
<p class="MsoNormal"> assert(Action != Promote && "Can't promote condition code!");<o:p></o:p></p>
<p class="MsoNormal"> return Action;<o:p></o:p></p>
<p class="MsoNormal"> }<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">The other options are to use a BitVector, or to have a different array for each Legalized action. This approach however seems to use the minimum amount of memory/instructions.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Ideas?<o:p></o:p></p>
<p class="MsoNormal">Micah<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></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""> llvmdev-bounces@cs.uiuc.edu [mailto:llvmdev-bounces@cs.uiuc.edu]
<b>On Behalf Of </b>Villmow, Micah<br>
<b>Sent:</b> Thursday, July 26, 2012 11:29 AM<br>
<b>To:</b> Developers Mailing List<br>
<b>Subject:</b> [LLVMdev] Why is this assertion here?<o:p></o:p></span></p>
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<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">I'm trying to understand why this assertion is here.<o:p></o:p></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:9.5pt;font-family:Consolas">LegalizeAction<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:9.5pt;font-family:Consolas"> getCondCodeAction(ISD::CondCode CC, EVT VT)
<span style="color:blue">const</span> {<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:9.5pt;font-family:Consolas"> assert((<span style="color:blue">unsigned</span>)CC < array_lengthof(CondCodeActions) &&<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:9.5pt;font-family:Consolas"> (<span style="color:blue">unsigned</span>)VT.getSimpleVT().SimpleTy <
<span style="color:blue">sizeof</span>(CondCodeActions[0])*4 &&<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:9.5pt;font-family:Consolas">
<span style="color:#A31515">"Table isn't big enough!"</span>);<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:9.5pt;font-family:Consolas"> LegalizeAction Action = (LegalizeAction)<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:9.5pt;font-family:Consolas"> ((CondCodeActions[CC] >> (2*VT.getSimpleVT().SimpleTy)) & 3);<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:9.5pt;font-family:Consolas"> assert(Action != Promote &&
<span style="color:#A31515">"Can't promote condition code!"</span>);<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:9.5pt;font-family:Consolas">
<span style="color:blue">return</span> Action;<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:9.5pt;font-family:Consolas"> }<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:9.5pt;font-family:Consolas"><o:p> </o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:9.5pt;font-family:Consolas">The first part of the assertion I can understand, but why is there an assertion<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:9.5pt;font-family:Consolas">that there are only 32 types? in TOT LLVM if this code is called with v8f32,v2f64<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:9.5pt;font-family:Consolas">or v4f64, this assert is triggered.<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:9.5pt;font-family:Consolas">Shouldn't the assert be:<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:9.5pt;font-family:Consolas">(<span style="color:blue">unsigned</span>)VT.getSimpleVT().SimpleTy <
<span style="color:blue">MVT::MAX_ALLOWED_VALUETYPE</span> &&<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:9.5pt;font-family:Consolas">or<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:9.5pt;font-family:Consolas">(<span style="color:blue">unsigned</span>)VT.getSimpleVT().SimpleTy <
<span style="color:blue">MVT::LAST_VECTOR_VALUETYPE</span> &&<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:9.5pt;font-family:Consolas">?<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:9.5pt;font-family:Consolas"><o:p> </o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:9.5pt;font-family:Consolas">Thanks,<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:9.5pt;font-family:Consolas">Micah<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:9.5pt;font-family:Consolas"><o:p> </o:p></span></p>
<p class="MsoNormal"><o:p> </o:p></p>
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