1 //===- RegAllocEvictionAdvisor.cpp - eviction advisor ---------------------===//
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
7 //===----------------------------------------------------------------------===//
11 //===----------------------------------------------------------------------===//
30     "regalloc-enable-advisor", cl::Hidden,
42     "enable-local-reassign", cl::Hidden,
49     "regalloc-eviction-max-interference-cutoff", cl::Hidden,
52              "is a compilation cost-saving consideration. To "
63 INITIALIZE_PASS(RegAllocEvictionAdvisorAnalysis, "regalloc-evict",
76     return R->getAdvisorMode() == AdvisorMode::Default;  in classof()
130       MRI(&VRM->getRegInfo()), TRI(MF.getSubtarget().getRegisterInfo()),  in RegAllocEvictionAdvisor()
131       RegClassInfo(RA.getRegClassInfo()), RegCosts(TRI->getRegisterCosts(MF)),  in RegAllocEvictionAdvisor()
136 /// shouldEvict - determine if A should evict the assigned live range B. The
166 /// canEvictHintInterference - return true if the interference for VirtReg
177 /// canEvictInterferenceBasedOnCost - Return true if all interferences between
190   if (Matrix->checkInterference(VirtReg, PhysReg) > LiveRegMatrix::IK_VirtReg)  in canEvictInterferenceBasedOnCost()
193   bool IsLocal = VirtReg.empty() || LIS->intervalIsInOneMBB(VirtReg);  in canEvictInterferenceBasedOnCost()
205   for (MCRegUnit Unit : TRI->regunits(PhysReg)) {  in canEvictInterferenceBasedOnCost()
206     LiveIntervalUnion::Query &Q = Matrix->query(VirtReg, Unit);  in canEvictInterferenceBasedOnCost()
214       assert(Intf->reg().isVirtual() &&  in canEvictInterferenceBasedOnCost()
218       // of last-chance recoloring and this virtual register is one that we  in canEvictInterferenceBasedOnCost()
220       if (FixedRegisters.count(Intf->reg()))  in canEvictInterferenceBasedOnCost()
226       // Once a live range becomes small enough, it is urgent that we find a  in canEvictInterferenceBasedOnCost()
228       // urgent live ranges get to evict almost anything.  in canEvictInterferenceBasedOnCost()
230       // Also allow urgent evictions of unspillable ranges from a strictly  in canEvictInterferenceBasedOnCost()
232       bool Urgent =  in canEvictInterferenceBasedOnCost()  local
234           (Intf->isSpillable() ||  in canEvictInterferenceBasedOnCost()
235            RegClassInfo.getNumAllocatableRegs(MRI->getRegClass(VirtReg.reg())) <  in canEvictInterferenceBasedOnCost()
237                    MRI->getRegClass(Intf->reg())));  in canEvictInterferenceBasedOnCost()
239       unsigned IntfCascade = RA.getExtraInfo().getCascade(Intf->reg());  in canEvictInterferenceBasedOnCost()
244         if (!Urgent)  in canEvictInterferenceBasedOnCost()
246         // We permit breaking cascades for urgent evictions. It should be the  in canEvictInterferenceBasedOnCost()
251       bool BreaksHint = VRM->hasPreferredPhys(Intf->reg());  in canEvictInterferenceBasedOnCost()
254       Cost.MaxWeight = std::max(Cost.MaxWeight, Intf->weight());  in canEvictInterferenceBasedOnCost()
258       if (Urgent)  in canEvictInterferenceBasedOnCost()
260       // Apply the eviction policy for non-urgent evictions.  in canEvictInterferenceBasedOnCost()
266       if (!MaxCost.isMax() && IsLocal && LIS->intervalIsInOneMBB(*Intf) &&  in canEvictInterferenceBasedOnCost()