diff --git a/lib/CodeGen/RegAllocGreedy.cpp b/lib/CodeGen/RegAllocGreedy.cpp index 244b8ba5980..723553ad53f 100644 --- a/lib/CodeGen/RegAllocGreedy.cpp +++ b/lib/CodeGen/RegAllocGreedy.cpp @@ -90,12 +90,21 @@ class RAGreedy : public MachineFunctionPass, // range splitting algorithm terminates, something that is otherwise hard to // ensure. enum LiveRangeStage { - RS_New, ///< Never seen before. - RS_First, ///< First time in the queue. - RS_Second, ///< Second time in the queue. - RS_Global, ///< Produced by global splitting. - RS_Local, ///< Produced by local splitting. - RS_Spill ///< Produced by spilling. + /// Newly created live range that has never been queued. + RS_New, + + /// Only attempt assignment and eviction. Then requeue as RS_Split. + RS_Assign, + + /// Attempt live range splitting if assignment is impossible. + RS_Split, + + /// Live range will be spilled. No more splitting will be attempted. + RS_Spill, + + /// There is nothing more we can do to this live range. Abort compilation + /// if it can't be assigned. + RS_Done }; static const char *const StageName[]; @@ -234,12 +243,11 @@ char RAGreedy::ID = 0; #ifndef NDEBUG const char *const RAGreedy::StageName[] = { - "RS_New", - "RS_First", - "RS_Second", - "RS_Global", - "RS_Local", - "RS_Spill" + "RS_New", + "RS_Assign", + "RS_Split", + "RS_Spill", + "RS_Done" }; #endif @@ -351,9 +359,9 @@ void RAGreedy::enqueue(LiveInterval *LI) { ExtraRegInfo.grow(Reg); if (ExtraRegInfo[Reg].Stage == RS_New) - ExtraRegInfo[Reg].Stage = RS_First; + ExtraRegInfo[Reg].Stage = RS_Assign; - if (ExtraRegInfo[Reg].Stage == RS_Second) + if (ExtraRegInfo[Reg].Stage == RS_Split) // Unsplit ranges that couldn't be allocated immediately are deferred until // everything else has been allocated. Long ranges are allocated last so // they are split against realistic interference. @@ -443,7 +451,7 @@ unsigned RAGreedy::tryAssign(LiveInterval &VirtReg, /// @param BreaksHint True when B is already assigned to its preferred register. bool RAGreedy::shouldEvict(LiveInterval &A, bool IsHint, LiveInterval &B, bool BreaksHint) { - bool CanSplit = getStage(B) <= RS_Second; + bool CanSplit = getStage(B) <= RS_Split; // Be fairly aggressive about following hints as long as the evictee can be // split. @@ -488,7 +496,7 @@ bool RAGreedy::canEvictInterference(LiveInterval &VirtReg, unsigned PhysReg, if (TargetRegisterInfo::isPhysicalRegister(Intf->reg)) return false; // Never evict spill products. They cannot split or spill. - if (getStage(*Intf) == RS_Spill) + if (getStage(*Intf) == RS_Done) return false; // Once a live range becomes small enough, it is urgent that we find a // register for it. This is indicated by an infinite spill weight. These @@ -974,7 +982,7 @@ void RAGreedy::splitAroundRegion(LiveInterval &VirtReg, // Remainder interval. Don't try splitting again, spill if it doesn't // allocate. if (IntvMap[i] == 0) { - setStage(Reg, RS_Global); + setStage(Reg, RS_Spill); continue; } @@ -985,7 +993,7 @@ void RAGreedy::splitAroundRegion(LiveInterval &VirtReg, DEBUG(dbgs() << "Main interval covers the same " << OrigBlocks << " blocks as original.\n"); // Don't allow repeated splitting as a safe guard against looping. - setStage(Reg, RS_Global); + setStage(Reg, RS_Spill); } continue; } @@ -1172,17 +1180,17 @@ unsigned RAGreedy::tryLocalSplit(LiveInterval &VirtReg, AllocationOrder &Order, // // Instead we use these rules: // - // 1. Allow any split for ranges with getStage() < RS_Local. (Except for the + // 1. Allow any split for ranges with getStage() < RS_Spill. (Except for the // noop split, of course). - // 2. Require progress be made for ranges with getStage() >= RS_Local. All + // 2. Require progress be made for ranges with getStage() >= RS_Spill. All // the new ranges must have fewer instructions than before the split. - // 3. New ranges with the same number of instructions are marked RS_Local, + // 3. New ranges with the same number of instructions are marked RS_Spill, // smaller ranges are marked RS_New. // // These rules allow a 3 -> 2+3 split once, which we need. They also prevent // excessive splitting and infinite loops. // - bool ProgressRequired = getStage(VirtReg) >= RS_Local; + bool ProgressRequired = getStage(VirtReg) >= RS_Spill; // Best split candidate. unsigned BestBefore = NumGaps; @@ -1301,7 +1309,7 @@ unsigned RAGreedy::tryLocalSplit(LiveInterval &VirtReg, AllocationOrder &Order, DebugVars->splitRegister(VirtReg.reg, LREdit.regs()); // If the new range has the same number of instructions as before, mark it as - // RS_Local so the next split will be forced to make progress. Otherwise, + // RS_Spill so the next split will be forced to make progress. Otherwise, // leave the new intervals as RS_New so they can compete. bool LiveBefore = BestBefore != 0 || BI.LiveIn; bool LiveAfter = BestAfter != NumGaps || BI.LiveOut; @@ -1311,7 +1319,7 @@ unsigned RAGreedy::tryLocalSplit(LiveInterval &VirtReg, AllocationOrder &Order, assert(!ProgressRequired && "Didn't make progress when it was required."); for (unsigned i = 0, e = IntvMap.size(); i != e; ++i) if (IntvMap[i] == 1) { - setStage(*LREdit.get(i), RS_Local); + setStage(*LREdit.get(i), RS_Spill); DEBUG(dbgs() << PrintReg(LREdit.get(i)->reg)); } DEBUG(dbgs() << '\n'); @@ -1341,7 +1349,7 @@ unsigned RAGreedy::trySplit(LiveInterval &VirtReg, AllocationOrder &Order, // Don't iterate global splitting. // Move straight to spilling if this range was produced by a global split. - if (getStage(VirtReg) >= RS_Global) + if (getStage(VirtReg) >= RS_Spill) return 0; SA->analyze(&VirtReg); @@ -1368,7 +1376,7 @@ unsigned RAGreedy::trySplit(LiveInterval &VirtReg, AllocationOrder &Order, LiveRangeEdit LREdit(VirtReg, NewVRegs, this); SE->reset(LREdit); SE->splitSingleBlocks(Blocks); - setStage(NewVRegs.begin(), NewVRegs.end(), RS_Global); + setStage(NewVRegs.begin(), NewVRegs.end(), RS_Spill); if (VerifyEnabled) MF->verify(this, "After splitting live range around basic blocks"); } @@ -1394,9 +1402,9 @@ unsigned RAGreedy::selectOrSplit(LiveInterval &VirtReg, << " Cascade " << ExtraRegInfo[VirtReg.reg].Cascade << '\n'); // Try to evict a less worthy live range, but only for ranges from the primary - // queue. The RS_Second ranges already failed to do this, and they should not + // queue. The RS_Split ranges already failed to do this, and they should not // get a second chance until they have been split. - if (Stage != RS_Second) + if (Stage != RS_Split) if (unsigned PhysReg = tryEvict(VirtReg, Order, NewVRegs)) return PhysReg; @@ -1405,8 +1413,8 @@ unsigned RAGreedy::selectOrSplit(LiveInterval &VirtReg, // The first time we see a live range, don't try to split or spill. // Wait until the second time, when all smaller ranges have been allocated. // This gives a better picture of the interference to split around. - if (Stage == RS_First) { - setStage(VirtReg, RS_Second); + if (Stage < RS_Split) { + setStage(VirtReg, RS_Split); DEBUG(dbgs() << "wait for second round\n"); NewVRegs.push_back(&VirtReg); return 0; @@ -1414,7 +1422,7 @@ unsigned RAGreedy::selectOrSplit(LiveInterval &VirtReg, // If we couldn't allocate a register from spilling, there is probably some // invalid inline assembly. The base class wil report it. - if (Stage >= RS_Spill || !VirtReg.isSpillable()) + if (Stage >= RS_Done || !VirtReg.isSpillable()) return ~0u; // Try splitting VirtReg or interferences. @@ -1426,7 +1434,7 @@ unsigned RAGreedy::selectOrSplit(LiveInterval &VirtReg, NamedRegionTimer T("Spiller", TimerGroupName, TimePassesIsEnabled); LiveRangeEdit LRE(VirtReg, NewVRegs, this); spiller().spill(LRE); - setStage(NewVRegs.begin(), NewVRegs.end(), RS_Spill); + setStage(NewVRegs.begin(), NewVRegs.end(), RS_Done); if (VerifyEnabled) MF->verify(this, "After spilling");