diff --git a/include/llvm/CodeGen/LiveVariables.h b/include/llvm/CodeGen/LiveVariables.h index a7bf600e1e6..fc5ea6f968b 100644 --- a/include/llvm/CodeGen/LiveVariables.h +++ b/include/llvm/CodeGen/LiveVariables.h @@ -124,6 +124,11 @@ private: /// std::vector VirtRegInfo; + /// PHIJoins - list of virtual registers that are PHI joins. These registers + /// may have multiple definitions, and they require special handling when + /// building live intervals. + SparseBitVector<> PHIJoins; + /// ReservedRegisters - This vector keeps track of which registers /// are reserved register which are not allocatable by the target machine. /// We can not track liveness for values that are in this set. @@ -295,6 +300,12 @@ public: void addNewBlock(MachineBasicBlock *BB, MachineBasicBlock *DomBB, MachineBasicBlock *SuccBB); + + /// isPHIJoin - Return true if Reg is a phi join register. + bool isPHIJoin(unsigned Reg) { return PHIJoins.test(Reg); } + + /// setPHIJoin - Mark Reg as a phi join register. + void setPHIJoin(unsigned Reg) { PHIJoins.set(Reg); } }; } // End llvm namespace diff --git a/lib/CodeGen/LiveIntervalAnalysis.cpp b/lib/CodeGen/LiveIntervalAnalysis.cpp index 0b38ffb9703..ebcfd60a711 100644 --- a/lib/CodeGen/LiveIntervalAnalysis.cpp +++ b/lib/CodeGen/LiveIntervalAnalysis.cpp @@ -329,24 +329,43 @@ void LiveIntervals::handleVirtualRegisterDef(MachineBasicBlock *mbb, DEBUG(dbgs() << " +" << NewLR); interval.addRange(NewLR); - // Iterate over all of the blocks that the variable is completely - // live in, adding [insrtIndex(begin), instrIndex(end)+4) to the - // live interval. - for (SparseBitVector<>::iterator I = vi.AliveBlocks.begin(), - E = vi.AliveBlocks.end(); I != E; ++I) { - MachineBasicBlock *aliveBlock = mf_->getBlockNumbered(*I); - LiveRange LR(getMBBStartIdx(aliveBlock), getMBBEndIdx(aliveBlock), ValNo); - interval.addRange(LR); - DEBUG(dbgs() << " +" << LR); + bool PHIJoin = lv_->isPHIJoin(interval.reg); + + if (PHIJoin) { + // A phi join register is killed at the end of the MBB and revived as a new + // valno in the killing blocks. + assert(vi.AliveBlocks.empty() && "Phi join can't pass through blocks"); + DEBUG(dbgs() << " phi-join"); + ValNo->addKill(indexes_->getTerminatorGap(mbb)); + ValNo->setHasPHIKill(true); + } else { + // Iterate over all of the blocks that the variable is completely + // live in, adding [insrtIndex(begin), instrIndex(end)+4) to the + // live interval. + for (SparseBitVector<>::iterator I = vi.AliveBlocks.begin(), + E = vi.AliveBlocks.end(); I != E; ++I) { + MachineBasicBlock *aliveBlock = mf_->getBlockNumbered(*I); + LiveRange LR(getMBBStartIdx(aliveBlock), getMBBEndIdx(aliveBlock), ValNo); + interval.addRange(LR); + DEBUG(dbgs() << " +" << LR); + } } // Finally, this virtual register is live from the start of any killing // block to the 'use' slot of the killing instruction. for (unsigned i = 0, e = vi.Kills.size(); i != e; ++i) { MachineInstr *Kill = vi.Kills[i]; - SlotIndex killIdx = - getInstructionIndex(Kill).getDefIndex(); - LiveRange LR(getMBBStartIdx(Kill->getParent()), killIdx, ValNo); + SlotIndex Start = getMBBStartIdx(Kill->getParent()); + SlotIndex killIdx = getInstructionIndex(Kill).getDefIndex(); + + // Create interval with one of a NEW value number. Note that this value + // number isn't actually defined by an instruction, weird huh? :) + if (PHIJoin) { + ValNo = interval.getNextValue(SlotIndex(Start, true), 0, false, + VNInfoAllocator); + ValNo->setIsPHIDef(true); + } + LiveRange LR(Start, killIdx, ValNo); interval.addRange(LR); ValNo->addKill(killIdx); DEBUG(dbgs() << " +" << LR); @@ -409,48 +428,11 @@ void LiveIntervals::handleVirtualRegisterDef(MachineBasicBlock *mbb, interval.print(dbgs(), tri_); }); } else { - // Otherwise, this must be because of phi elimination. If this is the - // first redefinition of the vreg that we have seen, go back and change - // the live range in the PHI block to be a different value number. - if (interval.containsOneValue()) { - - VNInfo *VNI = interval.getValNumInfo(0); - // Phi elimination may have reused the register for multiple identical - // phi nodes. There will be a kill per phi. Remove the old ranges that - // we now know have an incorrect number. - for (unsigned ki=0, ke=vi.Kills.size(); ki != ke; ++ki) { - MachineInstr *Killer = vi.Kills[ki]; - SlotIndex Start = getMBBStartIdx(Killer->getParent()); - SlotIndex End = getInstructionIndex(Killer).getDefIndex(); - DEBUG({ - dbgs() << "\n\t\trenaming [" << Start << "," << End << "] in: "; - interval.print(dbgs(), tri_); - }); - interval.removeRange(Start, End); - - // Replace the interval with one of a NEW value number. Note that - // this value number isn't actually defined by an instruction, weird - // huh? :) - LiveRange LR(Start, End, - interval.getNextValue(SlotIndex(Start, true), - 0, false, VNInfoAllocator)); - LR.valno->setIsPHIDef(true); - interval.addRange(LR); - LR.valno->addKill(End); - } - - MachineBasicBlock *killMBB = getMBBFromIndex(VNI->def); - VNI->addKill(indexes_->getTerminatorGap(killMBB)); - VNI->setHasPHIKill(true); - DEBUG({ - dbgs() << " RESULT: "; - interval.print(dbgs(), tri_); - }); - } - + assert(lv_->isPHIJoin(interval.reg) && "Multiply defined register"); // In the case of PHI elimination, each variable definition is only // live until the end of the block. We've already taken care of the // rest of the live range. + SlotIndex defIndex = MIIdx.getDefIndex(); if (MO.isEarlyClobber()) defIndex = MIIdx.getUseIndex(); @@ -468,7 +450,7 @@ void LiveIntervals::handleVirtualRegisterDef(MachineBasicBlock *mbb, interval.addRange(LR); ValNo->addKill(indexes_->getTerminatorGap(mbb)); ValNo->setHasPHIKill(true); - DEBUG(dbgs() << " +" << LR); + DEBUG(dbgs() << " phi-join +" << LR); } } diff --git a/lib/CodeGen/LiveVariables.cpp b/lib/CodeGen/LiveVariables.cpp index 8a124dc79bd..68c85394d4c 100644 --- a/lib/CodeGen/LiveVariables.cpp +++ b/lib/CodeGen/LiveVariables.cpp @@ -510,6 +510,7 @@ bool LiveVariables::runOnMachineFunction(MachineFunction &mf) { PHIVarInfo = new SmallVector[MF->getNumBlockIDs()]; std::fill(PhysRegDef, PhysRegDef + NumRegs, (MachineInstr*)0); std::fill(PhysRegUse, PhysRegUse + NumRegs, (MachineInstr*)0); + PHIJoins.clear(); /// Get some space for a respectable number of registers. VirtRegInfo.resize(64); diff --git a/lib/CodeGen/PHIElimination.cpp b/lib/CodeGen/PHIElimination.cpp index 9e4bc0c273f..bdfd448acdb 100644 --- a/lib/CodeGen/PHIElimination.cpp +++ b/lib/CodeGen/PHIElimination.cpp @@ -223,6 +223,7 @@ void llvm::PHIElimination::LowerAtomicPHINode( // Increment use count of the newly created virtual register. VI.NumUses++; + LV->setPHIJoin(IncomingReg); // When we are reusing the incoming register, it may already have been // killed in this block. The old kill will also have been inserted at diff --git a/test/CodeGen/X86/2010-02-23-SingleDefPhiJoin.ll b/test/CodeGen/X86/2010-02-23-SingleDefPhiJoin.ll new file mode 100644 index 00000000000..aeed4014617 --- /dev/null +++ b/test/CodeGen/X86/2010-02-23-SingleDefPhiJoin.ll @@ -0,0 +1,146 @@ +; RUN: llc < %s +; PR6363 +; +; This test case creates a phi join register with a single definition. The other +; predecessor blocks are implicit-def. +; +; If LiveIntervalAnalysis fails to recognize this as a phi join, the coalescer +; will detect an infinity valno loop. +; +target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128" +target triple = "x86_64-unknown-linux-gnu" + +define i32 @decode(i8* nocapture %input, i32 %offset, i8* nocapture %output) nounwind { +entry: + br i1 undef, label %meshBB86, label %meshBB102 + +bb: ; preds = %meshBB106, %meshBB102 + br i1 false, label %bb9, label %meshBB90 + +bb.nph: ; preds = %meshBB90 + br label %meshBB114 + +bb.nph.fragment: ; preds = %meshBB114 + br label %meshBB118 + +bb1.fragment: ; preds = %meshBB118 + br i1 false, label %bb2, label %bb3 + +bb2: ; preds = %bb1.fragment + br label %meshBB74 + +bb2.fragment15: ; preds = %meshBB74 + br label %meshBB98 + +bb3: ; preds = %bb1.fragment + br i1 undef, label %meshBB, label %meshBB102 + +bb4: ; preds = %meshBB + br label %meshBB118 + +bb4.fragment: ; preds = %meshBB118 + br label %meshBB82 + +bb5: ; preds = %meshBB102, %meshBB82 + br i1 false, label %bb6, label %bb7 + +bb6: ; preds = %bb5 + br label %bb7 + +bb7: ; preds = %meshBB98, %bb6, %bb5 + br label %meshBB114 + +bb7.fragment: ; preds = %meshBB114 + br i1 undef, label %meshBB74, label %bb9 + +bb9: ; preds = %bb7.fragment, %bb + br label %bb1.i23 + +bb1.i23: ; preds = %meshBB110, %bb9 + br i1 undef, label %meshBB106, label %meshBB110 + +skip_to_newline.exit26: ; preds = %meshBB106 + br label %meshBB86 + +skip_to_newline.exit26.fragment: ; preds = %meshBB86 + br i1 false, label %meshBB90, label %meshBB106 + +bb11.fragment: ; preds = %meshBB90, %meshBB86 + br label %meshBB122 + +bb1.i: ; preds = %meshBB122, %meshBB + %ooffset.2.lcssa.phi.SV.phi203 = phi i32 [ 0, %meshBB122 ], [ %ooffset.2.lcssa.phi.SV.phi233, %meshBB ] ; [#uses=1] + br label %meshBB98 + +bb1.i.fragment: ; preds = %meshBB98 + br i1 undef, label %meshBB78, label %meshBB + +skip_to_newline.exit: ; preds = %meshBB78 + br i1 undef, label %bb12, label %meshBB110 + +bb12: ; preds = %skip_to_newline.exit + br label %meshBB94 + +bb12.fragment: ; preds = %meshBB94 + br i1 false, label %bb13, label %meshBB78 + +bb13: ; preds = %bb12.fragment + br label %meshBB82 + +bb13.fragment: ; preds = %meshBB82 + br i1 undef, label %meshBB94, label %meshBB122 + +bb14: ; preds = %meshBB94 + ret i32 %ooffset.2.lcssa.phi.SV.phi250 + +bb15: ; preds = %meshBB122, %meshBB110, %meshBB78 + unreachable + +meshBB: ; preds = %bb1.i.fragment, %bb3 + %ooffset.2.lcssa.phi.SV.phi233 = phi i32 [ undef, %bb3 ], [ %ooffset.2.lcssa.phi.SV.phi209, %bb1.i.fragment ] ; [#uses=1] + br i1 undef, label %bb1.i, label %bb4 + +meshBB74: ; preds = %bb7.fragment, %bb2 + br i1 false, label %meshBB118, label %bb2.fragment15 + +meshBB78: ; preds = %bb12.fragment, %bb1.i.fragment + %ooffset.2.lcssa.phi.SV.phi239 = phi i32 [ %ooffset.2.lcssa.phi.SV.phi209, %bb1.i.fragment ], [ %ooffset.2.lcssa.phi.SV.phi250, %bb12.fragment ] ; [#uses=1] + br i1 false, label %bb15, label %skip_to_newline.exit + +meshBB82: ; preds = %bb13, %bb4.fragment + br i1 false, label %bb5, label %bb13.fragment + +meshBB86: ; preds = %skip_to_newline.exit26, %entry + br i1 undef, label %skip_to_newline.exit26.fragment, label %bb11.fragment + +meshBB90: ; preds = %skip_to_newline.exit26.fragment, %bb + br i1 false, label %bb11.fragment, label %bb.nph + +meshBB94: ; preds = %bb13.fragment, %bb12 + %ooffset.2.lcssa.phi.SV.phi250 = phi i32 [ 0, %bb13.fragment ], [ %ooffset.2.lcssa.phi.SV.phi239, %bb12 ] ; [#uses=2] + br i1 false, label %bb12.fragment, label %bb14 + +meshBB98: ; preds = %bb1.i, %bb2.fragment15 + %ooffset.2.lcssa.phi.SV.phi209 = phi i32 [ undef, %bb2.fragment15 ], [ %ooffset.2.lcssa.phi.SV.phi203, %bb1.i ] ; [#uses=2] + br i1 undef, label %bb1.i.fragment, label %bb7 + +meshBB102: ; preds = %bb3, %entry + br i1 undef, label %bb5, label %bb + +meshBB106: ; preds = %skip_to_newline.exit26.fragment, %bb1.i23 + br i1 undef, label %bb, label %skip_to_newline.exit26 + +meshBB110: ; preds = %skip_to_newline.exit, %bb1.i23 + br i1 false, label %bb15, label %bb1.i23 + +meshBB114: ; preds = %bb7, %bb.nph + %meshStackVariable115.phi = phi i32 [ 19, %bb7 ], [ 8, %bb.nph ] ; [#uses=0] + br i1 undef, label %bb.nph.fragment, label %bb7.fragment + +meshBB118: ; preds = %meshBB74, %bb4, %bb.nph.fragment + %meshCmp121 = icmp eq i32 undef, 10 ; [#uses=1] + br i1 %meshCmp121, label %bb4.fragment, label %bb1.fragment + +meshBB122: ; preds = %bb13.fragment, %bb11.fragment + br i1 false, label %bb1.i, label %bb15 +}