-#undef DEBUG_TYPE
-#define DEBUG_TYPE "ppc-vsx-fma-mutate"
-
-namespace {
- // PPCVSXFMAMutate pass - For copies between VSX registers and non-VSX registers
- // (Altivec and scalar floating-point registers), we need to transform the
- // copies into subregister copies with other restrictions.
- struct PPCVSXFMAMutate : public MachineFunctionPass {
- static char ID;
- PPCVSXFMAMutate() : MachineFunctionPass(ID) {
- initializePPCVSXFMAMutatePass(*PassRegistry::getPassRegistry());
- }
-
- LiveIntervals *LIS;
- const PPCInstrInfo *TII;
-
-protected:
- bool processBlock(MachineBasicBlock &MBB) {
- bool Changed = false;
-
- MachineRegisterInfo &MRI = MBB.getParent()->getRegInfo();
- const TargetRegisterInfo *TRI = &TII->getRegisterInfo();
- for (MachineBasicBlock::iterator I = MBB.begin(), IE = MBB.end();
- I != IE; ++I) {
- MachineInstr *MI = I;
-
- // The default (A-type) VSX FMA form kills the addend (it is taken from
- // the target register, which is then updated to reflect the result of
- // the FMA). If the instruction, however, kills one of the registers
- // used for the product, then we can use the M-form instruction (which
- // will take that value from the to-be-defined register).
-
- int AltOpc = PPC::getAltVSXFMAOpcode(MI->getOpcode());
- if (AltOpc == -1)
- continue;
-
- // This pass is run after register coalescing, and so we're looking for
- // a situation like this:
- // ...
- // %vreg5<def> = COPY %vreg9; VSLRC:%vreg5,%vreg9
- // %vreg5<def,tied1> = XSMADDADP %vreg5<tied0>, %vreg17, %vreg16,
- // %RM<imp-use>; VSLRC:%vreg5,%vreg17,%vreg16
- // ...
- // %vreg9<def,tied1> = XSMADDADP %vreg9<tied0>, %vreg17, %vreg19,
- // %RM<imp-use>; VSLRC:%vreg9,%vreg17,%vreg19
- // ...
- // Where we can eliminate the copy by changing from the A-type to the
- // M-type instruction. Specifically, for this example, this means:
- // %vreg5<def,tied1> = XSMADDADP %vreg5<tied0>, %vreg17, %vreg16,
- // %RM<imp-use>; VSLRC:%vreg5,%vreg17,%vreg16
- // is replaced by:
- // %vreg16<def,tied1> = XSMADDMDP %vreg16<tied0>, %vreg18, %vreg9,
- // %RM<imp-use>; VSLRC:%vreg16,%vreg18,%vreg9
- // and we remove: %vreg5<def> = COPY %vreg9; VSLRC:%vreg5,%vreg9
-
- SlotIndex FMAIdx = LIS->getInstructionIndex(MI);
-
- VNInfo *AddendValNo =
- LIS->getInterval(MI->getOperand(1).getReg()).Query(FMAIdx).valueIn();
- MachineInstr *AddendMI = LIS->getInstructionFromIndex(AddendValNo->def);
-
- // The addend and this instruction must be in the same block.
-
- if (!AddendMI || AddendMI->getParent() != MI->getParent())
- continue;
-
- // The addend must be a full copy within the same register class.
-
- if (!AddendMI->isFullCopy())
- continue;
-
- unsigned AddendSrcReg = AddendMI->getOperand(1).getReg();
- if (TargetRegisterInfo::isVirtualRegister(AddendSrcReg)) {
- if (MRI.getRegClass(AddendMI->getOperand(0).getReg()) !=
- MRI.getRegClass(AddendSrcReg))
- continue;
- } else {
- // If AddendSrcReg is a physical register, make sure the destination
- // register class contains it.
- if (!MRI.getRegClass(AddendMI->getOperand(0).getReg())
- ->contains(AddendSrcReg))
- continue;
- }
-
- // In theory, there could be other uses of the addend copy before this
- // fma. We could deal with this, but that would require additional
- // logic below and I suspect it will not occur in any relevant
- // situations. Additionally, check whether the copy source is killed
- // prior to the fma. In order to replace the addend here with the
- // source of the copy, it must still be live here. We can't use
- // interval testing for a physical register, so as long as we're
- // walking the MIs we may as well test liveness here.
- bool OtherUsers = false, KillsAddendSrc = false;
- for (auto J = std::prev(I), JE = MachineBasicBlock::iterator(AddendMI);
- J != JE; --J) {
- if (J->readsVirtualRegister(AddendMI->getOperand(0).getReg())) {
- OtherUsers = true;
- break;
- }
- if (J->modifiesRegister(AddendSrcReg, TRI) ||
- J->killsRegister(AddendSrcReg, TRI)) {
- KillsAddendSrc = true;
- break;
- }
- }
-
- if (OtherUsers || KillsAddendSrc)
- continue;
-
- // Find one of the product operands that is killed by this instruction.
-
- unsigned KilledProdOp = 0, OtherProdOp = 0;
- if (LIS->getInterval(MI->getOperand(2).getReg())
- .Query(FMAIdx).isKill()) {
- KilledProdOp = 2;
- OtherProdOp = 3;
- } else if (LIS->getInterval(MI->getOperand(3).getReg())
- .Query(FMAIdx).isKill()) {
- KilledProdOp = 3;
- OtherProdOp = 2;
- }
-
- // If there are no killed product operands, then this transformation is
- // likely not profitable.
- if (!KilledProdOp)
- continue;
-
- // For virtual registers, verify that the addend source register
- // is live here (as should have been assured above).
- assert((!TargetRegisterInfo::isVirtualRegister(AddendSrcReg) ||
- LIS->getInterval(AddendSrcReg).liveAt(FMAIdx)) &&
- "Addend source register is not live!");
-
- // Transform: (O2 * O3) + O1 -> (O2 * O1) + O3.
-
- unsigned AddReg = AddendMI->getOperand(1).getReg();
- unsigned KilledProdReg = MI->getOperand(KilledProdOp).getReg();
- unsigned OtherProdReg = MI->getOperand(OtherProdOp).getReg();
-
- unsigned AddSubReg = AddendMI->getOperand(1).getSubReg();
- unsigned KilledProdSubReg = MI->getOperand(KilledProdOp).getSubReg();
- unsigned OtherProdSubReg = MI->getOperand(OtherProdOp).getSubReg();
-
- bool AddRegKill = AddendMI->getOperand(1).isKill();
- bool KilledProdRegKill = MI->getOperand(KilledProdOp).isKill();
- bool OtherProdRegKill = MI->getOperand(OtherProdOp).isKill();
-
- bool AddRegUndef = AddendMI->getOperand(1).isUndef();
- bool KilledProdRegUndef = MI->getOperand(KilledProdOp).isUndef();
- bool OtherProdRegUndef = MI->getOperand(OtherProdOp).isUndef();
-
- unsigned OldFMAReg = MI->getOperand(0).getReg();
-
- // The transformation doesn't work well with things like:
- // %vreg5 = A-form-op %vreg5, %vreg11, %vreg5;
- // so leave such things alone.
- if (OldFMAReg == KilledProdReg)
- continue;
-
- assert(OldFMAReg == AddendMI->getOperand(0).getReg() &&
- "Addend copy not tied to old FMA output!");
-
- DEBUG(dbgs() << "VSX FMA Mutation:\n " << *MI;);
-
- MI->getOperand(0).setReg(KilledProdReg);
- MI->getOperand(1).setReg(KilledProdReg);
- MI->getOperand(3).setReg(AddReg);
- MI->getOperand(2).setReg(OtherProdReg);
-
- MI->getOperand(0).setSubReg(KilledProdSubReg);
- MI->getOperand(1).setSubReg(KilledProdSubReg);
- MI->getOperand(3).setSubReg(AddSubReg);
- MI->getOperand(2).setSubReg(OtherProdSubReg);
-
- MI->getOperand(1).setIsKill(KilledProdRegKill);
- MI->getOperand(3).setIsKill(AddRegKill);
- MI->getOperand(2).setIsKill(OtherProdRegKill);
-
- MI->getOperand(1).setIsUndef(KilledProdRegUndef);
- MI->getOperand(3).setIsUndef(AddRegUndef);
- MI->getOperand(2).setIsUndef(OtherProdRegUndef);
-
- MI->setDesc(TII->get(AltOpc));
-
- DEBUG(dbgs() << " -> " << *MI);
-
- // The killed product operand was killed here, so we can reuse it now
- // for the result of the fma.
-
- LiveInterval &FMAInt = LIS->getInterval(OldFMAReg);
- VNInfo *FMAValNo = FMAInt.getVNInfoAt(FMAIdx.getRegSlot());
- for (auto UI = MRI.reg_nodbg_begin(OldFMAReg), UE = MRI.reg_nodbg_end();
- UI != UE;) {
- MachineOperand &UseMO = *UI;
- MachineInstr *UseMI = UseMO.getParent();
- ++UI;
-
- // Don't replace the result register of the copy we're about to erase.
- if (UseMI == AddendMI)
- continue;
-
- UseMO.setReg(KilledProdReg);
- UseMO.setSubReg(KilledProdSubReg);
- }
-
- // Extend the live intervals of the killed product operand to hold the
- // fma result.
-
- LiveInterval &NewFMAInt = LIS->getInterval(KilledProdReg);
- for (LiveInterval::iterator AI = FMAInt.begin(), AE = FMAInt.end();
- AI != AE; ++AI) {
- // Don't add the segment that corresponds to the original copy.
- if (AI->valno == AddendValNo)
- continue;
-
- VNInfo *NewFMAValNo =
- NewFMAInt.getNextValue(AI->start,
- LIS->getVNInfoAllocator());
-
- NewFMAInt.addSegment(LiveInterval::Segment(AI->start, AI->end,
- NewFMAValNo));
- }
- DEBUG(dbgs() << " extended: " << NewFMAInt << '\n');
-
- FMAInt.removeValNo(FMAValNo);
- DEBUG(dbgs() << " trimmed: " << FMAInt << '\n');
-
- // Remove the (now unused) copy.
-
- DEBUG(dbgs() << " removing: " << *AddendMI << '\n');
- LIS->RemoveMachineInstrFromMaps(AddendMI);
- AddendMI->eraseFromParent();
-
- Changed = true;
- }
-
- return Changed;
- }
-
-public:
- bool runOnMachineFunction(MachineFunction &MF) override {
- // If we don't have VSX then go ahead and return without doing
- // anything.
- const PPCSubtarget &STI = MF.getSubtarget<PPCSubtarget>();
- if (!STI.hasVSX())
- return false;
-
- LIS = &getAnalysis<LiveIntervals>();
-
- TII = STI.getInstrInfo();
-
- bool Changed = false;
-
- if (DisableVSXFMAMutate)
- return Changed;
-
- for (MachineFunction::iterator I = MF.begin(); I != MF.end();) {
- MachineBasicBlock &B = *I++;
- if (processBlock(B))
- Changed = true;
- }
-
- return Changed;
- }
-
- void getAnalysisUsage(AnalysisUsage &AU) const override {
- AU.addRequired<LiveIntervals>();
- AU.addPreserved<LiveIntervals>();
- AU.addRequired<SlotIndexes>();
- AU.addPreserved<SlotIndexes>();
- MachineFunctionPass::getAnalysisUsage(AU);
- }
- };
-}
-
-INITIALIZE_PASS_BEGIN(PPCVSXFMAMutate, DEBUG_TYPE,
- "PowerPC VSX FMA Mutation", false, false)
-INITIALIZE_PASS_DEPENDENCY(LiveIntervals)
-INITIALIZE_PASS_DEPENDENCY(SlotIndexes)
-INITIALIZE_PASS_END(PPCVSXFMAMutate, DEBUG_TYPE,
- "PowerPC VSX FMA Mutation", false, false)
-
-char &llvm::PPCVSXFMAMutateID = PPCVSXFMAMutate::ID;
-
-char PPCVSXFMAMutate::ID = 0;
-FunctionPass*
-llvm::createPPCVSXFMAMutatePass() { return new PPCVSXFMAMutate(); }
-
projects / oota-llvm.git / blobdiff