#include "PPCTargetMachine.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/Statistic.h"
+#include "llvm/CodeGen/LiveIntervalAnalysis.h"
#include "llvm/CodeGen/MachineFrameInfo.h"
#include "llvm/CodeGen/MachineFunctionPass.h"
#include "llvm/CodeGen/MachineInstrBuilder.h"
#include "llvm/CodeGen/MachineMemOperand.h"
#include "llvm/CodeGen/MachineRegisterInfo.h"
#include "llvm/CodeGen/PseudoSourceValue.h"
+#include "llvm/CodeGen/SlotIndexes.h"
#include "llvm/MC/MCAsmInfo.h"
#include "llvm/Support/CommandLine.h"
+#include "llvm/Support/Debug.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/TargetRegistry.h"
#include "llvm/Support/raw_ostream.h"
static cl::opt<bool> DisableCmpOpt("disable-ppc-cmp-opt",
cl::desc("Disable compare instruction optimization"), cl::Hidden);
+static cl::opt<bool> DisableVSXFMAMutate("disable-ppc-vsx-fma-mutation",
+cl::desc("Disable VSX FMA instruction mutation"), cl::Hidden);
+
// Pin the vtable to this file.
void PPCInstrInfo::anchor() {}
}
}
+#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 PPCTargetMachine *TM;
+ const PPCInstrInfo *TII;
+
+protected:
+ bool processBlock(MachineBasicBlock &MBB) {
+ bool Changed = false;
+
+ MachineRegisterInfo &MRI = MBB.getParent()->getRegInfo();
+ 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->getParent() != MI->getParent())
+ continue;
+
+ // The addend must be a full copy within the same register class.
+
+ if (!AddendMI->isFullCopy())
+ continue;
+
+ if (MRI.getRegClass(AddendMI->getOperand(0).getReg()) !=
+ MRI.getRegClass(AddendMI->getOperand(1).getReg()))
+ 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.
+ bool OtherUsers = 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 (OtherUsers)
+ 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;
+
+ // In order to replace the addend here with the source of the copy,
+ // it must still be live here.
+ if (!LIS->getInterval(AddendMI->getOperand(1).getReg()).liveAt(FMAIdx))
+ continue;
+
+ // 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();
+
+ 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:
+ virtual bool runOnMachineFunction(MachineFunction &MF) {
+ LIS = &getAnalysis<LiveIntervals>();
+
+ TM = static_cast<const PPCTargetMachine *>(&MF.getTarget());
+ TII = TM->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;
+ }
+
+ virtual void getAnalysisUsage(AnalysisUsage &AU) const {
+ 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(); }
#undef DEBUG_TYPE
#define DEBUG_TYPE "ppc-vsx-copy"
projects / oota-llvm.git / blobdiff