[mips][microMIPS] Use swm32/lwm32 instructions in function prologue/epilogue

[zoran.jovanovic]

Fixed issues with test cases.

[zoran.jovanovic]

Fixed issue with non sequential register allocation order.

[zoran.jovanovic]

Fixed issues. Rebased.

[sstankovic]

LGTM

[Eugene.Zelenko]

Looks like patch was not committed.

[petarj]

This patch needs to be double-checked, tested again and hopefully committed.

[sdardis]

Please rebase this.

lib/Target/Mips/MicroMipsInstrInfo.td

492

This requires a target flag like hasForbiddenSlot, isUnsafeInDelaySlot to mark these instructions as being unsafe in delay slots. The delay slot filler should recognise that flag. That flag should also be added to lwp and swp.

That should be done as a separate patch.

500

As above.

test/CodeGen/Mips/micromips-swm-lwm.ll

2

Use the update_llc_checks.py script to generate the tests.

10

Remove the #0 from this function definition.

28

Here too.

[atanasyan]

lib/Target/Mips/MipsSEFrameLowering.cpp

683

Use early-return:

if (!STI.inMicroMipsMode())
    return false;

707

Replace SWM by LWM.

lib/Target/Mips/MicroMipsInstrInfo.td

def reglist16 : Operand<i32> {
   let EncoderMethod = "getRegisterListOpValue16";
   let DecoderMethod = "DecodeRegListOperand16";
   let PrintMethod = "printRegisterList";
   let ParserMatchClass = RegList16AsmOperand;
 }
 
 class StoreMultMM<string opstr,
             InstrItinClass Itin = NoItinerary, ComplexPattern Addr = addr> :
-  InstSE<(outs), (ins reglist:$rt, mem_mm_12:$addr),
+  InstSE<(outs), (ins reglist:$rt, variable_ops, mem_mm_12:$addr),
          !strconcat(opstr, "\t$rt, $addr"), [], Itin, FrmI, opstr> {
   let DecoderMethod = "DecodeMemMMImm12";
   let mayStore = 1;
 }
 
 class LoadMultMM<string opstr,
             InstrItinClass Itin = NoItinerary, ComplexPattern Addr = addr> :
-  InstSE<(outs reglist:$rt), (ins mem_mm_12:$addr),
+  InstSE<(outs reglist:$rt, variable_ops), (ins mem_mm_12:$addr),
           !strconcat(opstr, "\t$rt, $addr"), [], Itin, FrmI, opstr> {
   let DecoderMethod = "DecodeMemMMImm12";
   let mayLoad = 1;
 }
 
 class StoreMultMM16<string opstr,
                     InstrItinClass Itin = NoItinerary,
                     ComplexPattern Addr = addr> :
   MicroMipsInst16<(outs), (ins reglist16:$rt, mem_mm_4sp:$addr),
                   !strconcat(opstr, "\t$rt, $addr"), [], Itin, FrmI> {
   let mayStore = 1;

lib/Target/Mips/MipsSEFrameLowering.h

void eliminateCallFramePseudoInstr(MachineFunction &MF,
                                   MachineBasicBlock &MBB,
                                   MachineBasicBlock::iterator I) const override;
 
   bool spillCalleeSavedRegisters(MachineBasicBlock &MBB,
                                  MachineBasicBlock::iterator MI,
                                  const std::vector<CalleeSavedInfo> &CSI,
                                  const TargetRegisterInfo *TRI) const override;
 
+  bool
+  restoreCalleeSavedRegisters(MachineBasicBlock &MBB,
+                              MachineBasicBlock::iterator MI,
+                              const std::vector<CalleeSavedInfo> &CSI,
+                              const TargetRegisterInfo *TRI) const override;
+
   bool hasReservedCallFrame(const MachineFunction &MF) const override;
 
   void processFunctionBeforeCalleeSavedScan(MachineFunction &MF,
                                             RegScavenger *RS) const override;
   unsigned ehDataReg(unsigned I) const;
 };
 
 } // End llvm namespace
 
 #endif

lib/Target/Mips/MipsSEFrameLowering.cpp

static std::pair<unsigned, unsigned> getMFHiLoOpc(unsigned Src) {
 
   if (Mips::ACC128RegClass.contains(Src))
     return std::make_pair((unsigned)Mips::PseudoMFHI64,
                           (unsigned)Mips::PseudoMFLO64);
 
   return std::make_pair(0, 0);
 }
 
+static void BuildMultipleMemAccess(MachineBasicBlock &MBB,
+                                   MachineBasicBlock::iterator MI,
+                                   const std::vector<CalleeSavedInfo> &CSI,
+                                   int FirstIndx, int Counter,
+                                   unsigned Opcode) {
+  MachineFunction *MF = MBB.getParent();
+  int FI = CSI[FirstIndx].getFrameIdx();
+  const TargetInstrInfo &TII = *MF->getSubtarget().getInstrInfo();
+  unsigned Flag = ((Opcode == Mips::SWM32_MM) ? MachineMemOperand::MOStore
+                                              : MachineMemOperand::MOLoad);
+
+  // Insert swm instruction.
+  DebugLoc DL;
+  if (MI != MBB.end())
+    DL = MI->getDebugLoc();
+
+  MachineFrameInfo &MFI = *MF->getFrameInfo();
+  unsigned Align = MFI.getObjectAlignment(FI);
+
+  MachineMemOperand *MMO =
+      MF->getMachineMemOperand(MachinePointerInfo::getFixedStack(FI), Flag,
+                               MFI.getObjectSize(FI), Align);
+  Counter++;
+  MachineInstrBuilder MIB =
+      BuildMI(*(MI->getParent()), MI, DL, TII.get(Opcode));
+
+  // Insert all registers into instruction.
+  for (int j = FirstIndx; j > FirstIndx - Counter; j--) {
+    unsigned SReg = CSI[j].getReg();
+
+    bool IsRAAndRetAddrIsTaken = (SReg == Mips::RA || SReg == Mips::RA_64) &&
+                                 MF->getFrameInfo()->isReturnAddressTaken();
+    bool IsKill = !IsRAAndRetAddrIsTaken;
+    unsigned Flag = Opcode == Mips::SWM32_MM ? getKillRegState(IsKill)
+                                             : getDefRegState(true);
+    MIB.addReg(SReg, Flag);
+  }
+  MIB.addFrameIndex(FI);
+  MIB.addImm(0);
+  MIB.addMemOperand(MMO);
+}
+
 /// Helper class to expand pseudos.
 class ExpandPseudo {
 public:
   ExpandPseudo(MachineFunction &MF);
   bool expand();
 
 private:
   bool expandInstr(MachineBasicBlock &MBB, Iter I);

 spillCalleeSavedRegisters(MachineBasicBlock &MBB,
                           MachineBasicBlock::iterator MI,
                           const std::vector<CalleeSavedInfo> &CSI,
                           const TargetRegisterInfo *TRI) const {
   MachineFunction *MF = MBB.getParent();
   MachineBasicBlock *EntryBlock = MF->begin();
   const TargetInstrInfo &TII = *STI.getInstrInfo();
 
+  if (STI.inMicroMipsMode()) {
+    unsigned Size = CSI.size();
+    unsigned Counter = 0;
+    int FirstIndx = 0;
+    for (int i = Size - 1; i >= 0; --i) {
+      // Add the callee-saved register as live-in. Do not add if the register is
+      // RA and return address is taken, because it has already been added in
+      // method MipsTargetLowering::LowerRETURNADDR.
+      // It's killed at the spill, unless the register is RA and return address
+      // is taken.
+      unsigned NextReg = i ? CSI[i - 1].getReg() : 0;
+      unsigned Reg = CSI[i].getReg();
+      bool IsRAAndRetAddrIsTaken = (Reg == Mips::RA || Reg == Mips::RA_64)
+          && MF->getFrameInfo()->isReturnAddressTaken();
+      if (!IsRAAndRetAddrIsTaken)
+        EntryBlock->addLiveIn(Reg);
+
+      if (Reg == Mips::S0) {
+        FirstIndx = i;
+        Counter++;
+      } else if (Counter && (NextReg == Reg + 1 || NextReg == Mips::FP ||
+                             NextReg == Mips::RA)) {
+        Counter++;
+      } else if (Counter) {
+        // Emit SWM instruction.
+        BuildMultipleMemAccess(MBB, MI, CSI, FirstIndx, Counter,
+                               Mips::SWM32_MM);
+        Counter = 0;
+      } else {
+        // Insert the spill to the stack frame.
+        bool IsKill = !IsRAAndRetAddrIsTaken;
+        const TargetRegisterClass *RC = TRI->getMinimalPhysRegClass(Reg);
+        TII.storeRegToStackSlot(*EntryBlock, MI, Reg, IsKill,
+                                CSI[i].getFrameIdx(), RC, TRI);
+      }
+    }
+  } else {
     for (unsigned i = 0, e = CSI.size(); i != e; ++i) {
       // Add the callee-saved register as live-in. Do not add if the register is
       // RA and return address is taken, because it has already been added in
       // method MipsTargetLowering::LowerRETURNADDR.
       // It's killed at the spill, unless the register is RA and return address
       // is taken.
       unsigned Reg = CSI[i].getReg();
       bool IsRAAndRetAddrIsTaken = (Reg == Mips::RA || Reg == Mips::RA_64)
           && MF->getFrameInfo()->isReturnAddressTaken();
       if (!IsRAAndRetAddrIsTaken)
         EntryBlock->addLiveIn(Reg);
 
       // Insert the spill to the stack frame.
       bool IsKill = !IsRAAndRetAddrIsTaken;
       const TargetRegisterClass *RC = TRI->getMinimalPhysRegClass(Reg);
       TII.storeRegToStackSlot(*EntryBlock, MI, Reg, IsKill,
                               CSI[i].getFrameIdx(), RC, TRI);
     }
+  }
 
   return true;
 }
 
+bool MipsSEFrameLowering::
+restoreCalleeSavedRegisters(MachineBasicBlock &MBB,
+                            MachineBasicBlock::iterator MI,
+                            const std::vector<CalleeSavedInfo> &CSI,
+                            const TargetRegisterInfo *TRI) const {
+
+  if (STI.inMicroMipsMode()) {
+    MachineFunction *MF = MBB.getParent();
+    const TargetInstrInfo &TII = *MF->getSubtarget().getInstrInfo();
+    bool AtStart = MI == MBB.begin();
+    MachineBasicBlock::iterator BeforeI = MI;
+    unsigned Counter = 0;
+    unsigned Size = CSI.size();
+    int FirstIndx = 0;
+
+    if (!AtStart)
+      --BeforeI;
+
+    for (int i = Size - 1; i >= 0; --i) {
+      unsigned Reg = CSI[i].getReg();
+      unsigned NextReg = i ? CSI[i - 1].getReg() : 0;
+
+      if (Reg == Mips::S0) {
+        FirstIndx = i;
+        Counter++;
+      } else if (Counter && (NextReg == Reg + 1 || NextReg == Mips::FP ||
+                             NextReg == Mips::RA)) {
+        Counter++;
+      } else if (Counter) {
+        // Emit SWM instruction.
+        BuildMultipleMemAccess(MBB, MI, CSI, FirstIndx, Counter,
+                               Mips::LWM32_MM);
+        Counter = 0;
+      } else {
+        const TargetRegisterClass *RC = TRI->getMinimalPhysRegClass(Reg);
+        TII.loadRegFromStackSlot(MBB, MI, Reg, CSI[i].getFrameIdx(), RC, TRI);
+      }
+
+      assert(MI != MBB.begin() &&
+             "loadRegFromStackSlot didn't insert any code!");
+      // Insert in reverse order.  loadRegFromStackSlot can insert
+      // multiple instructions.
+      if (AtStart)
+        MI = MBB.begin();
+      else {
+        MI = BeforeI;
+        ++MI;
+      }
+    }
+    return true;
+  }
+
+  return false;
+}
+
 bool
 MipsSEFrameLowering::hasReservedCallFrame(const MachineFunction &MF) const {
   const MachineFrameInfo *MFI = MF.getFrameInfo();
 
   // Reserve call frame if the size of the maximum call frame fits into 16-bit
   // immediate field and there are no variable sized objects on the stack.
   // Make sure the second register scavenger spill slot can be accessed with one
   // instruction.

test/CodeGen/Mips/micromips-swm-lwm.ll

+; RUN: llc -march=mipsel -mcpu=mips32r2 -mattr=+micromips \
+; RUN:   -relocation-model=pic -O3 < %s | FileCheck %s
+
+@g1 = global i32 0, align 4
+@g2 = global i32 0, align 4
+@g3 = global i32 0, align 4
+@g4 = global i32 0, align 4
+
+define i32 @_Z3fooiiii(i32 %arg1, i32 %arg2, i32 %arg3, i32 %arg4) #0 {
+entry:
+  %add = add nsw i32 %arg2, %arg1
+  %add1 = add nsw i32 %add, %arg3
+  %add2 = add nsw i32 %add1, %arg4
+  %0 = load i32* @g1, align 4
+  %add3 = add nsw i32 %add2, %0
+  %1 = load i32* @g2, align 4
+  %add4 = add nsw i32 %add3, %1
+  %2 = load i32* @g3, align 4
+  %add5 = add nsw i32 %add4, %2
+  %3 = load i32* @g4, align 4
+  %add6 = add nsw i32 %add5, %3
+  %call = tail call i32 @_Z3bariiii(i32 %arg1, i32 %arg2, i32 %arg3, i32 %arg4)
+  %add7 = add nsw i32 %add6, %call
+  ret i32 %add7
+}
+
+declare i32 @_Z3bariiii(i32, i32, i32, i32) #0
+
+; CHECK: swm32
+; CHECK: lwm32
+