[mips][mips64r6] ll, sc, lld, and scd are re-encoded on MIPS32r6/MIPS…

…64r6.

Summary:
The linked-load, store-conditional operations have been re-encoded such
that have a 9-bit offset instead of the 16-bit offset they have prior to
MIPS32r6/MIPS64r6.

While implementing this, I noticed that the atomic load/store pseudos always
emit a sign extension using sll and sra. I have improved this to use seb/seh
when they are available (MIPS32r2/MIPS64r2 and above).

Depends on D4118

Reviewers: jkolek, zoran.jovanovic, vmedic

Reviewed By: vmedic

Differential Revision: http://reviews.llvm.org/D4119

llvm-svn: 211018

llvm/lib/Target/Mips/Disassembler/MipsDisassembler.cpp

@@ -272,6 +272,11 @@ static DecodeStatus DecodeFMem(MCInst &Inst, unsigned Insn,
                                uint64_t Address,
                                const void *Decoder);
 
+static DecodeStatus DecodeSpecial3LlSc(MCInst &Inst,
+                                       unsigned Insn,
+                                       uint64_t Address,
+                                       const void *Decoder);
+
 static DecodeStatus DecodeSimm16(MCInst &Inst,
                                  unsigned Insn,
                                  uint64_t Address,
@@ -1068,6 +1073,27 @@ static DecodeStatus DecodeFMem(MCInst &Inst,
   return MCDisassembler::Success;
 }
 
+static DecodeStatus DecodeSpecial3LlSc(MCInst &Inst,
+                                       unsigned Insn,
+                                       uint64_t Address,
+                                       const void *Decoder) {
+  int64_t Offset = SignExtend64<9>((Insn >> 7) & 0x1ff);
+  unsigned Rt = fieldFromInstruction(Insn, 16, 5);
+  unsigned Base = fieldFromInstruction(Insn, 21, 5);
+
+  Rt = getReg(Decoder, Mips::GPR32RegClassID, Rt);
+  Base = getReg(Decoder, Mips::GPR32RegClassID, Base);
+
+  if(Inst.getOpcode() == Mips::SC_R6 || Inst.getOpcode() == Mips::SCD_R6){
+    Inst.addOperand(MCOperand::CreateReg(Rt));
+  }
+
+  Inst.addOperand(MCOperand::CreateReg(Rt));
+  Inst.addOperand(MCOperand::CreateReg(Base));
+  Inst.addOperand(MCOperand::CreateImm(Offset));
+
+  return MCDisassembler::Success;
+}
 
 static DecodeStatus DecodeHWRegsRegisterClass(MCInst &Inst,
                                               unsigned RegNo,

llvm/lib/Target/Mips/MCTargetDesc/MipsNaClELFStreamer.cpp

@@ -203,6 +203,7 @@ bool isBasePlusOffsetMemoryAccess(unsigned Opcode, unsigned *AddrIdx,
   case Mips::LWC1:
   case Mips::LDC1:
   case Mips::LL:
+  case Mips::LL_R6:
   case Mips::LWL:
   case Mips::LWR:
     *AddrIdx = 1;
@@ -223,6 +224,7 @@ bool isBasePlusOffsetMemoryAccess(unsigned Opcode, unsigned *AddrIdx,
 
   // Store instructions with base address register in position 2.
   case Mips::SC:
+  case Mips::SC_R6:
     *AddrIdx = 2;
     if (IsStore)
       *IsStore = true;

llvm/lib/Target/Mips/Mips32r6InstrFormats.td

@@ -39,6 +39,7 @@ def OPGROUP_DAUI     : OPGROUP<0b011101>;
 def OPGROUP_PCREL    : OPGROUP<0b111011>;
 def OPGROUP_REGIMM   : OPGROUP<0b000001>;
 def OPGROUP_SPECIAL  : OPGROUP<0b000000>;
+// The spec occasionally names this value LL, LLD, SC, or SCD.
 def OPGROUP_SPECIAL3 : OPGROUP<0b011111>;
 // The spec names this constant LWC2, LDC2, SWC2, and SDC2 in different places.
 def OPGROUP_COP2LDST : OPGROUP<0b010010>;
@@ -84,6 +85,12 @@ def OPCODE6_DBITSWAP : OPCODE6<0b100100>;
 def OPCODE6_JALR     : OPCODE6<0b001001>;
 def OPCODE6_CACHE    : OPCODE6<0b100101>;
 def OPCODE6_PREF     : OPCODE6<0b110101>;
+// The next four constants are unnamed in the spec. These names are taken from
+// the OPGROUP names they are used with.
+def OPCODE6_LL       : OPCODE6<0b110110>;
+def OPCODE6_LLD      : OPCODE6<0b110111>;
+def OPCODE6_SC       : OPCODE6<0b100110>;
+def OPCODE6_SCD      : OPCODE6<0b100111>;
 
 class FIELD_FMT<bits<5> Val> {
   bits<5> Value = Val;
@@ -411,6 +418,23 @@ class SPECIAL3_DALIGN_FM<OPCODE6 Operation> : MipsR6Inst {
   let Inst{5-0}   = Operation.Value;
 }
 
+class SPECIAL3_LL_SC_FM<OPCODE6 Operation> : MipsR6Inst {
+  bits<5> rt;
+  bits<21> addr;
+  bits<5> base = addr{20-16};
+  bits<9> offset = addr{8-0};
+
+  bits<32> Inst;
+
+  let Inst{31-26} = OPGROUP_SPECIAL3.Value;
+  let Inst{25-21} = base;
+  let Inst{20-16} = rt;
+  let Inst{15-7} = offset;
+  let Inst{5-0} = Operation.Value;
+
+  string DecoderMethod = "DecodeSpecial3LlSc";
+}
+
 class REGIMM_FM<OPCODE5 Operation> : MipsR6Inst {
   bits<5> rs;
   bits<16> imm;

llvm/lib/Target/Mips/Mips32r6InstrInfo.td

@@ -18,7 +18,6 @@ include "Mips32r6InstrFormats.td"
 // Reencoded: clo, clz
 // Reencoded: jr -> jalr
 // Reencoded: jr.hb -> jalr.hb
-// Reencoded: ll, sc
 // Reencoded: sdbbp
 
 def brtarget21 : Operand<OtherVT> {
@@ -158,6 +157,9 @@ class LWC2_R6_ENC : COP2LDST_FM<OPCODE5_LWC2>;
 class SDC2_R6_ENC : COP2LDST_FM<OPCODE5_SDC2>;
 class SWC2_R6_ENC : COP2LDST_FM<OPCODE5_SWC2>;
 
+class LL_R6_ENC : SPECIAL3_LL_SC_FM<OPCODE6_LL>;
+class SC_R6_ENC : SPECIAL3_LL_SC_FM<OPCODE6_SC>;
+
 class CMP_CONDN_DESC_BASE<string CondStr, string Typestr,
                           RegisterOperand FGROpnd,
                           SDPatternOperator Op = null_frag> {
@@ -563,6 +565,27 @@ class COP2ST_DESC_BASE<string instr_asm, RegisterOperand COPOpnd> {
 class SDC2_R6_DESC : COP2ST_DESC_BASE<"sdc2", COP2Opnd>;
 class SWC2_R6_DESC : COP2ST_DESC_BASE<"swc2", COP2Opnd>;
 
+class LL_R6_DESC_BASE<string instr_asm, RegisterOperand GPROpnd> {
+  dag OutOperandList = (outs GPROpnd:$rt);
+  dag InOperandList = (ins mem_simm9:$addr);
+  string AsmString = !strconcat(instr_asm, "\t$rt, $addr");
+  list<dag> Pattern = [];
+  bit mayLoad = 1;
+}
+
+class LL_R6_DESC : LL_R6_DESC_BASE<"ll", GPR32Opnd>;
+
+class SC_R6_DESC_BASE<string instr_asm, RegisterOperand GPROpnd> {
+  dag OutOperandList = (outs GPROpnd:$dst);
+  dag InOperandList = (ins GPROpnd:$rt, mem_simm9:$addr);
+  string AsmString = !strconcat(instr_asm, "\t$rt, $addr");
+  list<dag> Pattern = [];
+  bit mayStore = 1;
+  string Constraints = "$rt = $dst";
+}
+
+class SC_R6_DESC : SC_R6_DESC_BASE<"sc", GPR32Opnd>;
+
 //===----------------------------------------------------------------------===//
 //
 // Instruction Definitions
@@ -613,6 +636,7 @@ def JIALC : JIALC_ENC, JIALC_DESC, ISA_MIPS32R6;
 def JIC : JIC_ENC, JIC_DESC, ISA_MIPS32R6;
 def JR_HB_R6 : JR_HB_R6_ENC, JR_HB_R6_DESC, ISA_MIPS32R6;
 def LDC2_R6 : LDC2_R6_ENC, LDC2_R6_DESC, ISA_MIPS32R6;
+def LL_R6 : LL_R6_ENC, LL_R6_DESC, ISA_MIPS32R6;
 // def LSA; // See MSA
 def LWC2_R6 : LWC2_R6_ENC, LWC2_R6_DESC, ISA_MIPS32R6;
 def LWPC : LWPC_ENC, LWPC_DESC, ISA_MIPS32R6;
@@ -639,6 +663,7 @@ def NAL; // BAL with rd=0
 def PREF_R6 : PREF_ENC, PREF_DESC, ISA_MIPS32R6;
 def RINT_D : RINT_D_ENC, RINT_D_DESC, ISA_MIPS32R6;
 def RINT_S : RINT_S_ENC, RINT_S_DESC, ISA_MIPS32R6;
+def SC_R6 : SC_R6_ENC, SC_R6_DESC, ISA_MIPS32R6;
 def SDC2_R6 : SDC2_R6_ENC, SDC2_R6_DESC, ISA_MIPS32R6;
 def SELEQZ : SELEQZ_ENC, SELEQZ_DESC, ISA_MIPS32R6, GPR_32;
 def SELEQZ_D : SELEQZ_D_ENC, SELEQZ_D_DESC, ISA_MIPS32R6;

llvm/lib/Target/Mips/Mips64InstrInfo.td

@@ -167,8 +167,8 @@ def SDR   : StoreLeftRight<"sdr", MipsSDR, GPR64Opnd, II_SDR>, LW_FM<0x2d>,
             ISA_MIPS3_NOT_32R6_64R6;
 
 /// Load-linked, Store-conditional
-def LLD : LLBase<"lld", GPR64Opnd>, LW_FM<0x34>, ISA_MIPS3;
-def SCD : SCBase<"scd", GPR64Opnd>, LW_FM<0x3c>, ISA_MIPS3;
+def LLD : LLBase<"lld", GPR64Opnd>, LW_FM<0x34>, ISA_MIPS3_NOT_32R6_64R6;
+def SCD : SCBase<"scd", GPR64Opnd>, LW_FM<0x3c>, ISA_MIPS3_NOT_32R6_64R6;
 
 /// Jump and Branch Instructions
 let isCodeGenOnly = 1 in {

llvm/lib/Target/Mips/Mips64r6InstrInfo.td

@@ -13,7 +13,6 @@
 
 // Notes about removals/changes from MIPS32r6:
 // Reencoded: dclo, dclz
-// Reencoded: lld, scd
 
 //===----------------------------------------------------------------------===//
 //
@@ -35,6 +34,8 @@ class DMUHU_ENC   : SPECIAL_3R_FM<0b00011, 0b111001>;
 class DMUL_R6_ENC : SPECIAL_3R_FM<0b00010, 0b111000>;
 class DMULU_ENC   : SPECIAL_3R_FM<0b00010, 0b111001>;
 class LDPC_ENC    : PCREL18_FM<OPCODE3_LDPC>;
+class LLD_R6_ENC : SPECIAL3_LL_SC_FM<OPCODE6_LLD>;
+class SCD_R6_ENC : SPECIAL3_LL_SC_FM<OPCODE6_SCD>;
 
 //===----------------------------------------------------------------------===//
 //
@@ -63,7 +64,8 @@ class DMUHU_DESC   : MUL_R6_DESC_BASE<"dmuhu", GPR64Opnd, mulhu>;
 class DMUL_R6_DESC : MUL_R6_DESC_BASE<"dmul", GPR64Opnd, mul>;
 class DMULU_DESC   : MUL_R6_DESC_BASE<"dmulu", GPR64Opnd>;
 class LDPC_DESC    : PCREL_DESC_BASE<"ldpc", GPR64Opnd, simm18_lsl3>;
-
+class LLD_R6_DESC   : LL_R6_DESC_BASE<"lld", GPR64Opnd>;
+class SCD_R6_DESC   : SC_R6_DESC_BASE<"scd", GPR64Opnd>;
 class SELEQZ64_DESC : SELEQNE_Z_DESC_BASE<"seleqz", GPR64Opnd>;
 class SELNEZ64_DESC : SELEQNE_Z_DESC_BASE<"selnez", GPR64Opnd>;
 
@@ -88,6 +90,8 @@ def DMUHU: DMUHU_ENC, DMUHU_DESC, ISA_MIPS64R6;
 def DMUL_R6: DMUL_R6_ENC, DMUL_R6_DESC, ISA_MIPS64R6;
 def DMULU: DMULU_ENC, DMULU_DESC, ISA_MIPS64R6;
 def LDPC: LDPC_ENC, LDPC_DESC, ISA_MIPS64R6;
+def LLD_R6 : LLD_R6_ENC, LLD_R6_DESC, ISA_MIPS32R6;
+def SCD_R6 : SCD_R6_ENC, SCD_R6_DESC, ISA_MIPS32R6;
 let DecoderNamespace = "Mips32r6_64r6_GP64" in {
   def SELEQZ64 : SELEQZ_ENC, SELEQZ64_DESC, ISA_MIPS32R6, GPR_64;
   def SELNEZ64 : SELNEZ_ENC, SELNEZ64_DESC, ISA_MIPS32R6, GPR_64;

llvm/lib/Target/Mips/MipsISelLowering.cpp

@@ -958,16 +958,20 @@ MipsTargetLowering::emitAtomicBinary(MachineInstr *MI, MachineBasicBlock *BB,
   unsigned LL, SC, AND, NOR, ZERO, BEQ;
 
   if (Size == 4) {
-    LL = isMicroMips ? Mips::LL_MM : Mips::LL;
-    SC = isMicroMips ? Mips::SC_MM : Mips::SC;
+    if (isMicroMips) {
+      LL = Mips::LL_MM;
+      SC = Mips::SC_MM;
+    } else {
+      LL = Subtarget->hasMips32r6() ? Mips::LL : Mips::LL_R6;
+      SC = Subtarget->hasMips32r6() ? Mips::SC : Mips::SC_R6;
+    }
     AND = Mips::AND;
     NOR = Mips::NOR;
     ZERO = Mips::ZERO;
     BEQ = Mips::BEQ;
-  }
-  else {
-    LL = Mips::LLD;
-    SC = Mips::SCD;
+  } else {
+    LL = Subtarget->hasMips64r6() ? Mips::LLD : Mips::LLD_R6;
+    SC = Subtarget->hasMips64r6() ? Mips::SCD : Mips::SCD_R6;
     AND = Mips::AND64;
     NOR = Mips::NOR64;
     ZERO = Mips::ZERO_64;
@@ -1029,11 +1033,39 @@ MipsTargetLowering::emitAtomicBinary(MachineInstr *MI, MachineBasicBlock *BB,
   return exitMBB;
 }
 
-MachineBasicBlock *
-MipsTargetLowering::emitAtomicBinaryPartword(MachineInstr *MI,
-                                             MachineBasicBlock *BB,
-                                             unsigned Size, unsigned BinOpcode,
-                                             bool Nand) const {
+MachineBasicBlock *MipsTargetLowering::emitSignExtendToI32InReg(
+    MachineInstr *MI, MachineBasicBlock *BB, unsigned Size, unsigned DstReg,
+    unsigned SrcReg) const {
+  const TargetInstrInfo *TII = getTargetMachine().getInstrInfo();
+  DebugLoc DL = MI->getDebugLoc();
+
+  if (Subtarget->hasMips32r2() && Size == 1) {
+    BuildMI(BB, DL, TII->get(Mips::SEB), DstReg).addReg(SrcReg);
+    return BB;
+  }
+
+  if (Subtarget->hasMips32r2() && Size == 2) {
+    BuildMI(BB, DL, TII->get(Mips::SEH), DstReg).addReg(SrcReg);
+    return BB;
+  }
+
+  MachineFunction *MF = BB->getParent();
+  MachineRegisterInfo &RegInfo = MF->getRegInfo();
+  const TargetRegisterClass *RC = getRegClassFor(MVT::i32);
+  unsigned ScrReg = RegInfo.createVirtualRegister(RC);
+
+  assert(Size < 32);
+  int64_t ShiftImm = 32 - (Size * 8);
+
+  BuildMI(BB, DL, TII->get(Mips::SLL), ScrReg).addReg(SrcReg).addImm(ShiftImm);
+  BuildMI(BB, DL, TII->get(Mips::SRA), DstReg).addReg(ScrReg).addImm(ShiftImm);
+
+  return BB;
+}
+
+MachineBasicBlock *MipsTargetLowering::emitAtomicBinaryPartword(
+    MachineInstr *MI, MachineBasicBlock *BB, unsigned Size, unsigned BinOpcode,
+    bool Nand) const {
   assert((Size == 1 || Size == 2) &&
          "Unsupported size for EmitAtomicBinaryPartial.");
 
@@ -1063,7 +1095,6 @@ MipsTargetLowering::emitAtomicBinaryPartword(MachineInstr *MI,
   unsigned StoreVal = RegInfo.createVirtualRegister(RC);
   unsigned MaskedOldVal1 = RegInfo.createVirtualRegister(RC);
   unsigned SrlRes = RegInfo.createVirtualRegister(RC);
-  unsigned SllRes = RegInfo.createVirtualRegister(RC);
   unsigned Success = RegInfo.createVirtualRegister(RC);
 
   // insert new blocks after the current block
@@ -1169,19 +1200,14 @@ MipsTargetLowering::emitAtomicBinaryPartword(MachineInstr *MI,
   //  sinkMBB:
   //    and     maskedoldval1,oldval,mask
   //    srl     srlres,maskedoldval1,shiftamt
-  //    sll     sllres,srlres,24
-  //    sra     dest,sllres,24
+  //    sign_extend dest,srlres
   BB = sinkMBB;
-  int64_t ShiftImm = (Size == 1) ? 24 : 16;
 
   BuildMI(BB, DL, TII->get(Mips::AND), MaskedOldVal1)
     .addReg(OldVal).addReg(Mask);
   BuildMI(BB, DL, TII->get(Mips::SRLV), SrlRes)
       .addReg(MaskedOldVal1).addReg(ShiftAmt);
-  BuildMI(BB, DL, TII->get(Mips::SLL), SllRes)
-      .addReg(SrlRes).addImm(ShiftImm);
-  BuildMI(BB, DL, TII->get(Mips::SRA), Dest)
-      .addReg(SllRes).addImm(ShiftImm);
+  BB = emitSignExtendToI32InReg(MI, BB, Size, Dest, SrlRes);
 
   MI->eraseFromParent(); // The instruction is gone now.
 
@@ -1302,7 +1328,6 @@ MipsTargetLowering::emitAtomicCmpSwapPartword(MachineInstr *MI,
   unsigned MaskedOldVal1 = RegInfo.createVirtualRegister(RC);
   unsigned StoreVal = RegInfo.createVirtualRegister(RC);
   unsigned SrlRes = RegInfo.createVirtualRegister(RC);
-  unsigned SllRes = RegInfo.createVirtualRegister(RC);
   unsigned Success = RegInfo.createVirtualRegister(RC);
 
   // insert new blocks after the current block
@@ -1399,17 +1424,12 @@ MipsTargetLowering::emitAtomicCmpSwapPartword(MachineInstr *MI,
 
   //  sinkMBB:
   //    srl     srlres,maskedoldval0,shiftamt
-  //    sll     sllres,srlres,24
-  //    sra     dest,sllres,24
+  //    sign_extend dest,srlres
   BB = sinkMBB;
-  int64_t ShiftImm = (Size == 1) ? 24 : 16;
 
   BuildMI(BB, DL, TII->get(Mips::SRLV), SrlRes)
       .addReg(MaskedOldVal0).addReg(ShiftAmt);
-  BuildMI(BB, DL, TII->get(Mips::SLL), SllRes)
-      .addReg(SrlRes).addImm(ShiftImm);
-  BuildMI(BB, DL, TII->get(Mips::SRA), Dest)
-      .addReg(SllRes).addImm(ShiftImm);
+  BB = emitSignExtendToI32InReg(MI, BB, Size, Dest, SrlRes);
 
   MI->eraseFromParent();   // The instruction is gone now.
 

llvm/lib/Target/Mips/MipsISelLowering.h

@@ -598,6 +598,12 @@ namespace llvm {
 
     unsigned getJumpTableEncoding() const override;
 
+    /// Emit a sign-extension using sll/sra, seb, or seh appropriately.
+    MachineBasicBlock *emitSignExtendToI32InReg(MachineInstr *MI,
+                                                MachineBasicBlock *BB,
+                                                unsigned Size, unsigned DstReg,
+                                                unsigned SrcRec) const;
+
     MachineBasicBlock *emitAtomicBinary(MachineInstr *MI, MachineBasicBlock *BB,
                     unsigned Size, unsigned BinOpcode, bool Nand = false) const;
     MachineBasicBlock *emitAtomicBinaryPartword(MachineInstr *MI,

llvm/lib/Target/Mips/MipsInstrInfo.td

@@ -1189,8 +1189,8 @@ let EncodingPredicates = []<Predicate>, // FIXME: Lack of HasStdEnc is probably
 def WAIT : WAIT_FT<"wait">, WAIT_FM;
 
 /// Load-linked, Store-conditional
-def LL : LLBase<"ll", GPR32Opnd>, LW_FM<0x30>, ISA_MIPS2;
-def SC : SCBase<"sc", GPR32Opnd>, LW_FM<0x38>, ISA_MIPS2;
+def LL : LLBase<"ll", GPR32Opnd>, LW_FM<0x30>, ISA_MIPS2_NOT_32R6_64R6;
+def SC : SCBase<"sc", GPR32Opnd>, LW_FM<0x38>, ISA_MIPS2_NOT_32R6_64R6;
 }
 
 /// Jump and Branch Instructions

llvm/lib/Target/Mips/MipsSubtarget.h

@@ -161,7 +161,7 @@ class MipsSubtarget : public MipsGenSubtargetInfo {
   bool hasMips32() const { return MipsArchVersion >= Mips32; }
   bool hasMips32r2() const {
     return MipsArchVersion == Mips32r2 || MipsArchVersion == Mips32r6 ||
-           MipsArchVersion == Mips64r2;
+           MipsArchVersion == Mips64r2 || MipsArchVersion == Mips64r6;
   }
   bool hasMips32r6() const {
     return MipsArchVersion == Mips32r6 || MipsArchVersion == Mips64r6;