[RISCV][GISel] Add manual isel for s8/s16/s32 load/store for the GPR bank.

llvm/lib/Target/RISCV/GISel/RISCVInstructionSelector.cpp

@@ -675,6 +675,45 @@ static void getOperandsForBranch(Register CondReg, RISCVCC::CondCode &CC,
   CC = getRISCVCCFromICmp(Pred);
 }
 
+/// Select the RISC-V Zalasr opcode for the G_LOAD or G_STORE operation
+/// \p GenericOpc, appropriate for the GPR register bank and of memory access
+/// size \p OpSize.
+static unsigned selectZalasrLoadStoreOp(unsigned GenericOpc, unsigned OpSize) {
+  const bool IsStore = GenericOpc == TargetOpcode::G_STORE;
+  switch (OpSize) {
+  default:
+    llvm_unreachable("Unexpected memory size");
+  case 8:
+    return IsStore ? RISCV::SB_RL : RISCV::LB_AQ;
+  case 16:
+    return IsStore ? RISCV::SH_RL : RISCV::LH_AQ;
+  case 32:
+    return IsStore ? RISCV::SW_RL : RISCV::LW_AQ;
+  case 64:
+    return IsStore ? RISCV::SD_RL : RISCV::LD_AQ;
+  }
+}
+
+/// Select the RISC-V regimm opcode for the G_LOAD or G_STORE operation
+/// \p GenericOpc, appropriate for the GPR register bank and of memory access
+/// size \p OpSize. \returns \p GenericOpc if the combination is unsupported.
+static unsigned selectRegImmLoadStoreOp(unsigned GenericOpc, unsigned OpSize) {
+  const bool IsStore = GenericOpc == TargetOpcode::G_STORE;
+  switch (OpSize) {
+  case 8:
+    // Prefer unsigned due to no c.lb in Zcb.
+    return IsStore ? RISCV::SB : RISCV::LBU;
+  case 16:
+    return IsStore ? RISCV::SH : RISCV::LH;
+  case 32:
+    return IsStore ? RISCV::SW : RISCV::LW;
+  case 64:
+    return IsStore ? RISCV::SD : RISCV::LD;
+  }
+
+  return GenericOpc;
+}
+
 bool RISCVInstructionSelector::select(MachineInstr &MI) {
   MachineIRBuilder MIB(MI);
 
@@ -836,6 +875,59 @@ bool RISCVInstructionSelector::select(MachineInstr &MI) {
     return selectImplicitDef(MI, MIB);
   case TargetOpcode::G_UNMERGE_VALUES:
     return selectUnmergeValues(MI, MIB);
+  case TargetOpcode::G_LOAD:
+  case TargetOpcode::G_STORE: {
+    GLoadStore &LdSt = cast<GLoadStore>(MI);
+    const Register ValReg = LdSt.getReg(0);
+    const Register PtrReg = LdSt.getPointerReg();
+    LLT PtrTy = MRI->getType(PtrReg);
+
+    const RegisterBank &RB = *RBI.getRegBank(ValReg, *MRI, TRI);
+    if (RB.getID() != RISCV::GPRBRegBankID)
+      return false;
+
+#ifndef NDEBUG
+    const RegisterBank &PtrRB = *RBI.getRegBank(PtrReg, *MRI, TRI);
+    // Check that the pointer register is valid.
+    assert(PtrRB.getID() == RISCV::GPRBRegBankID &&
+           "Load/Store pointer operand isn't a GPR");
+    assert(PtrTy.isPointer() && "Load/Store pointer operand isn't a pointer");
+#endif
+
+    // Can only handle AddressSpace 0.
+    if (PtrTy.getAddressSpace() != 0)
+      return false;
+
+    unsigned MemSize = LdSt.getMemSizeInBits().getValue();
+    AtomicOrdering Order = LdSt.getMMO().getSuccessOrdering();
+
+    if (isStrongerThanMonotonic(Order)) {
+      MI.setDesc(TII.get(selectZalasrLoadStoreOp(Opc, MemSize)));
+      return constrainSelectedInstRegOperands(MI, TII, TRI, RBI);
+    }
+
+    const unsigned NewOpc = selectRegImmLoadStoreOp(MI.getOpcode(), MemSize);
+    if (NewOpc == MI.getOpcode())
+      return false;
+
+    // Check if we can fold anything into the addressing mode.
+    auto AddrModeFns = selectAddrRegImm(MI.getOperand(1));
+    if (!AddrModeFns)
+      return false;
+
+    // Folded something. Create a new instruction and return it.
+    auto NewInst = MIB.buildInstr(NewOpc, {}, {}, MI.getFlags());
+    if (isa<GStore>(MI))
+      NewInst.addUse(ValReg);
+    else
+      NewInst.addDef(ValReg);
+    NewInst.cloneMemRefs(MI);
+    for (auto &Fn : *AddrModeFns)
+      Fn(NewInst);
+    MI.eraseFromParent();
+
+    return constrainSelectedInstRegOperands(*NewInst, TII, TRI, RBI);
+  }
   default:
     return false;
   }

llvm/lib/Target/RISCV/RISCVGISel.td

@@ -100,39 +100,11 @@ def : LdPat<load, LD, PtrVT>;
 def : StPat<store, SD, GPR, PtrVT>;
 }
 
-// Load and store patterns for i16, needed because Zfh makes s16 load/store
-// legal and regbank select may not constrain registers to FP.
-def : LdPat<load, LH, i16>;
-def : StPat<store, SH, GPR, i16>;
-
-def : LdPat<extloadi8, LBU, i16>; // Prefer unsigned due to no c.lb in Zcb.
-def : StPat<truncstorei8, SB, GPR, i16>;
-
-let Predicates = [HasAtomicLdSt] in {
-  // Prefer unsigned due to no c.lb in Zcb.
-  def : LdPat<relaxed_load<atomic_load_aext_8>,    LBU, i16>;
-  def : LdPat<relaxed_load<atomic_load_nonext_16>, LH,  i16>;
-
-  def : StPat<relaxed_store<atomic_store_8>,  SB, GPR, i16>;
-  def : StPat<relaxed_store<atomic_store_16>, SH, GPR, i16>;
-}
-
-let Predicates = [HasAtomicLdSt, IsRV64] in {
-  // Load pattern is in RISCVInstrInfoA.td and shared with RV32.
-  def : StPat<relaxed_store<atomic_store_32>, SW, GPR, i32>;
-}
-
 //===----------------------------------------------------------------------===//
 // RV64 i32 patterns not used by SelectionDAG
 //===----------------------------------------------------------------------===//
 
 let Predicates = [IsRV64] in {
-def : LdPat<extloadi8, LBU, i32>; // Prefer unsigned due to no c.lb in Zcb.
-def : LdPat<extloadi16, LH, i32>;
-
-def : StPat<truncstorei8, SB, GPR, i32>;
-def : StPat<truncstorei16, SH, GPR, i32>;
-
 def : Pat<(sext (i32 GPR:$src)), (ADDIW GPR:$src, 0)>;
 
 def : Pat<(sext_inreg (i64 (add GPR:$rs1, simm12_lo:$imm)), i32),

llvm/lib/Target/RISCV/RISCVInstrInfo.td

@@ -1980,7 +1980,7 @@ def : LdPat<sextloadi8, LB>;
 def : LdPat<extloadi8, LBU>; // Prefer unsigned due to no c.lb in Zcb.
 def : LdPat<sextloadi16, LH>;
 def : LdPat<extloadi16, LH>;
-def : LdPat<load, LW, i32>;
+def : LdPat<load, LW, i32>, Requires<[IsRV32]>;
 def : LdPat<zextloadi8, LBU>;
 def : LdPat<zextloadi16, LHU>;
 
@@ -1994,7 +1994,7 @@ class StPat<PatFrag StoreOp, RVInst Inst, RegisterClass StTy,
 
 def : StPat<truncstorei8, SB, GPR, XLenVT>;
 def : StPat<truncstorei16, SH, GPR, XLenVT>;
-def : StPat<store, SW, GPR, i32>;
+def : StPat<store, SW, GPR, i32>, Requires<[IsRV32]>;
 
 /// Fences
 

llvm/lib/Target/RISCV/RISCVInstrInfoA.td

@@ -174,8 +174,9 @@ let Predicates = [HasAtomicLdSt] in {
   def : StPat<relaxed_store<atomic_store_8>,  SB, GPR, XLenVT>;
   def : StPat<relaxed_store<atomic_store_16>, SH, GPR, XLenVT>;
   def : StPat<relaxed_store<atomic_store_32>, SW, GPR, XLenVT>;
+}
 
-  // Used by GISel for RV32 and RV64.
+let Predicates = [HasAtomicLdSt, IsRV32] in {
   def : LdPat<relaxed_load<atomic_load_nonext_32>, LW, i32>;
 }
 

llvm/lib/Target/RISCV/RISCVInstrInfoZalasr.td

@@ -96,8 +96,8 @@ let Predicates = [HasStdExtZalasr] in {
 } // Predicates = [HasStdExtZalasr]
 
 let Predicates = [HasStdExtZalasr, IsRV32] in {
-  def : PatLAQ<acquiring_load<atomic_load_nonext_32>, LW_AQ>;
-  def : PatLAQ<seq_cst_load<atomic_load_nonext_32>, LW_AQ>;
+  def : PatLAQ<acquiring_load<atomic_load_nonext_32>, LW_AQ, i32>;
+  def : PatLAQ<seq_cst_load<atomic_load_nonext_32>, LW_AQ, i32>;
 } // Predicates = [HasStdExtZalasr, IsRV32]
 
 let Predicates = [HasStdExtZalasr, IsRV64] in {