[M68k] Add support for basic memory constraints in inline asm

[myhsu]

Summary

This patch adds support for 'm', 'Q', and 'U' memory constraints.

[0x59616e]

A few minor adjustments are required.

[0x59616e]

Shoot. I mixed it up with my own one. I'm sorry.

I can't find any isseu in this patch and it LGTM. Thanks.

clang/lib/Basic/Targets/M68k.cpp

case 'C':
     case 'i': // constant integer
     case 'j': // integer constant that doesn't fit in 16 bits
       info.setRequiresImmediate();
       return true;
     default:
       break;
     }
     break;
+  case 'Q': // address register indirect addressing
+  case 'U': // address register indirect w/ constant offset addressing
+    // TODO: Handle 'S' (basically 'm' when pc-rel is enforced) when
+    // '-mpcrel' flag is properly handled by the driver.
+    info.setAllowsMemory();
+    return true;
   default:
     break;
   }
   return false;
 }
 
 std::optional<std::string>
 M68kTargetInfo::handleAsmEscapedChar(char EscChar) const {

clang/test/Sema/inline-asm-validate-m68k.c

 // Register constraints
 void a(int x) {
   asm ("" :: "a"(x));
 }
 
 void d(int x) {
   asm ("" :: "d"(x));
 }
+
+// Memory constraints
+void mem() {
+  int x;
+  asm ("" :: "m"(x));
+  asm ("" :: "Q"(x));
+  asm ("" :: "U"(x));
+}
 #endif
 

llvm/lib/Target/M68k/M68kAsmPrinter.h

 ///
 //===----------------------------------------------------------------------===//
 
 #ifndef LLVM_LIB_TARGET_M68K_M68KASMPRINTER_H
 #define LLVM_LIB_TARGET_M68K_M68KASMPRINTER_H
 
 #include "M68kMCInstLower.h"
 #include "M68kTargetMachine.h"
+#include "MCTargetDesc/M68kMemOperandPrinter.h"
 
 #include "llvm/CodeGen/AsmPrinter.h"
 #include "llvm/MC/MCStreamer.h"
 #include "llvm/Support/Compiler.h"
 #include "llvm/Target/TargetMachine.h"
 #include <memory>
 #include <utility>
 
 namespace llvm {
 class MCStreamer;
 class MachineInstr;
 class MachineBasicBlock;
 class Module;
 class raw_ostream;
 
 class M68kSubtarget;
 class M68kMachineFunctionInfo;
 
-class LLVM_LIBRARY_VISIBILITY M68kAsmPrinter : public AsmPrinter {
+class LLVM_LIBRARY_VISIBILITY M68kAsmPrinter
+    : public AsmPrinter,
+      public M68kMemOperandPrinter<M68kAsmPrinter, MachineInstr> {
+
+  friend class M68kMemOperandPrinter;
 
   void EmitInstrWithMacroNoAT(const MachineInstr *MI);
 
   void printOperand(const MachineInstr *MI, int OpNum, raw_ostream &OS);
 
+  void printDisp(const MachineInstr *MI, unsigned OpNum, raw_ostream &OS);
+  void printAbsMem(const MachineInstr *MI, unsigned OpNum, raw_ostream &OS);
+
 public:
   const M68kSubtarget *Subtarget;
   const M68kMachineFunctionInfo *MMFI;
   std::unique_ptr<M68kMCInstLower> MCInstLowering;
 
   explicit M68kAsmPrinter(TargetMachine &TM,
                           std::unique_ptr<MCStreamer> Streamer)
       : AsmPrinter(TM, std::move(Streamer)) {
     Subtarget = static_cast<M68kTargetMachine &>(TM).getSubtargetImpl();
   }
 
   StringRef getPassName() const override { return "M68k Assembly Printer"; }
 
   virtual bool runOnMachineFunction(MachineFunction &MF) override;
 
   bool PrintAsmOperand(const MachineInstr *MI, unsigned OpNo,
                        const char *ExtraCode, raw_ostream &OS) override;
+  bool PrintAsmMemoryOperand(const MachineInstr *MI, unsigned OpNo,
+                             const char *ExtraCode, raw_ostream &OS) override;
 
   void emitInstruction(const MachineInstr *MI) override;
   void emitFunctionBodyStart() override;
   void emitFunctionBodyEnd() override;
   void emitStartOfAsmFile(Module &M) override;
   void emitEndOfAsmFile(Module &M) override;
 };
 } // namespace llvm
 
 #endif // LLVM_LIB_TARGET_M68K_M68KASMPRINTER_H

llvm/lib/Target/M68k/M68kAsmPrinter.cpp

if (!ExtraCode || !ExtraCode[0]) {
     printOperand(MI, OpNo, OS);
     return false;
   }
 
   // Fallback to the default implementation.
   return AsmPrinter::PrintAsmOperand(MI, OpNo, ExtraCode, OS);
 }
 
+void M68kAsmPrinter::printDisp(const MachineInstr *MI, unsigned opNum,
+                               raw_ostream &O) {
+  // Print immediate displacement without the '#' predix
+  const MachineOperand &Op = MI->getOperand(opNum);
+  if (Op.isImm()) {
+    O << Op.getImm();
+    return;
+  }
+  // Displacement is relocatable, so we're pretty permissive about what
+  // can be put here.
+  printOperand(MI, opNum, O);
+}
+
+void M68kAsmPrinter::printAbsMem(const MachineInstr *MI, unsigned OpNum,
+                                 raw_ostream &O) {
+  const MachineOperand &MO = MI->getOperand(OpNum);
+  if (MO.isImm())
+    O << format("$%0" PRIx64, (uint64_t)MO.getImm());
+  else
+    PrintAsmMemoryOperand(MI, OpNum, nullptr, O);
+}
+
+bool M68kAsmPrinter::PrintAsmMemoryOperand(const MachineInstr *MI,
+                                           unsigned OpNo, const char *ExtraCode,
+                                           raw_ostream &OS) {
+  const MachineOperand &MO = MI->getOperand(OpNo);
+  switch (MO.getType()) {
+  case MachineOperand::MO_Immediate:
+    // Immediate value that goes here is the addressing mode kind we set
+    // in M68kDAGToDAGISel::SelectInlineAsmMemoryOperand.
+    using namespace M68k;
+    // Skip the addressing mode kind operand.
+    ++OpNo;
+    // Decode MemAddrModeKind.
+    switch (static_cast<MemAddrModeKind>(MO.getImm())) {
+    case MemAddrModeKind::j:
+      printARIMem(MI, OpNo, OS);
+      break;
+    case MemAddrModeKind::o:
+      printARIPIMem(MI, OpNo, OS);
+      break;
+    case MemAddrModeKind::e:
+      printARIPDMem(MI, OpNo, OS);
+      break;
+    case MemAddrModeKind::p:
+      printARIDMem(MI, OpNo, OS);
+      break;
+    case MemAddrModeKind::f:
+    case MemAddrModeKind::F:
+      printARIIMem(MI, OpNo, OS);
+      break;
+    case MemAddrModeKind::k:
+      printPCIMem(MI, 0, OpNo, OS);
+      break;
+    case MemAddrModeKind::q:
+      printPCDMem(MI, 0, OpNo, OS);
+      break;
+    case MemAddrModeKind::b:
+      printAbsMem(MI, OpNo, OS);
+      break;
+    default:
+      llvm_unreachable("Unrecognized memory addressing mode");
+    }
+    return false;
+  case MachineOperand::MO_GlobalAddress:
+    PrintSymbolOperand(MO, OS);
+    return false;
+  case MachineOperand::MO_BlockAddress:
+    GetBlockAddressSymbol(MO.getBlockAddress())->print(OS, MAI);
+    return false;
+  case MachineOperand::MO_Register:
+    // This is a special case where it is treated as a memory reference, with
+    // the register holding the address value. Thus, we print it as ARI here.
+    if (M68kII::isAddressRegister(MO.getReg())) {
+      printARIMem(MI, OpNo, OS);
+      return false;
+    }
+    break;
+  default:
+    break;
+  }
+  return AsmPrinter::PrintAsmMemoryOperand(MI, OpNo, ExtraCode, OS);
+}
+
 void M68kAsmPrinter::emitInstruction(const MachineInstr *MI) {
   M68k_MC::verifyInstructionPredicates(MI->getOpcode(),
                                        getSubtargetInfo().getFeatureBits());
 
   switch (MI->getOpcode()) {
   default: {
     if (MI->isPseudo()) {
       LLVM_DEBUG(dbgs() << "Pseudo opcode(" << MI->getOpcode()

llvm/lib/Target/M68k/M68kISelDAGToDAG.cpp

#include "M68kGenDAGISel.inc"
   bool SelectARIPD(SDNode *Parent, SDValue N, SDValue &Base);
   bool SelectARID(SDNode *Parent, SDValue N, SDValue &Imm, SDValue &Base);
   bool SelectARII(SDNode *Parent, SDValue N, SDValue &Imm, SDValue &Base,
                   SDValue &Index);
   bool SelectAL(SDNode *Parent, SDValue N, SDValue &Sym);
   bool SelectPCD(SDNode *Parent, SDValue N, SDValue &Imm);
   bool SelectPCI(SDNode *Parent, SDValue N, SDValue &Imm, SDValue &Index);
 
+  bool SelectInlineAsmMemoryOperand(const SDValue &Op, unsigned ConstraintID,
+                                    std::vector<SDValue> &OutOps) override;
+
   // If Address Mode represents Frame Index store FI in Disp and
   // Displacement bit size in Base. These values are read symmetrically by
   // M68kRegisterInfo::eliminateFrameIndex method
   inline bool getFrameIndexAddress(M68kISelAddressMode &AM, const SDLoc &DL,
                                    SDValue &Disp, SDValue &Base) {
     if (AM.BaseType == M68kISelAddressMode::Base::FrameIndexBase) {
       Disp = getI32Imm(AM.Disp, DL);
       Base = CurDAG->getTargetFrameIndex(
bool M68kDAGToDAGISel::SelectARI(SDNode *Parent, SDValue N, SDValue &Base) {
   if (AM.hasBaseReg()) {
     Base = AM.BaseReg;
     LLVM_DEBUG(dbgs() << "SUCCESS\n");
     return true;
   }
 
   return false;
 }
+
+bool M68kDAGToDAGISel::SelectInlineAsmMemoryOperand(
+    const SDValue &Op, unsigned ConstraintID, std::vector<SDValue> &OutOps) {
+  // In order to tell AsmPrinter the exact addressing mode we select here, which
+  // might comprise of multiple SDValues (hence MachineOperands), a 32-bit
+  // immediate value is prepended to the list of selected SDValues to indicate
+  // the addressing mode kind.
+  using AMK = M68k::MemAddrModeKind;
+  auto addKind = [this](SDValue &Opnd, AMK Kind) -> bool {
+    Opnd = CurDAG->getTargetConstant(unsigned(Kind), SDLoc(), MVT::i32);
+    return true;
+  };
+
+  switch (ConstraintID) {
+  // Generic memory operand.
+  case InlineAsm::Constraint_m: {
+    // Try every supported (memory) addressing modes.
+    SDValue Operands[4];
+
+    // TODO: The ordering of the following SelectXXX is relatively...arbitrary,
+    // right now we simply sort them by descending complexity. Maybe we should
+    // adjust this by code model and/or relocation mode in the future.
+    if (SelectARII(nullptr, Op, Operands[1], Operands[2], Operands[3]) &&
+        addKind(Operands[0], AMK::f)) {
+      OutOps.insert(OutOps.end(), &Operands[0], Operands + 4);
+      return false;
+    }
+
+    if ((SelectPCI(nullptr, Op, Operands[1], Operands[2]) &&
+         addKind(Operands[0], AMK::k)) ||
+        (SelectARID(nullptr, Op, Operands[1], Operands[2]) &&
+         addKind(Operands[0], AMK::p))) {
+      OutOps.insert(OutOps.end(), &Operands[0], Operands + 3);
+      return false;
+    }
+
+    if ((SelectPCD(nullptr, Op, Operands[1]) && addKind(Operands[0], AMK::q)) ||
+        (SelectARI(nullptr, Op, Operands[1]) && addKind(Operands[0], AMK::j)) ||
+        (SelectAL(nullptr, Op, Operands[1]) && addKind(Operands[0], AMK::b))) {
+      OutOps.insert(OutOps.end(), {Operands[0], Operands[1]});
+      return false;
+    }
+
+    return true;
+  }
+  // 'Q': Address register indirect addressing.
+  case InlineAsm::Constraint_Q: {
+    SDValue AMKind, Base;
+    // 'j' addressing mode.
+    // TODO: Add support for 'o' and 'e' after their
+    // select functions are implemented.
+    if (SelectARI(nullptr, Op, Base) && addKind(AMKind, AMK::j)) {
+      OutOps.insert(OutOps.end(), {AMKind, Base});
+      return false;
+    }
+    return true;
+  }
+  // 'U': Address register indirect w/ constant offset addressing.
+  case InlineAsm::Constraint_Um: {
+    SDValue AMKind, Base, Offset;
+    // 'p' addressing mode.
+    if (SelectARID(nullptr, Op, Offset, Base) && addKind(AMKind, AMK::p)) {
+      OutOps.insert(OutOps.end(), {AMKind, Offset, Base});
+      return false;
+    }
+    return true;
+  }
+  default:
+    return true;
+  }
+}

llvm/lib/Target/M68k/M68kISelLowering.h

EmitInstrWithCustomInserter(MachineInstr &MI,
                               MachineBasicBlock *MBB) const override;
 
   CCAssignFn *getCCAssignFn(CallingConv::ID CC, bool Return,
                             bool IsVarArg) const;
 
   AtomicExpansionKind
   shouldExpandAtomicRMWInIR(AtomicRMWInst *RMW) const override;
 
+  unsigned getInlineAsmMemConstraint(StringRef ConstraintCode) const override;
+
 private:
   unsigned GetAlignedArgumentStackSize(unsigned StackSize,
                                        SelectionDAG &DAG) const;
 
   SDValue getReturnAddressFrameIndex(SelectionDAG &DAG) const;
 
   /// Emit a load of return address if tail call
   /// optimization is performed and it is required.

llvm/lib/Target/M68k/M68kISelLowering.cpp

 
 TargetLoweringBase::AtomicExpansionKind
 M68kTargetLowering::shouldExpandAtomicRMWInIR(AtomicRMWInst *RMW) const {
   return Subtarget.atLeastM68020()
              ? TargetLoweringBase::AtomicExpansionKind::CmpXChg
              : TargetLoweringBase::AtomicExpansionKind::None;
 }
 
+unsigned
+M68kTargetLowering::getInlineAsmMemConstraint(StringRef ConstraintCode) const {
+  return StringSwitch<unsigned>(ConstraintCode)
+      .Case("Q", InlineAsm::Constraint_Q)
+      .Case("U", InlineAsm::Constraint_Um) // We borrow Constraint_Um for 'U'.
+      .Default(TargetLowering::getInlineAsmMemConstraint(ConstraintCode));
+}
+
 EVT M68kTargetLowering::getSetCCResultType(const DataLayout &DL,
                                            LLVMContext &Context, EVT VT) const {
   // M68k SETcc producess either 0x00 or 0xFF
   return MVT::i8;
 }
 
 MVT M68kTargetLowering::getScalarShiftAmountTy(const DataLayout &DL,
                                                EVT Ty) const {
case 'C':
         case '0':
         case 'i':
         case 'j':
           return C_Immediate;
         default:
           break;
         }
       break;
+    case 'Q':
+    case 'U':
+      return C_Memory;
     default:
       break;
     }
   }
 
   return TargetLowering::getConstraintType(Constraint);
 }
 

llvm/lib/Target/M68k/MCTargetDesc/M68kBaseInfo.h

 
 /// Enums for pc-relative memory operand decoding. Supports these forms:
 /// (d,PC)
 /// (d,PC,Xn)
 /// ([bd,PC],Xn,od)
 /// ([bd,PC,Xn],od)
 enum { PCRelDisp = 0, PCRelIndex = 1, PCRelOuter = 2 };
 
+enum class MemAddrModeKind : unsigned {
+  j = 1, // (An)
+  o,     // (An)+
+  e,     // -(An)
+  p,     // (d,An)
+  f,     // (d,An,Xn.L)
+  F,     // (d,An,Xn.W)
+  g,     // (d,An,Xn.L,SCALE)
+  G,     // (d,An,Xn.W,SCALE)
+  u,     // ([bd,An],Xn.L,SCALE,od)
+  U,     // ([bd,An],Xn.W,SCALE,od)
+  v,     // ([bd,An,Xn.L,SCALE],od)
+  V,     // ([bd,An,Xn.W,SCALE],od)
+  b,     // abs.L
+  B,     // abs.W
+  q,     // (d,PC)
+  k,     // (d,PC,Xn.L)
+  K,     // (d,PC,Xn.W)
+  l,     // (d,PC,Xn.L,SCALE)
+  L,     // (d,PC,Xn.W,SCALE)
+  x,     // ([bd,PC],Xn.L,SCALE,od)
+  X,     // ([bd,PC],Xn.W,SCALE,od)
+  y,     // ([bd,PC,Xn.L,SCALE],od)
+  Y      // ([bd,PC,Xn.W,SCALE],od)
+};
+
 // On a LE host:
 // MSB                   LSB    MSB                   LSB
 // | 0x12 0x34 | 0xAB 0xCD | -> | 0xAB 0xCD | 0x12 0x34 |
 // (On a BE host nothing changes)
 template <typename value_t> value_t swapWord(value_t Val) {
   const unsigned NumWords = sizeof(Val) / 2;
   if (NumWords <= 1)
     return Val;

llvm/test/CodeGen/M68k/inline-asm.ll

 ; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
 ; RUN: llc -mtriple=m68k < %s -o - | FileCheck %s
 
+@g = internal global i32 10, align 4
+
 ; This function is primarily testing constant constraints that can NOT
 ; be easily checked by Clang. For example, 'K' and 'M' are both
 ; constraints for values that are outside certain numerical range.
 define void @constant_constraints() {
 ; CHECK-LABEL: constant_constraints:
 ; CHECK:         .cfi_startproc
 ; CHECK-NEXT:  ; %bb.0: ; %entry
 ; CHECK-NEXT:    ;APP
entry:
   store i32 %0, i32* %out, align 4
   %1 = call i32 asm sideeffect "move.l #87, $0", "=d"()
   store i32 %1, i32* %out, align 4
   %2 = call i32 asm sideeffect "move.l #66, $0", "=a"()
   store i32 %2, i32* %out, align 4
   ret void
 }
 
+define void @memory_constraints() {
+; CHECK-LABEL: memory_constraints:
+; CHECK:         .cfi_startproc
+; CHECK-NEXT:  ; %bb.0: ; %entry
+; CHECK-NEXT:    suba.l #4, %sp
+; CHECK-NEXT:    .cfi_def_cfa_offset -8
+; CHECK-NEXT:    ;APP
+; CHECK-NEXT:    move.l (0,%sp), %d1
+; CHECK-NEXT:    ;NO_APP
+; CHECK-NEXT:    ;APP
+; CHECK-NEXT:    move.l (g,%pc), %d2
+; CHECK-NEXT:    ;NO_APP
+; CHECK-NEXT:    lea (0,%sp), %a0
+; CHECK-NEXT:    ;APP
+; CHECK-NEXT:    move.l (%a0), %d3
+; CHECK-NEXT:    ;NO_APP
+; CHECK-NEXT:    ;APP
+; CHECK-NEXT:    move.l (0,%sp), %d4
+; CHECK-NEXT:    ;NO_APP
+; CHECK-NEXT:    adda.l #4, %sp
+; CHECK-NEXT:    rts
+entry:
+  %x = alloca i32, align 4
+  call void asm sideeffect "move.l $0, %d1", "*m"(ptr elementtype(i32) %x)
+  call void asm sideeffect "move.l $0, %d2", "*m"(ptr elementtype(i32) @g)
+  call void asm sideeffect "move.l $0, %d3", "*Q"(ptr elementtype(i32) %x)
+  call void asm sideeffect "move.l $0, %d4", "*U"(ptr elementtype(i32) %x)
+  ret void
+}
+