[AVR] Add the AVRMCInstLower class

Summary:
This class deals with the lowering of CodeGen `MachineInstr` objects to
MC `MCInst` objects.

Reviewers: kparzysz, arsenm

Subscribers: wdng, beanz, japaric, mgorny

Differential Revision: https://reviews.llvm.org/D25269

llvm-svn: 283522

lib/Target/AVR/AVRMCInstLower.cpp

@@ -0,0 +1,100 @@
+//===-- AVRMCInstLower.cpp - Convert AVR MachineInstr to an MCInst --------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file contains code to lower AVR MachineInstrs to their corresponding
+// MCInst records.
+//
+//===----------------------------------------------------------------------===//
+
+#include "AVRMCInstLower.h"
+
+#include "AVRInstrInfo.h"
+#include "MCTargetDesc/AVRMCExpr.h"
+
+#include "llvm/CodeGen/AsmPrinter.h"
+#include "llvm/IR/Mangler.h"
+#include "llvm/MC/MCInst.h"
+#include "llvm/Support/ErrorHandling.h"
+
+namespace llvm {
+
+MCOperand AVRMCInstLower::lowerSymbolOperand(const MachineOperand &MO,
+                                             MCSymbol *Sym) const {
+  unsigned char TF = MO.getTargetFlags();
+  const MCExpr *Expr = MCSymbolRefExpr::create(Sym, Ctx);
+
+  bool IsNegated = false;
+  if (TF & AVRII::MO_NEG) { IsNegated = true; }
+
+  if (!MO.isJTI() && MO.getOffset()) {
+    Expr = MCBinaryExpr::createAdd(
+        Expr, MCConstantExpr::create(MO.getOffset(), Ctx), Ctx);
+  }
+
+  if (TF & AVRII::MO_LO) {
+    Expr = AVRMCExpr::create(AVRMCExpr::VK_AVR_LO8, Expr, IsNegated, Ctx);
+  } else if (TF & AVRII::MO_HI) {
+    Expr = AVRMCExpr::create(AVRMCExpr::VK_AVR_HI8, Expr, IsNegated, Ctx);
+  } else if (TF != 0) {
+    llvm_unreachable("Unknown target flag on symbol operand");
+  }
+
+  return MCOperand::createExpr(Expr);
+}
+
+void AVRMCInstLower::lowerInstruction(const MachineInstr &MI, MCInst &OutMI) const {
+  OutMI.setOpcode(MI.getOpcode());
+
+  for (MachineOperand const &MO : MI.operands()) {
+    MCOperand MCOp;
+
+    switch (MO.getType()) {
+    default:
+      MI.dump();
+      llvm_unreachable("unknown operand type");
+    case MachineOperand::MO_Register:
+      // Ignore all implicit register operands.
+      if (MO.isImplicit())
+        continue;
+      MCOp = MCOperand::createReg(MO.getReg());
+      break;
+    case MachineOperand::MO_Immediate:
+      MCOp = MCOperand::createImm(MO.getImm());
+      break;
+    case MachineOperand::MO_GlobalAddress:
+      MCOp = lowerSymbolOperand(MO, Printer.getSymbol(MO.getGlobal()));
+      break;
+    case MachineOperand::MO_ExternalSymbol:
+      MCOp = lowerSymbolOperand(
+          MO, Printer.GetExternalSymbolSymbol(MO.getSymbolName()));
+      break;
+    case MachineOperand::MO_MachineBasicBlock:
+      MCOp = MCOperand::createExpr(
+          MCSymbolRefExpr::create(MO.getMBB()->getSymbol(), Ctx));
+      break;
+    case MachineOperand::MO_RegisterMask:
+      continue;
+    case MachineOperand::MO_BlockAddress:
+      MCOp = lowerSymbolOperand(
+          MO, Printer.GetBlockAddressSymbol(MO.getBlockAddress()));
+      break;
+    case MachineOperand::MO_JumpTableIndex:
+      MCOp = lowerSymbolOperand(MO, Printer.GetJTISymbol(MO.getIndex()));
+      break;
+    case MachineOperand::MO_ConstantPoolIndex:
+      MCOp = lowerSymbolOperand(MO, Printer.GetCPISymbol(MO.getIndex()));
+      break;
+    }
+
+    OutMI.addOperand(MCOp);
+  }
+}
+
+} // end of namespace llvm
+

lib/Target/AVR/AVRMCInstLower.h

@@ -0,0 +1,43 @@
+//===-- AVRMCInstLower.h - Lower MachineInstr to MCInst ---------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_AVR_MCINST_LOWER_H
+#define LLVM_AVR_MCINST_LOWER_H
+
+#include "llvm/Support/Compiler.h"
+
+namespace llvm {
+
+class AsmPrinter;
+class MachineInstr;
+class MachineOperand;
+class MCContext;
+class MCInst;
+class MCOperand;
+class MCSymbol;
+
+/// Lowers `MachineInstr` objects into `MCInst` objects.
+class AVRMCInstLower {
+public:
+  AVRMCInstLower(MCContext &Ctx, AsmPrinter &Printer)
+      : Ctx(Ctx), Printer(Printer) {}
+
+  /// Lowers a `MachineInstr` into a `MCInst`.
+  void lowerInstruction(const MachineInstr &MI, MCInst &OutMI) const;
+  MCOperand lowerSymbolOperand(const MachineOperand &MO, MCSymbol *Sym) const;
+
+private:
+  MCContext &Ctx;
+  AsmPrinter &Printer;
+};
+
+} // end namespace llvm
+
+#endif // LLVM_AVR_MCINST_LOWER_H
+

lib/Target/AVR/CMakeLists.txt

@@ -10,6 +10,7 @@ add_public_tablegen_target(AVRCommonTableGen)
 add_llvm_target(AVRCodeGen
   AVRFrameLowering.cpp
   AVRInstrInfo.cpp
+  AVRMCInstLower.cpp
   AVRRegisterInfo.cpp
   AVRSubtarget.cpp
   AVRTargetMachine.cpp