[AVR] Add the assembly instruction printer

[dylanmckay]

Summary

This change adds the AVR assembly instruction printer.

No tests are included in this patch. I have left them downstream so we can
add them once llc successfully runs (there's very few components left
to upstream until this).

[kparzysz]

lib/Target/AVR/InstPrinter/AVRInstPrinter.cpp

94

Please prefer to spell out the type when it's not immediately obvious what the type is. In a case like this there is not much to be saved by using auto anyway.

158

Please replace "auto" with the type. Especially given that line 131 lists the type explicitly.

[dylanmckay]

Remove 'auto' in favor of concrete types in a few cases

It helps readablilty.

lib/Target/AVR/CMakeLists.txt

add_llvm_target(AVRCodeGen
   AVRRegisterInfo.cpp
   AVRSubtarget.cpp
   AVRTargetMachine.cpp
   AVRTargetObjectFile.cpp
 )
 
 add_dependencies(LLVMAVRCodeGen intrinsics_gen)
 
+add_subdirectory(AsmParser)
+add_subdirectory(InstPrinter)
 add_subdirectory(MCTargetDesc)
 add_subdirectory(TargetInfo)
-add_subdirectory(AsmParser)
 

lib/Target/AVR/InstPrinter/AVRInstPrinter.h

+//===- AVRInstPrinter.h - Convert AVR MCInst to assembly syntax -*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This class prints an AVR MCInst to a .s file.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_AVR_INST_PRINTER_H
+#define LLVM_AVR_INST_PRINTER_H
+
+#include "llvm/MC/MCInstPrinter.h"
+
+#include "MCTargetDesc/AVRMCTargetDesc.h"
+
+namespace llvm {
+
+/// Prints AVR instructions to a textual stream.
+class AVRInstPrinter : public MCInstPrinter {
+public:
+  AVRInstPrinter(const MCAsmInfo &MAI, const MCInstrInfo &MII,
+                 const MCRegisterInfo &MRI)
+      : MCInstPrinter(MAI, MII, MRI) {}
+
+  static const char *getPrettyRegisterName(unsigned RegNo,
+                                           MCRegisterInfo const &MRI);
+
+  void printInst(const MCInst *MI, raw_ostream &O, StringRef Annot,
+                 const MCSubtargetInfo &STI) override;
+
+private:
+  static const char *getRegisterName(unsigned RegNo,
+                                     unsigned AltIdx = AVR::NoRegAltName);
+
+  void printOperand(const MCInst *MI, unsigned OpNo, raw_ostream &O);
+  void printPCRelImm(const MCInst *MI, unsigned OpNo, raw_ostream &O);
+  void printMemri(const MCInst *MI, unsigned OpNo, raw_ostream &O);
+
+  // Autogenerated by TableGen.
+  void printInstruction(const MCInst *MI, raw_ostream &O);
+  bool printAliasInstr(const MCInst *MI, raw_ostream &O);
+  void printCustomAliasOperand(const MCInst *MI, unsigned OpIdx,
+                               unsigned PrintMethodIdx, raw_ostream &O);
+};
+
+} // end namespace llvm
+
+#endif // LLVM_AVR_INST_PRINTER_H
+

lib/Target/AVR/InstPrinter/AVRInstPrinter.cpp

+//===-- AVRInstPrinter.cpp - Convert AVR MCInst to assembly syntax --------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This class prints an AVR MCInst to a .s file.
+//
+//===----------------------------------------------------------------------===//
+
+#include "AVRInstPrinter.h"
+
+#include "MCTargetDesc/AVRMCTargetDesc.h"
+
+#include "llvm/MC/MCExpr.h"
+#include "llvm/MC/MCInst.h"
+#include "llvm/MC/MCInstrDesc.h"
+#include "llvm/MC/MCInstrInfo.h"
+#include "llvm/MC/MCRegisterInfo.h"
+#include "llvm/Support/ErrorHandling.h"
+#include "llvm/Support/FormattedStream.h"
+
+#include <cstring>
+
+#define DEBUG_TYPE "asm-printer"
+
+namespace llvm {
+
+// Include the auto-generated portion of the assembly writer.
+#define PRINT_ALIAS_INSTR
+#include "AVRGenAsmWriter.inc"
+
+void AVRInstPrinter::printInst(const MCInst *MI, raw_ostream &O,
+                               StringRef Annot, const MCSubtargetInfo &STI) {
+  unsigned Opcode = MI->getOpcode();
+
+  // First handle load and store instructions with postinc or predec
+  // of the form "ld reg, X+".
+  // TODO: We should be able to rewrite this using TableGen data.
+  switch (Opcode) {
+  case AVR::LDRdPtr:
+  case AVR::LDRdPtrPi:
+  case AVR::LDRdPtrPd:
+    O << "\tld\t";
+    printOperand(MI, 0, O);
+    O << ", ";
+
+    if (Opcode == AVR::LDRdPtrPd)
+      O << '-';
+
+    printOperand(MI, 1, O);
+
+    if (Opcode == AVR::LDRdPtrPi)
+      O << '+';
+    break;
+  case AVR::STPtrRr:
+    O << "\tst\t";
+    printOperand(MI, 0, O);
+    O << ", ";
+    printOperand(MI, 1, O);
+    break;
+  case AVR::STPtrPiRr:
+  case AVR::STPtrPdRr:
+    O << "\tst\t";
+
+    if (Opcode == AVR::STPtrPdRr)
+      O << '-';
+
+    printOperand(MI, 1, O);
+
+    if (Opcode == AVR::STPtrPiRr)
+      O << '+';
+
+    O << ", ";
+    printOperand(MI, 2, O);
+    break;
+  default:
+    if (!printAliasInstr(MI, O))
+      printInstruction(MI, O);
+
+    printAnnotation(O, Annot);
+    break;
+  }
+}
+
+const char *AVRInstPrinter::getPrettyRegisterName(unsigned RegNum,
+                                                  MCRegisterInfo const &MRI) {
+  // GCC prints register pairs by just printing the lower register
+  // If the register contains a subregister, print it instead
+  if (MRI.getNumSubRegIndices() > 0) {
+    auto RegLoNum = MRI.getSubReg(RegNum, AVR::sub_lo);
+    RegNum = (RegLoNum != AVR::NoRegister) ? RegLoNum : RegNum;
+  }
+
+  return getRegisterName(RegNum);
+}
+
+void AVRInstPrinter::printOperand(const MCInst *MI, unsigned OpNo,
+                                  raw_ostream &O) {
+  const MCOperand &Op = MI->getOperand(OpNo);
+  const MCOperandInfo &MOI = this->MII.get(MI->getOpcode()).OpInfo[OpNo];
+
+  if (Op.isReg()) {
+    bool isPtrReg = (MOI.RegClass == AVR::PTRREGSRegClassID) ||
+                    (MOI.RegClass == AVR::PTRDISPREGSRegClassID) ||
+                    (MOI.RegClass == AVR::ZREGSRegClassID);
+
+    if (isPtrReg) {
+      O << getRegisterName(Op.getReg(), AVR::ptr);
+    } else {
+      O << getPrettyRegisterName(Op.getReg(), MRI);
+    }
+  } else if (Op.isImm()) {
+    O << Op.getImm();
+  } else {
+    assert(Op.isExpr() && "Unknown operand kind in printOperand");
+    O << *Op.getExpr();
+  }
+}
+
+/// This is used to print an immediate value that ends up
+/// being encoded as a pc-relative value.
+void AVRInstPrinter::printPCRelImm(const MCInst *MI, unsigned OpNo,
+                                   raw_ostream &O) {
+  const MCOperand &Op = MI->getOperand(OpNo);
+
+  if (Op.isImm()) {
+    int64_t Imm = Op.getImm();
+    O << '.';
+
+    // Print a position sign if needed.
+    // Negative values have their sign printed automatically.
+    if (Imm >= 0)
+      O << '+';
+
+    O << Imm;
+  } else {
+    assert(Op.isExpr() && "Unknown pcrel immediate operand");
+    O << *Op.getExpr();
+  }
+}
+
+void AVRInstPrinter::printMemri(const MCInst *MI, unsigned OpNo,
+                                raw_ostream &O) {
+  const MCOperand &RegOp = MI->getOperand(OpNo);
+  const MCOperand &OffsetOp = MI->getOperand(OpNo + 1);
+
+  assert(RegOp.isReg() && "Expected a register");
+
+  // Print the register.
+  printOperand(MI, OpNo, O);
+
+  // Print the {+,-}offset.
+  if (OffsetOp.isImm()) {
+    auto Offset = OffsetOp.getImm();
+
+    if (Offset >= 0)
+      O << '+';
+
+    O << Offset;
+  } else if (OffsetOp.isExpr()) {
+    O << *OffsetOp.getExpr();
+  } else {
+    llvm_unreachable("unknown type for offset");
+  }
+}
+
+} // end of namespace llvm
+

lib/Target/AVR/InstPrinter/CMakeLists.txt

+include_directories( ${CMAKE_CURRENT_BINARY_DIR}/..
+                     ${CMAKE_CURRENT_SOURCE_DIR}/.. )
+
+add_llvm_library(LLVMAVRAsmPrinter
+  AVRInstPrinter.cpp
+  )
+
+add_dependencies(LLVMAVRAsmPrinter AVRCommonTableGen)
 No newline at end of file

lib/Target/AVR/InstPrinter/LLVMBuild.txt

-;===- ./lib/Target/AVR/LLVMBuild.txt ---------------------------*- Conf -*--===;
+;===- ./lib/Target/AVR/InstPrinter/LLVMBuild.txt ----------------*- Conf -*--===;
 ;
 ;                     The LLVM Compiler Infrastructure
 ;
 ; This file is distributed under the University of Illinois Open Source
 ; License. See LICENSE.TXT for details.
 ;
 ;===------------------------------------------------------------------------===;
 ;
 ; This is an LLVMBuild description file for the components in this subdirectory.
 ;
 ; For more information on the LLVMBuild system, please see:
 ;
 ;   http://llvm.org/docs/LLVMBuild.html
 ;
 ;===------------------------------------------------------------------------===;
 
-[common]
-subdirectories = TargetInfo
-
 [component_0]
-type = TargetGroup
-name = AVR
-parent = Target
-has_asmprinter = 0
-has_asmparser = 1
-
-[component_1]
 type = Library
-name = AVRCodeGen
+name = AVRAsmPrinter
 parent = AVR
-required_libraries = AsmPrinter CodeGen Core MC AVRInfo SelectionDAG Support Target
-add_to_library_groups = AVR
+required_libraries = MC Support
+add_to_library_groups = AVR
 No newline at end of file

lib/Target/AVR/LLVMBuild.txt

 
 [common]
 subdirectories = TargetInfo
 
 [component_0]
 type = TargetGroup
 name = AVR
 parent = Target
-has_asmprinter = 0
+has_asmprinter = 1
 has_asmparser = 1
 
 [component_1]
 type = Library
 name = AVRCodeGen
 parent = AVR
 required_libraries = AsmPrinter CodeGen Core MC AVRInfo SelectionDAG Support Target
 add_to_library_groups = AVR