Adding the MicroBlaze backend.

The MicroBlaze is a highly configurable 32-bit soft-microprocessor for
use on Xilinx FPGAs. For more information see:
http://www.xilinx.com/tools/microblaze.htm
http://en.wikipedia.org/wiki/MicroBlaze

The current LLVM MicroBlaze backend generates assembly which can be
compiled using the an appropriate binutils assembler.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@96969 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 368 insertions, 0 deletions

diff --git a/lib/Target/MBlaze/MBlazeISelDAGToDAG.cpp b/lib/Target/MBlaze/MBlazeISelDAGToDAG.cpp
new file mode 100644
index 0000000000..f4b4c3d6ad
--- /dev/null
+++ b/lib/Target/MBlaze/MBlazeISelDAGToDAG.cpp
@@ -0,0 +1,368 @@
+//===-- MBlazeISelDAGToDAG.cpp - A dag to dag inst selector for MBlaze ----===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file defines an instruction selector for the MBlaze target.
+//
+//===----------------------------------------------------------------------===//
+
+#define DEBUG_TYPE "mblaze-isel"
+#include "MBlaze.h"
+#include "MBlazeISelLowering.h"
+#include "MBlazeMachineFunction.h"
+#include "MBlazeRegisterInfo.h"
+#include "MBlazeSubtarget.h"
+#include "MBlazeTargetMachine.h"
+#include "llvm/GlobalValue.h"
+#include "llvm/Instructions.h"
+#include "llvm/Intrinsics.h"
+#include "llvm/Support/CFG.h"
+#include "llvm/Type.h"
+#include "llvm/CodeGen/MachineConstantPool.h"
+#include "llvm/CodeGen/MachineFunction.h"
+#include "llvm/CodeGen/MachineFrameInfo.h"
+#include "llvm/CodeGen/MachineInstrBuilder.h"
+#include "llvm/CodeGen/MachineRegisterInfo.h"
+#include "llvm/CodeGen/SelectionDAGISel.h"
+#include "llvm/Target/TargetMachine.h"
+#include "llvm/Support/Debug.h"
+#include "llvm/Support/ErrorHandling.h"
+#include "llvm/Support/raw_ostream.h"
+using namespace llvm;
+
+//===----------------------------------------------------------------------===//
+// Instruction Selector Implementation
+//===----------------------------------------------------------------------===//
+
+//===----------------------------------------------------------------------===//
+// MBlazeDAGToDAGISel - MBlaze specific code to select MBlaze machine
+// instructions for SelectionDAG operations.
+//===----------------------------------------------------------------------===//
+namespace {
+
+class MBlazeDAGToDAGISel : public SelectionDAGISel {
+
+  /// TM - Keep a reference to MBlazeTargetMachine.
+  MBlazeTargetMachine &TM;
+
+  /// Subtarget - Keep a pointer to the MBlazeSubtarget around so that we can
+  /// make the right decision when generating code for different targets.
+  const MBlazeSubtarget &Subtarget;
+
+public:
+  explicit MBlazeDAGToDAGISel(MBlazeTargetMachine &tm) :
+  SelectionDAGISel(tm),
+  TM(tm), Subtarget(tm.getSubtarget<MBlazeSubtarget>()) {}
+
+  virtual void InstructionSelect();
+
+  // Pass Name
+  virtual const char *getPassName() const {
+    return "MBlaze DAG->DAG Pattern Instruction Selection";
+  }
+private:
+  // Include the pieces autogenerated from the target description.
+  #include "MBlazeGenDAGISel.inc"
+
+  /// getTargetMachine - Return a reference to the TargetMachine, casted
+  /// to the target-specific type.
+  const MBlazeTargetMachine &getTargetMachine() {
+    return static_cast<const MBlazeTargetMachine &>(TM);
+  }
+
+  /// getInstrInfo - Return a reference to the TargetInstrInfo, casted
+  /// to the target-specific type.
+  const MBlazeInstrInfo *getInstrInfo() {
+    return getTargetMachine().getInstrInfo();
+  }
+
+  SDNode *getGlobalBaseReg();
+  SDNode *Select(SDNode *N);
+
+  // Complex Pattern.
+  bool SelectAddr(SDNode *Op, SDValue N,
+                  SDValue &Base, SDValue &Offset);
+
+  // Address Selection
+  bool SelectAddrRegReg(SDNode *Op, SDValue N, SDValue &Base, SDValue &Index);
+  bool SelectAddrRegImm(SDNode *Op, SDValue N, SDValue &Disp, SDValue &Base);
+
+  // getI32Imm - Return a target constant with the specified value, of type i32.
+  inline SDValue getI32Imm(unsigned Imm) {
+    return CurDAG->getTargetConstant(Imm, MVT::i32);
+  }
+
+
+  #ifndef NDEBUG
+  unsigned Indent;
+  #endif
+};
+
+}
+
+/// isIntS32Immediate - This method tests to see if the node is either a 32-bit
+/// or 64-bit immediate, and if the value can be accurately represented as a
+/// sign extension from a 32-bit value.  If so, this returns true and the
+/// immediate.
+static bool isIntS32Immediate(SDNode *N, int32_t &Imm) {
+  unsigned Opc = N->getOpcode();
+  if (Opc != ISD::Constant)
+    return false;
+
+  Imm = (int32_t)cast<ConstantSDNode>(N)->getZExtValue();
+  if (N->getValueType(0) == MVT::i32)
+    return Imm == (int32_t)cast<ConstantSDNode>(N)->getZExtValue();
+  else
+    return Imm == (int64_t)cast<ConstantSDNode>(N)->getZExtValue();
+}
+
+static bool isIntS32Immediate(SDValue Op, int32_t &Imm) {
+  return isIntS32Immediate(Op.getNode(), Imm);
+}
+
+/// InstructionSelect - This callback is invoked by
+/// SelectionDAGISel when it has created a SelectionDAG for us to codegen.
+void MBlazeDAGToDAGISel::InstructionSelect() {
+  // Codegen the basic block.
+  DEBUG(errs() << "===== Instruction selection begins:\n");
+  DEBUG(Indent = 0);
+
+  // Select target instructions for the DAG.
+  SelectRoot(*CurDAG);
+
+  DEBUG(errs() << "===== Instruction selection ends:\n");
+
+  CurDAG->RemoveDeadNodes();
+}
+
+/// SelectAddressRegReg - Given the specified addressed, check to see if it
+/// can be represented as an indexed [r+r] operation.  Returns false if it
+/// can be more efficiently represented with [r+imm].
+bool MBlazeDAGToDAGISel::
+SelectAddrRegReg(SDNode *Op, SDValue N, SDValue &Base, SDValue &Index) {
+  if (N.getOpcode() == ISD::FrameIndex) return false;
+  if (N.getOpcode() == ISD::TargetExternalSymbol ||
+      N.getOpcode() == ISD::TargetGlobalAddress)
+    return false;  // direct calls.
+
+  if (N.getOperand(0).getOpcode() == ISD::TargetJumpTable ||
+      N.getOperand(1).getOpcode() == ISD::TargetJumpTable)
+    return false; // jump tables.
+
+  int32_t imm = 0;
+  if (N.getOpcode() == ISD::ADD || N.getOpcode() == ISD::OR) {
+    if (isIntS32Immediate(N.getOperand(1), imm))
+      return false;    // r+i
+
+    Base = N.getOperand(1);
+    Index = N.getOperand(0);
+    return true;
+  }
+
+  return false;
+}
+
+/// Returns true if the address N can be represented by a base register plus
+/// a signed 32-bit displacement [r+imm], and if it is not better
+/// represented as reg+reg.
+bool MBlazeDAGToDAGISel::
+SelectAddrRegImm(SDNode *Op, SDValue N, SDValue &Disp, SDValue &Base) {
+  // If this can be more profitably realized as r+r, fail.
+  if (SelectAddrRegReg(Op, N, Disp, Base))
+    return false;
+
+  if (N.getOpcode() == ISD::ADD || N.getOpcode() == ISD::OR) {
+    int32_t imm = 0;
+    if (isIntS32Immediate(N.getOperand(1), imm)) {
+      Disp = CurDAG->getTargetConstant(imm, MVT::i32);
+      if (FrameIndexSDNode *FI = dyn_cast<FrameIndexSDNode>(N.getOperand(0))) {
+        Base = CurDAG->getTargetFrameIndex(FI->getIndex(), N.getValueType());
+      } else {
+        Base = N.getOperand(0);
+      }
+      DEBUG( errs() << "WESLEY: Using Operand Immediate\n" );
+      return true; // [r+i]
+    }
+  } else if (ConstantSDNode *CN = dyn_cast<ConstantSDNode>(N)) {
+    // Loading from a constant address.
+    uint32_t Imm = CN->getZExtValue();
+    Disp = CurDAG->getTargetConstant(Imm, CN->getValueType(0));
+    Base = CurDAG->getRegister(MBlaze::R0, CN->getValueType(0));
+    DEBUG( errs() << "WESLEY: Using Constant Node\n" );
+    return true;
+  }
+
+  Disp = CurDAG->getTargetConstant(0, TM.getTargetLowering()->getPointerTy());
+  if (FrameIndexSDNode *FI = dyn_cast<FrameIndexSDNode>(N))
+    Base = CurDAG->getTargetFrameIndex(FI->getIndex(), N.getValueType());
+  else
+    Base = N;
+  return true;      // [r+0]
+}
+
+/// getGlobalBaseReg - Output the instructions required to put the
+/// GOT address into a register.
+SDNode *MBlazeDAGToDAGISel::getGlobalBaseReg() {
+  unsigned GlobalBaseReg = getInstrInfo()->getGlobalBaseReg(MF);
+  return CurDAG->getRegister(GlobalBaseReg, TLI.getPointerTy()).getNode();
+}
+
+/// ComplexPattern used on MBlazeInstrInfo
+/// Used on MBlaze Load/Store instructions
+bool MBlazeDAGToDAGISel::
+SelectAddr(SDNode *Op, SDValue Addr, SDValue &Offset, SDValue &Base) {
+  // if Address is FI, get the TargetFrameIndex.
+  if (FrameIndexSDNode *FIN = dyn_cast<FrameIndexSDNode>(Addr)) {
+    Base   = CurDAG->getTargetFrameIndex(FIN->getIndex(), MVT::i32);
+    Offset = CurDAG->getTargetConstant(0, MVT::i32);
+    return true;
+  }
+
+  // on PIC code Load GA
+  if (TM.getRelocationModel() == Reloc::PIC_) {
+    if ((Addr.getOpcode() == ISD::TargetGlobalAddress) ||
+        (Addr.getOpcode() == ISD::TargetConstantPool) ||
+        (Addr.getOpcode() == ISD::TargetJumpTable)){
+      Base   = CurDAG->getRegister(MBlaze::R15, MVT::i32);
+      Offset = Addr;
+      return true;
+    }
+  } else {
+    if ((Addr.getOpcode() == ISD::TargetExternalSymbol ||
+        Addr.getOpcode() == ISD::TargetGlobalAddress))
+      return false;
+  }
+
+  // Operand is a result from an ADD.
+  if (Addr.getOpcode() == ISD::ADD) {
+    if (ConstantSDNode *CN = dyn_cast<ConstantSDNode>(Addr.getOperand(1))) {
+      if (Predicate_immSExt16(CN)) {
+
+        // If the first operand is a FI, get the TargetFI Node
+        if (FrameIndexSDNode *FIN = dyn_cast<FrameIndexSDNode>
+                                    (Addr.getOperand(0))) {
+          Base = CurDAG->getTargetFrameIndex(FIN->getIndex(), MVT::i32);
+        } else {
+          Base = Addr.getOperand(0);
+        }
+
+        Offset = CurDAG->getTargetConstant(CN->getZExtValue(), MVT::i32);
+        return true;
+      }
+    }
+  }
+
+  Base   = Addr;
+  Offset = CurDAG->getTargetConstant(0, MVT::i32);
+  return true;
+}
+
+/// Select instructions not customized! Used for
+/// expanded, promoted and normal instructions
+SDNode* MBlazeDAGToDAGISel::Select(SDNode *Node) {
+  unsigned Opcode = Node->getOpcode();
+  DebugLoc dl = Node->getDebugLoc();
+
+  // Dump information about the Node being selected
+  DEBUG(errs().indent(Indent) << "Selecting: ";
+        Node->dump(CurDAG);
+        errs() << "\n");
+  DEBUG(Indent += 2);
+
+  // If we have a custom node, we already have selected!
+  if (Node->isMachineOpcode()) {
+    DEBUG(errs().indent(Indent-2) << "== ";
+          Node->dump(CurDAG);
+          errs() << "\n");
+    DEBUG(Indent -= 2);
+    return NULL;
+  }
+
+  ///
+  // Instruction Selection not handled by the auto-generated
+  // tablegen selection should be handled here.
+  ///
+  switch(Opcode) {
+    default: break;
+
+    // Get target GOT address.
+    case ISD::GLOBAL_OFFSET_TABLE:
+      return getGlobalBaseReg();
+
+    case ISD::FrameIndex: {
+        SDValue imm = CurDAG->getTargetConstant(0, MVT::i32);
+        int FI = dyn_cast<FrameIndexSDNode>(Node)->getIndex();
+        EVT VT = Node->getValueType(0);
+        SDValue TFI = CurDAG->getTargetFrameIndex(FI, VT);
+        unsigned Opc = MBlaze::ADDI;
+        if (Node->hasOneUse())
+          return CurDAG->SelectNodeTo(Node, Opc, VT, TFI, imm);
+        return CurDAG->getMachineNode(Opc, dl, VT, TFI, imm);
+    }
+
+
+    /// Handle direct and indirect calls when using PIC. On PIC, when
+    /// GOT is smaller than about 64k (small code) the GA target is
+    /// loaded with only one instruction. Otherwise GA's target must
+    /// be loaded with 3 instructions.
+    case MBlazeISD::JmpLink: {
+      if (TM.getRelocationModel() == Reloc::PIC_) {
+        SDValue Chain  = Node->getOperand(0);
+        SDValue Callee = Node->getOperand(1);
+        SDValue R20Reg = CurDAG->getRegister(MBlaze::R20, MVT::i32);
+        SDValue InFlag(0, 0);
+
+        if ( (isa<GlobalAddressSDNode>(Callee)) ||
+             (isa<ExternalSymbolSDNode>(Callee)) )
+        {
+          /// Direct call for global addresses and external symbols
+          SDValue GPReg = CurDAG->getRegister(MBlaze::R15, MVT::i32);
+
+          // Use load to get GOT target
+          SDValue Ops[] = { Callee, GPReg, Chain };
+          SDValue Load = SDValue(CurDAG->getMachineNode(MBlaze::LW, dl,
+                                 MVT::i32, MVT::Other, Ops, 3), 0);
+          Chain = Load.getValue(1);
+
+          // Call target must be on T9
+          Chain = CurDAG->getCopyToReg(Chain, dl, R20Reg, Load, InFlag);
+        } else
+          /// Indirect call
+          Chain = CurDAG->getCopyToReg(Chain, dl, R20Reg, Callee, InFlag);
+
+        // Emit Jump and Link Register
+        SDNode *ResNode = CurDAG->getMachineNode(MBlaze::BRLID, dl, MVT::Other,
+                                                 MVT::Flag, R20Reg, Chain);
+        Chain  = SDValue(ResNode, 0);
+        InFlag = SDValue(ResNode, 1);
+        ReplaceUses(SDValue(Node, 0), Chain);
+        ReplaceUses(SDValue(Node, 1), InFlag);
+        return ResNode;
+      }
+    }
+  }
+
+  // Select the default instruction
+  SDNode *ResNode = SelectCode(Node);
+
+  DEBUG(errs().indent(Indent-2) << "=> ");
+  if (ResNode == NULL || ResNode == Node)
+    DEBUG(Node->dump(CurDAG));
+  else
+    DEBUG(ResNode->dump(CurDAG));
+  DEBUG(errs() << "\n");
+  DEBUG(Indent -= 2);
+
+  return ResNode;
+}
+
+/// createMBlazeISelDag - This pass converts a legalized DAG into a
+/// MBlaze-specific DAG, ready for instruction scheduling.
+FunctionPass *llvm::createMBlazeISelDag(MBlazeTargetMachine &TM) {
+  return new MBlazeDAGToDAGISel(TM);
+}