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
diff --git a/lib/Target/MBlaze/MBlazeMachineFunction.h b/lib/Target/MBlaze/MBlazeMachineFunction.h
new file mode 100644
index 0000000..a89ba13
--- /dev/null
+++ b/lib/Target/MBlaze/MBlazeMachineFunction.h
@@ -0,0 +1,140 @@
+//===-- MBlazeMachineFunctionInfo.h - Private data ----------------*- C++ -*-=//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file declares the MBlaze specific subclass of MachineFunctionInfo.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef MBLAZE_MACHINE_FUNCTION_INFO_H
+#define MBLAZE_MACHINE_FUNCTION_INFO_H
+
+#include "llvm/ADT/SmallVector.h"
+#include "llvm/ADT/VectorExtras.h"
+#include "llvm/CodeGen/MachineFunction.h"
+#include "llvm/CodeGen/MachineFrameInfo.h"
+
+namespace llvm {
+
+/// MBlazeFunctionInfo - This class is derived from MachineFunction private
+/// MBlaze target-specific information for each MachineFunction.
+class MBlazeFunctionInfo : public MachineFunctionInfo {
+
+private:
+  /// Holds for each function where on the stack the Frame Pointer must be 
+  /// saved. This is used on Prologue and Epilogue to emit FP save/restore
+  int FPStackOffset;
+
+  /// Holds for each function where on the stack the Return Address must be 
+  /// saved. This is used on Prologue and Epilogue to emit RA save/restore
+  int RAStackOffset;
+
+  /// At each function entry, two special bitmask directives must be emitted
+  /// to help debugging, for CPU and FPU callee saved registers. Both need
+  /// the negative offset from the final stack size and its higher registers
+  /// location on the stack.
+  int CPUTopSavedRegOff;
+  int FPUTopSavedRegOff;
+
+  /// MBlazeFIHolder - Holds a FrameIndex and it's Stack Pointer Offset
+  struct MBlazeFIHolder {
+
+    int FI;
+    int SPOffset;
+
+    MBlazeFIHolder(int FrameIndex, int StackPointerOffset)
+      : FI(FrameIndex), SPOffset(StackPointerOffset) {}
+  };
+
+  /// When PIC is used the GP must be saved on the stack on the function 
+  /// prologue and must be reloaded from this stack location after every 
+  /// call. A reference to its stack location and frame index must be kept 
+  /// to be used on emitPrologue and processFunctionBeforeFrameFinalized.
+  MBlazeFIHolder GPHolder;
+
+  /// On LowerFormalArguments the stack size is unknown, so the Stack
+  /// Pointer Offset calculation of "not in register arguments" must be 
+  /// postponed to emitPrologue. 
+  SmallVector<MBlazeFIHolder, 16> FnLoadArgs;
+  bool HasLoadArgs;
+
+  // When VarArgs, we must write registers back to caller stack, preserving 
+  // on register arguments. Since the stack size is unknown on 
+  // LowerFormalArguments, the Stack Pointer Offset calculation must be
+  // postponed to emitPrologue. 
+  SmallVector<MBlazeFIHolder, 4> FnStoreVarArgs;
+  bool HasStoreVarArgs;
+
+  /// SRetReturnReg - Some subtargets require that sret lowering includes
+  /// returning the value of the returned struct in a register. This field
+  /// holds the virtual register into which the sret argument is passed.
+  unsigned SRetReturnReg;
+
+  /// GlobalBaseReg - keeps track of the virtual register initialized for
+  /// use as the global base register. This is used for PIC in some PIC
+  /// relocation models.
+  unsigned GlobalBaseReg;
+
+public:
+  MBlazeFunctionInfo(MachineFunction& MF) 
+  : FPStackOffset(0), RAStackOffset(0), CPUTopSavedRegOff(0), 
+    FPUTopSavedRegOff(0), GPHolder(-1,-1), HasLoadArgs(false), 
+    HasStoreVarArgs(false), SRetReturnReg(0), GlobalBaseReg(0)
+  {}
+
+  int getFPStackOffset() const { return FPStackOffset; }
+  void setFPStackOffset(int Off) { FPStackOffset = Off; }
+
+  int getRAStackOffset() const { return RAStackOffset; }
+  void setRAStackOffset(int Off) { RAStackOffset = Off; }
+
+  int getCPUTopSavedRegOff() const { return CPUTopSavedRegOff; }
+  void setCPUTopSavedRegOff(int Off) { CPUTopSavedRegOff = Off; }
+
+  int getFPUTopSavedRegOff() const { return FPUTopSavedRegOff; }
+  void setFPUTopSavedRegOff(int Off) { FPUTopSavedRegOff = Off; }
+
+  int getGPStackOffset() const { return GPHolder.SPOffset; }
+  int getGPFI() const { return GPHolder.FI; }
+  void setGPStackOffset(int Off) { GPHolder.SPOffset = Off; }
+  void setGPFI(int FI) { GPHolder.FI = FI; }
+  bool needGPSaveRestore() const { return GPHolder.SPOffset != -1; }
+
+  bool hasLoadArgs() const { return HasLoadArgs; }
+  bool hasStoreVarArgs() const { return HasStoreVarArgs; } 
+
+  void recordLoadArgsFI(int FI, int SPOffset) {
+    if (!HasLoadArgs) HasLoadArgs=true;
+    FnLoadArgs.push_back(MBlazeFIHolder(FI, SPOffset));
+  }
+  void recordStoreVarArgsFI(int FI, int SPOffset) {
+    if (!HasStoreVarArgs) HasStoreVarArgs=true;
+    FnStoreVarArgs.push_back(MBlazeFIHolder(FI, SPOffset));
+  }
+
+  void adjustLoadArgsFI(MachineFrameInfo *MFI) const {
+    if (!hasLoadArgs()) return;
+    for (unsigned i = 0, e = FnLoadArgs.size(); i != e; ++i) 
+      MFI->setObjectOffset( FnLoadArgs[i].FI, FnLoadArgs[i].SPOffset );
+  }
+  void adjustStoreVarArgsFI(MachineFrameInfo *MFI) const {
+    if (!hasStoreVarArgs()) return; 
+    for (unsigned i = 0, e = FnStoreVarArgs.size(); i != e; ++i) 
+      MFI->setObjectOffset( FnStoreVarArgs[i].FI, FnStoreVarArgs[i].SPOffset );
+  }
+
+  unsigned getSRetReturnReg() const { return SRetReturnReg; }
+  void setSRetReturnReg(unsigned Reg) { SRetReturnReg = Reg; }
+
+  unsigned getGlobalBaseReg() const { return GlobalBaseReg; }
+  void setGlobalBaseReg(unsigned Reg) { GlobalBaseReg = Reg; }
+};
+
+} // end of namespace llvm
+
+#endif // MBLAZE_MACHINE_FUNCTION_INFO_H