Add AArch64 as an experimental target.

This patch adds support for AArch64 (ARM's 64-bit architecture) to
LLVM in the "experimental" category. Currently, it won't be built
unless requested explicitly.

This initial commit should have support for:
    + Assembly of all scalar (i.e. non-NEON, non-Crypto) instructions
      (except the late addition CRC instructions).
    + CodeGen features required for C++03 and C99.
    + Compilation for the "small" memory model: code+static data <
      4GB.
    + Absolute and position-independent code.
    + GNU-style (i.e. "__thread") TLS.
    + Debugging information.

The principal omission, currently, is performance tuning.

This patch excludes the NEON support also reviewed due to an outbreak of
batshit insanity in our legal department. That will be committed soon bringing
the changes to precisely what has been approved.

Further reviews would be gratefully received.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@174054 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 103 insertions, 0 deletions

diff --git a/lib/Target/AArch64/AArch64FrameLowering.h b/lib/Target/AArch64/AArch64FrameLowering.h
new file mode 100644
index 0000000..dfa66ec
--- /dev/null
+++ b/lib/Target/AArch64/AArch64FrameLowering.h
@@ -0,0 +1,103 @@
+//==- AArch64FrameLowering.h - Define frame lowering for AArch64 -*- C++ -*--=//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+//
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_AARCH64_FRAMEINFO_H
+#define LLVM_AARCH64_FRAMEINFO_H
+
+#include "AArch64Subtarget.h"
+#include "llvm/Target/TargetFrameLowering.h"
+
+namespace llvm {
+class AArch64Subtarget;
+
+class AArch64FrameLowering : public TargetFrameLowering {
+private:
+  // In order to unify the spilling and restoring of callee-saved registers into
+  // emitFrameMemOps, we need to be able to specify which instructions to use
+  // for the relevant memory operations on each register class. An array of the
+  // following struct is populated and passed in to achieve this.
+  struct LoadStoreMethod {
+    const TargetRegisterClass *RegClass; // E.g. GPR64RegClass
+
+    // The preferred instruction. 
+    unsigned PairOpcode; // E.g. LSPair64_STR
+
+    // Sometimes only a single register can be handled at once.
+    unsigned SingleOpcode; // E.g. LS64_STR
+  };
+protected:
+  const AArch64Subtarget &STI;
+
+public:
+  explicit AArch64FrameLowering(const AArch64Subtarget &sti)
+    : TargetFrameLowering(TargetFrameLowering::StackGrowsDown, 16, 0, 16),
+      STI(sti) {
+  }
+
+  /// emitProlog/emitEpilog - These methods insert prolog and epilog code into
+  /// the function.
+  virtual void emitPrologue(MachineFunction &MF) const;
+  virtual void emitEpilogue(MachineFunction &MF, MachineBasicBlock &MBB) const;
+
+  /// Decides how much stack adjustment to perform in each phase of the prologue
+  /// and epilogue.
+  void splitSPAdjustments(uint64_t Total, uint64_t &Initial,
+                          uint64_t &Residual) const;
+
+  int64_t resolveFrameIndexReference(MachineFunction &MF, int FrameIndex,
+                                     unsigned &FrameReg, int SPAdj,
+                                     bool IsCalleeSaveOp) const;
+
+  virtual void processFunctionBeforeCalleeSavedScan(MachineFunction &MF,
+                                                    RegScavenger *RS) const;
+
+  virtual bool spillCalleeSavedRegisters(MachineBasicBlock &MBB,
+                                        MachineBasicBlock::iterator MI,
+                                        const std::vector<CalleeSavedInfo> &CSI,
+                                        const TargetRegisterInfo *TRI) const;
+  virtual bool restoreCalleeSavedRegisters(MachineBasicBlock &MBB,
+                                        MachineBasicBlock::iterator MI,
+                                        const std::vector<CalleeSavedInfo> &CSI,
+                                        const TargetRegisterInfo *TRI) const;
+
+  /// If the register is X30 (i.e. LR) and the return address is used in the
+  /// function then the callee-save store doesn't actually kill the register,
+  /// otherwise it does.
+  bool determinePrologueDeath(MachineBasicBlock &MBB, unsigned Reg) const;
+
+  /// This function emits the loads or stores required during prologue and
+  /// epilogue as efficiently as possible.
+  ///
+  /// The operations involved in setting up and tearing down the frame are
+  /// similar enough to warrant a shared function, particularly as discrepancies
+  /// between the two would be disastrous.
+  void emitFrameMemOps(bool isStore, MachineBasicBlock &MBB,
+                       MachineBasicBlock::iterator MI,
+                       const std::vector<CalleeSavedInfo> &CSI,
+                       const TargetRegisterInfo *TRI,
+                       LoadStoreMethod PossibleClasses[],
+                       unsigned NumClasses) const;
+
+
+  virtual bool hasFP(const MachineFunction &MF) const;
+
+  virtual bool useFPForAddressing(const MachineFunction &MF) const;
+
+  /// On AA
+  virtual bool hasReservedCallFrame(const MachineFunction &MF) const;
+
+};
+
+} // End llvm namespace
+
+#endif