Second try of initial ARM/Thumb disassembler check-in. It consists of a tablgen

backend (ARMDecoderEmitter) which emits the decoder functions for ARM and Thumb,
and the disassembler core which invokes the decoder function and builds up the
MCInst based on the decoded Opcode.

Reviewed by Chris Latter and Bob Wilson.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@100233 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 280 insertions, 0 deletions

diff --git a/lib/Target/ARM/Disassembler/ARMDisassemblerCore.h b/lib/Target/ARM/Disassembler/ARMDisassemblerCore.h
new file mode 100644
index 0000000000..8bf84dad93
--- /dev/null
+++ b/lib/Target/ARM/Disassembler/ARMDisassemblerCore.h
@@ -0,0 +1,280 @@
+//===- ARMDisassemblerCore.h - ARM disassembler helpers ---------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file is part of the ARM Disassembler.
+//
+// The first part defines the enumeration type of ARM instruction format, which
+// specifies the encoding used by the instruction, as well as a helper function
+// to convert the enums to printable char strings.
+//
+// It also contains code to represent the concepts of Builder, Builder Factory,
+// as well as the Algorithm to solve the problem of disassembling an ARM instr.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef ARMDISASSEMBLERCORE_H
+#define ARMDISASSEMBLERCORE_H
+
+#include "llvm/MC/MCInst.h"
+#include "llvm/Target/TargetInstrInfo.h"
+#include "ARMInstrInfo.h"
+#include "ARMDisassembler.h"
+
+namespace llvm {
+
+class ARMUtils {
+public:
+  static const char *OpcodeName(unsigned Opcode);
+};
+
+/////////////////////////////////////////////////////
+//                                                 //
+//  Enums and Utilities for ARM Instruction Format //
+//                                                 //
+/////////////////////////////////////////////////////
+
+#define ARM_FORMATS                   \
+  ENTRY(ARM_FORMAT_PSEUDO,         0) \
+  ENTRY(ARM_FORMAT_MULFRM,         1) \
+  ENTRY(ARM_FORMAT_BRFRM,          2) \
+  ENTRY(ARM_FORMAT_BRMISCFRM,      3) \
+  ENTRY(ARM_FORMAT_DPFRM,          4) \
+  ENTRY(ARM_FORMAT_DPSOREGFRM,     5) \
+  ENTRY(ARM_FORMAT_LDFRM,          6) \
+  ENTRY(ARM_FORMAT_STFRM,          7) \
+  ENTRY(ARM_FORMAT_LDMISCFRM,      8) \
+  ENTRY(ARM_FORMAT_STMISCFRM,      9) \
+  ENTRY(ARM_FORMAT_LDSTMULFRM,    10) \
+  ENTRY(ARM_FORMAT_LDSTEXFRM,     11) \
+  ENTRY(ARM_FORMAT_ARITHMISCFRM,  12) \
+  ENTRY(ARM_FORMAT_EXTFRM,        13) \
+  ENTRY(ARM_FORMAT_VFPUNARYFRM,   14) \
+  ENTRY(ARM_FORMAT_VFPBINARYFRM,  15) \
+  ENTRY(ARM_FORMAT_VFPCONV1FRM,   16) \
+  ENTRY(ARM_FORMAT_VFPCONV2FRM,   17) \
+  ENTRY(ARM_FORMAT_VFPCONV3FRM,   18) \
+  ENTRY(ARM_FORMAT_VFPCONV4FRM,   19) \
+  ENTRY(ARM_FORMAT_VFPCONV5FRM,   20) \
+  ENTRY(ARM_FORMAT_VFPLDSTFRM,    21) \
+  ENTRY(ARM_FORMAT_VFPLDSTMULFRM, 22) \
+  ENTRY(ARM_FORMAT_VFPMISCFRM,    23) \
+  ENTRY(ARM_FORMAT_THUMBFRM,      24) \
+  ENTRY(ARM_FORMAT_NEONFRM,       25) \
+  ENTRY(ARM_FORMAT_NEONGETLNFRM,  26) \
+  ENTRY(ARM_FORMAT_NEONSETLNFRM,  27) \
+  ENTRY(ARM_FORMAT_NEONDUPFRM,    28) \
+  ENTRY(ARM_FORMAT_MISCFRM,       29) \
+  ENTRY(ARM_FORMAT_THUMBMISCFRM,  30) \
+  ENTRY(ARM_FORMAT_NLdSt,         31) \
+  ENTRY(ARM_FORMAT_N1RegModImm,   32) \
+  ENTRY(ARM_FORMAT_N2Reg,         33) \
+  ENTRY(ARM_FORMAT_NVCVT,         34) \
+  ENTRY(ARM_FORMAT_NVecDupLn,     35) \
+  ENTRY(ARM_FORMAT_N2RegVecShL,   36) \
+  ENTRY(ARM_FORMAT_N2RegVecShR,   37) \
+  ENTRY(ARM_FORMAT_N3Reg,         38) \
+  ENTRY(ARM_FORMAT_N3RegVecSh,    39) \
+  ENTRY(ARM_FORMAT_NVecExtract,   40) \
+  ENTRY(ARM_FORMAT_NVecMulScalar, 41) \
+  ENTRY(ARM_FORMAT_NVTBL,         42)
+
+// ARM instruction format specifies the encoding used by the instruction.
+#define ENTRY(n, v) n = v,
+typedef enum {
+  ARM_FORMATS
+  ARM_FORMAT_NA
+} ARMFormat;
+#undef ENTRY
+
+// Converts enum to const char*.
+static const inline char *stringForARMFormat(ARMFormat form) {
+#define ENTRY(n, v) case n: return #n;
+  switch(form) {
+    ARM_FORMATS
+  case ARM_FORMAT_NA:
+  default:
+    return "";
+  }
+#undef ENTRY
+}
+
+/// Expands on the enum definitions from ARMBaseInstrInfo.h.
+/// They are being used by the disassembler implementation.
+namespace ARMII {
+  enum {
+    NEONRegMask = 15,
+    GPRRegMask = 15,
+    NEON_RegRdShift = 12,
+    NEON_D_BitShift = 22,
+    NEON_RegRnShift = 16,
+    NEON_N_BitShift = 7,
+    NEON_RegRmShift = 0,
+    NEON_M_BitShift = 5
+  };
+}
+
+/// Utility function for extracting [From, To] bits from a uint32_t.
+static inline unsigned slice(uint32_t Bits, unsigned From, unsigned To) {
+  assert(From < 32 && To < 32 && From >= To);
+  return (Bits >> To) & ((1 << (From - To + 1)) - 1);
+}
+
+/// Utility function for setting [From, To] bits to Val for a uint32_t.
+static inline void setSlice(uint32_t &Bits, unsigned From, unsigned To,
+                            uint32_t Val) {
+  assert(From < 32 && To < 32 && From >= To);
+  uint32_t Mask = ((1 << (From - To + 1)) - 1);
+  Bits &= ~(Mask << To);
+  Bits |= (Val & Mask) << To;
+}
+
+/// Various utilities for checking the target specific flags.
+
+/// A unary data processing instruction doesn't have an Rn operand.
+static inline bool isUnaryDP(unsigned TSFlags) {
+  return (TSFlags & ARMII::UnaryDP);
+}
+
+/// This four-bit field describes the addressing mode used.
+/// See also ARMBaseInstrInfo.h.
+static inline unsigned getAddrMode(unsigned TSFlags) {
+  return (TSFlags & ARMII::AddrModeMask);
+}
+
+/// {IndexModePre, IndexModePost}
+/// Only valid for load and store ops.
+/// See also ARMBaseInstrInfo.h.
+static inline unsigned getIndexMode(unsigned TSFlags) {
+  return (TSFlags & ARMII::IndexModeMask) >> ARMII::IndexModeShift;
+}
+
+/// Pre-/post-indexed operations define an extra $base_wb in the OutOperandList.
+static inline bool isPrePostLdSt(unsigned TSFlags) {
+  return (TSFlags & ARMII::IndexModeMask) != 0;
+}
+
+// Forward declaration.
+class ARMBasicMCBuilder;
+
+// Builder Object is mostly ignored except in some Thumb disassemble functions.
+typedef ARMBasicMCBuilder *BO;
+
+/// DisassembleFP - DisassembleFP points to a function that disassembles an insn
+/// and builds the MCOperand list upon disassembly.  It returns false on failure
+/// or true on success.  The number of operands added is updated upon success.
+typedef bool (*DisassembleFP)(MCInst &MI, unsigned Opcode, uint32_t insn,
+    unsigned short NumOps, unsigned &NumOpsAdded, BO Builder);
+
+/// ARMAlgorithm - ARMAlgorithm implements the ARM/Thumb disassembly by solving
+/// the problem of building the MCOperands of an MCInst.  Construction of
+/// ARMAlgorithm requires passing in a function pointer with the DisassembleFP
+/// data type.
+class ARMAlgorithm {
+public:
+  /// GetInstance - GetInstance returns an instance of ARMAlgorithm given the
+  /// encoding Format.  API clients should not free up the returned instance.
+  static ARMAlgorithm *GetInstance(ARMFormat Format);
+
+  /// Return true if this algorithm successfully disassembles the instruction.
+  /// NumOpsAdded is updated to reflect the number of operands added by the
+  /// algorithm.  NumOpsAdded may be less than NumOps, in which case, there are
+  /// operands unaccounted for which need to be dealt with by the API client.
+  bool Solve(MCInst &MI, unsigned Opcode, uint32_t insn, unsigned short NumOps,
+      unsigned &NumOpsAdded, BO Builder) const {
+    if (Disassemble == NULL)
+      return false;
+
+    return (*Disassemble)(MI, Opcode, insn, NumOps, NumOpsAdded, Builder);
+  }
+
+private:
+  ARMAlgorithm(DisassembleFP fp) : Disassemble(fp) {}
+  ARMAlgorithm(ARMAlgorithm &AA) : Disassemble(AA.Disassemble) {}
+
+  virtual ~ARMAlgorithm() {}
+
+  DisassembleFP Disassemble;
+};
+
+/// ARMBasicMCBuilder - ARMBasicMCBuilder represents an ARM MCInst builder that
+/// knows how to build up the MCOperand list.
+class ARMBasicMCBuilder {
+  unsigned Opcode;
+  ARMFormat Format;
+  unsigned short NumOps;
+  const ARMAlgorithm &Algo;
+  Session *SP;
+
+public:
+  ARMBasicMCBuilder(ARMBasicMCBuilder &B)
+    : Opcode(B.Opcode), Format(B.Format), NumOps(B.NumOps), Algo(B.Algo),
+      SP(B.SP)
+  {}
+
+  /// Opcode, Format, NumOperands, and Algo make an ARM Basic MCBuilder.
+  ARMBasicMCBuilder(unsigned opc, ARMFormat format, unsigned short num,
+                    const ARMAlgorithm &algo)
+    : Opcode(opc), Format(format), NumOps(num), Algo(algo), SP(0)
+  {}
+
+  void setSession(Session *sp) {
+    SP = sp;
+  }
+
+  /// TryPredicateAndSBitModifier - TryPredicateAndSBitModifier tries to process
+  /// the possible Predicate and SBitModifier, to build the remaining MCOperand
+  /// constituents.
+  bool TryPredicateAndSBitModifier(MCInst& MI, unsigned Opcode,
+      uint32_t insn, unsigned short NumOpsRemaning);
+
+  /// InITBlock - InITBlock returns true if we are inside an IT block.
+  bool InITBlock() {
+    if (SP)
+      return SP->ITCounter > 0;
+
+    return false;
+  }
+
+  /// Build - Build delegates to BuildIt to perform the heavy liftling.  After
+  /// that, it invokes RunBuildAfterHook where some housekeepings can be done.
+  virtual bool Build(MCInst &MI, uint32_t insn) {
+    bool Status = BuildIt(MI, insn);
+    return RunBuildAfterHook(Status, MI, insn);
+  }
+
+  /// BuildIt - BuildIt performs the build step for this ARM Basic MC Builder.
+  /// The general idea is to set the Opcode for the MCInst, followed by adding
+  /// the appropriate MCOperands to the MCInst.  ARM Basic MC Builder delegates
+  /// to the Algo (ARM Disassemble Algorithm) object to perform Format-specific
+  /// disassembly, followed by class method TryPredicateAndSBitModifier() to do
+  /// PredicateOperand and OptionalDefOperand which follow the Dst/Src Operands.
+  virtual bool BuildIt(MCInst &MI, uint32_t insn);
+
+  /// RunBuildAfterHook - RunBuildAfterHook performs operations deemed necessary
+  /// after BuildIt is finished.
+  virtual bool RunBuildAfterHook(bool Status, MCInst &MI, uint32_t insn);
+
+private:
+  /// Get condition of the current IT instruction.
+  unsigned GetITCond() {
+    assert(SP);
+    return slice(SP->ITState, 7, 4);
+  }
+};
+
+/// CreateMCBuilder - Return an ARMBasicMCBuilder that can build up the MC
+/// infrastructure of an MCInst given the Opcode and Format of the instr.
+/// Return NULL if it fails to create/return a proper builder.  API clients
+/// are responsible for freeing up of the allocated memory.  Cacheing can be
+/// performed by the API clients to improve performance.
+extern ARMBasicMCBuilder *CreateMCBuilder(unsigned Opcode, ARMFormat Format);
+
+} // namespace llvm
+
+#endif