1 files changed, 54 insertions, 4 deletions

diff --git a/include/llvm/MC/MCDisassembler.h b/include/llvm/MC/MCDisassembler.h
index ce8759a..454277d 100644
--- a/include/llvm/MC/MCDisassembler.h
+++ b/include/llvm/MC/MCDisassembler.h
@@ -15,6 +15,7 @@
 namespace llvm {
   
 class MCInst;
+class MCSubtargetInfo;
 class MemoryObject;
 class raw_ostream;
 class MCContext;
@@ -25,8 +26,38 @@ struct EDInstInfo;
 ///   and provides an array of assembly instructions.
 class MCDisassembler {
 public:
+  /// Ternary decode status. Most backends will just use Fail and
+  /// Success, however some have a concept of an instruction with
+  /// understandable semantics but which is architecturally
+  /// incorrect. An example of this is ARM UNPREDICTABLE instructions
+  /// which are disassemblable but cause undefined behaviour.
+  ///
+  /// Because it makes sense to disassemble these instructions, there
+  /// is a "soft fail" failure mode that indicates the MCInst& is
+  /// valid but architecturally incorrect.
+  ///
+  /// The enum numbers are deliberately chosen such that reduction
+  /// from Success->SoftFail ->Fail can be done with a simple
+  /// bitwise-AND:
+  ///
+  ///   LEFT & TOP =  | Success       Unpredictable   Fail
+  ///   --------------+-----------------------------------
+  ///   Success       | Success       Unpredictable   Fail
+  ///   Unpredictable | Unpredictable Unpredictable   Fail
+  ///   Fail          | Fail          Fail            Fail
+  ///
+  /// An easy way of encoding this is as 0b11, 0b01, 0b00 for
+  /// Success, SoftFail, Fail respectively.
+  enum DecodeStatus {
+    Fail = 0,
+    SoftFail = 1,
+    Success = 3
+  };
+
   /// Constructor     - Performs initial setup for the disassembler.
-  MCDisassembler() : GetOpInfo(0), DisInfo(0), Ctx(0) {}
+  MCDisassembler(const MCSubtargetInfo &STI) : GetOpInfo(0), SymbolLookUp(0),
+                                               DisInfo(0), Ctx(0),
+                                               STI(STI), CommentStream(0) {}
   
   virtual ~MCDisassembler();
   
@@ -41,12 +72,17 @@ public:
   /// @param address  - The address, in the memory space of region, of the first
   ///                   byte of the instruction.
   /// @param vStream  - The stream to print warnings and diagnostic messages on.
-  /// @return         - True if the instruction is valid; false otherwise.
-  virtual bool          getInstruction(MCInst& instr,
+  /// @param cStream  - The stream to print comments and annotations on.
+  /// @return         - MCDisassembler::Success if the instruction is valid,
+  ///                   MCDisassembler::SoftFail if the instruction was 
+  ///                                            disassemblable but invalid,
+  ///                   MCDisassembler::Fail if the instruction was invalid.
+  virtual DecodeStatus  getInstruction(MCInst& instr,
                                        uint64_t& size,
                                        const MemoryObject &region,
                                        uint64_t address,
-                                       raw_ostream &vStream) const = 0;
+                                       raw_ostream &vStream,
+                                       raw_ostream &cStream) const = 0;
 
   /// getEDInfo - Returns the enhanced instruction information corresponding to
   ///   the disassembler.
@@ -62,23 +98,37 @@ private:
   //
   // The function to get the symbolic information for operands.
   LLVMOpInfoCallback GetOpInfo;
+  // The function to lookup a symbol name.
+  LLVMSymbolLookupCallback SymbolLookUp;
   // The pointer to the block of symbolic information for above call back.
   void *DisInfo;
   // The assembly context for creating symbols and MCExprs in place of
   // immediate operands when there is symbolic information.
   MCContext *Ctx;
+protected:
+  // Subtarget information, for instruction decoding predicates if required.
+  const MCSubtargetInfo &STI;
 
 public:
   void setupForSymbolicDisassembly(LLVMOpInfoCallback getOpInfo,
+                                   LLVMSymbolLookupCallback symbolLookUp,
                                    void *disInfo,
                                    MCContext *ctx) {
     GetOpInfo = getOpInfo;
+    SymbolLookUp = symbolLookUp;
     DisInfo = disInfo;
     Ctx = ctx;
   }
   LLVMOpInfoCallback getLLVMOpInfoCallback() const { return GetOpInfo; }
+  LLVMSymbolLookupCallback getLLVMSymbolLookupCallback() const {
+    return SymbolLookUp;
+  }
   void *getDisInfoBlock() const { return DisInfo; }
   MCContext *getMCContext() const { return Ctx; }
+
+  // Marked mutable because we cache it inside the disassembler, rather than
+  // having to pass it around as an argument through all the autogenerated code.
+  mutable raw_ostream *CommentStream;
 };
 
 } // namespace llvm