For the 'C' disassembler API, add a new ReferenceType for the

SymbolLookUp() call back to return a demangled C++ name to
be used as a comment.

For example darwin's otool(1) program the uses the llvm
disassembler now can produce disassembly like:

callq   __ZNK4llvm6Target20createMCDisassemblerERKNS_15MCSubtargetInfoE ## llvm::Target::createMCDisassembler(llvm::MCSubtargetInfo const&) const

Also fix a bug in LLVMDisasmInstruction() that was not flushing
the raw_svector_ostream for the disassembled instruction string
before copying it to the output buffer that was causing truncation
of the output.

rdar://10173828

llvm-svn: 198637

include/llvm-c/Disassembler.h

@@ -141,6 +141,9 @@ typedef const char *(*LLVMSymbolLookupCallback)(void *DisInfo,
 /* The output reference is to a Objective-C class ref. */
 #define LLVMDisassembler_ReferenceType_Out_Objc_Class_Ref 8
 
+/* The output reference is to a C++ symbol name. */
+#define LLVMDisassembler_ReferenceType_DeMangled_Name 9
+
 #ifdef __cplusplus
 extern "C" {
 #endif /* !defined(__cplusplus) */

lib/MC/MCDisassembler/Disassembler.cpp

@@ -298,6 +298,7 @@ size_t LLVMDisasmInstruction(LLVMDisasmContextRef DCR, uint8_t *Bytes,
       emitLatency(DC, Inst);
 
     emitComments(DC, FormattedOS);
+    OS.flush();
 
     assert(OutStringSize != 0 && "Output buffer cannot be zero size");
     size_t OutputSize = std::min(OutStringSize-1, InsnStr.size());

lib/MC/MCExternalSymbolizer.cpp

@@ -56,6 +56,9 @@ bool MCExternalSymbolizer::tryAddingSymbolicOperand(MCInst &MI,
     if (Name) {
       SymbolicOp.AddSymbol.Name = Name;
       SymbolicOp.AddSymbol.Present = true;
+      // If Name is a C++ symbol name put the human readable name in a comment.
+      if(ReferenceType == LLVMDisassembler_ReferenceType_DeMangled_Name)
+        cStream << ReferenceName;
     }
     // For branches always create an MCExpr so it gets printed as hex address.
     else if (IsBranch) {