[ARC] Prevent InstPrinter from crashing on unknown condition codes.

[tatyana-krasnukha]

Summary

Instruction printer shouldn't crash with assertions due to incorrect input data. llvm_unreachable is not intended for runtime error handling.

[petecoup]

Thanks, can you add a test to make sure the disassembler doesn't crash in this case?

[tatyana-krasnukha]

Added a test for bcc instruction with unknown condition code.

[petecoup]

Great, thanks for doing this!

llvm/trunk/lib/Target/ARC/InstPrinter/ARCInstPrinter.cpp

 #include "MCTargetDesc/ARCInfo.h"
 #include "llvm/ADT/StringExtras.h"
 #include "llvm/MC/MCExpr.h"
 #include "llvm/MC/MCInst.h"
 #include "llvm/MC/MCInstrInfo.h"
 #include "llvm/MC/MCSymbol.h"
 #include "llvm/Support/Casting.h"
 #include "llvm/Support/Debug.h"
-#include "llvm/Support/ErrorHandling.h"
 #include "llvm/Support/raw_ostream.h"
 
 using namespace llvm;
 
 #define DEBUG_TYPE "asm-printer"
 
 #include "ARCGenAsmWriter.inc"
 
+template <class T>
+static const char *BadConditionCode(T cc) {
+  DEBUG(dbgs() << "Unknown condition code passed: " << cc << "\n");
+  return "{unknown-cc}";
+}
+
 static const char *ARCBRCondCodeToString(ARCCC::BRCondCode BRCC) {
   switch (BRCC) {
   case ARCCC::BREQ:
     return "eq";
   case ARCCC::BRNE:
     return "ne";
   case ARCCC::BRLT:
     return "lt";
   case ARCCC::BRGE:
     return "ge";
   case ARCCC::BRLO:
     return "lo";
   case ARCCC::BRHS:
     return "hs";
   }
-  llvm_unreachable("Unhandled ARCCC::BRCondCode");
+  return BadConditionCode(BRCC);
 }
 
 static const char *ARCCondCodeToString(ARCCC::CondCode CC) {
   switch (CC) {
   case ARCCC::EQ:
     return "eq";
   case ARCCC::NE:
     return "ne";
case ARCCC::PNZ:
     return "pnz";
   case ARCCC::AL:
     return "al";
   case ARCCC::NZ:
     return "nz";
   case ARCCC::Z:
     return "z";
   }
-  llvm_unreachable("Unhandled ARCCC::CondCode");
+  return BadConditionCode(CC);
 }
 
 void ARCInstPrinter::printRegName(raw_ostream &OS, unsigned RegNo) const {
   OS << StringRef(getRegisterName(RegNo)).lower();
 }
 
 void ARCInstPrinter::printInst(const MCInst *MI, raw_ostream &O,
                                StringRef Annot, const MCSubtargetInfo &STI) {

llvm/trunk/test/MC/Disassembler/ARC/br.txt

 0x0c 0x01 0x01 0x00
 
 # CHECK: bhi 416
 0xa0 0x01 0x0d 0x00
 
 # CHECK: b -68
 0xbd 0x07 0xcf 0xff
 
+# CHECK: b{unknown-cc} 4096
+0x00 0x00 0x9e 0x00
 No newline at end of file