Fix a bug where an incorrect bit mask would be generated if a target's last asm

string began at a power of 2 in the string index.  For example, if "ret" started
at position 16, the ret instruction would be assigned code 16, but the mask would be AsmChars[] + Code & 15, not Code & 31.

llvm-svn: 49433

llvm/utils/TableGen/AsmWriterEmitter.cpp

@@ -536,7 +536,7 @@ void AsmWriterEmitter::run(std::ostream &O) {
   }
   
   // Figure out how many bits we used for the string index.
-  unsigned AsmStrBits = Log2_32_Ceil(MaxStringIdx);
+  unsigned AsmStrBits = Log2_32_Ceil(MaxStringIdx+1);
   
   // To reduce code size, we compactify common instructions into a few bits
   // in the opcode-indexed table.