Delete instruction using PIN - c++

Question

I am using the Intel PIN tool to emulate some new instructions and check the corresponding results. For this purpose I am using illegal opcodes of x86_64 to represent my instructions. For example- opcodes 0x16, 0x17 are illegal in x86_64. which represent my instruction opcodes. I am using a C program to generate an executable and then pass it to the Pintool. A C program I am using is this -
#include <stdio.h>
int main()
{
asm(".byte 0x16");
asm(".byte 0x17");
return 0;
}
So if we see the instruction trace 0x16 and 0x17 will appear as bad instructions and if we try to run the executable we get -
Illegal instruction (core dumped)
which is expected as 0x16, 0x17 are illegal in x86_64 and hence the executable should not pass. I am using this executable as input to my Pintool, which examines the instruction trace and hence will encounter 0x16 and 0x17 in the trace.
The Pintool I am using is this -
#include "pin.H"
#include <iostream>
#include <fstream>
#include <cstdint>
UINT64 icount = 0;
using namespace std;
KNOB<string> KnobOutputFile(KNOB_MODE_WRITEONCE, "pintool", "o", "test.out","This pin tool simulates ULI");
FILE * op;
//====================================================================
// Analysis Routines
//====================================================================
VOID simulate_ins(VOID *ip, UINT32 size) {
fprintf(op,"Wrong instruction encountered here\n");
// Do something based on the instruction
}
//====================================================================
// Instrumentation Routines
//====================================================================
VOID Instruction(INS ins, void *v) {
UINT8 opcodeBytes[15];
UINT64 fetched = PIN_SafeCopy(&opcodeBytes[0],(void *)INS_Address(ins),INS_Size(ins));
if (fetched != INS_Size(ins))
fprintf(op,"\nBad\n");
else {
if(opcodeBytes[0]==0x16 || opcodeBytes[0]==0x17) {
INS_InsertCall( ins, IPOINT_BEFORE, (AFUNPTR)simulate_ins, IARG_INST_PTR, IARG_UINT64, INS_Size(ins) , IARG_END);
INS_Delete(ins);
}
}
VOID Fini(INT32 code, VOID *v) {
//Display some end result
}
INT32 Usage() {
PIN_ERROR("This Pintool failed\n" + KNOB_BASE::StringKnobSummary() + "\n");
return -1;
}
int main(int argc, char *argv[])
{
op = fopen("test.out", "w");
if (PIN_Init(argc, argv))
return Usage();
PIN_InitSymbols();
PIN_AddInternalExceptionHandler(ExceptionHandler,NULL);
INS_AddInstrumentFunction(Instruction, 0);
PIN_AddFiniFunction(Fini, 0);
PIN_StartProgram();
return 0;
}
So I am extracting my assembly opcodes and if the first byte is 0x16 or 0x17 I am sending the instruction to my analysis routine and then deleting the instruction. But however when I run this Pintool on the executable I still get the Illegal instruction (core dumped) error and my code fails to run. My understanding is that the Instrumentation routine is called every time a new instruction is encountered in the trace and the analysis routine is called before the instruction is executed. Here I am checking for the opcode and based on the result I am sending the code to the analysis routine and deleting the instruction. I will be simulating my new instruction in the analysis routine so, I just need to delete the old instruction and let the program proceed futher and make sure it dosen't give the illegal instruction error again.
Anywhere I am doing something wrong?