g++ generates undefined instruction(ud2) when trying to access 0x00 from kernel

I'm trying to write a small Kernel. This code is executing in 32-bit Protected mode with paging and interrupts disabled.

As the title suggests when I try to access 0x00 from my Kernel, the compiler generates ud2 (undefined instruction) causing a triple fault.

This is the dissasembly of the function when I try to access 0x00

void SetupX64Paging()
{
  100070:   31 c0                   xor    %eax,%eax
  100072:   8d b4 26 00 00 00 00    lea    0x0(%esi,%eiz,1),%esi
  100079:   8d b4 26 00 00 00 00    lea    0x0(%esi,%eiz,1),%esi
    // The paging directory will be at 0x00h
    uint64_t *pageDirBase = (uint64_t *)0x00;
    //uint64_t *pageDirBase = (uint64_t *)0x00007BFF;

    // clear area for 4 tables (16KB)
    for(uint64_t i = 0; i < 512 * 4; i++)
        pageDirBase[i] = 0;
  100080:   c7 00 00 00 00 00       movl   $0x0,(%eax)
  100086:   83 c0 04                add    $0x4,%eax
    for(uint64_t i = 0; i < 512 * 4; i++)
  100089:   3d 00 20 00 00          cmp    $0x2000,%eax
  10008e:   75 f0                   jne    100080 <_Z14SetupX64Pagingv+0x10>
    PDPT = (uint64_t *)PML4 + 0x1000;  // 4KB
    PDT  = (uint64_t *)PML4 + 0x2000;  // 8KB
    PT   = (uint64_t *)PML4 + 0x3000;  // 12KB

    // Map each table entry into its parent and set the r/w and present flags
    PML4[0] = (uint64_t)PDPT | 0x3;
  100090:   c7 05 00 00 00 00 00    movl   $0x0,0x0
  100097:   00 00 00 
  10009a:   0f 0b                   ud2    
  10009c:   66 90                   xchg   %ax,%ax
  10009e:   66 90                   xchg   %ax,%ax

Although it does not show in the disassembly, PML4 is initialized to pageDirBase In this setup, the kernel has just jumped to protected mode. Interrupts are disabled, Paging is disabled.

The code in this file is compiled as :

i686-elf-g++ -c Paging.cpp -ffreestanding -O2 -Wall -Wextra -fno-exceptions -fno-rtti -g -I../Common -I../Include                                  

Is there a compiler directive that should be used to make compiler not generate undefined instruction.

One peculiar thing to note is that the loop which zeros out the memory at %eip = 100080 works just fine