TM4C123GH6PM: bootloader, jump, boot, loader, boot loader

I need help please, the boot loader does not jump to the location of the app, the compiler is IAR.

the boot of the app is 0x0000

the address of the appis 0x1000

function call app

void app(uint32_t ui32StartAddr)
{
IntDisable();
SysTickIntDisable();
SysTickDisable();
//IntMasterEnable();
//SysTickDisable();

HWREG(NVIC_VTABLE) =0x1000;//app_vector;

__asm(" ldr r1, [r0]\n"
" mov sp, r1\n");

__asm(" ldr r0, [r0, #0x4]\n"
" bx r0\n");

}