segfault

/*
Ubuntu 20.04.1 LTS (Focal Fossa)
gcc (Ubuntu 9.3.0-10ubuntu2) 9.3.0

gcc -std=c99 -Wall -Wextra -Wpedantic -Wshadow -O0 -DDEBUG -g main.c

Program received signal SIGSEGV, Segmentation fault.
0x0000555555555180 in main () at main.c:31
31  {


gcc -std=c99 -Wall -Wextra -Wpedantic -Wshadow -O1 -DNDEBUG -g main.c OK
gcc -std=c99 -Wall -Wextra -Wpedantic -Wshadow -O2 -DNDEBUG -g main.c OK
gcc -std=c99 -Wall -Wextra -Wpedantic -Wshadow -O3 -DNDEBUG -g main.c OK

edit:
possible stack overflow

solution:
use malloc

https://pastebin.com/fYRAbMtb
or https://pastebin.com/EuPakt7a

Tnx to ##C on Freenode !
*/

#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include <stdbool.h>

#define TEST_A_MAX_SIZE 1000000

struct thread_test_a
{
    uint32_t variables[TEST_A_MAX_SIZE];
    uint32_t test_count;
};

int main()
{ // line 31

    struct thread_test_a thread_test_1;
    struct thread_test_a thread_test_2;
    struct thread_test_a thread_test_3;

    thread_test_1.test_count = TEST_A_MAX_SIZE;
    thread_test_2.test_count = 10;
    thread_test_3.test_count = 50;

    thread_test_1.variables[TEST_A_MAX_SIZE-1] = 1;
    thread_test_2.variables[10] = 2;
    thread_test_3.variables[50] = 3;

    printf( "%d\n", thread_test_1.variables[TEST_A_MAX_SIZE-1] );
    printf( "%d\n", thread_test_2.variables[10] );
    printf( "%d\n", thread_test_3.variables[50] );

    return 0;
}