Why is gcc-multilib output incorrect for bitwise operation?

bug.c

#include <stdio.h>

int main()
{
    int x = 0x7fffffff;
    printf("%x\n", x);
    printf("%x\n", ~x);
    printf("%x\n", ~x + ~x);
    printf("%x\n", !(~x + ~x));
}

I compile using gcc -m32 bug.c -o bug This outputs:

7fffffff
80000000
0
0

It should output

7fffffff
80000000
0
1

I am using gcc 9.3 and gcc-multilib on Ubuntu 20.04. I have also tested this with gcc8 and gcc10. The output was correct when I used clang. Does anyone have any idea why this is happening?

Enable all warnings and undefined behavior sanitizer with the -Wall -Wextra -pedantic -fanalyzer -fsanitize=undefined options and you'll see that gcc outputs this error

example.cpp:8:11: runtime error: signed integer overflow: -2147483648 * 2 cannot be represented in type 'int'

You can also specify more sanitizers like this -fsanitize=signed-integer-overflow,leak,undefined,address

See demo on Compiler Explorer. Notice that Clang also reports UB:

example.cpp:8:23: runtime error: signed integer overflow: -2147483648 + -2147483648 cannot be represented in type 'int'
SUMMARY: UndefinedBehaviorSanitizer: undefined-behavior example.cpp:8:23 in 
example.cpp:9:25: runtime error: signed integer overflow: -2147483648 + -2147483648 cannot be represented in type 'int'
SUMMARY: UndefinedBehaviorSanitizer: undefined-behavior example.cpp:9:25 in