Hard to understand GCC assembly instructions to calculate conditional jump

Question

I have the following code:

if(( a<0 ) || ( a>global_count ))  //global_count is a global int
{
    print error;
}

normal_flow
    ...

Now here's the assembler that GCC generates:

cmpl 0x0 , 0x10(%ebp) //first check
js print_error
mov 0x8(%ebp) , %eax
mov 0x8(%eax) , %eax 
cmp 0x10(%ebp) , %eax //second check
jge normal_flow
print_error

I don't understand why the jge ? I see it's using mov , instead of movl , but I believe it should be jle in this case or jg if we change jump target... or am I thinking wrong here?

Answer 1

It's jge because the compiler swapped both the operands and the condition. It's doing global_count >= a . Notice that 0x10(%ebp) is a and %eax is global_count . To complicate matters further, at&t syntax itself has operands reversed.