[fpc-devel] Dangerous optimization in CASE..OF

[Ondrej Pokorny]

On 16.07.2017 20:42, Florian Klämpfl wrote:
> "Ungültiger Maschinenbefehl (Speicherabzug geschrieben)" = Invalid 
> opcode (memory dump written).
> Why? Because it does not range check before entering the jump table.

OK, I confess I am not a C guy (I hated it in the university even more 
than fortran). But for me:

default-ondrej at ondrej-linux:~/ctest$ cat test.c
#include <stdio.h>

typedef enum { e1,e2,e3,e4,e5,e6,e7,e8 } tenum;

int f(tenum e)
{
   switch (e)
{
     case e1:
       printf("Hello 1 %d\n",e1);
       return 1;
     case e2:
       return 354;
     case e3:
       return 351;
     case e4:
       return 315;
     case e5:
       return 35;
     case e6:
       printf("Hello asdf\n");
       return 1;
     case e7:
       printf("Hello \n");
       return 2;
     case e8:
printf("Hello\n");
       return 3;
default:
printf("default");
       return 0;
}
}

int main()
{
f(12);
}

ondrej at ondrej-linux:~/ctest$ gcc test.c
ondrej at ondrej-linux:~/ctest$ ./a.out
defaultondrej at ondrej-linux:~/ctest$

No error if I remove the default statement.

Ondrej