Following program miscompiles with -O1 on (32 bit) Darwin.  Works with -O0.
It appears that RTL generation for

printf (&"cmp.func is %p (expected %p)\n"[0], comparator_matrixD.2001[0][(intD.2) (D.2150 == 2)], 
compare_e_stringD.2019);

is incorrect, but I haven't dug deeply yet.  I will be fixing this unless somebody recognizes it as a dup

#include <stdio.h>

#define test(a) ((a) ? 1 : 0)

typedef int (*arg_cmp_func)();

class Item_func 
{
public:
    enum Functype { UNKNOWN_FUNC, EQ_FUNC, EQUAL_FUNC };
    virtual enum Functype functype() const { return UNKNOWN_FUNC; }
};

class Item_bool_func2 : public Item_func
{
public:
    virtual enum Functype functype() const { return EQUAL_FUNC; }
};

class Arg_comparator 
{
public:
    Item_bool_func2 *owner;
    arg_cmp_func func;
    static arg_cmp_func comparator_matrix[4][2];

    int Arg_comparator::set_compare_func(Item_bool_func2 *item, int type)
    {
        owner = item;

        /****************** problematic line is here ************************/

        func = comparator_matrix[type][test(owner->functype() == Item_func::EQUAL_FUNC)];
        return 0;
    }
};

int compare_string() { return 0; }
int compare_e_string() { return 0; }
int compare_real() { return 0; }
int compare_e_real() { return 0; }
int compare_int_signed() { return 0; }
int compare_e_int() { return 0; }
int compare_row() { return 0; }
int compare_e_row() { return 0; }

arg_cmp_func Arg_comparator::comparator_matrix[4][2] =
    {{&compare_string,     &compare_e_string},
     {&compare_real,       &compare_e_real},
     {&compare_int_signed, &compare_e_int},
     {&compare_row,        &compare_e_row}};


int main()
{
    Arg_comparator cmp;
    Item_bool_func2 equal_func;

    cmp.set_compare_func(&equal_func, 0);
    printf("cmp.func is %p (expected %p)\n", cmp.func, &compare_e_string);
}