How does GCC > 3.* do the padding in memory allocation?

hi,
I am trying the Alpha One's "Smashing The Stack For Fun And Profit". But i
realise that the new GCC compiler has add a random padding between the last
local variable and return address during the memory allocation.

For example:
void function(int a, int b, int c)
{
    int z[1];
}

For for this arrray z, the gcc behave normally for z[1], z[2] , it will
allocate 4 byte for z[1], and 8 byte for z[2].  When I increase to z[3] and
z[4] the compiler will allocate 24 bytes.  When z[5] is 5, it will allocate
40 bytes.

My question is how the compile do the padding? Any specific algorithm?

regards,
Rick



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