On 3/8/07, Duncan Sands <[EMAIL PROTECTED]> wrote:
> in tree.def, in DEFTREECODE for call_expr, it says operand 2 is the > static chain argument, or NULL. Can someone tell me or reference me to > what static chain argument is?It's for nested functions, eg int parent (int n) { int child (int m) { return m * n; } return child (2); } Notice how child using a variable of parent, namely the parameter n. This gets lowered to something like: struct frame { int n; }; int child (struct frame *static_chain, int m) { return m * static_chain->n; } int parent (int n) { struct frame FRAME; FRAME.n = n; return child (&FRAME, 2); }
Ah, nice, didn't know that was possible in C. Is that new in C99 or it's a GCC extension? Cheers, Paulo Matos
Ciao, Duncan.
-- Paulo Jorge Matos - pocm at soton.ac.uk http://www.personal.soton.ac.uk/pocm PhD Student @ ECS University of Southampton, UK
