Okay, who made scalar replacement of aggregates work?

[Daniel Berlin <dan at cgsoftware dot com>]

I was told we only do it if the entire class fits in a register.

This is no longer true.


We'll do it to single members of classes/structs now to.

In other words, we do full scalar replacement of aggregates.


Try the following (for C):


typedef enum { APPLE, BANANA, ORANGE } VARIETY;
typedef enum { LONG, ROUND } SHAPE;
typedef struct fruit {
VARIETY variety;
SHAPE shape; 
int fred;
int george;
int a;
int b;
int c;
int d;
}
FRUIT;
char * Red="red";
char * Yellow = "yellow";
char *Orange = "orange";

int george (CurrentFruit)
	FRUIT *CurrentFruit;
{
	return CurrentFruit->george;
}
char *color (CurrentFruit)
FRUIT *CurrentFruit;
{

switch (CurrentFruit->variety) {
case APPLE: return Red;
break;
case BANANA: return Yellow;
break;
case ORANGE: return Orange;
}
}
main( )
{
FRUIT snack;
snack.variety = APPLE;
snack.shape = ROUND;
snack.fred = 30;
snack.george = 3;
printf("%s\n", color (&snack));
printf("%d\n", george (&snack));
}


Even though snack can't fit in a register, some of it's components
will, and we sure as hell put them there.

Make snack as big as you like. We'll still do the repacements we can.


Same with the C++ version.


extern "C" int printf(const char *, ...);
enum VARIETY
{ APPLE, BANANA, ORANGE };
enum SHAPE { LONG, ROUND };
class FRUIT 
{
	public:
		enum VARIETY variety;
		enum SHAPE shape; 
		int george;
		int fred;
                int a;
                int b;
                int c;
                int d;
};

char * Red="red";
char * Yellow = "yellow";
char *Orange = "orange";

char *color (FRUIT *CurrentFruit)
{

	switch (CurrentFruit->variety) {
		case APPLE: return Red;
			    break;
		case BANANA: return Yellow;
			     break;
		case ORANGE: return Orange;
	}
}
int main( )
{
	FRUIT snack;
	snack.variety = APPLE;
	snack.shape = ROUND;
	snack.george = 5;
	snack.fred = 30;
	printf("%s\n", color (&snack));
	printf("%d\n", snack.fred);
}



--Dan
-- 
"It's a good thing we have gravity, or else when birds died
they'd just stay right up there.  Hunters would be all confused.
"-Steven Wright