[webkit-dev] Proposal about integer types used in WebKit

[Geoffrey Garen]

> Am I missing something? Is there some real benefit to using types  
> like int32_t instead of int in some places in our code and not  
> others? If so, what are these critical places and what makes them  
> different from the rest of the code?

In JavaScriptCore, some structures have integer members that must be  
32bits in size, regardless of processor type. In those places, int32_t  
and uint32_t are useful.

Less clear to me is whether clients of such structures should also use  
int32_t / uint32_t. For example:

struct {
	int32_t i;
} s;

int32_t i32 = s.i; // option 1
int i = s.i; // option 2

Technically, option 2, which converts from int32_t to int, requires a  
"32bit move with sign extension to 64bit" instead of just a "32bit  
move", but Intel's documentation says that 32bit to 64bit sign  
extension is the very fastest instruction on the processor, so maybe  
it doesn't matter.

Geoff