On 2013-04-17 13:43, John Colvin wrote:
clang just happened to put the arguments to foo in to registers
different on 10.6.3
Instead of loading the 0 argument in to eax it loaded the pointer to the
struct like it would in system V ABI (linux)
I have no idea whether this is a complete coincidence, or whether clang
has changed it's approach to the OS X abi, or whether the ABI itself has
changed.
Ok, I see. The docs for the ABI says:
The called function returns structures according to their aligned size.
* Structures 1 or 2 bytes in size are placed in EAX.
* Structures 4 or 8 bytes in size are placed in: EAX and EDX.
* Structures of other sizes are placed at the address supplied by the
caller. For example, the C++ language occasionally forces the compiler
to return a value in memory when it would normally be returned in
registers. See “Passing Arguments” for more information.
--
/Jacob Carlborg
