No, you can never make that assumption. Every different port of GCC uses a different calling sequence. Sometimes switches will change the calling sequence. Some ABI's will pass nothing in registers (i386 classic), some will pass the first few arguments in certain registers depending on the type of the arguments, some will pass some things on the stack and other things in registers. The standard way to write your program is to convert it to use stdarg.h, and use va_arg to get at the arguments. Be sure that the variable argument function is properly declared, since some ports have different calling sequences for functions with a fixed number of arguments and with a variable number. -- Michael Meissner AMD, MS 83-29 90 Central Street Boxborough, MA 01719 -----Original Message----- From: gcc-help-owner@xxxxxxxxxxx [mailto:gcc-help-owner@xxxxxxxxxxx] On Behalf Of Emmanuel Pacaud Sent: Tuesday, January 17, 2006 10:33 AM To: gcc-help@xxxxxxxxxxx Subject: Question about function call stack Hi, In a project I'm working on, I've to fix an issue which is dependant on the target platform. You'll find below a code snippet that shows the issue. When compiled for a 32 bit platform, with gcc 3.2.2, I get the expected behaviour, which is the following output: 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 But, if compiled for a 64 bit platform, with gcc 3.4.3, output is: 1 548682058152 4194884 0 -72340172838076673 0 0 1 2 3 0 1 2 3 4 5 6 7 8 9 Here's my question: Is the assumption made in code snippet that pushing an ulong array on the stack, then retrieving values via function arguments correct ? Regards, Emmanuel.
