8dfc7699a6
reverse order to easily support variadic arguments. Thus, instead of using the proper stdarg.h macros (that nowadays are compiler-dependent), it may be tempting to directly take the address of the last argument and considering it as the start of an array. This is a shortcut that avoid looping to get all the arguments as the CPU already pushed them on the stack before the call to the function. Unfortunately, such an assumption is strictly compiler-dependent and compilers are free to move the last argument on the stack, as a local variable, and return the address of the location where the argument was stored, if asked for. This will break things as the rest of the array's argument are stored elsewhere (typically, a couple of words above the location where the argument was stored). This patch fixes the issue by allowing ACK to take the shortcut and enabling gcc/llvm-gcc to follow the right way.
21 lines
646 B
C
21 lines
646 B
C
/* Definitions for ACK-specific features. */
|
|
|
|
#ifndef _MINIX_COMPILER_ACK_H
|
|
#define _MINIX_COMPILER_ACK_H
|
|
|
|
/* ACK expects the caller to pop the hidden pointer on struct return. */
|
|
#define BYTES_TO_POP_ON_STRUCT_RETURN
|
|
|
|
/*
|
|
* ACK doesn't move the last argument of a variadic arguments function
|
|
* anywhere, once it's on the stack as a function parameter. Thus, it is
|
|
* possible to make strong assumption on the immutability of the stack
|
|
* layout and use the address of that argument as the start of an array.
|
|
*
|
|
* If you're curious, just look at lib/libc/posix/_execl*.c ;-)
|
|
*/
|
|
|
|
#define FUNC_ARGS_ARRAY 1
|
|
|
|
#endif /* _MINIX_COMPILER_ACK_H */
|