[Tinycc-devel] inlined alloca()

[Zdenek Pavlas]

Hello everybody!

I've seen the recently submitted alloca() code and wondered: Why not use 
tcc's inline asm?

- much simpler and probably slightly faster.
- bound checking is still probably broken (no __bound_delete_region 
called).  I'd rather drop it completely for now.
- alloca(4096+) may have issues on PE target.

What do you think?

--

Zdenek Pavlas


#ifndef ALLOCA_H
#define ALLOCA_H

#ifndef __i386__
# error Sorry, i386 only
#endif

#ifdef __BOUNDS_CHECKING_ON
# define __alloca_pad 1
#else
# define __alloca_pad 0
# define __bound_new_region(ptr, size)
#endif

#define alloca(size) ({ \
    void * ptr; \
    __asm__("sub %1, %%esp\nmov %%esp, %0" \
        : "=g"(ptr) : "g"(((size) + __alloca_pad + 3) & -4)); \
    __bound_new_region(ptr, size); \
    ptr; })

#endif