z88dk: allow object files generated by zsdcc and sccz80 to be mixed in the same binary about z88dk HOT 4 OPEN

Another point of difference is in how char parameters are push onto the stack. sdcc will push one byte for each char whereas sccz80 will push a word.

from z88dk.

Just thinking out loud: could we add attributes to function entry points and change the linker to search a matching function name and function attributes? This would require changes in the compilers and assembler, to pass the attributes to the object file, and in the linker to search for a matching function.

from z88dk.

A simpler variation on that is to get the preprocessor to substitute different names for function entry points depending on which compiler is running:

#ifdef __SDCC
#define strcpy sdcc_strcpy
#endif

#ifdef __SCCZ80
#define strcpy sccz80_strcpy
#endif

Then have C entry points for each that collect parameters and then jump into the common asm implementation.

So the compiler and attributes get encoded in the name rather than having to modify any of the toolchain.

from z88dk.

A note regarding function renaming for zsdcc. sdcc will inline a handful of string functions:

#ifndef __SDCC_DISABLE_BUILTIN

#undef memcpy
#undef strcpy
#undef strncpy
#undef strchr
#undef memset

#define memcpy(dst, src, n) __builtin_memcpy(dst, src, n)
#define strcpy(dst, src) __builtin_strcpy(dst, src)
#define strncpy(dst, src, n) __builtin_strncpy(dst, src, n)
#define strchr(s, c) __builtin_strchr(s, c)
#define memset(dst, c, n) __builtin_memset(dst, c, n)

#endif

This replaces the macro magic we use for fastcall/callee linkage in favour of selecting sdcc's built-ins for these functions. In practice, sdcc's inlining of these functions are a big win in terms of speed.

Sometimes sdcc is unable to inline these functions and instead the compiler will insert a call to the c library's implementation. However, this insertion happens after the preprocessor has already run so we do not get callee/fastcall linkage selected as we would want.

Instead, this case is caught by copt in post-processing along with the other calls that sdcc makes to its support functions.

If we adopt naming as suggested in the last post, the case of built-ins must be kept in mind.

from z88dk.