gcc-bebbo: argc is always 0

[sparhawk]

I was wondering if this is a bug, or am I missing some library, because when I try to parse commandline arguments, they don't exist. "argc" is always 0.


I' using gcc from bebbo: https://github.com/bebbo/amiga-gcc

[Samurai_Crow]

What runtime library are you using? The default is IXEmul.library but libNix is preferred.

[sparhawk]

I'm using -lnix13.

[alkis]

There is no problem with argc.

This as args.c

#include <stdio.h>

int main(int argc, char *argv[])
{
  printf("Argc = %d\n", argc);
  for(int i = 0; i < argc; ++i)
    printf("arg(%d) = \"%s\"\n", i, argv[i]);
  return 0;
}

compiled with

m68k-amigaos-gcc -mcrt=nix13 -s -Os -o args args.c

works fine in (emulated) A500

[sparhawk]

Strange. My commandline looks like this.

m68k-amigaos-gcc  -D AMIGA_OS --save-temps -fverbose-asm -Wall -pedantic -mcrt=nix13 -fno-exceptions -fno-rtti -std=c++11 -O2 -mregparm -fno-rtti -O3 -DNDEBUG  -Wl,--enable-auto-import CMakeFiles/TestMemfill.dir/main.cpp.o  -o ../bin/TestMemfill.exe -Wl,--out-implib,../bin/libTestMemfill.dll.a -L/opt/amiga/utils/lib -lAmigaUtils -lAmigaGCCUtils

[alkis]

Originally Posted by sparhawk

Strange. My commandline looks like this.

m68k-amigaos-gcc  -D AMIGA_OS --save-temps -fverbose-asm -Wall -pedantic -mcrt=nix13 -fno-exceptions -fno-rtti -std=c++11 -O2 -mregparm -fno-rtti -O3 -DNDEBUG  -Wl,--enable-auto-import CMakeFiles/TestMemfill.dir/main.cpp.o  -o ../bin/TestMemfill.exe -Wl,--out-implib,../bin/libTestMemfill.dll.a -L/opt/amiga/utils/lib -lAmigaUtils -lAmigaGCCUtils

Can you provide a minimum compilable source code that exhibits the problem?

[sparhawk]

I compiled bebbos repo using regparm and I can see in monam that my main expects argc and argv in d0/a0. When I put __stdargs in front of main() then it works, because the startup code uses parameter passing on the stack, instead of registers.
Is this a bug or am I missing something when I compiled gcc? AFAIK it should use the same calling convention as compiled, right? or is there some header where the correct main() is declared?

[alkis]

It is working as designed. You should have the __stdargs in front of your main.

I tried the same on linux, has the same behavior.

alex[0]@omen 13$ cat >args.c
#include <stdio.h>

int main(int argc, char *argv[])
{
  printf("Argc = %d\n", argc);
  for(int i = 0; i < argc; ++i)
    printf("arg(%d) = \"%s\"\n", i, argv[i]);
  return 0;
}
alex[0]@omen 13$ gcc -o args args.c
alex[0]@omen 13$ ./args 1 2 3 4
Argc = 5
arg(0) = "./args"
arg(1) = "1"
arg(2) = "2"
arg(3) = "3"
arg(4) = "4"
alex[0]@omen 13$ gcc -mregparm=2 -o args args.c
cc1: warning: ‘-mregparm’ is ignored in 64-bit mode
alex[0]@omen 13$ gcc -mregparm=2 -m32 -o args args.c
alex[0]@omen 13$ ./args 1 2 3 4
Argc = -135120888

[sparhawk]

Thanks! I was a bit surprised, about that, as I would think that the compile should select the correct calling convention for main, regardless of how it is compiled.

OK. It's not as bad as I feared, as I know now how to get around it.