Re: [WIP v3] Introduce mescc.a for division algorithm and move the latter there.

[Danny Milosavljevic]

Hi Janneke,

On Fri, 29 May 2020 15:44:56 +0200
Jan Nieuwenhuizen <janneke@gnu.org> wrote:

> > (1) gcc-lib
> >
> > Failed tests:
> >  
> >>lib/tests/scaffold/7l-struct-any-size-array-simple.c

Char isn't signed on ARM gcc.  The C standard doesn't say one way or another 
either.

You can change behavior by "gcc -fsigned-char" or "gcc -funsigned-char" though.

See:
$ cat b.c
#include <stdio.h>

int main() {
        char x = -3;
        printf("%d\n", x);
        return 0;
}

$ gcc b.c # on armhf machine
$ ./a.out
253
$ gcc -fsigned-char b.c
$ ./a.out
-3

Also, the test has an array of packed structs.  Eeew.

struct foo13
{
  int a;
  int b;
  int c;
  char d;
} __attribute__ ((packed));

struct foo13 tab14[3];

Not sure what that is--but I have the sudden urge to take a shower :P

That one doesn't fail on mescc, probably because mescc doesn't pack the struct 
in the first place... which is the correct solution almost always anyway 
(except when hardware or file format expects packed struct--even then, C 
standard recommends to do the arithmetic yourself and not use structs).

> >>lib/tests/scaffold/7r-sign-extend.c  

That one doesn't fail on mescc ;)

Reason for failure: Char is unsigned on ARM gcc, and the test does this:

  {
    char c = -1;
    int i = c;
    if (i != -1)
      return 1; <---- reached
  }

Just no :P

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