divdi3: incomplete fix in db3d848e154b?

[Alexey Neyman]

Hi,

I was compiling glibc (2.25 + d40dbe722f004) for sh4-unknown-linux-gnu 
and the build failed due to rtld pulling abort.os again. This has been 
"fixed" in master in db3d848e154b - which made divdi3 built only for 
certain architectures. However, I think this just masks the real issue 
that GCC7 inserts a trap where it knows something gets divided by zero.

Here is a fragment of generated code for i686-unknown-linux:

objdump -dlr csu/divdi3.os:
/home/avn/work/ctng/crosstool-ng/.build/src/glibc-2.25/csu/../sysdeps/wordsize-32/divdi3.c:91
   d0:   85 db                   test   %ebx,%ebx
   d2:   75 0c                   jne    e0 <__udivmoddi4+0xe0>
   d4:   0f 0b                   ud2

divdi3.c:
90          if (d0 == 0)
91            d0 = 1 / d0;        /* Divide intentionally by zero.  */

Isn't the purpose of this intentional division to generate a SIGFPE, 
rather than SIGILL?

Shouldn't divdi3.c do something else here, e.g. raise(SIGFPE) or be 
compiled with -fno-sanitize=integer-divide-by-zero?

Regards,
Alexey.