_Unwind_Resume() references in libgcc division functions

Sebastian Huber sebastian.huber@embedded-brains.de
Tue Jun 21 13:13:19 GMT 2022


I noticed that several division related routines provided by libgcc such 
as __divdi3, __moddi3 and __umoddi3 have references to _Unwind_Resume 
for the sparc-rtems target. For example:

	.file	"libgcc2.c"
! GNU C17 (GCC) version 13.0.0 20220621 (experimental) [master 
r13-1187-gab981aab92c] (sparc-rtems6)
!	compiled by GNU C version 12.1.1 20220517 [revision 
325d82b08696da17fb26bd2e1b6ba607649357fb], GMP version 6.1.0, MPFR 
version 3.1.4, MPC version 1.0.3, isl version isl-0.16.1-GMP

! GGC heuristics: --param ggc-min-expand=30 --param ggc-min-heapsize=4096
! options passed: -msoft-float -mcpu=leon3 -g -g -g -O0 -O2 -O0 
-fbuilding-libgcc -fno-stack-protector -fexceptions 
-fnon-call-exceptions -fvisibility=hidden

! /home/EB/sebastian_h/src/gcc/libgcc/libgcc2.c:1225:   w = __udivmoddi4 
(uu.ll, vv.ll, (UDWtype *) 0);
	.loc 1 1225 5
	std	%g2, [%fp-16]	! D.3900, w
! /home/EB/sebastian_h/src/gcc/libgcc/libgcc2.c:1226:   if (c)
	.loc 1 1226 6
	ld	[%fp-4], %g1	! c, tmp284
	cmp	%g1, 0	! tmp284,
	be	.LL25
	 nop		!
	b	.LL28
	 nop	!
	mov	%i0, %g1	!, tmp283
	mov	%g1, %o0	! D.3909,
	call	_Unwind_Resume, 0
	 nop	!,

Could someone please give me a hint, why the compiler generates this 
code? I was unable to figure this out by looking at the pre-processed 
code. I tried to reproduce it with a simple division by zero test case, 
but this didn't work:

unsigned f(unsigned i)
         return i / 0;

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