https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69750
--- Comment #1 from dhowells at redhat dot com <dhowells at redhat dot com> --- Doing gdb ./gcc/cc1 and running it with: r -quiet foo.c -g -fexceptions -o /tmp/cc5gm5ki.s shows the failure as: Program received signal SIGSEGV, Segmentation fault. _IO_vfprintf_internal (s=s@entry=0x7ffffbfff4e0, format=format@entry=0xea2d7b "*%s%s%ld", ap=ap@entry=0x7ffffbfff608) at vfprintf.c:1311 1311 f = lead_str_end = __find_specmb ((const UCHAR_T *) format); Asking for a backtrace gives at least 6000 entries, starting like this: #0 _IO_vfprintf_internal (s=s@entry=0x7ffffbfff4e0, format=format@entry=0xea2d7b "*%s%s%ld", ap=ap@entry=0x7ffffbfff608) at vfprintf.c:1311 #1 0x00007ffff66e488b in __IO_vsprintf (string=0x7ffffbfff7b0 "\004", format=0xea2d7b "*%s%s%ld", args=args@entry=0x7ffffbfff608) at iovsprintf.c:42 #2 0x00007ffff66c7e57 in __sprintf (s=s@entry=0x7ffffbfff7b0 "\004", format=format@entry=0xea2d7b "*%s%s%ld") at sprintf.c:32 #3 0x0000000000b716f4 in force_const_mem (mode=mode@entry=SImode, x=x@entry=0x7fffea163e70) at ../../gcc-6.0.0-20160205/gcc/varasm.c:3732 #4 0x00000000006cdc43 in emit_move_insn (x=x@entry=0x7fffea163eb8, y=y@entry=0x7fffea163e70) at ../../gcc-6.0.0-20160205/gcc/expr.c:3559 #5 0x00000000006b3c70 in force_reg (mode=mode@entry=SImode, x=x@entry=0x7fffea163e70) at ../../gcc-6.0.0-20160205/gcc/explow.c:631 #6 0x00000000006b490e in force_reg (x=0x7fffea163e70, mode=SImode) at ../../gcc-6.0.0-20160205/gcc/explow.c:451 #7 memory_address_addr_space (mode=SImode, x=0x7fffea163e70, as=<optimized out>) at ../../gcc-6.0.0-20160205/gcc/explow.c:457 #8 0x00000000006a0775 in change_address_1 (memref=0x7fffea163ea0, mode=SImode, mode@entry=VOIDmode, addr=0x7fffea163e70, validate=validate@entry=1, inplace=<optimized out>) at ../../gcc-6.0.0-20160205/gcc/emit-rtl.c:2127 #9 0x00000000006a3880 in replace_equiv_address (memref=<optimized out>, addr=<optimized out>, inplace=inplace@entry=true) at ../../gcc-6.0.0-20160205/gcc/emit-rtl.c:2399 #10 0x00000000006b467a in validize_mem (ref=<optimized out>, ref@entry=0x7fffea163ea0) at ../../gcc-6.0.0-20160205/gcc/explow.c:495 at this point, #4-#10 repeat: #11 0x00000000006cdbbb in emit_move_insn (x=x@entry=0x7fffea163e58, y=0x7fffea163ea0, y@entry=0x7fffea163e10) at ../../gcc-6.0.0-20160205/gcc/expr.c:3582 #12 0x00000000006b3c70 in force_reg (mode=mode@entry=SImode, x=x@entry=0x7fffea163e10) at ../../gcc-6.0.0-20160205/gcc/explow.c:631 #13 0x00000000006b490e in force_reg (x=0x7fffea163e10, mode=SImode) at ../../gcc-6.0.0-20160205/gcc/explow.c:451 #14 memory_address_addr_space (mode=SImode, x=0x7fffea163e10, as=<optimized out>) at ../../gcc-6.0.0-20160205/gcc/explow.c:457 #15 0x00000000006a0775 in change_address_1 (memref=0x7fffea163e40, mode=SImode, mode@entry=VOIDmode, addr=0x7fffea163e10, validate=validate@entry=1, inplace=<optimized out>) at ../../gcc-6.0.0-20160205/gcc/emit-rtl.c:2127 #16 0x00000000006a3880 in replace_equiv_address (memref=<optimized out>, addr=<optimized out>, inplace=inplace@entry=true) at ../../gcc-6.0.0-20160205/gcc/emit-rtl.c:2399 and repeat: #17 0x00000000006b467a in validize_mem (ref=<optimized out>, ref@entry=0x7fffea163e40) at ../../gcc-6.0.0-20160205/gcc/explow.c:495 #18 0x00000000006cdbbb in emit_move_insn (x=x@entry=0x7fffea163df8, ...