http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59311
--- Comment #3 from H.J. Lu <hjl.tools at gmail dot com> ---
(gdb) f 0
#0 dwarf2out_frame_debug (insn=0x7ffff5980ca8) at
/export/gnu/import/git/gcc/gcc/dwarf2cfi.c:2000
2000 fde->vdrap_reg = dwf_regno (n);
(gdb) p n
$2 = (rtx_def *) 0x7ffff597cd40
(gdb) call debug_rtx (n)
(reg:SI 177)
(gdb) call debug_rtx (insn)
(insn/f 202 254 2 2 (set (mem/c:SI (plus:SI (reg/f:SI 6 bp)
(const_int -48 [0xffffffffffffffd0])) [0 %sfp+-48 S4 A32])
(reg:SI 2 cx)) 86 {*movsi_internal}
(expr_list:REG_CFA_SET_VDRAP (reg:SI 177)
(nil)))
reg:SI 177 isn't a hard register and there is no DWARF register
for it.
