https://gcc.gnu.org/bugzilla/show_bug.cgi?id=77343
Bug ID: 77343
Summary: ICE in dwarf2out_frame_debug_expr, at dwarf2cfi.c:1596
Product: gcc
Version: 6.2.0
Status: UNCONFIRMED
Keywords: ice-on-valid-code
Severity: normal
Priority: P3
Component: debug
Assignee: unassigned at gcc dot gnu.org
Reporter: rguenth at gcc dot gnu.org
Target Milestone: ---
Host: x86_64-*-*
Reduced from some kernel crypto code.
static int
crypto_cbc_decrypt_inplace(int bsize)
{
unsigned char last_iv[bsize];
}
when compiled with -mno-sse -mpreferred-stack-boundary=3 -ffixed-rbp:
> gcc-6 -ffixed-rbp cbc.3.i -S -mno-sse -mpreferred-stack-boundary=3
cbc.3.i: In function 'crypto_cbc_decrypt_inplace':
cbc.3.i:5:1: internal compiler error: in dwarf2out_frame_debug_expr, at
dwarf2cfi.c:1596
}
^
0x9ccaff dwarf2out_frame_debug_expr
/space/rguenther/src/svn/trunk/gcc/dwarf2cfi.c:1594
0x9cdc39 dwarf2out_frame_debug
/space/rguenther/src/svn/trunk/gcc/dwarf2cfi.c:2089
0x9ce79f scan_insn_after
/space/rguenther/src/svn/trunk/gcc/dwarf2cfi.c:2415
0x9ced75 scan_trace
/space/rguenther/src/svn/trunk/gcc/dwarf2cfi.c:2572
0x9cee8c create_cfi_notes
/space/rguenther/src/svn/trunk/gcc/dwarf2cfi.c:2611
0x9cf9ad execute_dwarf2_frame
/space/rguenther/src/svn/trunk/gcc/dwarf2cfi.c:2974
The assert is
/* Saving a register in a register. */
gcc_assert (!fixed_regs [REGNO (dest)]
/* For the SPARC and its register window. */
|| (dwf_regno (src) == DWARF_FRAME_RETURN_COLUMN));
not sure why it is present. When removing it we generate the following code
which makes this wrong-code(?) because we use %rbp even though the user
specified it as fixed. OTOH docs for -ffixed- say "except perhaps as a stack
pointer, frame pointer or in some other fixed role" which means the assert
above is over-zealous?
crypto_cbc_decrypt_inplace:
.LFB0:
.cfi_startproc
leaq 8(%rsp), %r10
.cfi_def_cfa 10, 0
andq $-16, %rsp
pushq -8(%r10)
pushq %rbp
.cfi_escape 0x10,0x6,0x2,0x76,0
movq %rsp, %rbp
pushq %r10
.cfi_escape 0xf,0x3,0x76,0x78,0x6
subq $40, %rsp
movl %edi, -36(%rbp)
movq %rsp, %rax
movq %rax, %rcx
movl -36(%rbp), %eax
movslq %eax, %rdx
subq $1, %rdx
movq %rdx, -24(%rbp)
movslq %eax, %rdx
movq %rdx, %r10
movl $0, %r11d
movslq %eax, %rdx
movq %rdx, %r8
movl $0, %r9d
cltq
movl $8, %edx
subq $1, %rdx
addq %rdx, %rax
movl $8, %esi
movl $0, %edx
divq %rsi
imulq $8, %rax, %rax
subq %rax, %rsp
movq %rsp, %rax
addq $0, %rax
movq %rax, -32(%rbp)
movq %rcx, %rsp
nop
movq -8(%rbp), %r10
.cfi_def_cfa 10, 0
leave
leaq -8(%r10), %rsp
.cfi_def_cfa 7, 8
ret
.cfi_endproc
