https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101080
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |NEW
Keywords| |wrong-code
Last reconfirmed| |2021-06-16
Ever confirmed|0 |1
CC| |jamborm at gcc dot gnu.org
--- Comment #1 from Richard Biener <rguenth at gcc dot gnu.org> ---
Confirmed. Also happens with -O3 -fno-tree-vectorize which produces
Program received signal SIGSEGV, Segmentation fault.
0x00000000004003b7 in main ()
(gdb) disassemble
Dump of assembler code for function main:
0x00000000004003a0 <+0>: movzbl 0x200c95(%rip),%eax # 0x60103c
<d>
0x00000000004003a7 <+7>: cmp $0x14,%al
0x00000000004003a9 <+9>: je 0x4003da <main+58>
0x00000000004003ab <+11>: nopl 0x0(%rax,%rax,1)
0x00000000004003b0 <+16>: add $0x4,%eax
0x00000000004003b3 <+19>: cmp $0x14,%al
0x00000000004003b5 <+21>: jne 0x4003b0 <main+16>
=> 0x00000000004003b7 <+23>: andb $0xf8,0x186(%rip) # 0x400544 <c>
0x00000000004003be <+30>: movl $0x0,0x200c70(%rip) # 0x601038
<e>
0x00000000004003c8 <+40>: movq $0x0,0x200c5d(%rip) # 0x601030
<f>
0x00000000004003d3 <+51>: movb $0x14,0x200c62(%rip) # 0x60103c
<d>
0x00000000004003da <+58>: xor %eax,%eax
0x00000000004003dc <+60>: ret
simpler IL testcase (elide g) - note the inlining is critical.
struct a {
unsigned b : 3;
} const c;
char d;
int e;
long f;
static void g(const struct a h)
{
for (; d != 20; d = d + 4) {
int i = h.b;
e = h.b;
f = h.b || 0;
}
}
int main()
{
g(c);
}
so the issue is we store to 'c' which resides in .rodata - suspect this is
a dup of the pending SRA issue. -fno-tree-sra fixes it.
But it's a nice testcase.
