https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70593
Bug ID: 70593
Summary: [6 Regression] Miscompilation of xen starting with
r226901
Product: gcc
Version: 6.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: middle-end
Assignee: unassigned at gcc dot gnu.org
Reporter: jakub at gcc dot gnu.org
Target Milestone: ---
__attribute__((noinline, noclone)) unsigned long
foo (unsigned long x, unsigned long y, unsigned z)
{
unsigned long a, b, c, d = z;
asm volatile ("xorl\t%k1, %k1\n\txorl\t%k2, %k2\n\txorl\t%k3,
%k3\n\tmovl\t$7, %k0"
: "=&c" (d), "=&D" (a), "=&S" (b), "=&r" (c) : "0" (d), "1"
(x), "2" (y), "3" (d) : "memory");
return d;
}
int
main ()
{
if (foo (1, 2, 3) != 7)
__builtin_abort ();
return 0;
}
is miscompiled on x86_64-linux at -O2 starting with r226901, -O2
-fno-tree-coalesce-vars works. The return value d is in %rcx at the end of the
inline asm, but with -O2 the copy of %rcx to %rax is lost.
