https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91900
Bug ID: 91900
Summary: [10 regression] mipsisa64r6-*-* rejects lo clobber
Product: gcc
Version: 10.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: target
Assignee: unassigned at gcc dot gnu.org
Reporter: nsz at gcc dot gnu.org
Target Milestone: ---
mips64 syscall code in musl is like
#define __NR_getpid 5038
static inline long __syscall0(long n)
{
register long r7 __asm__("$7");
register long r2 __asm__("$2") = n;
__asm__ __volatile__ (
"syscall"
: "+&r"(r2), "=r"(r7)
:
: "$1", "$3", "$10", "$11", "$12", "$13", "$14", "$15", "$24", "$25", "hi",
"lo", "memory");
return r7 ? -r2 : r2;
}
int getpid()
{
return __syscall0(__NR_getpid);
}
because linux clobbers all sorts of registers.
this compiles with mips64-linux-musl-gcc and
up to gcc-9 with mipsisa64r6-linux-musl-gcc too,
but mipsisa64r6-* fails with trunk gcc
(gcc version 10.0.0 20190924):
t.c: In function '__syscall0':
t.c:7:2: error: the register 'lo' cannot be clobbered in 'asm' for the current
target
7 | __asm__ __volatile__ (
| ^~~~~~~
