https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67552
--- Comment #4 from H.J. Lu <hjl.tools at gmail dot com> ---
MMX instructions should be disallowed in interrupt handler:
[hjl@gnu-6 interrupt-1]$ cat m.i
typedef short __v4hi __attribute__ ((__vector_size__ (8)));
typedef int __m64 __attribute__ ((__vector_size__ (8), __may_alias__));
extern __m64 y, x;
void
__attribute__((interrupt))
fn1 (void)
{
x = (__m64) __builtin_ia32_packsswb ((__v4hi) x, (__v4hi) y);
}
[hjl@gnu-6 interrupt-1]$ make m.s
/export/build/gnu/gcc-5/build-x86_64-linux/gcc/xgcc
-B/export/build/gnu/gcc-5/build-x86_64-linux/gcc/ -O2 -S -o m.s m.i
[hjl@gnu-6 interrupt-1]$ cat m.s
.file "m.i"
.section .text.unlikely,"ax",@progbits
.LCOLDB0:
.text
.LHOTB0:
.p2align 4,,15
.globl fn1
.type fn1, @function
fn1:
.LFB0:
.cfi_startproc
movq x(%rip), %mm0
addq $-128, %rsp
packsswb y(%rip), %mm0
movq %mm0, x(%rip)
ret
.cfi_endproc
.LFE0:
.size fn1, .-fn1
.section .text.unlikely
.LCOLDE0:
.text
.LHOTE0:
.ident "GCC: (GNU) 5.2.1 20150911"
.section .note.GNU-stack,"",@progbits
[hjl@gnu-6 interrupt-1]$
