https://llvm.org/bugs/show_bug.cgi?id=26411
Bug ID: 26411
Summary: __attribute__((interrupt)) trashes MMX registers
Product: new-bugs
Version: trunk
Hardware: PC
OS: All
Status: NEW
Severity: normal
Priority: P
Component: new bugs
Assignee: [email protected]
Reporter: [email protected]
CC: [email protected], [email protected]
Classification: Unclassified
[hjl@gnu-6 interrupt-8]$ cat z.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 *frame)
{
x = (__m64) __builtin_ia32_packsswb ((__v4hi) x, (__v4hi) y);
}
[hjl@gnu-6 interrupt-8]$ make z.s
/export/build/gnu/llvm-clang-bootstrap/stage1/build-x86_64-linux/bin/clang -O2
-Wall -march=nehalem -S -o z.s z.i
[hjl@gnu-6 interrupt-8]$ cat z.s
.text
.file "z.i"
.globl fn1
.p2align 4, 0x90
.type fn1,@function
fn1: # @fn1
.cfi_startproc
# BB#0:
movq x(%rip), %mm0
packsswb y(%rip), %mm0
movq %mm0, x(%rip)
iretq
.Lfunc_end0:
.size fn1, .Lfunc_end0-fn1
.cfi_endproc
.ident "clang version 3.9.0 (http://llvm.org/git/clang.git
1f64ddbc4c5d1036b68ec896765a7535537ded85) (http://llvm.org/git/llvm.git
43b517fe4e0a181b1cf20f36fd9eb92f7b32946c)"
.section ".note.GNU-stack","",@progbits
[hjl@gnu-6 interrupt-8]$
Interrupt handler must preserve MMX and X87 states. It shouldn't be
allowed to use MMX nor x87 registers.
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